ENGINE SHAFT

[Guest]

Can anyone give me any advice on how to drill an engine shaft hole through a keel and keep it aligned. My hull & keel are wood and it is in the upright position, topsides finished so unable to turn, any help on techniques tools etc would be great. Thanks Ed

 

[Guest]

Hi, This is a task for an experienced boat builder. You can do it but need to be very careful and use only very sharp auger bits etc. Carefully calculate the angle of the shaft and mark internally and externally where it sould go. Make a jig, offset to one side but aligned as near to perfectly as is possible on the outside away from the hole mark. this is used to help you keep the drill in line while you are boring. Lengthen a small auger to the length required to penetrate the shaft log probably 6-10 mm dia put this in a drill line things up and start boring. DO NOT RUSH, take it easy , keep the hole clear by withdrawing the drill often and do not force the drill let it cut at it's own pace using the jig to keep everything straight. Once the breakthrough is achieved hopefully exactly on the inside mark, then follow through the hole with a larger auger of the correct size for the shaft. When that is through a boring bar is employed to straighten the hole and allow the shaft clearance between the internal and external bearings when they are in place. Now block the bottom end and then fill the hole with good paint then pull the plug out and catch the extra paint in a tin leaving the inside coated. The bearing can now be fitted to the outside, the shaft installed and the stuffing box and internal bearing fitted inside the boat now the engine can be installed and aligned then bolted down.
Hope this helps ,....Good luck!
Regards, B

 

[vyv_cox]

Bert,

Perhaps you would care to elaborate on-

"Carefully calculate the angle of the shaft and mark internally and externally where it sould go."

I have never tried to do this job but I have installed a new engine in a GRP boat and found the measurement side of that to be quite challenging, even with the drawings provided by the manufacturers. Boat hulls are not easy things to measure and I would be interested to know how you propose to measure up. The task appears to be far more complicated with a wooden boat where structural items get in the way.

Thanks, Vyv

 

[Guest]

vyv,,You are dead right about being difficult in the measuring dept. I have only done this once a longtime ago but this is what I did. I made wooden frame which I screwed to the engine beds to represent the centre line of the shaft. I then jacked up the boat until the frame was laying horizontal (i.e. lifted back of boat). Then I made up what can best be described as a very long outboard bearing tube to take the drill (boring tool). Because without exception you want the shaft to exit the centre-line of the skeg midway between hull and bottom, you know where to start. I fixed the the tube onto skeg making sure its horizontal and bored away,,,worked a treat,,,but maybe i was lucky

 

[Strathglass]

Re: ENGINE SHAFT not easy

I did it about 2 years ago on an unused 33ft fin keel grp hull. As the hull was 20 years old and had no engine mounts and all the drawings I had were very small scale reproductions from magazines it was not easy. It involved many hours of measurement and drawing and redrawing. I made an XYZ template of the engine/gearbox/sterncoupling/shaft seal including the engine mounts using ply and softwood bracings. This had lines marked in down angle between 5 and 15 degrees. The engine mountings beds were made to match the template assembly to the hull. Using this enabled me to determine the positioning, lengths and angles for the stern tube, prop shaft, prop and P-bracket. Some of the problems I had were self inflicted. They included, trying to shoestring a Ford XLD engine into a space originally intended for a 10 HP single cylinder engine, fitting the engine as far aft as possible to save on living space and using a 1.125" prop shaft as that fitted a folding prop I had purchased previously.
Drilling the actual hole was relatively easy compared with all the work and calculations involved in determining where to drill it.