Rotted cored hull! Help?!?

[clshortt]

Hi everyone and thanks for reading my post.
I own a 2000 Glaston Carlson CSX21 that we bought brand new. it’s still in really nice shape. We thought we took great care of this boat and watched the water we allowed in the boat.
our last boat (95 VIP) needed ALL the wood replaced, floor, seat wood, seat frames, stringers and keel stiffener, luckily the transom was good. So I learned how important it is to keep the boat as dry as possible.
Well, this boat has not been in the water in two years so I started doing some basic cleaning and maintenance. I pulled the fuel tank cover to check the two year old fuel and to figure out why the ski well was slow to drain.
What I found was quite a mess. What found was the fuel tank was installed with some dinky 1 inch wide foam rubber strips that have worked their way out and to the drain area below the tank. This formed a dam under the tank and held water. The tank then rubbed holes in the hull fiberglass and formed holes into the core of the hull. Now the core is rotten, the hull is soft and “crunchy” when stepped on.
here is where I need help. How do I repair this damage? Looking for those of you that have experience with repairing cored hulls. Lots of sailboats on YouTube but no power boats that I can find.
Any help is appreciated!!

 

[Golfman25]

Get a multi tool and a dremel/grinder. Cut out the top skin of fiberglass. Remove the core. Replace with new core. Fiberglass over. A lot will depend on how much damage you have. If it's excessive you may be better off scraping the boat and selling the parts. Good luck.

 

[clshortt]

Get a multi tool and a dremel/grinder. Cut out the top skin of fiberglass. Remove the core. Replace with new core. Fiberglass over. A lot will depend on how much damage you have. If it's excessive you may be better off scraping the boat and selling the parts. Good luck.

Oh lord. I hope that’s not the case.

 

[PascalG]

Hard to see what is going on from the pictures. You first need to know how big is the area with rotted core. Best way is to tap the hull from the outside with a hammer and listen for spots that sound hollow. Do that all over the hull and transom and mark the area. If you have more than a couple of square feet of bad core, it may not be worth fixing.

If you decide to fix it, cut the top skin, dig out the rotted core, put new core and glass the the inside with cloth not chop mat. Use epoxy to get a good chemical bond.

A reasonably small spot may not affect the structure much but if the damage is extensive you will need to be sure the new lamination is strong enough and extends way beyond the affected area

For the new core, look into Divinicel foam core. Good stuff

 

[BillK]

Surprised that boat has a cored hull. Most small boats are solid glass with usually a wood cored transom and encapsulated stringers. That hole looks like there is a hull liner and an open space there, at least from the pictures. If there is a core and it’s wet, there should be wet rotting wood in there.

 

[ddurand]

Surprised that boat has a cored hull. Most small boats are solid glass with usually a wood cored transom and encapsulated stringers. That hole looks like there is a hull liner and an open space there, at least from the pictures. If there is a core and it’s wet, there should be wet rotting wood in there.

When you put your finger in that hole how far to the next section of fiberglass.

Where is the wet and rotten core?