Spider crack question

"I am replacing my gimbalhousi

"I am replacing my gimbalhousing assembly on a 1980 Aquasport. Since i had it all apart, i decided to sand down all the paint on the transom. In doing so, i noticed alot of spider cracks. it looks like someone put some kind of clear resin or apoxy over them. My question is: will marine-tex work on the cracks, or is there something i can buy at a marine store that i can do myself?"

Can you post a pic? I can'

Can you post a pic? I can't picture what the set-up looks like but sometimes cast aluminum looks that way when there's really no issue.

"MistaHays,
Sorry,

"MistaHays,
Sorry, the cracks are on the transom, not the gimbal housing, if that's what you ment."

"Got it. I didn't read clo

"Got it. I didn't read close enough! Can't answer the fiberglass question, but Guy Gasper can... if he sees this.

I would wonder if your transom is waterlogged."

"here is some info on how to f

"here is some info on how to fix.
Before you begin, wash the area with soap and water and rinse it thoroughly. If the surface is oxidized, restore it with a rubbing compound so you’ll be able to match its colour accurately. Once the surface is clean and dry, mark off the repair area .
Next, gouge out small, narrow cracks scratches that are too deep to remove with until they are wide enough to fill with gelcoat paste. A miniature grinding tool like a Dremel is ideal, but the sharp point of a can opener will work too. (If you don’t open the crack, you won’t be able to force the gelcoat into the repair area or expose enough surface area for the repair to adhere.) Then sand lightly with 220-grit sandpaper. After sanding, thoroughly clean the area with acetone to remove the sanding residue and any waxes or other contaminants that might interfere with the bond between the damaged surface and gelcoat.
The next step is to match the colour of your existing gelcoat. Start with a white or neutral gelcoat paste (not resin) and begin adding tiny amounts of coloring agent. Mix several test batches of gelcoat and pigment, add hardener and allow them to cure (gelcoat changes colour during the curing process). Once you’ve found an acceptable match (an exact one is nearly impossible), mix a final batch using the same ratio.

Next, using a putty knife, fill the areas to be repaired with the paste you’ve mixed. Force out any air holes and be sure to overfill, as gelcoat has a tendency to shrink as it cures. When you are finished filling, seal the repair off from the air with a PVA curing agent or a piece of Saran Wrap or wax paper – gelcoat does not cure properly when exposed to air.

Once the gelcoat has fully cured, sand the repair smooth (wet sanding works particularly well with gelcoat). You can start with 220-grit sandpaper and, for a really slick surface, finish with at least 400- or 600-grit. Finally, apply a coat of high-quality marine polish and your repair is complete."

"You don't say how old the

"You don't say how old the boat is but spider cracks are indications of age, and stress on a transom. Before you go ahead with the cosmetic fixes I would encourage to make sure that the transom itself is not comprimised with water. Most older boat transoms are a sandwich of plywood between to layers of glass. If water seeps into the wood it will not take long for rot to start and all the outside patching will do no good other than fooling a prospective buyer."

As I understand...

tap the

As I understand...

tap the transom with a hammer to see if you get a dull thud or a tight knock. Dull thud means waterlogged.

Drill a series of 1/4 inch deep holes on the inside of the transome. Any black shavings or water weeping from the holes means the transom is waterlogged and probably done.

The holes may be filled with fiberglass work.

"adding to MistaHays' inpu

"adding to MistaHays' input:

tap with a 'no bounce' hammer for best results.

if you get a thud, determine the area(s) and mark with a grease pencil. If not too extensive, the drill & fill approach, using 'gitrot' or some similar product may be viable. If extensive, best results are obtained by rebuilding the transom. Not a cheap solution; if you have to go this way, don't skimp and buy cheap.

It is highly possible that the install wasn't optimal from the factory. The outer plate-transom seal 'leaked', a lamination bond let loose, and then the cycle repeats. Using the boat then 'flexes' the transom and the cracks are evidence. that said there are other causes for those types of cracks. If in doubt, you can always hire a marine surveyor for a second opinion.

good luck!"

"I was gonna throw in my 4 cen

"I was gonna throw in my 4 cents but the guys above answered the question pretty well.
One thing that needs to be addressed though is whether the cracking is just the gel coat or is it also into the substrate or laminate below. If it's into the 'glass you may have to open them up a little deeper and wider with the Dremel . Rough up the grooves as best as you can w/folded 80 or 60 grit to give it some "tooth".
Mix a paste of vinylester resin and milled glass fiber & catalyze it. Force the mix into the cracks. Let it cure, Rough it up again wiping with acetone then do your finish work with the gelcoat. Sand to at least 800 or finer then compound.
The problem with spider cracks is even after all this they may very well come back due to stress on that area or other underlying problem.
As stated above a wet core could be a cause. And if it's wet and you have to deal with winter that wet core can freeze and expand causing cracking. Or, then again it could just be from fatigue. As 'glass ages it will "dry out" so to speak, especially with some of the old poly. resins and become a little less forgivng when it flexes.
Good Luck from me too."