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Inboard Engine Installation :: Inboard Installation 2 :: Inboard Installation 3

Inboard Engine Installation - Page 3 of 3

Engine Alignment:

Proper alignment is extremely important.
With the shaft tube and all fiberglass around it fully cured, proceed with the engine alignment.

At this point, the engine mounts are loose, not bolted to the girders.

You will move the engine back until the transmission coupling touches the shaft coupling. Since you have a flexible shaft packing gland, the shaft can move a little bit up and down and sideways. Block the shaft somewhere in the center the tube: if it moves vertically 1/2?, block it 1/4? up from the bottom, same thing for sideways movement. Great precision is not necessary.

Now look at your two couplings: they should touch all around, make good contact with their full surface.

This is probably not the case and you will have to move your engine to mate the two couplings perfectly.

You will use the engine mounts to move the engine, first up and down then left and right.

At that point the couplings should fit into each other: there is a little recess in one and a shoulder in the other one. They should slide into each other easily.

Put your engine neutral and turn the output coupling by hand.
Once the couplings fit, take a flash light and look for gaps. Unless you are extremely lucky, there will be a gap on one side.
You must close that gap by turning the engine around its axis.
You can move the engine front up and down or left and right with the adjustable engine mounts.

Once the gap is small, let's say 1/8?, you can bolt the engine to its girders but leave the mounts loose for the final adjustment.
That final adjustment is done with feeler gages.
The two couplings are precisely machined.
Fine tune the position of your engine with the mounts, gaps measured between couplings must be smaller than 3 thousands of 1? in all directions.
Tighten all your mount bolts and free the coupling by pushing it back 1/4?. The boat will move during the transport and we do not want to bind the shaft.

Alignment must be checked immediately after launching the boat. The hull shape will slightly change: launch the boat with an open coupling, check alignment in the water and bolt coupling.
Not all boat yards are aware of that procedure.

A removable drip pan under the engine is convenient. That drip pan can be made to fit tightly in the keel. Do not install it now: you need access to the inside of the keel for the optional trim ballast.

Fuel system:
See the plans and notes above. A good fuel filter is a must.

Exhaust and Air:
Diesel engines require more air and larger exhausts than gas engines. The engine room must have an air intake either through a louver vent under the steps or through large diameter hoses feeding air from under the gunwale.

Do not skimp on exhaust hose diameter.

To prevent the cooling water to fill the exhaust manifold, you must install a waterlock at the lowest possible level.
To prevent siphoning, you need a siphon break valve or vent in the water injection system. We prefer an overboard vent as shown on the plans but the cooling system diagram shows an anti-siphon valve. At the transom, the exhaust must be fitted with a gooseneck to prevent seawater from entering the system. All exhaust parts and hoses are available as a kit from

Water Cooling System:
The engine is cooled by seawater through a fresh water heat exchanger. The seawater pick up is fitted with a valve (seacock) and a scoop strainer on the outside. The water supply goes through an optional sea water filter mounted on a bulkhead.

The engine room compartment can be insulated for noise and heat.

Refer to the manufacturers instructions for the installation of a marine head. There is room for holding tanks between the water tanks or under the seats.

With the engine and other mechanical components installed, we can now proceed with deck installation.

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Inboard Engine Installation :: Inboard Installation 2 :: Inboard Installation 3