Motor and Motor Bracket, Part 8, Installation of Components

The transom plate and motor bracket installed
Having painted the transom plate and the backing plates, it was now time to install the components on either side of the transom. This was a somewhat messy and time-consuming process, despite its seeming simplicity. How I carried this out on Oystercatcher, my Ericson 25, is the subject of this posting.
I began by dry-fitting the three components to ensure that all the holes would freely accept the screws. Better to know this now rather than later, when all these components would be oozing with adhesive.
I mentioned this in a previous posting, but it's worth pointing out again. The transom is curved. This required me to bend the aluminum transom plate into position whenever I screwed it to the transom.

Satisfied with the dry-fit, I turned my attention to the cleaning of the transom and the cut-out. There were many years worth of dirt and grime in these areas.
I used xylene for this job. This solvent is the best at removing wax and adhesive residue from contaminated surfaces. I had no idea what the previous owners had applied to the gelcoat of this boat. Whatever it was, I wanted it gone.
The rag says it all.

The xylene did not remove the entire dirt stain from the exterior of the transom. 220 grit sandpaper helped.
Xylene was good for the finishing touches.
See the circular cutout? I mentioned in a previous posting that I had earlier created this cutout for a circular hatch. Behind it I planned to hang docklines. Without this circular cutout I would not have been able to access this space behind the transom.
I scrubbed the transom area in this circular cutout space especially well. There was still an oily residue here that had resulted from the previous owner storing gasoline in the adjacent cockpit locker.
Down in the lazarette I cleaned the backing plate that I had earlier installed against the transom. I discuss my installation of this backing plate in a separate posting on my work in the lazarette:
Now that everything was nice and clean, I took out my drill and installed a countersink bit. I used this to bevel the screw holes slightly. This would allow the adhesive to form small gaskets of sorts around each hole.

When I had finished beveling all of these holes, I cleaned each one of them with xylene.
Now it was time to clean the plates themselves.

I used sandpaper to give this unpainted surface some additional "tooth" for the adhesive I would soon apply.

I did the same thing with the painted surfaces. The only difference was that I used a sandpaper with a milder grit. The two-part paint is quite slick once it cures.

With everything ready to go, I broke out the caulk gun and the adhesive. This was Sikaflex 291 LOT, a polyurethane adhesive/sealant. I had used this same type of adhesive for the installation of the bronze through-hulls, and I had used it for the installation of several other pieces of hardware, such as the bow eye and the stern rail. This is a strong, marine adhesive but it's not nearly as strong as 3M 5200, which is only good for permanent installations. The letters "LOT" in the product designation stand for "Long Open Time." This means that this type of Sikaflex doesn't set-up as quickly as the normal type. I've never used that normal type, but I can tell you that I don't think I would ever want to use it. This LOT type does indeed give you a window of time before the adhesive starts to set-up. But this window is quite small. This stuff becomes sticky very quickly, and granted you can still move things around during this sticky phase, but it makes your work with these things difficult. The Sikaflex gets all over your hands and tools and everything else that is near.
It helped that I had a buddy visiting from out of town.
One of us applied the Sikaflex while the other picked things up and moved them around.

We started by setting this wooden backing plate into place.

Then we applied Sikaflex to the aluminum transom plate.

We made certain that the edges of the transom plate received plenty of Sikaflex. We didn't want any water to find its way between the bare aluminum and the transom.
We then applied additional Sikaflex to the joint between the wooden backing plate and the transom cutout.

Finally, we applied Sikaflex to the surface of the painted wood itself.

With the transom plate all ready to go, one of us picked it up and pressed it against the transom while the other slid a few of the screws into place.
We didn't want to install all of the screws and the nuts until we had installed the final backing plate.
Below, we see the aluminum backing plate that would face the cockpit. This was the third of the three components that we needed to put into place.

As soon as we put this third component into place, we began to install the screws in earnest.
One of us stood outside the boat, while the other sat in the cockpit. As we slowly turned the screws and the nuts, the transom plate slowly conformed to the curvature of the transom itself. At the same time, the Sikaflex slowly oozed out from the joints.
On the cockpit side, the aluminum backing plate sandwiched the wooden backing plate snugly.
Now it was time to install the motor bracket. For this we also used Sikaflex. We were not as interested in its adhesive qualities as we were in its sealing qualities. You'll recall that some of the bolt holes for this bracket were in the lazarette. No one wants seawater in that part of the boat.
To join the bracket to the transom we used carriage bolts. Yes, the bracket does appear to be out of plumb, but this is just an optical illusion on account of the curvature of the hull. Believe me, I checked for plumb many a time.
You'll recall that I could not use two of the holes in the bracket on account of their interference with the cockpit sole. In other words, some of the bolts were above the cockpit sole, while others were beneath it in the lazarette.
It took a lot of jiggling to seat the carriage bolts properly in their square cutouts in the black aluminum bracket.

It took even more work to clean up all the excess Sikaflex. The stuff was everywhere.
We probably used an entire roll of paper towels and a quarter can of mineral spirits wiping off the excess and wiping away the residue. It's easy to think you've gotten all this stuff off when you really haven't. If you're not careful, you can leave a thin translucent residue that's very difficult to remove if you let it sit too long.
Many months later I came back and cut off the ends of the screws with an angle grinder. I did not like the way they projected into the cockpit. You might ask why I didn't just buy shorter screws. The answer is that I needed these longer ones to pull all three of the components together.
In the lazarette I left the long screws alone, although I would have preferred to have removed them, if I had been able to get my angle grinder in there. I wasn't going to use my Dremel to cut these off. I had burned up the motor on an earlier Dremel cutting off a stainless steel 1/4 inch crew elsewhere in the lazarette.
Believe it or not the installation of these components took the better part of a chilly spring day.
After we were finished with everything, we still had to check on our work, tightening a screw here and there and wiping up a little more excess here and there as the plates and the Sikaflex beneath them hissed and popped and slowly settled into place.
Meanwhile, my buddy and I basted some ribs and nursed a few cold ones by the smoker. All in all, it was a pretty good day.
This ends this posting on how I installed the motor bracket and its various components on Oystercatcher, my Ericson 25.

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