Hot Water

By DIY Boat Owner

If you live and cook aboard for longer that the occasional weekend cruise, hot running water is more than a convenience.
The good news is that if your boat has a 110-volt shorepower system and cold water, you're already halfway to a hot-water system.
There are two completely different approaches to the problem: a storage-tank heater or a flow-through "demand" heater. The former is the most common type of system. It has a storage tank very similar to a household unit but with a smaller capacity. Heat is usually provided at dockside by a 1,500-watt 110-volt AC heating element and, while underway, by hot engine coolant recirculating through a heat exchanger in the tank.

Units are available from Atlantic Marine, Raritan, Seaward and others. Never install a household water heater which is not ignition protected and could spark and cause a fire.
Demand heaters that do not store water but heat it immediately before use are usually fired by propane, are less common on boats and are beyond the scope of a do-it-yourself article. Work with explosive propane and the handling of combustible gases should be left to a licensed gas fitter.
In a similar vein, if you are not familiar with the basic 110-volt wiring required to hook up your hot-water heating element, you should seek the assistance of someone who is experienced. At the very least, have your connections checked prior to plugging in the heater.
Before cutting or drilling anything when running piping, check on each side of the bulkhead or partition to ensure you don’t cut into structural stringers or tabbing that hold the bulkhead in place.
PLANNING THE SYSTEM
When planning the layout of the system, especially the tank location, try to arrange a close look at the same model boat already equipped with a factory-installed system   and copy it if that is practical. Or you can contact the builder (if they're still in business) for guidelines. A professional-looking "stock" installation will always raise the resale value of your boat. You do, however, have the freedom to install more deluxe fixtures should your budget allow it.
The tank will need to sit on a level surface so a solid 3/4-inch (19mm) plywood epoxy-painted shelf will need to be prepared and screwed or fiberglass tabbed into place. Once the tank is shoehorned into place (usually a tight fit in a cockpit locker or in the engine room) and fastened securely, run your cold water (in) and hot water (out) lines with hose.
For the "hot" side, good quality clear-braid PVC hose is pressure-rated at 150 degrees Fahrenheit and connects the traditional way with adapters and double clamps. (Make sure the clamps are tight, but not so tight they cut into the hose. If you see hose squishing through the cracks in the clamp, you've destroyed the hose.)
An even better choice is semi-flexible plastic pipe, which is more durable, less prone to kinks and usually has fittings that are less likely to leak and easier to assemble.
RUNNING THE LINES
Threading piping through the boat is time-consuming and fiddly work. Access is often difficult and you will probably have to drill many holes through bulkheads. Be very careful!
Before cutting or drilling anything, check on each side of the bulkhead or partition to ensure you don't cut into a tank, wiring or other piping, or structural stringers or tabbing that hold the bulkhead in place. Fasten the plumbing every few feet with cable clamps or wire ties and try to keep it out of the bilge to prevent contamination.
Avoid tight bends that can kink hose; instead, install 90-degree elbows. The tee connection to the cold-water system can be made anywhere downstream of the pressure pump and before the first fixture. Hot water heaters need a check valve, either at the water inlet to the tank or at the tee connection, so the hot water cannot flow back into the cold water. Make sure you have one. You may have to remove the sink to get access for your connections to the mixer or faucet. Provide for easy access to the tank, fittings and all connections for maintenance.
Any 110-volt wire used should be at least 14-gauge copper multi-strand boat cable and must be sized to the amperage and wattage of the heater; depending on the routing, you may need 12 or 10 gauge. Household single-strand cable is not safe in a boat because engine vibration and jarring from when the boat slams into waves fatigues the wire, leading to breaks and shorts and possibly fires. The hot (black) wire connects to one terminal of the element and the neutral (white) wire connects to the other. Ground the tank via the green or bare copper wire.

Assuming you have a 110-volt system   a breaker panel and hull inlet with circuit protection that was installed to nationally-recognized codes (NFPA)   connect the white to the common neutral buss and install the breaker into an empty slot in the panel connecting the hot (black) lead to the breaker and the breaker's other pole to the hot distribution buss. Never directly connect a water heater to a power cord plugged into an outlet on shore.
Don't do any wiring until you have unplugged and stowed your shorepower cord   a well-meaning soul just might plug it back in again at an awkward moment. Keep all 110-volt A/C wiring physically separate from your DC wiring. Make sure no neutral (white) wires connect to any ground within the boat   this is critical   and make sure your shorepower cord and main AC supply is properly grounded through the dockside power system. Now turn on the pump, fill the tank and turn on the power in that order to avoid heater element meltdown. Check for leaks. There will be a few.
Next, hook up your engine hot-water heat exchanger, but consult a mechanic or your local engine representative first. Some raw-water-cooled engines (early Yanmars for example) won't put out a steady supply of hot water; the temperature alternates between hot and cold as the thermostat opens and closes. Others, such as Atomic 4s, need a separate recirculating pump to help move the engine coolant through the heat exchanger.
When all is done, and you are sure the system works, take a hot shower. You will have earned it!

A version of this story ran previously in Mad Mariner's DIY Boat Owner magazine.

Storing the Dinghy

By Jan Mundy

One of the pleasures of boating is landing at a favorite anchorage, launching the dinghy then going touring, visiting other boats, water-skiing or diving, fishing or exploring ashore.
All dinghies, whether inflatable or hardshell, require secure storage. Towing isn't practical all of the time and downright risky in rough weather. Ditto for deck storage on most boats. Better quarters for the dinghy are davits, systems that hold the dinghy, keep it clean and deter theft.
When accurately configured for your boat, properly sized to the dinghy, aptly installed and correctly set up, davits should function trouble-free. Most problems occur from overloading, faulty installation or an unbridled dinghy – if not secured so absolutely motionless, a swaying 200 pound dinghy can be a lethal load.
Because of the myriad boat styles and mounting arrangements, davit systems are built on a semi-custom basis and typically purchased manufacturer direct. This way, the buyer presumably gets expert advice in mixing and matching components to obtain the best configuration for their boat.

Before davit selection can begin, however, you need to do some planning: select the dinghy, decide where it will be mounted, and then determine the overall lifting weight.
DINGHY SELECTION
Before purchasing a davit system, you should first choose a dinghy and decide where best to store it. Saltwater cruisers may need a more robust dinghy than inland boaters, one that handles seas without drenching the crew or swamping. A good rule of thumb is to have the dinghy's load capacity twice that of its weight. For example, a dinghy weighing 200 pounds should be able to safely load 400 pounds.
Another consideration is the potential to change a boat's handling characteristics by adding a heavy mass concentrated in a small area. A typical 10-foot dinghy, with a 15 horsepower motor, weighs anywhere from 250 to 280 pounds in actual weight. Transom mounting a dinghy with a 6-horsepower engine in davits on a 32-footer likely will have no effect. Double the weight by carrying a personal watercraft (PWC) on the same boat and you're sure to alter the characteristics.
Examine your boat's transom (or deck) and determine the amount of usable space without interference from engine vents, ladder, platform, tanks and other items. Most stern-mounted davits look best when they are mounted perpendicular to stanchions (rails). Measure the distance apart for mounting of the davit arms. As a rule, the reach of the arms for stern davits is half the beam of the dinghy, except on boats with canoe sterns, which generally require a greater reach.
To help configure the best system for your boat, some manufacturers supply full-size paper templates at no-charge, to be cut out, mounted onto cardboard and placed onboard.
Many of the answers to storage questions lie in how much your tender weighs.
Now estimate the location of the dinghy pick-up points. You'll need to mate these points to the davit spacing, because many systems allow for a misalignment of only a few inches. The next step is to marry the dinghy to a davit system properly sized to your boat.
PRODUCTS AND OPTIONS
There are five basic systems to hoist a dinghy: clip-on, where the dinghy rests on end on the swim platform; rail mounts, both fixed and rotating, which fasten to stanchions and the dinghy hangs over the deck or stern; traditional bolts to the deck or transom, so the dinghy hangs over the stern; rotating mounts on foredeck, bridge deck or swim platform; and professionally installed, hydraulic-powered elevators that mount on a swim platform to lift large dinghies or PWC of 1,000 pounds or more. There are also newer, more exotic options, but we'll stick to the basics.
Clip-on davits, also called Weaver davits, are an economical choice for powerboats in sheltered waters with small inflatables and outboards up to 10 horsepower, but the motor must be removed before hoisting. If you want to leave the motor on, you'll need a rail, traditional or rotating system. Of these solutions, rail mounts are the least expensive and most popular, especially for sailboats.
Easily installed in a couple hours, fittings fasten to the rail and universal bases mount to the deck or transom. If your dinghy is heavier than a rail-mount davit system can safely carry, you'll need a traditional or rotating system. Designed for heavier dinghy-engine packages, deck- or transom-mounted traditional davit systems come with fixed or adjustable riser arms in lengths of 10 to 40 inches, depending on the boat's requirements. Heavy dinghies may require optional support kits mounted on the transom or swim platform.
Rotating davits lift, rotate, then put the dinghy onto the foredeck, bridge deck or a wide swim platform. If the deck can support the load, these systems can be flush mounted, rather than placing a compression post through the deck to the keel. Manually-operated rotating systems can lift about 180 pounds onto a swim platform, and 150 pounds up on the foredeck. The higher you lift the more difficult hoisting becomes. Optional electric winches simplify this task, but mechanical hand winches with a 25:1 purchase, which means 25 cranks for every 1 inch of lift, aren't practical to manually hoist a dinghy six feet or higher. Dinghies with large motors (30 horsepower or more) often combine a rotating davit on the transom with a cradle mounted on the swim platform.
GLEN JUSTICEDavits can be a single crane or a pair of lifts, depending on your needs.
Swim platform lifts have become popular on large yachts to lift heavy dinghies or PWC. Most are hydraulic powered and not easily owner installed. Prices for davit systems increase incrementally with the lifting load – the heavier the dinghy, the more expensive the system. Installation, if done professionally, adds to the price tag. And there also costs you may not anticipate. Many published prices do not include complete systems. Tie-downs, ratcheted straps, lifting slings, stabilizing bars, transom strut supports and manual or 12-volt winches are some such additional equipment. Boats with weak rails or decks that cannot support the extra weight sometimes require support kits.
Where the lift is higher than six feet, you should consider a power winch system–and that too can add to the cost. One of the most popular options is a tackle upgrade with purchases ranging from 2:1 to 8:1. With a 4:1 block and tackle you can comfortably hoist an 80-pound dinghy. Add a 10 horsepower outboard and you'll likely need a 6:1 tackle.
Davits are generally fabricated of stainless-steel pipe, bent to shape and welded, or cast aluminum and anodized. Bent pipe davits have a high-gloss finish compared to less attractive, satin-coated cast units, but require frequent cleaning to deter corrosion. Because welding changes the molecular structure of the stainless steel, look for small welds, usually formed by TIG welding, compared to the hotter MIG welding method that forms large welds that may corrode. The wall thickness of the tubing also varies: .083 tube is more expensive than .065, but has greater weight carrying limits.
CALCULATING LOADS
Bigger is better when it comes to buying a davit system. It should be able to take the strain of a 600-mile passage, support a rainwater-filled dinghy and in rough weather ensure the dinghy won't break loose and hole the transom.
The strength of a davit system is a function of dinghy weight and boat speed. Davits are rated by breaking load, lifting capacity, test load or safe working load (SWL), which is the preferred rating as it measures the raw lift-and-hold capacity of one davit arm. The faster the boat, the greater the pounding forces. When comparing an express cruiser and trawler with identical dinghies, for example, davit loading is substantially higher on the cruiser.
To determine the SWL, multiply the total load (dinghy plus gear and motor) by 75 percent, then add a 15 percent safety factor (that allows for a water-filled dinghy). Consider this example for stern-mount davits: a 10-foot dinghy and 10 horsepower motor with a total weight of 150 pounds times .75 equals 112.5 pounds. Multiply that by two (there are two davits) for a davit system carrying capacity of 225 pounds. Factor in the 15-percent safety margin, and the SWL is 180 pouns for the pair of davits. For a single crane davit, the SWL equals the total dinghy weight plus 15 percent.
FORMULAA PWC can weigh substantially more than an average inflatable tender.
With dinghy selection and placement completed, you'll need to provide the davit manufacturer with boat year and model, packaged weight, selected davit type, mounting distance between davit arms (if it is a dual arm system), davit arm height and reach plus desired options. Many builders have a database of designs, so they know the boat's basic layout, but customization and add-ons can alter the mounting.
INSTALLATION GUIDE
Since davits put tremendous loads on the hull (or deck), few boatbuilders recommend installing them, especially on the rail or transom. Lifting a 100-pound package, for example, loads on the mounting base can be as high as 500 pounds with the boat stationary.
As a rule, fiberglass boats built before 1992 often have stronger transoms than newer boats, particularly sailboats with sloped transoms. That is an area where builders have cut thickness to save weight. Some boats require transom or deck reinforcing, as well as optional support kits. Since rail davit systems are limited by the strength of the rail, boats may require reinforcing and optional cable or strut support kits to reduce the load. Teak railings almost always require a complex rail-support structure.
Large loads may require adding extra layers of fiberglass under mounting brackets, or rail bases for rail davits, together with oversized backing plates at least the dimension of the davit base (and preferably as large as space allows). Because all boats and mounts are different, refer to the installation instructions supplied with the davit. These “manuals” range from excellent to poor, and some manufacturers offer a toll-free helpline as back-up. Depending on your mechanical ability, installation of a simple rail system may take only a few hours. For more complex systems, the job may take 40 hours or more. Power davits are more complicated, especially the wiring, and often require professional installation.

This story was previously published in Mad Mariner's DIY Boat Owner.

Ventilation

By Susan Canfield

When moist warm air is cooled, it drops its moisture. Outdoors, this moisture is called rain. Inside a boat, the moisture that collects on hull and cabin surfaces is called condensation or sweat. However, when condensation gets so heavy it begins to drip (typically above your bunk), you can call that “rain,” too.
The solution would appear to be simple. Either you keep the air in your boat's cabin from becoming moist or you keep the moist cabin air from being cooled. But the devil is in the details.
Just consider how air inside a boat becomes moist or humid. First, there's ambient humidity outside the boat, which can vary from say 30 percent to 100 percent. Then there's the moisture produced when cooking or showering. Unvented (no chimney) fuel-burning appliances, such as galley stoves and cabin heaters, can put a gallon or more of moisture into the air for every gallon of fuel they burn. There may also be standing water in the bilge. And, of course, there's our own breathing.
High humidity and condensation – in the absence adequate ventilation – will damage electronics and cause fabrics to deteriorate, metal to corrode, paint to peel and wood to rot. Fortunately, humidity belowdecks can be minimized by managing ventilation in a number of ways – most of which are cost efficient. The key is to have a strategy.

BATTLING HUMIDITY
One of the best ways to battle humidity belowdecks is to keep the bilges dry – and I mean completely dry! If your boat's bilge pumps don't discharge all the water, use a bucket and sponge or a Shop Vac to remove what's left behind. After doing this for a few weeks, you will have a much better idea just how much water is leaking in, and perhaps be motivated to track down its source.
Then you can eliminate the leaks by rebedding deck hardware and thru-hulls, recaulking ports and windows or whatever else may be required. Your reward will be a dry, sweet-smelling boat, which is no small achievement.
You can also use passive and active (mechanical or powered) ventilation as needed to bring in fresh air and to exhaust stale air. Proper ventilation is essential in hot weather to moderate cabin temperatures and, in cold weather, to circulate heat throughout the boat.
Effective ventilation requires at least two openings to the outside: an intake (add to) and an exhaust (remove). In the absence of either, you'll never get proper airflow. Ideally, the intake should be at one end of the boat and the exhaust at the other.
Suggested placement of passive and active vents: (top) Underway, even in foul weather, clamshell vents circulate air through the engine compartment while active intake and exhaust solar vents move air throughout the cabin. (bottom) Passive cowl and solar vents move air throughout the entire cabin. Both layouts benefit from opening deck hatches and interior fans.
Generally speaking, if a hatch is positioned so the airflow outside the boat is deflected downward, it will bring air inside (intake). If positioned to deflect the airflow outside the boat upward, the hatch will create a partial vacuum and air will be sucked from the boat (exhaust). Opening ports, windows and doors function as intakes or exhausts, depending on their location relative to the airflow outside the boat. Cowl vents, which can be turned to face in any direction, can also serve as intakes or exhausts as needed.
PROPER VENTILATION
My 37-foot sailboat was designed for offshore use. It has three hatches (including a large butterfly hatch and louvered companionway doors), 11 opening ports and four Dorade vents. Consequently, there are many ventilation options available. I lived aboard comfortably, winter and summer, for more than 10 years.
In my work as a marine surveyor, however, I have seen many boats that have little or no provision for passive or active ventilation. When hatches, ports, windows and doors are closed, there is no air movement absent an air conditioning (or heating) system.
Fortunately, there are a number of options for improving a boat's ventilation. The trick is to use your boat's hatches, ports, windows and vents to provide adequate ventilation in fair weather and foul. There are no set rules governing how many vents you should have and where they should be located. A boat's natural ventilation can travel in any direction, fore and aft, port or starboard.
Before you buy and install vents – let alone hatches or ports – experiment with what's already available on your boat. When underway, at anchor and in port, adjust your hatches, ports and vents to optimize ventilation. Use a candle or incense to help you see air movement and locate dead spots. With experience, you'll find out what works best and where ventilation needs to be improved (and if you use incense, you're also likely to meet some interesting folks from neighboring boats). You can then address those problem areas with new additions.
UPGRADING YOUR VENTILATION
There are many options to alter the airflow on your boat. For example, in heavy seas or rain, hatches, ports and windows are apt to be closed. At these times, however, passive cowl vents can be effective, particularly when mounted on top of a Dorade box. Typically made of fiberglass or wood, a Dorade box covers a duct into the cabin, which is offset from the ventilator; the box has holes so that any water that enters can drain out.
Other types of passive vents, such as mushroom vents or clamshells, are less effective than cowls for cabin ventilation, but they work well in other applications. A mushroom vent, operable from inside the boat, can also be used to close off the air duct inside a Dorade box in heavy weather. Mushroom vents can be installed vertically too, on the side of a trunk cabin or over an exhaust fan duct from the galley or head. I use a low-profile mushroom vent as a deck cap for my boat's cabin heater flue pipe. In heavy weather, it can be closed to keep water from entering. Clamshell vents are best used where water intake is unlikely; for example, where the vent opening faces downward or away from the expected airflow.
Taller and wider is best when is comes to cowl vents for optimum airflow. A cowl vent with an opening that is 4 inches in diameter will allow roughly twice the airflow of a 3-inch vent of similar design.The airflow generated by passive vents is limited by the amount of air rushing over them. Powered vents, which operate day and night in all kinds of weather, provide a strong alternative. When there's little air moving over the deck, a powered vent provides airflow. These vents may be powered, either alone or in combination, by solar cells, an integral rechargeable Nicad battery, and/or 12-volt ship's power. They can be set to function as an intake or exhaust vent as needed.
Solar vents are a godsend for boats that are left unattended for even a few days. A solar-powered fan operates without any drain on the battery, provided there is sunlight. At night, when there is a slight breeze, it acts as a mushroom ventilator to exhaust or intake air. Combination solar vents provide 24-hour ventilation. Sunlight, when available, powers either an intake or exhaust fan and, when overcast and at nighttime, the fan runs off an internal battery.
When using a powered vent, you'll find that some are quieter than others. Consequently, it may be better to install a powered vent in your boat's head than directly above the V-berth. The fact that powered vents can fail (most often electrically) should be considered when upgrading your boat's ventilation system. If you spend many nights onboard, it's best to carry a spare.
Marine stores sell clamshell, cowl, mushroom and solar vents in styles to fit any boat. Vents can be installed in a hatch or through the deck, cabin top or sides. Before cutting holes in your deck make certain you won't accidentally be cutting through wiring or structural supports. Measure twice, cut once. A saber saw can be used, but a hole cutter of the proper size will give a more accurate cut. Be sure to seal any exposed deck core against water intrusion before installing the new vent and use an appropriate sealant such as 3M 4200 under the vent flange.
ADDITIONAL CONCERNS
There are many places on a boat that require ventilation, and not all are obvious. For example, storage lockers and bilges often require attention. Solid locker doors should be louvered or have cane inserts, grilles or decorative cutouts that allow air to move. If the locker doors on your boat are not ventilated, they can be easily modified or replaced. Cutouts, with screens or grilles if appropriate, can also be used in the backs or bottoms of drawers and lockers to provide additional ventilation.
How a Dorade vent works: baffles prevent any water from entering the interior and water exits via drain holes while air is funneled below.Condensation that collects on locker floors and under mattresses can be a particularly annoying problem. Here too there are several solutions. Dri-Deck self-draining ventilated vinyl panels are readily cut and custom fit to any locker or bunk. These interlocking “waffle” panels facilitate air circulation and the evaporation of moisture. I've used them successfully on locker floors for many years.
Ventair, a ½-inch thick, three-dimensional nylon mesh with polyester cover, can also be used under mattresses. It's lighter and easier to move about (when accessing storage lockers under berths) than Dri-Dek, and it provides additional cushioning.
Cabin fans, including hard wired 12-volt fixed or oscillating fans and battery-powered portable fans, can be used to augment a boat's ventilation system and to increase the effectiveness of air conditioning and heating systems. I installed a 12-volt exhaust fan in the head and one above the vented propane heater. Later, I used a windscoop on my boat's double-hinged forward hatch when anchoring.
Shielding your boat's cabin from a hot summer's sun with a well-fitting awning can also keep temperatures several degrees cooler below deck. When I ran my boat's air conditioning on hot, muggy days in Maryland, I appreciated the cool air, but disliked the noise and sense of being “canned.” With a couple of simple awnings (no battens, no frame), I didn't need air-conditioning during my six years in southern California and Hawaii.
As you work to improve ventilation onboard, don't forget that you may want to adjust airflow in late fall, winter or early spring. Most of the ventilation gear available in marine stores is intended for summer use, so you may need to get creative. When I lived aboard during winters in Maryland, I fabricated sliding acrylic panels to close off the louvered portion of the anchor locker and companionway doors. I adjusted the airflow from Dorade vents using acrylic discs (since the discs were transparent, I left them in place throughout the year).
Solar vent mounted on hatch provides intake air to aft cabin, resulting in a sweet smelling boat.ADDED INSULATION
Insulation is another concern. Without adequate insulation, the temperature inside a fiberglass or metal boat will quickly respond to the temperature outside. When it's hot outside, it will get hotter inside. And, when the temperature outside falls below the temperature inside, the hull, cabin and any metal-framed hatches or portholes will sweat. Wood is a better insulator than fiberglass or metal. Consequently, wood boats and wood-framed hatches have fewer condensation problems. Fortunately, the hatches on my boat are all framed with wood. I do get condensation on the cast bronze opening ports, but there are teak rails underneath that will catch and hold drips until they evaporate or are sponged away.
Cored (balsa or foam) fiberglass construction, typically used in fiberglass decks and some hulls, has both thermal and acoustic insulating qualities. If your boat's hull and deck are cored, you may find you do not need additional insulation. However, if the hull is solid fiberglass and you use your boat in cold waters or cold weather, you'll very likely want to install insulation. There many different insulating materials to choose from, so do some research and pick what will work best for your boat, geographic location, and the type of boating you do.
Whatever solutions you embrace, the bottom line is that, for a relatively small amount of money, you can make a dramatic difference in the comfort of your boat. Vents start at about $25 and run to a few hundred dollars, and can be installed yourself. Using a system of both intake and exhaust, passive and active vents, you can achieve a comfortable level of cross-ventilation that will keep mold, mildew and corrosion at bay and help regulate the temperature in the cabin. Just imagine having no more cooking odors, musty air or mildew. Proper ventilation will help to keep you, your crew and your boat happy and healthy.

Susan Canfield is a marine surveyor in Annapolis, Maryland. A version of this story was previously published in DIY Boat Owner magazine.

Replacing Keel Bolts

By Nick Bailey

Other than running aground, will you ever need to replace a keel bolt? If you keep your boat in fresh water, you aren't likely to have any problems for a very long time. Saltwater boats are another matter.
Consider these examples from Bristol Marine's service files: a 12-year-old racer-cruiser from a top-rated manufacturer was hauled out for some minor keel fairing. The owner also requested, as part of routine maintenance, that the keel bolts be tightened. Fifteen minutes into the job the technician returned and unceremoniously dropped a fractured 1-inch diameter stainless steel stud on my desk. Under very gentle torque, the bolt had snapped off deep inside the hull. Quick inspection confirmed that only 10 percent of the fracture face was freshly broken metal. The other 90 percent was badly corroded and had been for some time. A phone call to the owner confirmed that the boat had spent most of its life in saltwater.

On another occasion, a 15-year-old trailer boat was in for to have the fractured vermiculite and resin filler in the keel sump replaced. Upon removing the old filler to expose the bolts, we discovered some of the supposedly stainless bolts, buried in the cracked and soggy filler, were partly cut through due to corrosion. The exposed portion still looked nice and shiny. The boat had recently arrived from a saltwater location.
DAVID AIKENIntegral studs cast into keel.What happened here? In both examples, a process known as crevice corrosion destroyed the stainless-steel keel bolts.
WHAT LURKS UNSEEN
What makes crevice corrosion particularly nasty is that it only occurs in hidden and inaccessible locations, typically where keel bolts are buried in the hull. Small amounts of saltwater seep into contact with the bolts, stagnate and become de-oxygenated. Trouble begins when metal bolts are not in contact with oxygen. Stainless steel stays shiny and “stainless” under normal circumstances because it contains chromium, which forms a tough protective oxide when exposed to air and well-oxygenated water. Remove oxygen and the protective oxide coating breaks down, exposing metal to the water.
Saltwater provides the electrolyte required to set up a miniature galvanic cell, either on the surface, causing pitting corrosion, or inside a microscopic crack or crevice, causing the dreaded crevice corrosion. As long as stainless steel remains wet or even damp, corrosion proceeds unchecked, eating away at the metal. Crevice corrosion is surprisingly common in older salt-water boats and tends to be worse in tropical waters, due to lower oxygen content, higher salinity and the greater reactivity that warm temperatures provide.
DAVID AIKENEasy access, windows cast or cut into keel and filled with fairng putty have nuts and washers at bottom end.IDENTIFYING PROBLEMS
Most keel fastening systems are designed with a conservative safety factor and you can get away with one broken bolt. Real trouble begins when the next bolt goes. Various famous ocean racers, no doubt designed a little closer to the safety limit than your average family cruiser, have publicly demonstrated sailing without a keel. I don't recommend it.
There is no way to positively identify bolt condition without either removing the keel or the individual bolts. A broken or badly weakened bolt always becomes obvious when retorquing. It pops loose or turns indefinitely without tightening. Check with the manufacturer or your local yard to confirm the recommended maximum torque, but keep in mind that any 7/8 inches or larger diameter bolt requires tremendous leverage to the point where it's exceedingly difficult to over-torque.
DAVID AIKENHoles drilled and tapped into keep for threaded bolts have nuts and oversize washers or backing plates (preferred) on the top end.Another place to watch is the keel-hull joint. Anything much larger than a hairline crack here can be a sign of trouble, or at least may indicate it is time to tighten the bolts. This is best checked while the boat hangs in the slings. Once the boat is cradled and hull weight rests on the keel, any cracks tend to close up again. These signs may identify a broken bolt, but the only method to directly confirm if corrosion has begun an attack on the bolts is to expose them.
REPAIR STRATEGIES
Bolt configuration and ballast type largely dictate how to fix bolts that are severed or deeply pitted by corrosion. Keels with integral studs (Figure 1) are the worst case and the most common keel fastening method. The only practical option is to drop the keel (see sidebar) and, if there is enough room in the keel sump, install a supplementary, or sister, bolt.
This is done in one of two ways. Using an oxyacetylene torch, cut a window in the keel to access a nut (similar to Figure 2), then drill a hole down from above for a threaded rod or bolt. This method works best on lead keels. Alternatively, you can drill and tap the keel for a new sister fastener. This works best on cast iron. It may be possible to salvage the stud by threading on a heavy sleeve to bridge the damaged area and reinforce the bolt. This often requires excavating around the stud at the top of the keel to expose enough good threads to give any hope of success. It may also present difficulties refitting the keel due to the larger hole required in the hull. Most professional yards would do this sort of repair only on a “no guarantees” basis, as the sleeve will not be as strong as the original bolt.
DAVID AIKENExternal flange recessed or faired into hull has flat head bolts with nuts and oversize washers or backing plates on top.If you are faced with drilling or tapping large diameter holes, you will need to rent the appropriate power tools. However, the keel may need to be cradled and transported to a machine shop capable of handling large scale boring and cutting. Neither lead nor cast iron are easy materials to work with: lead jams and binds tools, cast iron is very hard and brittle.
Keel bolt configurations as shown in Figure 2, 3 and 4 can theoretically be removed, inspected and replaced. Because this is done one at a time, it may be practical to do this without dropping the keel. Haul out and cradling are still recommended to minimize the chance of disturbing the keel-hull bond. Aggressively caulk new bolts with a polyurethane or polysulphide sealant upon reinstallation. Boats with keel windows (Figure 2) or external flanges (Figure 4) have the bolt end hidden by fairing filler and may require lots of grinding and chiseling to expose the end. Broken bolts are more difficult to extract but can be knocked out of the external flange with a driving pin or, in the case of the window keel, driven down then cut off one piece at a time with a hacksaw (are we having fun yet?) An extractor tool designed for broken studs, called an Easyout, may also work with smaller bolts.
DAVID AIKENFull keel with external ballast converts to internal by adding a fiberglass laminate overlay.A broken tapped bolt (Figure 3) is very difficult to remove, particularly in cast-iron keels. The bolt is likely seized into place by corrosion. You may have to drill it out and retap the hole. I envision some difficulty getting the drill press down the companionway, so this one may also require keel removal and machine shop work as in keels with integral studs (Figure 1). For fiberglass boats with low-profile, full-keel configurations (Figure 5), it doesn't matter how the keel is fastened, because the repair approach is completely different. It may be more practical to laminate several layers of fiberglass to encase the keel and bond it to what becomes, in essence, a new part of the hull. This converts the boat from external ballast to internal. Many traditional full-keel glass boats are built this way and neatly sidestep the whole keel bolt corrosion issue.
Laminate thickness of the new keel should match the original hull thickness and overlap at least a foot or two onto the existing hull. As is normal practice, make sure the hull surface receiving the overlapping laminates is ground to bare glass and is clean and dry. If you are unfamiliar with glass lay up procedures, hire a professional.

A version of this story appeared in DIY Boat Owner magazine.

Dropping and Refitting a Keel

By

 Here are some steps to consider when dropping a keel for repairs.
1. Haul out and cradle. Put a jack under the keel to ease it down later or else use screw jacks on the cradle pads to raise the boat. For boats longer than 27 feet, or when the cradle is unsuitable, book a Travelift or crane. You may need to devise a way to separate the keel and hull.
2. Rent or borrow tools. You'll need extra deep sockets, a heavy drive bar, an extra-long lever arm (a pipe will do) and a long extension to reach into the bilge. You may also need a variety of wedges and a sledge hammer, plus glass tools for grinding, filling, fairing, etc. Professional yards rarely lend tools.
3. Undo keel nuts. Use a thread lubricant to help prevent stainless-on-stainless galling (binding and seizing).
4. Expose the joint. If needed, grind away fillers or fiberglass to expose the keel-hull joint.
5. Lifting. Lift the boat (or drop the keel) so that the full weight of the keel is suspended by 1/4-inch or so, then take a break. If the keel doesn't drop on its own (most won't), carefully drive wedges in between the keel and the hull at the joint. Lift the keel or lower the hull and repeat until 5cm to 7.6cm (2" to 3") of bolts are exposed.
6. Assess. Inspect bolts carefully to assess any corrosion damage.
7. Remove. To remove the keel, install braces to support the keel in an upright position. Lift the boat, or lower the keel the rest of the way.
8. Repair. Proceed with the bolt repair or replacement as required.
9. Clean. Clean mating surfaces on keel and hull with a mini grinder.
10. Start re-attachment. Reposition keel under hull and mate bolts to holes in hull.
11. Apply sealant. Apply thick bead of sealant around each bolt and hole only – don't cover mating surfaces with sealant as its flexibility makes the keel wiggle too much.
12. Apply adheasive. Mix up epoxy resin thickened with cabosil and chopped fiber to a thick paste. Apply liberally to top of keel.
13. Re-attach. Immediately join keel and hull together and torque into place using a staggered tightening pattern. Recradle if needed.
14. Clean again. Before epoxy fully cures, remove excess that has squeezed out. Make sure air temps are warm enough for epoxy to cure, otherwise set up heat lamps.
15. Finish work. Fill and fair the repair area, repaint and launch. Check for leaks. If it leaks, see Step 1 (we're not kidding). If not, go sailing in heavy air. Check again for leaks.

Fix Leaking Portholes

By Nick Bailey

Notwithstanding the old joke about the boat being a hole in the water into which money is poured, we all know any boat with a cabin is just a floating conveyance designed to be wet on the outside and dry on the inside. It's the "dry on the inside" part that's hard to achieve consistently. One common leak source is the cabin window, or "fixed port," if you prefer.
Boat builders have devised many approaches to fastening and sealing windows but the outcome generally falls into two categories: the window lens is either mounted or retained by a frame or is fastened without a frame. In the case of the frameless window, the lens attaches directly to the boat with adhesive, mechanical fasteners or a combination of the two.
To repair leaky windows, it's important to understand the characteristics and most common failure modes of different window styles.

THE 'FRANKENSTEIN' WINDOW
It wasn't long after fiberglass became the material of choice for production boat building that acrylic (Plexiglas) or polycarbonate (Lexan) began to replace glass as the predominant material for boat windows. These plastics are workable with standard woodworking tools and, unlike glass, they are flexible enough to conform to the curved surfaces of a typical cabin trunk. A lot of the early plastic windows were off-the-shelf fixed ports with aluminum frames. These were only available in stock sizes so many boat builders, looking for more distinctive styling, began to forego the frame altogether and simply attached the plastic window lens directly to the cabin.
The first of the frameless windows mounted with mechanical fasteners was the Mark I or “Frankenstein” window. The window lens, usually a slab of acrylic 0.25-inch to 0.5-inch (6mm to 12mm) thick was mechanically fastened with screws or bolts over a gasket or bead of sealant laid between the lens and the boat structure. This simple installation was popular on boats built in the late '70s and early '80s but fell out of favor as maintenance problems persisted.
NICK BAILEYThe classic mechanically fastened "Frankenstein" window.
The lens color of choice was usually a dark tint, which absorbs sunlight, heats up and then expands, pushing hard against the fasteners. This causes a variety of problems: cracks originating at the fastener holes would quickly migrate across the lens; fasteners work loose; the sealant (many of which don't stick that well to plastic) loses its grip on the lens and the leaks commenced. A Band-Aid solution was to drill the fastener holes over-sized to allow room for the lens to expand. This reduced lens cracking but the amount of thermal movement, especially with the long narrow windows popular on sailboats, would eventually break the seal. Unfortunately, this style of window is always prone to leaks and is a good candidate for re-engineering the installation with the addition of an external frame. Nonetheless, good repair technique can maximize the leak-free service interval.
If the decision is made not to upgrade the window installation with a frame, this is just a reseal job. The fasteners are removed and, starting at the location of the leak, the lens is gently pried loose by slipping a putty knife between the lens and cabin trunk. Clean all the old sealant off both mating surfaces. Carefully check the lens for cracks. If cracked, replacement of the lens is mandatory. This is also a good time to replace a weathered or crazed lens for cosmetic reasons. Use the old lens as a template, trace the shape of the new lens onto a sheet of new plastic and cut out with a bandsaw or jigsaw. In many cases, the lens also needs a bevel or cove cut into an edge of the lens with a router or belt sander. Edges also usually need sanding with 120 grit paper to achieve a smooth finish. When a shiny gloss is required at the cut edge, this is quickly achieved by kissing the edge with the flame of a torch. Next, the fastener holes are drilled in the lens and it is at this point some minor engineering improvements can be made.
Drill fastener holes oversize as needed in the new lens. For example, if the original holes were drilled 5/32-inch (3.9mm) for a 1/8-inch (3mm) fastener, the new hole is enlarged to 1/4-inch (6mm). The limiting factor is the size of the washer used on the outside of the window. It should bridge the hole. Flathead fasteners with cup washers have the lowest profile and hold sealant best. Another technical upgrade is to reseal the window with an ultra-flexible professional glazer's silicone such as Dow Corning 795 or equivalent. These silicone sealants have the ability to stretch or compress 50 percent so they are flexible enough to maintain a seal despite the thermal movement of the lens.
NICK BAILEYThe fastener-free frameless window.
Now the new window is dry fitted. From inside the cabin, the outline of the opening in the cabin trunk is traced onto the protective paper on the inside face of the lens. The lens is lifted out and the protective mask is carefully cut and removed to expose the outer bonding ring of the lens. The exposed area is sanded thoroughly with 80 grit to ensure good sealant adhesion. To prepare for caulking, masking tape is applied to the cabin trunk about 3/16-inch (4.7mm) outside of the lens all around the outside perimeter of the window. The small, unmasked gap allows for a tidy external sealant bead when finished. Once the dry fit and masking is complete, the window is again removed and sealant applied to the cabin trunk in two or three fat concentric beads within the area in contact with the window. Special care is taken to make sure each fastener hole is well caulked. To make positioning of the window more precise, two or three fasteners are pre-fitted to the lens to act as registration pins. The lens position is fixed by engaging these fasteners into the correct cabin trunk holes just as the lens is lowered into place onto the fresh sealant.
The remaining fasteners are now installed and the window is gently tightened using a sequence similar to torquing down an engine cylinder head. Care is taken to avoid over-tightening the fasteners, since the lens can crack easily and it's important to avoid squeezing out too much sealant. A thicker gasket of sealant has more compliance as the window expands and contracts. A bond line of about 1/16-inch to 3/32-inch (1.5mm to 2.3mm) thick is about right. Excess sealant that squeezes out is removed with a putty knife and the final caulking touch is achieved by smoothing a bead around the outside perimeter of the lens with a gloved forefinger. Masking tape is removed while the sealant is still wet. As soon as the caulking has cured, the protective mask on the lens is removed before it's exposed to rain, heavy dew or too much sun that render the masking painstakingly difficult to remove.
It's worth noting that some manufacturers have stuck with the mechanically fastened approach and have achieved a reliable window seal. A successful variant used by some boat builders uses screws and washers as retainer clips holding only the outside edge of the lens (e.g. no fastener holes through the window). The window sits in a recess and the perimeter fasteners are invisible, buried in the thick bead of black glazer's silicone that surrounds the window.
By the early '80s, boat builders, after many complaints, abandoned the Frankenstein frameless window to pursue the new technique of attaching a frameless window using advanced adhesives. Besides offering better leak resistance, boat designers also wanted to improve cosmetics and were glad to leave behind the fastener studded look.
(A) Example of Frankenstein Mark 11 window installation. (B) Typical installation of a frameless window without fasteners.
WINDOWS IN BONDAGE
A slick looking acrylic window glued in place with methacrylate adhesive is what I call the Mark II bonded window. This powerful adhesive supercedes mechanical fasteners and takes over the job of fastening the lens to the cabin trunk. The task of sealing the window is delegated to a bead of tough polyurethane sealant applied externally around the perimeter of the window. Particularly when flush mounted in a recess, this technique created a great looking, fastener-free window with what was supposed to be a bulletproof seal. Although this was usually the case in the early days (during the warranty period), as the years went by and these boats began to age, window problems developed.
Methacrylate is awesome stuff. It has an adhesive bond so strong that often the underlying laminate fails before the adhesive does and that is not a good thing. As the window lens expands in the hot sun, a powerful force is exerted on the bondline. Something has to give. First, the expanding window causes the cabin trunk to flex. In many cases the only indicator of the huge stresses involved are the “crow's feet” cracks radiating out from the corners of the window. Second, the adhesive can fail, or worse, the gelcoat tears away from the underlying glass laminate at the bond line. With time, it's not uncommon to see the window pop loose, but only in one corner. Special repair techniques are required to repair the problems created by the methacrylate bonded windows commonly found on older boats.
A leaking window of this type is first carefully assessed to determine exactly what repair is required. If the lens still seems to be well bonded, it may only be a simple matter of raking out and renewing the perimeter caulking. Nonetheless, if the lens is in any way debonded or loose, the perimeter caulking can't do its job of sealing the lens. If only one corner is loose, it may be possible to do a temporary repair by carefully installing one or two screws to secure the lens prior to raking and caulking the perimeter bead. A lens with more than a few inches of loose caulk requires complete removal and reinstallation.
The standard procedure is to first rake out the perimeter caulking and then carefully pry out the old lens, in one piece if possible. More often than not, however, the lens remains firmly bonded to some areas, so removal demands the use of a chisel or router. At this point, if removal might destroy the old lens, a cardboard template is made to preserve the pattern. After the lens pieces are removed, the residual adhesive is sanded away and any gelcoat or fiberglass damage to the bonding surfaces is repaired. If the old lens is salvageable, it's cleaned (or sanded) to prep it for reinstallation. If a replacement lens is required, it's cut following the instructions above.
Once the cabin surface and window is properly cleaned and prepped, a bead of methacrylate adhesive is applied to the cabin with a special mixing gun. The window is then immediately put in place and clamped firmly until the adhesive hardens. Methacrylate bonds and hardens almost immediately so the placement of the window is very much a one shot deal. The clamps, usually a few wood 2x4s jammed between the lifelines and window, are left in place for a few hours or overnight. To prep for the perimeter caulking the cabin and window are masked as outlined above and the sealant bead applied with a caulking gun. Theoretically, this style of window is not supposed to move around much so the less flexible polyurethane sealants (3M 5200, Sikaflex 252) can be used for the perimeter bead. In use, even a perfect repair may only last a few years before the window pops loose again.
(A) Alternate frameless installation uses fasteners, hidden by glazer's silicone, to retain outer edge of the window without drilling holes through it. (B) Sample add-on frame mounting.
FREE-FLOATING FRAMELESS WINDOW
In the long term, any attempt to restrain the thermal motion of a large plastic window creates problems. The window eventually leaks or cracks or the cabin trunk cracks and the window comes loose. In the last 10 years or so boat builders have recognized this and have taken a different tack. Many boats are now built with frameless window installations where the plastic lens is free to expand and contract. This is achieved by using the aforementioned high flex glazer's silicone to both seal and bond the window in place. This technique, similar to the way the lens in a framed deck hatch is installed requires the window to be mounted in a wide recess and works best when the window is nearly flat or is pre-molded to the shape of the cabin. No mechanical fasteners are used and the window is allowed to float in a thick silicone gasket. Here it can expand and contract freely without breaking the seal or coming loose. This installation technique is difficult to duplicate in the field, as the window must be fixed in place and left completely undisturbed for the two days (more or less depending on the temperature) required for the sealant to cure completely.
FRAMED WINDOWS
Framed windows, either off-the-shelf or custom, don't suffer the same kind of problems as outlined above but unfortunately are not 100 percent problem free. The advantage of a framed window is that the frame itself handles the job of fastening the window to the boat and the lens is freed from all those stresses. The flexible rubber gasket that secures the window in the frame also allows the lens to expand and contract. The disadvantage is the rubber gasket that eventually degrades and leaks. Many older boats have off-the-shelf fixed ports with aluminum frames. Excellent replacement ports are still made today by all the major hatch manufacturers but are only available in certain sizes. Rubber gaskets in such framed windows slowly deteriorate from exposure to sunlight and pollution, especially ground level ozone. Occasional gasket leaks can be dealt with by working Permatex penetrating windshield sealant (available at automotive shops) under the edge of the gasket. The sealant between the window frame and the boat occasionally leaks for some of the same reasons as outlined above with respect to frameless windows. When you cannot stop the leaks, you have no choice but to replace the gasket, if one is available.
A gasket replacement usually requires removal of the entire window assembly. Fasteners are removed, the frame is gently pried away from the cabin trunk and the sealant cut with the edge of a putty knife. Once the window assembly is on the workbench, the old gasket is peeled out and the lens freed. Each make of window has its own tricks. The one shown below was made by the Beclawat Company in Belleville, Ontario, and was supplied by the thousands to Canadian boat builders during the '70s. It uses a unique rubber gasket (still available) to seal the outside of the lens against the frame and double-sided foam adhesive tape to bond the inner side of the lens to the frame's inner flange.
NICK BAILEYWhite painted aluminum add-on frame goes over top of flush mounted window.
After removing the lens, all the old tape must be scraped off and the frame cleaned with solvent or a citrus cleaner capable of dissolving gummy residue. The old lens (if reusable) is also cleaned and polished before reinstallation. Acetone or lacquer thinner is never used to clean plastic lenses but stove alcohol is okay. If the lens is in poor condition, a new one is cut. The new gasket is measured and cut about 1” (25mm) longer than the old one to allow final trimming during installation. New double-sided foam adhesive tape is cut (3M Scotch- Brite VHB tape works well for this), the protective backing peeled off and the tape firmly applied to the frame's inner flange. The protective mask is peeled from the front of the tape and the lens is carefully placed onto the sticky surface and immediately pressed firmly to maximize the bond. Starting at the bottom of the frame, the new outer gasket is pushed in between the frame and the lens until the detent cut into the gasket “snaps” onto the frame. To enhance the seal, a little clear silicone is smeared onto the sealing surfaces of the gasket as it's pushed into place. Next, the window assembly is refastened to the cabin with fresh sealant (either polyurethane or silicone works fine in this application).
THE ULTIMATE FRAMELESS SOLUTION
When a frameless window installation is repeatedly defeated by the problem of expansion, a completely different method of securing the window is needed. Here is where a retrofitted external frame offers a permanent solution. The addition of an external frame does two important things. First, it mechanically fastens the frame to the cabin and takes over the job of securing the lens in place. No fasteners go through the lens and no ferocious bonding adhesives are required to retain the lens. This equates to less stress on the lens and the boat. Secondly, the lens, now that it's free of being rigidly fastened, remains restrained by the frame and is caulked with flexible glazing silicone allowing it to expand and contract freely without problems.
Frames are made of polished stainless, painted or anodized welded aluminum or wood. In many cases, a troublesome window doesn't need to be removed. The frame, together with a generous bead of caulking is simply installed overtop of the existing window. For maximum durability, the new frame is usually thru-bolted and acorn nuts are used on the inside of the cabin for best cosmetics. Many chronic window leaks have been banished forever by retrofitting a frame. (Including those on my own boat.) The only minor drawback is that an external frame doesn't appeal to everyone aesthetically. Compared to the way many windows look after repeated amateur attempts to seal leaks, an add-on frame is a big improvement.

A version of this story ran in DIY Boat Owner magazine.

Bleed Your Diesel Engine

By Lee Mairs

One routine task that strikes the fear in the hearts of novice mechanics is bleeding a diesel engine fuel system.
Each engine has its personality and the secret to a fearless approach to purging the fuel delivery system of air is to know thy engine. Your engine type might have an electric lift pump, a cam operated lift pump, one fuel-injection pump or a fuel-injection pump for each cylinder.
Sorting all this out requires a little background knowledge of the theory of diesel fuel delivery.

A generic diagram of a typical marine diesel engine fuel system (see photo) shows the lift pump sucking fuel from the tank through the pickup tube, fuel lines and through the primary fuel filter. Fuel is then pushed through the engine-mounted fuel filter and on to the engine's fuel injection pump(s).
The injection pump pressurizes the fuel to about 3,000 psi (this varies among engines), pushing the fuel through the injector pipes to the fuel injectors at the appropriate moment. Highly pressurized fuel causes the pintle to lift from the nozzle in the injector and a fine mist of fuel enters the cylinder combustion chamber, mixes with the compressed air and explodes into energy for the power stroke.
If there is any air in the fuel lines, the fuel injection pump pressurizes air instead of fuel, preventing an atomized mist from entering the cylinder. The engine staggers – its warnings of trouble – and finally stalls. The silence is deafening. The only option is to bleed, or purge, the air from the engine fuel supply lines, because the only thing you want in those lines is clean diesel fuel.
JOE VANVEENEN / LEE MAIRSTypical Marine Diesel Engine Fuel System.
BASIC BLEEDING
The only sticking point about explaining bleeding small engines is the seemingly endless possibilities for engine installations, fuel system design and components and idiosyncrasies, not the least of which is access. There are so many different combinations and configurations to consider that I can only describe the bleeding process in generic terms.
Even if you are comfortable with my explanations, hiring your mechanic for an hour or so to have him walk you through the process in a one-on-one tutoring exercise is money well spent, largely because, when the air hits the lines, he'll likely not be handy for coaching in situ. Make notes and be prepared to mark or label the various bleed screws and other points on the engine so that you can easily find them when your time comes – it's not an "if," it's a "when." Finally, write up the details of the process and post them handy to the engine or in your maintenance log. The stubbiest pencil always beats your memory!
PATRICIA KEARNSCummins OSC series 500-HP six-cylinder shows injection pump with fuel lines to a fuel rail that feeds fuel to the individual injectors that act independently. On smaller engines, the injector lines run directly from the pump to the cylinders.It's impossible to write a detailed, step-by-step, process for bleeding air from every kind of engine, but that doesn't relieve you of the responsibility to know how to bleed your engine when it needs it.
Small diesel engines are built primarily for use in industrial and agricultural applications, such as propelling a heavy street sweeper or plowing ground in a farmer's field. In cases where the fuel tank is mounted over the engine, gravity is usually sufficient to feed fuel from the tank to the engine and no lift pump is required. Marine engines are rarely installed to take advantage of this simple fluid dynamic. Because their position relative to the fuel supply, diesel must be pumped or sucked to the engine via a fuel pump.
Lets start with the assumption that your engine has a mechanically-operated lift pump (see photo). This pump works up and down on a cam, sucking fuel through the inlet valve and pushing it out through the outlet valve. There is a small lever on the pump that allows you to operate that pump manually. Otherwise, the eccentric camshaft works the rocker up and down in your stead.
Now, run your hand along the fuel outlet line until you come to the engine-mounted fuel filter. If the manufacturer used a small cartridge fuel filter, continue tracing the fuel line until you come to the injection pump. Carefully consult your engine owner's manual. Most engine-mounted, canister-style fuel filters and all fuel injection pumps have a bleed screw. Study your manual until you are sure that you can find the correct screw. Once you are certain, crack the bleed screw open a turn or two. At this point, you can probably better appreciate having your mechanic available for a bit of experienced handholding during a first time engine bleeding.
JOE VANVEENEN / LEE MAIRSMechanical fuel lift pump.Now, manually operate the mechanical lift pump lever until fuel begins to seep out the open bleed screw. You will see a frothy, bubbly mess that soon turns into clean fuel flow. As soon as this occurs, tighten the bleed screw the two turns. If you have just changed fuel filters, this pumping process may take awhile. Have faith. Be patient.
PURGING AIR
You have now purged all the air from between the fuel tank and the engine-mounted fuel filter canister. You can bleed any remaining air up to the fuel injection pump by similarly opening the bleed screw, manually pumping the fuel lift pump and then closing the bleed screw after clean fuel appears.
If you have solid fuel flow to the injection pump, most engines will start at this time; however, there are always a few recalcitrant machines out there that will require you to bleed air out of the injector pipes also. Crack open the fuel pipe nut slightly at the injector and crank the engine. Again, as soon as fuel appears tighten the nut and, if necessary, proceed to the next pipe. The engine should begin to cough its way back to life.
PATRICIA KEARNSBleeding a Yanmar 6YA-STE: (1) Loosen the priming pump knob then push it to feed fuel to the engine fuel filter; (2) Loosen bolt on top of fuel filter to release fuel until no air bubbles escape, then tighten bolt; (3) Push down and tighten priming pump knob.If your engine has an electrically powered fuel pump, the process is much the same, except you don't have to operate the lift pump lever with your finger. The click-click-click of the fuel pump pushes the fuel thorough the system until air bleeds out at the bleed point. Continue up the line towards the injection pump, opening and closing the bleed screws once fuel, free of air bubbles, appears.
It shouldn't take you long to master the correct bleeding technique for your specific engine once you understand the generic process and have invested some time with your mechanic. The best thing you can do for your engine to avoid the bleeding process is to be careful when you are changing fuel filters and make absolutely sure that you never run the engine out of fuel.
Fuel line integrity is very important when it comes to keeping air out. The fuel tank, primary filter and the lines connecting them to the lift pump are in a vacuum state relative to the outside world. A pinhole leak often will not reveal itself as a drip. Instead, every time the lift pump tries to suck fuel out of the tank, air can be sucked into the system (air is lighter and easier to suck then diesel fuel). If you suspect an air leak, it's your job to find it and fix it – because it could take hours to get that big engine bled on a Sunday evening, when a mechanic is scarce.

A version of this story previously ran in Mad Mariner's DIY Boat Owner magazaine.