82 transom repair

[Bwano]

I might cut fiberglass skin off outside of Arima and investigate extent of dry rot and ant 🐜 damage before install Suzuki. Easier now than later. 82 Chaser.
Pulled 90 HP 2 stroke Merc, poised to install 115 Suzuki 4 stroke.
Any transom repairs done here? Search did not find

[La-Z-Buoy]

To my knowledge (gleaned from this forum) there has never been a transom failure on an Arima. There has been mentioned cases of the wood being wet between the layers of glass though. Doesn't seem to affect the overall ability to carry the load.

[Danno]

Don at the Arima factory stated a few years ago that they've never had a transom fail. La-Z-Boy noted that but I wanted to back it up with Don's name. The wood in encased in fiberglass. If you think you have water in the transom wood, the typical treatment would be to put the Arima in a dry storage location, drill a few holes and train a light bulb or two on the hull to warm it up. A fan would also help. Give it lots of time to dry out and then plug the holes.

[Threeweight]

I believe the transom is 4 layers of fiberglass, with 3 layers of either 1/2 or 3/4" marine ply laminated in between.  Here's a photo that was posted a while back of a core that was cut out when I water pickup was installed:



I was worried about rot in my 89' Chaser transom when I repowered w/ my Suzuki, and was similarly told by Don that he would wouldn't worry about it, and any effort I made to replace the wood would only weaken the transom by cutting through the glass.

I have seen guys who beefed their transom up by installing an aluminum or stainless plate across it (on the outside), then mounting the motor over it.  If you feel like you've got some serious rot issues, that might be a way to go.

[croaker stroker]

My last Arima had water in the transom. To ease my mind, I did a lot of online research and found that dry rot does not occur in salt water. In fact, the old sailing ships used to use Rock salt in the bilges to prevent it.

I drilled a few 1/4" holes on the inside of the transom just above the bilge high water line and left them open.

[Bwano]

Thanks for the replies, folks. I definitely had dry rot in the plywood floors and stringers. Still undecided what to do at this point. I believe the Suzuki 4 stk 115 weighs a hundred pounds more than the Merc 90 2 stk. I have already made a 1/4" thick x 4" wide  x32" long plate for the inside of transom.

[Chief of the Boat]

Here's a drawing by Don.

[Markshoreline]

I love Don's drawings!  Would love to have a full set...

[Ssericz]

All the posts of no transom failures end today. I have been told by Belinda and don that there have been 2 cases of failure but due to owner/installation failures. Idk if they cut into it and didn't seal it up or what but that's what I know...


Does that mean I'm famous if a picture I take gets reposted by someone else? Haha that core shot was from my transom, there was some water at the very bottom but most likely from the drain plug. Not bad considering the boat was stored in a slip


Mark saltwater pickles the wood if in a 0 oxygen environment but it will rot the wood just it turns it to mush/pulp vs splinters

[Packman]

Don't worry about the wet wood, although you should try to dry it out some.  I bought an '89 Sea Ranger 19 that had about a dozen holes in the transom, most of which had been caulked and then had a screw driven in the hole, not a good fix.  When I removed the screws I saw brown water drip out. I was getting ready to install trim tabs, so I drilled the holes for the tabs for more "ventilation".  I then used a shop vac to suck out as much water as I could, while at the same time pressurizing the transom with an air compressor.
Quite a bit of water came out.  I then placed a small heater near the transom and let it dry out for a couple of weeks. I then filled the holes with MarineTex and installed the tabs.  The strength of the transom comes almost entirely from the layers of fiberglass, the wood is there for screws to have something to grab onto when mounting tabs or transducers.

[Markshoreline]

Very clever use of vacuum and pressure to get the wet out!

[croaker stroker]

In addition to salt discouraging wood rot....the transom plywood may be made with rot resistant Teak core plywood ?

My panels in both of my boats (both exposed to sun and freshwater baths for 20+ years) were surprisingly sound. They appeared to be made from Teak lumber core.  (Someone please correct me if I am wrong)  I have not been able to find a Teak lumber core plywood source.

[Chasin Baitman]

Sure would love to know more about those transom failures.  Like what the owners did wrong and how exactly the transoms failed.  Did their outboards go for a swim?

[Ssericz]

Unsealed holes in the transom, more than likely a failure in the form of fiberglass cracking but I doubt the ob went for a swim. I had a transom failure on my last boat but all that happened was the inner liner cracked due to the load. A week of work later the boat had a fresh transom...

[polarbill1999]

you are putting a 420# 4stroke on a 17?  wow

[Bwano]

Yes, Suzuki 115 4 stroke, is 416 lb. Mounted already. Done a couple sea trials. Have yet to take boat out for real fishing trip. Been waiting for my Yamaha T8 High Thrust, and the Arima Fixed Kicker mount.


Arima Fixed kicker mount arrived today. It is seriously massive, beautiful, and very high quality.

[Jay in Kitsap]

I am a structural engineer that about 10% of my work is on fiberglass structures - tanks, ductwork, fume hoods - not marine.  We often use plywood, 1x's, or 2x' as the form inside of fiberglass.  The strength of the wood is a great reserve but the design assumes that at some point that wood will be gone.

I know from discussions with Belinda and Don back around 2010 that the deck uses squares of plywood like 8"x8".  They are coated with resin, set on the lower glass mat when wet with a small gap between pieces.  If a hole allows water in and rot occurs the plywood square might be gone but the FRP is a two direction hollow tube shell.

I believe they do the transom in a similar way.  If where the engine mounts the wood is gone I would do a reinforcement plate.  I would also consider filling the void with a very low viscosity epoxy.  Sika makes some that run like diesel fuel.  Inject near top of void at one end until resin comes out the 2nd hole at the top of the far end.  One can get empty caulking cartridges to fill and inject.  West Marine has them I believe.