MacGregorSailors.com

Hello, everybody
On my original Mac 26 X, the engine (a 50 HP Johnson, eventually replaced with a 50HP ETEC) was mounted on a plastic plate. Two upper hefty bolts that go through the wall of the well, with bent washers. Two lower ones.

Last year, I switched to a 50HP Yamaha, which doesn't seem to be much heavier. After one season, I noticed that the lower two corners of the plate were cracked. The engine doesn't seem to be going anywhere, but I am still worried a little.

How do you guys have your engine mounted? Do you use two vertical (well, slightly slanted) metal tongues? Anybody else has a plastic plate? The dimensions of mine are 10 x 14, but the new one seems a thinner than the original one, if memory serves. And it's definitely brittle. The dealer who installed it claims that that is the standard plate he uses for a 50 HP... but he has no experience with Macs. Only power boatd

Thank you in advance!

Two bolts on the top and two on the bottom with a plastic spacer between the engine and the transom. The spacer is the width of the widest part of the engine bracket, about an inch longer, and 5/16" thick. I know for a fact it's been there for 15 years have no doubt that it has been there additional 10 without any cracks.

Thank you so much, Bill.

Anyone who has a different type of mounting? No one has the engine mounted on a square plastic plate?

March wrote: ↑Sun Aug 31, 2025 5:54 am Thank you so much, Bill.

Anyone who has a different type of mounting? No one has the engine mounted on a square plastic plate?

Here's a photo of my transom after 12 years of a BF50A and 9 of the ETEC90. The Etec was mounted on two aluminum wedges that in retrospect were not required, and they reduced the contact area on that plastic filler plate on the transom. As you can see, lots of surface cracks, but nothing in the actual fiberglass structure, as the dealer and I inspected the transom inside and out before installing the Suzuki. We cleaned up the surface and filled the cracks with thickened epoxy, a very easy process requiring no special knowledge or tools, and just some West Systems 105 resin, hardener, and silica filler.





When we mounted the Suzuki DF90A, we added an aluminum plate over the entire engine-mounting area of the transom, with a little 90-degree bend to hang it from the top of the transom (the black piece in the photo below):




The net result is very clean:

Nice job StarScream!
Very nice!

Indeed! Nicely done. I was thinking of an aluminum plate, too, but aluminum tends to corrode slightly. I concur with Bill: two tongues might do the job as well. A plate that covers everything in-between doesn't seem to have any major additional structural benefits--maybe?

Hi All!

We did something similar to StarScream when we upgraded to our Suzuki DF60AV.
Yes it was a bit over kill but after poking around inspecting the existing transom structure I felt it wouldn’t hurt to add a 3/4” thick G10 load distribution plate before we installed the new engine.
I trimmed the G10 plate (ordered through McMaster-Carr) to fit flush within the stern transom engine mount area. It was then given a radiused bullnose edge. Finally I epoxy primed it twice then applied 3 coats of ablative black paint.

When mounting it I used 3M 4200 to seal all the mounting bolt holes. (Yes I anticipate there will be adverse vocabulary used if I ever dis mount the engine but I’d rather never have to contend with ANY leakage or water penetration.
https://macgregorsailors.com/mods/index ... em&id=2188



G10 was selected over Aluminum given our usage will be in salt, brackish and fresh waters.
Giving the engine an even slightly larger reaction contact area only helps.

Best Regards
Over Easy

Way cool! I'll keep in mind the G10. Aluminum would still work, would it not? I have found a local craftsman willing to do it.
Thanks!
March

Hi March!

Yes, Aluminum will work with 5808 being the better aluminum alloy for in water use corrosion resistance.
It’s what most bare metal aluminum boat hulls are made from.
It’s a common industrial aluminum alloy but not everyone carries it.
A 3/8 to 1/2 thick plate should provide the stiffness to distribute the loads evenly.
Please remember it’s well worth getting the contact-to-hull surface edges radiused as large as you can.
You don’t want a sharp edge stress riser!

Corrosion is dependent upon several factors.
Time/duration in water is a big factor compounded by the type of water such as salt or fresh as well as the pH value (toward acidic or toward basic). A boat that only gets wet for a day or weekend is going to have a limited amount of corrosion but a boat that sits in the water for 8 months could be a different story.

McMaster-Carr and Grainger should be possible sources for either the aluminum or the G10 plate stock

Best Regards,
Over Easy

Here we go. Metal plate, at the lip.

SurfsideNomad wrote: ↑Tue Nov 11, 2025 10:47 am
Do you have any info on the kicker mount ? Did you do that yourself or was it already like that?
Thanks !

Did it myself, actually quite easy.

After several years of running like this, it won't be a perfect solution for everyone. It works fine for my usage case, in calm river and lake water, but it's mounted to high for ocean use. But if it was mounted lower, then it couldn't get out of the way of the wake created when running with the big motor.

It also sits unstarted for waaay too long during the season, and keeping the fuel fresh and the carb ungunked is a real challenge, one that I routinely lose.

If I had to do it over again, I'd go for an electric motor mounted in the same place. For me, it's an emergency motor that would help me make the last 100 ft back to a dock if I'm under sail because of a main motor failure.

Here's the link to my install:

viewtopic.php?t=27563&hilit=bf2.3