Delamination - Transom

[Joker757]

I have the engine, drive, and transom assembly removed. While prepping the bilge for paint I notice some fiberglass flaking around the bottom and sides of the hole in the transom where the drive goes. Upon further inspection I discovered that the fiberglass has started to delaminate round the edges on the sides and the bottom. On the bottom of the hole a very small section of the wood was rotted away. the rest is solid (inspeced by tapping with hammer) but still damp. I removed all of the fiberglass that would come off easily and where it sounded hollow. Did I catch this in time and how do I go about repairing it. I've attached some pics.

1999 Maxum 2800SCR - 7.4L MPI - BIII

Thanks.

 

[Yacht Dr.]

Re: Delamination - Transom

Hello Joker..

Without a moisture meter its kinda hard to say.. the percussion test sounds good..but do you want to encapsulate water in your trans ? Breeding ground for rot.

Thats really the only way to tell what your dealing with m8..

Unless you have Xray vision

Have it metered IMO..

YD

 

[Joker757]

Re: Delamination - Transom

I have a moisture meter I use for woodworking. Will that work?

 

[Joker757]

Re: Delamination - Transom

wouldn't the moisture meter only tell me the moisture content of the transom and not if it has delaminted? I know that there is no more delam. I would let this dry for as long as it took to get all the moisture out. Isn't that where the meter would come it? To tell me if its dry enough to glass? As far as the small amount that has rotted do I just glass that in or do I have to cut a section away and replace? I've alreay removed all of the rotted wood. What you see in the pic is sold but still damp.
Thanks.

 

[Yacht Dr.]

Re: Delamination - Transom

I have a moisture meter I use for woodworking. Will that work?

Hello Joker..

If you put your meter on the trans and reads "moist or wet" that is not good for laminating. If you want to use epoxy understand that its water soluble..meaning until its cured it can fail in cure.

YD.

 

[Joker757]

Re: Delamination - Transom

my meter gives me moisture content in %. What would be a good %? I'll have to let it dry for a day or two as I washed the bilge today to eventually prep for paint.

 

[Joker757]

Re: Delamination - Transom

OK...I've checked with my moisture meter. Right where the wood is damp (not rotted) the reading is 39%. I know this is way too high. One inch away at the surrounding areas it's 0% to 6%, this is pretty dry. In furniture making I want my hardwoods to be no more than 8% (I usually let it dry to 6% though). Given this it appears that the moisture is isolated to the immediate area at the bottom of the opening for the drive. I've exposed it (removed the glass). I'll keep an eye on it over the next few days. Hopefully we don't get any rain.

How should I go about repairing this?

Thanks.

 

[jonesg]

Re: Delamination - Transom

Put a heatgun to it, or heatlamps or direct sunlight and let dry.
Dig out the rot. Use a grinder if it will fit.
flush with acetone to displace any remaining water.

treat the rest of the wood surrounding rot with an organocide.
Antifreeze is supposedly the best, kills everything. (even cats!)

Dry it again.

soak wood with poly resin thinned 50/50 with acetone so it soaks in like water.
then you need a putty to build it up where you dug out the rot, use glass fiber in putty for strength.
Resin, cabosil and chopped fiber (scissor cut matting for chop'd fiber).

Then resin/matting over the whole repair, I would grind back all around the opening and resin/mat the whole thing to keep everything flat.

Paint the transom opening edges with resin to seal it up good,
let it soak in and repeat.

 

[Joker757]

Re: Delamination - Transom

Thanks jonesg!! I have some Epiglass and I'll order the rest. I'll get a cat from the pound on Monday to test the antifreeze theory....LOL. I'll post some pics of my progress. There wasn't much wood rot. I'm also going to take the plug casting out tomorrow. It sits right below the problem area so I want to make sure that nothing has migrated there and get it good and solid as well.

PS....just kidding about the cat.

 

[Joker757]

Re: Delamination - Transom

what should I use to grind the glass off? I have an pneumatic angle grinder. What type of media to use (sandpaper, wire wheel, etc)? Also can you recommend a good putty to use? Thanks again.

 

[jonesg]

Re: Delamination - Transom

angle grinder is good, 50-80 grit disk or whatever strips it off, I like diamond steel disks for masonry (dewalt).

DIY putty, unwaxed poly resin, mix with cabosil to mayonaise texture , add chopped fiber to peanut butter texture, then finally catalyst,
watch out it will go off in a flash of heat in 2 minutes or less.
Just mix up 1/2 cup to try it first.
You'll get a feel for it.

 

[Joker757]

Re: Delamination - Transom

I want this to be a permanant repair. Would it be better to cut the affeacted area out and replace. Would only be an are about 2inches by 3 inches. If I decided to go that route how would I go about it? What would you do if it where your boat? I want to do the best job possible given that I've gone this far.

 

[jonesg]

Re: Delamination - Transom

if the rot was all around the cutout I'd remove a 2 sq foot area and rebuild with laminated ply or seacast it, then glass over the whole thing.

A skill saw set to the right depth can be used to cut the outline then start chiseling ( when I say chisel I mean chainsaw) it all out, seacast can be done flat in a box on the ground with a plug of the cutout centered in it... then fitted into transom and glassed in place. WAX the box and cutout plug.

But from your description I'd do as I wrote initially, its a good fix and will be good for 20 yrs.

 

[Joker757]

Re: Delamination - Transom

thanks Jonesg. I really appreciate your input. the rot was only in the lower area of the drive opening as indicated in my pic. Just to be sure though should I drill a few holes to make sure? Heck if I can get 10 years out of it I'd be fine with that. The other edges of the opening are fine. If I drill holes to inspect what size and how many. I would think too many holes would weaken the transom.

 

[Joker757]

Re: Delamination - Transom

I drilled some holes from the outside going in this morning to see how far the rot has gotten. Here is a pic from one of the holes. The pinkish material is closer to the exterior and the darker stuff is from the interior side. I did several 1/4" holes about one inch apart. No water seeping from any of the holes. This sample is pretty consistant of what I got from all the holes.

Thoughts?

 

[Yacht Dr.]

Re: Delamination - Transom

Hello Joker..sorry for the delay

Anything over say 13-15% is iffy.. over that is wet ( but not necessarily bad m8 )

Take the Drain fitting out and let it dry naturally..( dont heat gun IMO or you could steam moisture deeper ) you could tent it and put a dehumidifier in there if you wish.

Meter the affected area.. mark were its too elevated and cut the fiberglass skin off. See whats under it..It might be good wood that just is moist and not rotted.. take some pics.

You might just have to do some minor scabbing like you said. Then just bevel the glass and re-glass the repair.

YD.

 

[Joker757]

Re: Delamination - Transom

I'm going to remove the inside skin 1ft out from the opening all the way around. Apply some antifreeze stick a fan in there for a few days and glass in. What do you think?

 

[Joker757]

Re: Delamination - Transom

Here's some pics. No rot just wet wood. I'm going to put a box fan and light in there for a few days and let it dry. Then I'll spray down with antifreeze and let dry some more. Check with my moisture meter and glass in.

Comments/suggestions are welcomed.

 

[Yacht Dr.]

Re: Delamination - Transom

Hello again Joker..

erm..from your pics I have some questions..

1st pic looks like dark wood ..almost half of it..( bad )..

2nd pic looks like rot starting on that port side edge..and bottom..( hard to tell on the bulk of the wood from dust ).

IMO..replace trans. you allready have all but some mat remaining on the inside trans..

Just how I would do it if it were in the shop m8..

No matter which way you go..you already have to grind all the gel/webbing off the bottom, hull..for prep on new layups... its only a matter of how much resin/glass or ply you would want to order....how far do you want to go m8..

Its debatable .. cut and scab..or replace.. Its up to you..I dont scab as a profession..but DIY might be OK to do..Ive just never done that and will never do it.. just me OK.. ( I have to live with knowing that Another family will ride in this boat..Ill only do repairs that I would have MY children be safe in. ( not to say other repairs are faulty..just Ill make sure there going out safe ! )

Hope this helps m8..

YD.

 

[Joker757]

Re: Delamination - Transom

Hello again Joker..

erm..from your pics I have some questions..

1st pic looks like dark wood ..almost half of it..( bad )..

2nd pic looks like rot starting on that port side edge..and bottom..( hard to tell on the bulk of the wood from dust ).

IMO..replace trans. you allready have all but some mat remaining on the inside trans..

Just how I would do it if it were in the shop m8..

No matter which way you go..you already have to grind all the gel/webbing off the bottom, hull..for prep on new layups... its only a matter of how much resin/glass or ply you would want to order....how far do you want to go m8..

Its debatable .. cut and scab..or replace.. Its up to you..I dont scab as a profession..but DIY might be OK to do..Ive just never done that and will never do it.. just me OK.. ( I have to live with knowing that Another family will ride in this boat..Ill only do repairs that I would have MY children be safe in. ( not to say other repairs are faulty..just Ill make sure there going out safe ! )

Hope this helps m8..

YD.

why replace dark wood even though it's not rotted?

didn't realize I had to grind the bottom of the hull. how far down do I go with this step? If replace how far up do I go? What you see is the section between the two stringers. Do I need to go all the way to both sides? Whats the best way to get the wood out while leaving the outside skin intact? I've never done fiberglass work before so as much detail you can give will help a lot. I'm in no way doubting what you recommend just would like to know why. I want to do the job properly. I have the engine and drive out and have gone this far and would hate to half *** it if it's not going to be expensive or beyond my capability. I'm an avid woodworker and I'm sure I have all the tools I could possibly need.

Lastly I have a pneumatic angle grinder. What kind of disc would you use to grind the glass off? I'll post a full pic of the stern so you have an idea as to what I'm dealing with.