There are certain jobs that cause high levels of dread. As a rule, any task involving drilling large holes through the underwater part of the hull invokes dread. That is especially true when the hole goes through a really valuable, critical part of the boat. As previously described, the “tailfeather” is one of those parts and it has two very large holes–one for the rudder shaft and one for the propeller shaft. The propeller shaft hole was very stressful because the diameter had to be exactly correct (don’t want sea water rushing into Mahdee from around the shaft log), the vertical angle needed to match the transmission output so the engine sits correctly and the horizontal line of the shaft should coincide with the centerline of Mahdee.

To get an idea of the tolerances of the latter, consider that the drilled hole is about 2 1/2 feet long, but the front end of the engine is about 8 feet in front of the hole. The engine should ideally sit on the centerline of the boat for several reasons: good thrust axis, good weight and balance, good aesthetics. But in addition to aesthetics, the front of the engine is adjacent to the head on Mahdee. It doesn’t take much of a twitch when drilling a 2 1/2 foot long hole before the front end of that engine is shifted into the head. The last thing one needs on a boat is a spinning V belt near your backside while using the head.

It took many different drill bits to get the hole right–two different pilot holes of 5/8 inch diameter (before I was happy with the lineup), then because we didn’t have just the right sized 2 3/8 inch auger, I used a 2 3/8 inch hole saw running on a 5/8 inch guide to track the pilot hole and followed by a 2 1/4 chaser to auger out the center of the hole. The final diameter of the hole was perfect. The two ends required some counter boring to make room for the fat end of the stuffing box and stern bearing fittings. John and I had to work hard to pound in the shaftlog, so it is tight and hopefully water tight.

The drilled hole seems a success (one can never be certain until the acid test of launching the boat), and the front end of the engine is only about 1/2 inch to right of centerline (opposite the side of the boat with the head in case you are wondering). Ultimately, we won’t know how far off the engine is until after we relaunch. As the wood takes up moisture, the alignment of the engine will change. We also increased the vertical angle of the shaftlog bore to better match the transmission output angle. And, I finally got the nerve to seal and tighten up the stuffing box fitting and stern bearing. Those two also required lag bolts.

If there is any consistent challenge with Mahdee its figuring out how to get all the bolts and fasteners into her without hitting each other. We had previously moved floor number 41 to the aft side of the frames, so we didn’t have to worry about the stuffing box bolts hitting the floor drifts. But, there are 3 big bolts for the tailfeather near the aft end, 2 of which pass around the shaftlog and one starts just above it. The new stern bearing was slightly narrower than the old one and the bottom two stern bearing bolts lined up with those 2 tailfeather bolts. Fortunately, I was able to angle the stern bearing bolts outward and missed hitting the tailfeather bolts. Of course that required machining an area on the stern bearing so that the bolts were flat against the bronze. Nothing is ever as simple as it should be.

But now that that dread task is over, I can get to work on the engine stringers. I didn’t want to install the engine bed on centerline and then discover that the extended propeller shaft required the engine to be somewhere else…