Hull chips above bunk boards? need opinions

[ZX180MI]

Hi all, Time to fix/ repair hull. I have a 96 Skeeter ZX180 I am repairing as I go. When I bought it I noticed above the inner bunk boards what looks like popped blisters. Some the size of a quarter. Looks like quite a few running above the bunk boards. Thats the only place I see this. Port side more than the Starboard. The chips are thru the gel/ I can see the smooth fiberglass top coating under them. Looks like the gel didnt seal to the fiberglass top coat in these areas. I can get pics this weekend. Cant figure out how to post pics, can someone help?. Can marine tex fix these? Or? Also Is it really that hard to lift / support back of the boat off the trailer? Anyone ever heard something like this before? (blistering of gel coat)?? Thank You..

[BASSCAT7]

Are these blisters where the carpeted bunks meet the hull ?

[ZX180MI]

Yeah where the bunks meet the hull. They look like blisters, but the glass underneath is solid. Look/feel more like chips. I'm thinking I could just re-gel coat them with the boat supported off the bunks? I seen some repair kits and vids on how to, but would like more opinions from you guys....

[BASSCAT7]

What has happened is a process called Osmosis.

Has nothing to do with the carpet thickness on the bunk boards. Nothing to do with the sun hitting the gelcoat.

This happens a lot on boats that are kept in the water, it is one of the reasons they paint the bottom with copper based sealing paints on water kept boats to prevent this.
Also happens on some trailered boats, depending on the quality of the gelcoat used, when they sit on the wet bunkboards.

Gelcoat is water resistant, but not totally " waterproof ".

If viewed under a high powered magnifier, you would see microscopic pores in the gelcoat, similar to pores in your skin.
These pores, depending on the quality of the polyester or vinyl ester resins used in the manufacturing process can actually let some water vapor pass thru overtime.

This is the reason you only see it on bass boats where they sit on the wet bunks.

Sometimes the water vapor is able to permeate the gelcoat thru the pores, and over time the water in the pore causes a chemical reaction with the chemicals in the gel forming a light acidic solvent formula, this creates pressure and a blister forms and fills with the water solvent formula.

The blisters will hold the water, and like a blister on your finger , will pop over time.

When this happens, the gelcoat layer will start to peel, exposing the glass mat/resin ( the actual hull structure ) to the water......this is where the real problem can develop. If the mat/resin had any breaks in it , it too can absorb water, only the glass mat will act as a sponge and hold the water.......this will lead to the hull delaminating over time if not fixed properly.

Most never know it is happening cause we rarely ever look at the hull that sits on the bunk boards.
Not too much you can do to prevent it from happening, other than jacking the boat up a little off the trailer and putting a coat of some type of polymer sealer like
Pro - Tec on the hull to seal the pores in the gelcoat.

Doesn't happen a lot, but when it does it can be expensive to repair in a shop if you can't get the manufacturer to cover it.

You can do it yourself with Marine - Tex or gelcoat. Just make sure the blisters are prepped well so the repair adheres right.

Good luck with your repairs.

[BASSCAT7]

It's an easy fix, but trying to get the color match is difficult.

Marine -Tex can be used on solid colors. can be tinted with the Evercoat repair kit tints.
Follow the directions for the Marine-Tex,. Clean the chipped area well, apply MT as smooth as possible to lessen the sanding when dry.

Get the flaked/colored gel coat directly from the boat manufacturer to get the best color match, they should be able to send you a small half pint container.

You'll need some catalyst MEKP,( Methyl Ethyl Ketone Peroxide ) can be bought at auto body supply or most larger auto parts stores. This is nasty stuff, treat it like you would acid.

You can thicken the gel by adding talc powder to make it a paste type to get on hard to reach areas.

Clean the blistered area real well, degrease with some Acetone, lightly sand the edges to remove any loose particles.
If there are any gouges into the actual glass use a Dremel tool, bevel the edges sloping into the repair area. Make sure there are no ledges.

Tape off the area around the repair.

Stay close to the repair. Make sure there are no tape ends in the sanding area. The purpose of the tape is to avoid a mess and protect the area around the repair from the sand paper.

Mix about 1/4 to 1/2 inch of Gelcoat in a waxed paper cup with 5-7 drops of MEKP.
Stir completely, in addition to mixing in the MEKP, the gelcoat is dissolving the wax off the cup and this will seal the repair.
If you don't have a waxed paper cup and use a plain cup you will need a piece of waxed paper over the repair to seal it off and help the curing........
Just lay the wax paper directly over the wet gelcoat to keep air off it.

Build the gel a little over as it will shrink some, if you see any air bubbles pop them gently with a pin..........should be cure in 4 hours, but waiting overnight to sand is best.
If the surface is still sticky on top but the gelcoat is hard underneath, wipe off the tackiness with acetone so your wet sand paper does not gum up.

Acetone is also used for the cleanup ( fingernail polish remover )

Use a small sanding block and 600-800 WET sandpaper to get a smooth finish, keeping the paper wet, if sanding lines are still seen up the sandpaper to 1000-1200
If you see a shadow below the sand area you are about to go through the Gelcoat and into the glass and resin. stop sanding.
Once you get the chip sanded smooth you can compound and wax.

[ZX180MI]

Thanks so much for the detailed info Basscat7. What is the easiest / safest way to support the rear of the boat? Also, other than Marine Tex are there any other chemicals to try that you would recommend?? Thanks again..