GRP hull repairs

[Tim M]

Having removed most of the anifoul and mud from the hull of the 3m I have just bought, I am now ready to start repairing the holes.
Below is a photo of the problem: a nasty gash that goes down the keel. Can anyone give me tips/products to use to repair this.
I only have experiance of filling little hole so this could be interesting!

[slimtim]

make the hole bigger and stick a jet drive in

sorry, couldn't resist

Interesting hull design. It'll certainly shift with a 30hp on it. My flatacraft which is half a metre longer and probably heavier is pretty lively with a 25hp on it.

[ADS]

Tim can you get to the crack from both sides? i.e Is it accessible from inside the boat? I think you would have to build it up with fiberglass matting on both sides of the damage.

Best of luck

Alex

[Bilge Rat]

Originally Posted by Tim M

Having removed most of the anifoul and mud from the hull of the 3m I have just bought, I am now ready to start repairing the holes.
Below is a photo of the problem: a nasty gash that goes down the keel. Can anyone give me tips/products to use to repair this.
I only have experiance of filling little hole so this could be interesting!

That looks like a nasty split, do you know any history about how it happened as this could determine how you need to go about fixing it, the gash is along the keel line so it might not be just a case of glassing it up inside and doing a gel coat job on the outside, this sort of damage can occur when boats are beached a lot or if its been lifted full of water.

[Tim M]

It broke free from it's mooring and was washed up.

I can't really get to the inside unless I remove a piece of the deck. This could be done if absolutly nessassery; there is a recessed bit for a fuel tank. I could cut the bottom out of this and then replace later. However, that is a last resort....

[slimtim]

I don't know much about GRP repair, but I would say that you would probably have to take quite a lot of the crappy material away from around the hole before you could start to repair, so you'll actually be repairing an even bigger hole

[Bilge Rat]

Originally Posted by slimtim

I don't know much about GRP repair, but I would say that you would probably have to take quite a lot of the crappy material away from around the hole before you could start to repair, so you'll actually be repairing an even bigger hole

Yep your correct, i'm by no way an expert at GRP repair but i have made a few kayaks in the past and in the early days before plastic boats used to repair my own kayaks, sadly quite a lot.

Your really going to need to get under the deck to repair this effectively, so this will be your start point, the easier the access to the site the easier the repair will be, remove all the water soaked and crap mat from around the damaged site and glass in new GRP to bridge the split, the outside is really just to tidy up and gel coat over the repair.

[slimtim]

Originally Posted by Bilge Rat

Yep your correct,

have it!

Tim, can you post a pic of the deck?

[stevetheboat]

Tim,
looking at the picture it looks as though the bottom has been worn away by wave action against rocks?
However as already pointed out by others, in order to make an effective repair to such damage you must have total access to the inside of the hull over the entire area before you start.
Once you have access you will need to ensure the entire area to be
re-laminated is bone dry.

At this point try to cover the exterior of the hole with tape or melinex sheeting, any smooth surface material that will form over the hole - this must be firmly affixed with tape or even screws into the hull - to prevent the glass and resin "falling" through the hole.

Once this is acheived you can then re-laminate over the hole and surrounding areas (try to cover at least 150mm either side of the hole if possible) with chopped strand mat and possibly a layer or two of woven roving.

Leave to cure.

Replace any stringers or frames that were removed prior to repair and make good floor panel.

Flip the boat over and grind away edges of original hole (without going through the repaired area) then fill the area with an epoxy repair filler such as Interspeed.
Flat back to produce a smooth fair surface then paint.

[slimtim]

Steve,

I guess he would have to treat whatever he was using to bung the hole with release agent so it can be whipped off again prior to grinding?

Tim