More dread tasks –the rudder shaft hole

If the propeller shaft log hole was stressful, then the rudder shaft hole almost induced catatonic shutdown. After all, if the engine was a little off the centerline of the boat, it wasn’t too big of a deal–just install the stringers over to the side some (and worse come to worse, move the head:)). First, the hole for the rudder shaft is bigger–almost 3 1/2 inches. There are no plates to seal the ends like the propeller shaft (which has a stuffing box and stern bearing). The rudder stock goes through a pipe which relies upon being tightly screwed into the tailfeather using its pipe threads. On its angle, the pipe threads through 12 inches of purple heart tailfeather (the tailfeather is not 12 inches thick in the shortest direction). The 4 foot pipe has less than 1/8 inch clearance between it and the rudder stock and the rudder stock must be centered at the top of the pipe where the seal is and, most importantly, line up exactly with the gudgeon on the bottom of the keel in both lateral and vertical directions. The keel, unlike the engine bed, is not something that is movable and the 2 1/2 inch diameter bronze rudder stock does not bend. Further, if the rudder angle is too steep, the Robinson worm gear will hit and potentially stick out the back of the transom. If the angle is too shallow, the Robinson work gear will hit the aft deck beams. The boat design has the gear almost brushing the bottom of the deck beams and touching the transom knees. No room for error at all.

I could put off the drilling of the hole as long as we didn’t have the rudder stock. I was almost happy that the manufacturer lost the old stock and didn’t make the new one until Brenda supplied them with a full sized printout from the plans. With the arrival of the new rudder stock, and given that we had some leftover 3 inch oak, John was eager to build the rudder. I realized the day of reckoning was here. The first pilot hole, made with braces and supports to duplicate the original hole wasn’t quite right. The top wasn’t centered on the tailfeather and the orientation put the bottom of the rudder stock somewhere off to port of the gudgeon. When I had a pilot hole going the right direction, I needed to fill in the voids to keep the drill guide from wandering off. I used a 7 foot long 5/8 inch diameter Pam-coated bronze rod to define the axis, sealed the bottom with leftover deck canvas and poured epoxy around the rod from the top. And, yes, that’s Pam, the cooking oil–it keeps things from sticking.

I tested several different hole saws in some scraps and as luck would have it, the 3 3/8 inch hole saw from the home store seemed about right. Because of the entry angle into the tailfeather, I needed a long 5/8″ center guide. I made one by drilling an old broken 5/8″ drill bit and pressing a 1/4 inch bit into the hole. It looked odd, but did the trick. This time, I didn’t have an auger close enough in size to remove the wood from within the hole saws cutting. I used a couple of different hole saws to remove material and then followed up with my old standby 2 1/4 inch chaser. I still had to chisel out some wood. But, several hours later, I had a hole all the way through.

I wanted to use the bronze rudder stock as a guide for screwing in the pipe to ensure alignment. But, before the 10 foot long rudder stock could be put into the hole in the tailfeather, a hole was needed in the ground under the boat. When we pulled Mahdee out of the water 18 months ago and moved Mahdee to the original yard, the yard owner said not to worry about the rudder until Mahdee was in the yard because we could dig a hole for removing the rudder. When Mahdee was in her resting spot in that yard, he informed us that, oops, we had a sewer main directly below the rudder. That was annoying, but once it was decided that we were going to replace the tailfeather we were able to remove the rudder by cutting it out of the tailfeather. How we were going to be able to reinstall the rudder was not figured out before we decided to remove Mahdee from that yard. In the new yard, Mahdee sits on gravel and the owner gave us permission to dig a hole. Others in the yard warned that the boat yard sits on an old used car dump with clay and gravel on top of the old cars. We were lucky that John owned a nifty jack hammer that made digging the 4 foot deep hole, much, much easier. We didn’t hit anything metal or really solid which caused one of the boatyard wags to comment that since we hit no metal car roofs we lucked out: that the rudder shaft must line up with the top of an old convertible.

John and I struggled to get the 200+ pound shaft into the hole and discovered that I dug an inch too shallow of a hole. John asked why I hadn’t measured, but I had. I then realized I forgot to add in the 1 1/2 inch for the gudgeon pin. A little more jack hammering and digging and the hole was deep enough. But, it didn’t line up enough to get the stock through the tailfeather. Some more digging and more struggling with the stock and it was in. At one point, John and I fantasized that we would build up the oak rudder on the bronze stock and get it all faired and glued up on the bench before putting it on the boat. The two of us could barely lift just the stock up and onto the gudgeon, so we went to plan “b.” My plan “b” is where John gets to figure out how to attach, build up and fair the rudder with the stock on the boat. Meanwhile, we leave the ditch just in case we need to go to plan “c.” I was also in favor of delaying threading the pipe into the tailfeather, but John wouldn’t let me get away with that procrastination. With the two of us armed with giant pipe wrenches and 5′ extender bars, we were just able to thread that pipe into the tailfeather. It most certainly isn’t too loose, and it didn’t split the tailfeather apart which was John’s fear.

The best part is that the alignment with the gudgeon is great and it appears that the steering gear will fit without any modifications to the transom or deck beams. It is really, really exciting to finally have a rudder on Mahdee.

Dread tasks –the propeller shaft hole

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…

Redrilling for the shaft log

Replacing the counter timber last year meant that the 2-3/8″ and 32″ long tube drilled though Mahdee’s stern post and counter had to be re-drilled. After re-drilling, David drilled a “counter sink” so to speak for the larger stuffing box and cutlass bearing to fit around the bronze shaft log.

Here, David is relieved and happy. The boring of the tube went fine and the counter-bore also went well. He rigged a funny little jig to do the counter-bore by using a hole sole (backwards) as a centering bit and another hole saw (forward) to drill out the counter bore.

shaft log

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