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A version of this article first appeared in Good Old Boat Magazine

The Inside Outboard

James Baldwin describes how he built a well for an outboard motor into a watertight locker on a 28-foot Taipan sailboat.

outboardClick photos to enlarge

When our boats were hauled for routine maintenance at a Trinidad boatyard recently, my friend Theo asked me for suggestions on how to improve his outboard motor installation. On his 1972 Hong Kong built Taipan sloop, Islander, instead of an inboard motor he has a 5 hp long shaft Mariner hung on a standard adjustable transom bracket. You know I dont like inboard motors, he said, But this outboard is a real pain. In any kind of sea the motors prop gets lifted out of the water one minute and then as the bow lifts, the motor gets dunked under water and stalls out. Its also difficult to lift it out of its storage locker and hang over the stern to set it up when the boat is bouncing around. There must be a better way.

We both have similar moderately full-keeled 28-foot fiberglass cruising sailboats. Both of us had removed our original inboard motors years ago and replaced them with outboards. I had removed my Pearson Tritons venerable gasoline Atomic 4 partly because it had become a maintenance nightmare and partly because I wanted to have a pure uncomplicated sailing experience. For over five years I cruised far and wide with only sails and a sculling oar and proved to myself that it was practical and rewarding. When my cruising style changed from making mostly long offshore passages to doing more coastal cruising and river trips, I reluctantly re-entered the motoring world by purchasing a 3.3 hp long-shaft outboard. The noisy little beast normally lay forgotten in a cockpit locker. When needed, I hung it on an adjustable stern bracket. It did work sort of. Besides the problems Theo mentioned, there is the question of esthetics; its plain ugly, hanging there on the stern like some tacky add-on afterthought. And there is the possibility of theft; some envious Brazilian fisherman had pinched my outboard a year earlier.

So I had been thinking about this problem for some time. When Theo asked for help, I was ready and enthusiastically leapt aboard Islander with tape measure and notepad. Theo eyed me quizzically as I crawled around measuring the overhang of the transom, emptying his lazarette locker and disappearing inside it head first. When I emerged I told him my plan: I can make an outboard well, or box, inside your aft cockpit locker. After discussing the extensive modifications necessary and the estimated cost, he said, Do it and left his cherished Islander in my hands while he flew home for a spell of work in Switzerland.

The Dirty Work

From my measurements I knew the well would need to be placed as close as possible to the forward vertical bulkhead of the lazarette, or aft cockpit locker. The access hole in the deck needed to be as large as practicable to allow adequate ventilation while the motor was running and to permit access to the furthest recesses of the locker while the motor was in place. Its probably best Theo wasnt around to see the destructive stage of the job beginning when I cut a huge hole into Islanders afterdeck. It looks much worse than it is, I replied when one neighbor asked, Does he know what youre doing to his boat? Once I cut this large section of deck out with a jig saw; the real dirty work began.

outboardThe outboard well box with motor and covers removed. outboardMotor in place with storage room alongside well box.

Using #36 grit pads on a grinder, I took most of the inside of the locker down to bare fiberglass. To protect skin and lungs from fiberglass dust, I wore a full Tyvek suit with hood, goggles, and respirator. Next, I carefully measured for the placement of the hole in the hull needed to accommodate the motors shaft. Originally I planned to cut a circular hole so that the motor could easily pivot to provide side thrust when needed to turn in tight quarters such as when a current has you pinned against a dock. Unfortunately, further measurements indicated that because of the angles involved this would not be possible, so I went ahead and cut as small a hole as necessary to allow clearance for the prop. I saved the slightly wedge-shaped rectangular fiberglass cutout, cut it in half fore and aft, and shaped it to fit around the outboard shaft at the appropriate height. I stiffened the cutout pieces with extra layers of epoxy-saturated fiberglass and attached them to the shaft with angled stainless steel brackets and -inch bolts. Although the outboard will not always be kept in its well, these new flanges are meant to stay permanently attached to the motor. When the motor is lowered into position, these flanges make a flush fit with the hull, ensuring minimal turbulence and preventing waves from entering and flooding over the inside of the well into the stern locker. The slight gap around the edge is sufficient to allow the motors cooling water to drain out.

Holding the motor temporarily in place, I measured for its exact placement. Ideally, the motor should sit as low as possible to ensure that the prop remains underwater when choppy seas cause the boat to raise her stern. The motor should also sit low so that the deck hatch box does not need to be built excessively high to fit over it. On the other hand, the motor should be situated as high above the waterline as possible to prevent it from being flooded by following seas or when the boat is heeled under sail. I struck a reasonable compromise by placing the prop about 10-inches below the the boat's at-rest waterline.

Working with cardboard and scissors, I made templates for the four sides of the well. The top of the well's box in this case worked out to be about 12-inches above the at-rest waterline. Three of the templates were then transferred to pieces of -inch marine plywood and cut out. The fourth piece, which was the forward end of the box to which the motor would be mounted, needed to be stronger, so for it I used -inch plywood. At the top portion of this piece, where the motor clamps would rest, the thickness of the wood was doubled to 1 -inch. The plywood was then sealed with epoxy resin and glassed into position using several layers of medium weight fiberglass mat chosen because it can be made to lie flat on uneven surfaces more readily than cloth. Although considerably more expensive than polyester resin, I used only epoxy laminating resin because of its better strength and adhesion. Vinylester resin would also be suitable. To fill gaps and corners I mixed talc-thickened epoxy to the consistency of peanut butter and applied it with a putty knife. Prior to applying the epoxy, I used rags soaked in acetone to thoroughly degrease all surfaces. To complete the box I block sanded the top edge perfectly level and epoxy-bedded four -inch bolts into holes drilled 2-inches deep into each top corner. The bolts stood proud by 1 -inch and their heads were cut off so that they could be used as alignment studs for a lid held down with wing nuts. This lid has a rubber gasket under it to seal the box and prevent incoming water from entering the boat when the motor is not installed.

To prevent unwanted turbulence, or drag, the hull also needed a flush-mounted plug to seal the cutout when the motor is not in place. This I made by cutting out a piece of plywood from a paper template that matched the hole and glued it onto a larger plywood backing piece. With the plug held in place by a similar system of inward facing -inch studs, I ground the plugs outside surface to match the contour of the hull. The plug was sealed against moisture with a coat of epoxy resin and then painted. Because this plug is so near the waterline I did not try the difficult task of making it 100% watertight. Instead, I expect it only to stop the main force of surging water and provide a smooth surface for water to flow past undisturbed. Whatever water does get into the box can seek its own level and will, in any case, ultimately be stopped by the gasket-sealed top lid.

Before going further, I had to modify the stern lockers bulkheads to ensure this locker was entirely watertight and isolated from the bilge in case of accidental flooding over of the well. I filled all gaps in the bulkheads with my epoxy filler mixture and then used fiberglass mat and resin to make it all watertight. For safety, I installed a drain hose leading from the locker floor to the bilge with an in-line shut-off valve accessible from the cabin. This way the locker could drain normally into the bilge or be shut off if there were ever any uncontrolled flooding. Ever since experiencing my first storm at sea Ive realized that all cockpit lockers should be constructed this way. When a boat is knocked down, pooped by a following sea, or held over flat by force of wind, the cockpit lockers may fill the bilge so fast with water as to risk sinking the boat, or at least require near-constant pumping out. At least with the drain valves shut off there is a limit to how much water can get in the boat.

The next step was to construct a box around the access hole in the deck to raise the hatch high enough to clear the top of the motor. Because of the motors height I needed to add about 5-inches along the rear over the afterdeck and 9-inches along the front edge where the hatch intruded on the cockpit seat area. Trinidad has its own sustainable teak farm which sells teak at less than half the cost of teak sold in the US, so I lavishly used 1 -inch thick teak planks for the boxs sides. The upper lid of -inch plywood was then fit over this, trimmed with teak, latches, and rubber gasket. Note that when measuring for the height of the hatch box, you need to take into account any extra clearance required by the throttle arm, although usually the handle can be operated in a folded back position. A round plastic access hatch is located on the forward side of the box to provide access to the motors starter cord. Final detailing involved painting the inside of the locker with epoxy primer and 2-part urethane paint. The locker lid got a finish coat of nonskid polyurethane. I coated all teak with four coats of clear polyurethane. It took about 70 hours to complete this job and we were both pleased with the results.

How it all works

Recently I had an opportunity to test the practicalities of this installation when Theo asked us to sail Islander from Venezuela to Brazil. The system performed better than expected on the 6,800 mile voyage which took us to the eastern tip of Brazil via Bermuda, the Azores and the Cape Verde Islands. When approaching landfall the motor was easily placed in the well and sea water never flooded over the well into the locker. On each offshore passage, once clear of land, the outboard is stowed in a cockpit locker to eliminate drag and the chance of snagging seaweed or other floating debris, as well as to protect it from the corrosive effects of sloshing seawater. For this reason, and to save your back, I would not choose a motor that is too heavy or too large to lift out and place in another locker. Since the motor cannot pivot back if caught on an obstruction, it makes sense to reduce the risk of unnecessarily dragging it long distances through the sea while under sail. In this case the flush-fitting hull plug is locked in place to present a strong smooth external hull surface. The top of the well is then sealed with its gasketed lid. Although there should not be any appreciable water intrusion into the main locker, the locker drain valve is left closed and can be checked and drained occasionally as needed. Around the sides of the well there is ample storage space for ropes and fenders nearly as much as before the well was added, because with the larger hatch, more of the lockers corner space is accessible. The upper hatch is held firmly in place by sturdy lockable latches on either side.

outboardOutboard motor surrounded by a flush fitting hull plug. outboardThe cover is normally set aside for increased ventilation when running the motor.

When the motor is needed, the top and inner hatch lids and the hull plug are removed, the motor set in place and secured. The main hatch lid is set aside and the plastic access hatch for the starter cord is removed. These hatches are normally left open to provide the engine with enough ventilation to operate properly. To protect the engine and locker from rain and spray we can leave the main hatch on, but propped open slightly at one end to provide the motor with the fresh air it needs to run. Alternatively, a hose could be led from the air intake to an outside vent to allow the motor to be run with the hatch closed. The motor operates in forward and reverse as normal and steering is done by the boat's tiller. In order to turn the motor for side thrust it must be put into neutral and the boat brought to a stop. Then the motor clamp screws are loosened and the motor raised 1 -inch by setting it on a spacer block. This raises the motor shaft flange clear of the hull and the motor can now be re-clamped, engaged and swiveled. Normally, I would not bother with this unless doing really close quarter maneuvering. Still, it is possible to use this swivel function, which is one of the advantages outboards have over fixed inboards. Another reason not to have the motor normally able to swivel would be to prevent it from accidentally turning sideways when sailing at speed, causing high side loads on all components. With the motor seated into its normal position, its flush rectangular-shaped hull plate totally prohibits any accidental swiveling. To safely remove the motor when under sail, it is necessary to bring the boat nearly to a stop by heaving-to.

This project was such a success that I hoped to repeat it on my own boat. Unfortunately, it appears my Triton lacks enough clearance between the forward lazarette bulkhead and transom for a 5-6 HP motor in a closed well design. In 2008 I constructed a modified outboard well on an Alberg 35. The aft cockpit bulkhead was cut out and the motor sits further forward in a well that is open to the cockpit. This type open well can work on the Triton (as was done on the Triton Pajaro) and I may do this modification to Atom as well. This means the lazarette is open to the cockpit and so reduces the total watertight locker volume that I was trying to maximize on my earlier voyages. Still, the new lazarette hull to deck bulkhead remains sealed from the boats interior to prevent flooding in heavy weather if the motor is unavoidably left in place. (April 2010 update: A new tilt-up open well has been added to Triton #503 Salty).

For better reserve buoyancy on some boats the lazarette can be divided into three sections with port and starboard sections sealed with additional bulkheads, but this means the motor can no longer be stored on its side in the locker, even if the transom is wide enough to permit this. On some boats a slot in the transom allows the motor to tilt forward to lift the motor shaft clear of the water. Still, as it is I think an open well is a good compromise, especially for a Triton or similar boat that is making coastal passages and wants better function of the outboard.

Obviously, this alteration will not be suitable for some other boat designs as well; careful measurements need to be made of rudder location, waterline height and existing locker layout before any work is begun. The advantages of the well versus hanging the motor on the stern are obvious. For those who do not need to motor long distances or require high power output, this system even has advantages over an inboard diesel. An outboard saves a great amount of space and weight. It is cheaper to buy and maintain. Repairs are easier. When it comes time for a new motor, installation is a snap. If you are going to have an outboard motor for your dinghy, the one motor might serve both purposes. Or you can carry two outboards of different size for the boat and dinghy and always have a standby ready in case of breakdowns. Try doing that with a diesel inboard! With the outboard now located inboard, we feel we have the best of both worlds.

Details of other projects on this boat are on the Taipan 28 Refit page.

Another outboard well project I've done is on the Alberg 35 Saga page. An open-cockpit well design is discussed on the Triton Pajaro page and a tilt-up version featured on the Triton Salty Projects page.

Alberg 35 outboard well:

SagaWell25kb85.JPG (87472 bytes)The motor in operating position on the Alberg 35. When the hull plates are removed by loosening the wing nuts, the motor can swivel some 25 degrees for limited side thrust if needed for departing a marina slip in a strong cross wind. SagaWell26kb86.JPG (88223 bytes)The 9.9 motor is too big to fit entirely within the lazarette since it needs to be this far forward to have the prop low enough in the water so this slotted cover board is used. A vinyl motor cover is available to protect the motor from sun and spray if left installed.

Triton Pajaro outboard well:

PajaroWell01kb52.JPG (53973 bytes)The open well design on Triton Pajaro with 5 HP Tohatsu. PajaroWell02kb65.JPG (66852 bytes)This open-type well, so-called because the well is open to the cockpit, is still still being worked on but has successfully passed sea trials.

Tilt-up well I installed on the Triton Salty:

SaltyWell22kb79.JPG (81301 bytes) SaltyHull05kb92.JPG (94763 bytes)


In 2011, the owner of this Able 32 sent me these photos of a tilt-up outboard well conversion he has nearly completed based on my recent Triton project. HonuOutboard02kb84.jpg (86941 bytes)
HonuOutboard01kb84.jpg (86924 bytes) HonuOutboard03kb84.jpg (86421 bytes)




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