Motor and Motor Bracket, Part 3, Transom Plate, Construction

The motor bracket and transom plate, dry-fitted
Having purchased a Garelick heavy duty motor bracket, and having determined where I should mount it on the transom, my next task was to construct a transom plate. This piece of aluminum would not only provide the additional space needed for the installation of the bracket in the area of the existing cutout, but also it would provide additional strength to the transom itself. This bracket and the Yamaha 9.9 High Thrust motor that I would mount on it were quite heavy. In 1975 when this boat was constructed, relatively lightweight two-stroke motors were the norm. Now that this beefy four-stroke would hang from this transom, this plate would make amends for a transom that had not been designed with this type of motor in mind. How I constructed this transom plate for Oystercatcher, my Ericson 25, is the subject of this posting.
I began by ordering some sheets of aluminum from I ordered two different sheets of .19 inch, i.e., 3/16 inch 6061 T6 aluminum. The first sheet was 24 inches x 24 inches. The other was 12 inches by 48 inches. The first would be for the transom plate. The second would be for the backing plate that I would install on the cockpit side of the transom. That is the subject of my next posting. I purchased 3/16 inch aluminum on the advice of a friend who specializes in marine aluminum work. This was the same friend who had advised me to reinforce the transom.
The first thing I did after I received the aluminum and set up my cut station next to the boat was to remove the protective film from the large sheet - the one that I would use to make the transom plate.
In terms of the materials that I assembled for this job, aside from the aluminum, one item was Tapfree, a cutting oil that I would use for each cut with the saw and each hole that I would drill.
I also got some Bosch brand T101A3 blades for my jigsaw. These were labeled as Plexiglass blades, but they were also suitable for cutting aluminum.
My first cut reduced the large sheet to the appropriate width.

As I made the cut, a friend gradually applied oil to the cut-line in front of the blade.
After I cleaned off the oil and aluminum sawdust, I clamped the piece to the transom.
This enabled me to scribe an arc that corresponded to the curvature of the hull.
I made sure that the arc was slightly recessed relative to the edge of the hull and transom. I of course did not want the edge of the aluminum to project beyond this edge of the boat.
Now it was time to make this long, graceful cut.
In order to ensure that the cut was as clean as possible, I made it without pausing for a rest. In front the blade once again a friend applied the oil as I moved along the line.
Not bad for free-handed work. Teamwork makes the dream work, as they say.
Believe it or not, almost a full year had passed since I had purchased that Yamaha motor during that annual camping trip with my buddies to Edisto Island. That's how busy I was with all the other projects involved with the refitting of Oystercatcher. This year, instead of camping at Edisto, my buddies and I decided to hang out at my house and work on the boat. This meant that we'd still do a lot of outdoor cooking, just like we would have done on Edisto. During the middle of the day, we fired up the burner and boiled some peanuts for a snack. We'd bought these green peanuts at a local Piggly Wiggly grocery store. For those unfamiliar with this fall and winter ritual in the American South, you boil green peanuts, i.e., fresh unroasted peanuts, in heavily salted water. After a few hours, the peanuts become soft, and the shells become mushy. When the time comes to eat them, you tear one half of the shell off and eat the peanuts out of the other half of the shell. To those who've never had boiled peanuts, this always sounds disgusting, but believe me, this warm, salty goodness is something that many people love, if they ever get a chance to try it.
One of the others things that my friends and I did on this day was to remove the rudder from the transom. This was definitely not something that I could have done by myself, and it was essential that we remove this to accomplish the necessary work on the transom plate.
Now that we had cut the piece of aluminum into its proper shape, we needed to drill the appropriate holes in the transom. The holes would then allow us to work backward, so to speak. The holes in the transom would serve as guides for the holes we would drill in the aluminum plate. More on this later.
We began by drilling the holes for the motor bracket. Only afterwards would we figure out where to drill the holes for the securing of the perimeter of the aluminum plate to the transom.
The bracket fit just right in the allowable space.
Notice how the bottom right corner of the bracket is flush with the edge of the transom. Also notice how the top of the bracket extends above the cutout. As I said, this was one reason why I needed this aluminum plate. Finally, notice how the bracket is offset relative to the center of the cutout. As I mentioned in my previous posting, I had determined that this was necessary in order to compensate for the offset tiller on the Yamaha motor.
One of the complaints that online reviewers had of the Garelick heavy duty bracket was that it was difficult or impossible to operate the swing lever mechanism. These complaints usually came from sailboat owners who did not have cutouts in their transoms. The picture below illustrates well how it would indeed be difficult to operate this swing lever mechanism without a cutout. I should note to Ericson 25 owners that despite this, it is still possible to insert a panel into the cutout after you have deployed or retracted the motor. When you have deployed the motor, the swing lever mechanism is out of the way, and when you have retracted the motor, it is possible to put the swing lever mechanism in a position more vertical than the one depicted here.
As we drilled the holes through the transom, we made sure that they cleared all obstructions, both in the cockpit and down below in the lazarette.
You'll recall that it was necessary for us to take into account the sole of the cockpit. Some of the bolt holes were above the sole, others below it.

After we had drilled the holes for the motor bracket, we marked and drilled the holes for the perimeter of the aluminum plate.
This took a lot of time and effort. Once again we had to take into account the cockpit sole. We also had to take into account other issues in the cockpit. Notice the circular hatch to the right of the cutout. I had earlier installed this hatch so as to take advantage of the wasted space in this area of the boat. It was here that I planned to stow docklines. Without the access to this space that this circular hatch provided, I would never have been able to install the hardware for the outer edge of the aluminum plate.
After we had drilled all the necessary holes in the transom, we clamped the aluminum plate to the transom and marked all of the holes. This required me to climb into the cockpit and mark the aluminum by sticking a pencil through all of the holes. I also had to climb into the lazarette and mark all of the holes in that area in a similar way.
Back at the cut table, we began the tedious process of drilling all of the holes.
One of us would drill, while the other would apply the oil to the drill bit. Ideally, we would have used a drill press for this, but with team work we were able to drill holes that were, for the most part, true. Two of us would stand at right angles to the driller to make sure that he was holding the drill bit as vertically as possible. We had used the same technique when we drilled the holes in the transom.
After we had drilled all the holes, we clamped the plate to the transom. It was at this time that we made fine adjustments, inserting screws into each hole, making sure that everything lined up perfectly. If a hole happened to be slightly off, we would insert the drill bit and widen it slightly.
Satisfied, we now began the task of countersinking each of the holes around the perimeter. This would allow the flathead screws to sit flush with the surface of the aluminum plate. Before we started the countersinking process, we practiced on one of the scrap pieces of aluminum.
Just as we had done when we had drilled the holes, when we countersunk them, one of us operated the drill while one of us oiled the bit.

After we had countersunk each of the holes around the perimeter, we did another dry-fit of the plate to the transom to make sure, once again, that everything was lining up just right.
We then dry-fit the bracket to the plate. This again required some additional drilling here and there to make sure that everything lined up perfectly.
Satisfied with our labor, we took a few pictures of our work before cracking open a few cans and firing up the smoker.

This ends this posting of how I, with a little help from my friends, constructed the aluminum transom plate for Oystercatcher, my Ericson 25.

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