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

Inboard Engine Installation - Page 2 of 3

The shaft axis will be our reference for the installation of all the drive train parts.

Note that this is the axis of the output shaft of the transmission. The shaft axis is not necessarily in the same plane than the crankshaft axis or engine mounts.
We did all the calculations for you. In most of our plans show the exact shaft axis and engine mounts location.

At this stage of the building, we will install the shaft tube and the small stuffing box frame.

The engine mounts are adjustable and give almost 2? to play with but we want to align that shaft tube as precisely as possible.

The first thing to do is to define the shaft axis.

Look at your plans: we show two points to locate that axis, one on a bulkhead in front of the engine and one on the skeg.

With the main bulkhead in place, drill two small holes, 3/8? or less, at the location of the shaft axis, in the rear face of the keel and in the main bulkhead.
A straight line between the center of those two holes is your shaft axis.

No need to have the boat level, if your bulkhead is properly installed, the axis will be correct.
That axis line can be a thin steel cable (fishing leader) or the beam of a laser pointer.

Next step, install the stuffing box frame.
That small frame is parallel to the other frames and it?s location is easy to mark by offsetting the marks for the frame just in front of it.
Drill the hole for the shaft tube before installing the frame.

Check that the shaft axis passes through the center of the hole before fiberglassing the frame to the hull. Great precision is not necessary. You can always make the hole a little larger since you will fiberglass over it later when installing the shaft tube.

Install the shaft tube and fiberglass it to the keel and frame.

The alignment can be done with the steel line or laser beam representing your shaft axis or better, with the shaft itself.
To align with the shaft, the engine or an engine template must be in the boat, sitting on the engine beds.

Assemble all your shaft components on the shaft: stern bearing, shaft tube, stuffing box and coupling. Mate the whole assembly either with the engine or engine template. Check the alignment and when satisfied (+ or ? 1/8?, 3mm), fiberglass the stern tube to the hull.

If you do not use the shaft but, we still recommend lining up the stern bearing at the same time. This will guarantee an easy alignment later.
All hardware temporarily installed should be covered with plastic sheets.

The shaft tube diameter usually fits closely inside the rear part of keel and can be spot welded to the sides with small pieces of glass. We will reinforce it later.

If you did not find the answer to your question, please use our message board and we will respond within a few hours.
Or explore the HowTo files at our technical support web site

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