Transom Dry Rot - UPDATE

M

MikeeH

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I'm installing a new FF/GPS combo unit on our 1988 Wellcraft 190 Classic (165 HP Mercruiser, Alpha 1 OD). I removed the old sounder from the transom and had to enlarge the hole in the transom where the cable came through to allow for the larger plug and cleaned out all the old caulking. At no ime did any water or wetness appear from the cable hole (well above the waterline) or the screw holes where the sounder was mounted on the transom (well below the waterline.) However, when I poked around in the hole I cut for the cable I found dry rotted wood! Bone dry! I don't get it... how does that happen? Fortunately, its not near the OD and that area appears solid.

I'm thinking of shooting expanding foam in the hole and then, after cleaning it up I'll epoxy the exposed area. Any thoughts? Good plan or not? TIA
 
Mike, before using expanding foam look into Smiths CPES...this is the best cure for rotten wood! You can google it for more info...the are a great company.
 
CPES doesn't really work for dry rot...unless it's a small area or you keep pouring it in til all the voids become solid, cured epoxy. a very expensive proposition. Just like making a sponge solid. CPES will kill all rot spores it contacts though.

Go in from the inside and drill holes to find the extent of the rot and dig it all out, then fill with thickened epoxy...unless there's a LOT of rot.

Who is John Gault???
 
Shooting expanding foam in the hole will do nothing but fill the void where you drilled.

Git rot is a kin to putting a band aid on a gun shot wound.

The source of the water to the core is the main concern. Followed by, how extensive is the rot. Really only way to tell is to either open it up, or drill holes in a grid pattern and poke around. (Method can be difficult to cosmetically cover up though).

Do you really feel like getting into a transom job? If you are confident that the majority of the core, and especially around the OD is solid, you could boat on and keep an eye on it.

Have you taken a mallet and sounded out the entire area? This will tell you real fast if you have a wide spread rot issue.
 
quote:
Originally posted by psalzer

quote:
Originally posted by Riverratt

Or maybe some "Git Rot"

Click to expand...

Git Rot = CPES

Click to expand...

My father used git-rot back in the day there were no fiberglass boats :)He swore by that stuff!

Walter
 
I did sound the transom with a rubber mallet and, like I said, it seems pretty solid around the OD. That said, since its not wet and the boat is in the water all season (I pulled it in September) I'm a bit perplexed about the cause and when this happened. I do have a package of Git Rot but its a small package. I hate the idea of drilling holes in a grid throughout the transom because I hate the idea of patching them afterwards but there may be no other option.
 
How big is the hole? You could just dig out the rotten wood around the hole with say an Allen key in a drill, wet it out with thin epoxy and then back fill with thickened epoxy. After that, depending how much you care about how the patch looks esthetically, you could just put a epoxy coated circular glass cloth patch or two over the filled hole area. Or gel coat it to match.
 
quote:
Originally posted by MikeeH

I did sound the transom with a rubber mallet and, like I said, it seems pretty solid around the OD. That said, since its not wet and the boat is in the water all season (I pulled it in September) I'm a bit perplexed about the cause and when this happened. I do have a package of Git Rot but its a small package. I hate the idea of drilling holes in a grid throughout the transom because I hate the idea of patching them afterwards but there may be no other option.

Click to expand...


Was there any difference in sound between the area around the OD and the area where you found the rotted wood? I had a boat surveyed that had a soaked area just to port of the OD, and I couldn't hear the difference. I guess I have a tin ear. Surveyor confirmed it with a moisture meter.

You really need to be certain that you know the extent of the rot.

My .02
 
If you have the room to work, drill from the inside.
 
Have a 200 lbs. (or more) friend jump up and down on the outdrive while in the down position and watch and see if the transom flexes any at all.
 
quote:
Originally posted by L. Keith

Have a 200 lbs. (or more) friend jump up and down on the outdrive while in the down position and watch and see if the transom flexes any at all.

Click to expand...


+1 Can't hurt. And it might make for a good video for YouTube. :-)
 
"Have a 200 lbs. (or more) friend jump up and down on the outdrive while in the down position and watch and see if the transom flexes any at all."

OK, now you guys are scaring me! ;)

I can hear the difference in the sound from where the hole is and the area around the transom. Its a very distinct difference. I'll see if I can poke some holes from the inside.
 
Check the stringers where they meet the transom. Just in case that be how the water transfered into the transom.

I drill the area to find the rot and or water.

If there is a alot of water I drill a few extra spots out high and low till I find the spot that lets water drain.

I inject thinned ( acetone ) epoxy into drilled holes after the core has dried a bit. Usualy from the inside and do a skim coat over the area after with a touch of paint after. I start at the top and hope to see epoxy bleed out from bottom holes. This can take a few days covering up the leaking holes and working your way to the top.

But if the transom core is a total loss it all comes apart from the inside of the boat.
 
Fortunately, after further investigation it seems all is OK. I took a closer look at the transom from inside the boat and found that the solid wood core appears to be only in the area immediate to the OD. In fact, when examining the transom from inside there is a noticable large difference in its thickness at the OD and in an area about 8" out from the OD, probably about 3" thick versus 1" or so on the outer limits. I also climbed onto the OD (I weigh 250) and bounced it with the trailer frame blocked No visible flex. And, I I said before, no wetness to be found anyhere that I removed hardware and poked around. I'm sure what to make of the stuff I thought was dry rot.

WHEW!!! I can sleep better now!!
 
I have seen transoms flex when the outdrive is trimmed up and then pulled/pushed up and down. If you ever see this, the transom is toast.
 
Charlie... I didn't "jump"... hell, I'm 63 years old and I can;t jump much of anything any longer... frustrates tbe hell out of the Admiral!! ;) No. I simply bounced it a bit.
 
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