Glass fibre repair on a tender

[LeonF]

Very unskilled at this hence the post. Have a new tender bought off e-bay, floats and rows fine , but found that rain water had seeped into the buoyancy tank in the bow. I need to seal the joins onto the hull. Can I use those kits of paste like isopon that they sell in places like Halford, or should I use tape and resin ? I did some repairs on a previous tender to the hull capping with resin and mat but although strong it looked a mess so am looking for an easier solution.

 

[lw395]

Is the tank structural strongly fixed to the hull but just leaks a bit through a few pinholes?
In this case, painting some epoxy resin over it will fill the pinholes, or you could use a polyurethane sealant like sikaflex.

If the join is not sound, a couple of layers of fibreglass tape will make a good repair. It's easier to be reasonable neat with tape. If you get some 100mm tape and some 50mm tape that would taper the reinforcement.
You should cover the resin with flow coat or paint ideally, as well as looking better it keeps the water and UV off.

 

[LeonF]

Thanks LW. It seems to be soundly attached, but had been sittting in the wet weather for some weeks before I got round to it and with her bows done it must have seeped in. There are rough edges though, so I'll trim these back and then use one of the methods you suggested. Thanks again.

 

[Avocet]

I'm not sure I'd bother with epoxy. It's certainly good stuff. but very finnick about application conditions. If you're trying to fill a crack or hole that has been letting in water for some time, you'll find the surrounding laminate will be wet for ages unless yu can put the boat somewhere warm and dry. Does that buoyancy tank have a drain plug?

Depending on the size of the hole, and whether or not you're confident that the whole tank is attached to the rest of the bhull well enough, I'd be inclined to grind away the area round the hole / crack (pretty mercilessly, to be honest - at least to the point where you're about to go right through the laminate), and then fill with polyester resin and short chopped strands of glass like these:

http://www.cfsnet.co.uk/acatalog/CFS_Catalogue__Chopped_Strands_399.html

Paint some neat resin on the laminate, then mix some of these into a paste with the rest of the resin and fill the hole. Finally, get some gelcoat pigment, mix that with some more resin and paint it over the top to make it look pretty. Obviously, the chopped strands, being only about 6mm long, can't bridge that much of a gap though!

Isopon P40 (the "hairy" filler they sell in places like Halfrauds) is basically the same thing.

Obviously, larger holes or cracks will need to be taped or repaired using glass matting.

 

[LeonF]

Avocet there are no holes, just hairline cracks or pin pricks, which is why I was surprised to find water in the forward tank. Nothing immediately visible. When turned on it's side it emptied from one corner where it was attached to the hull, so it might be just a small detachment that needs filling. It had been stored upside down in someone's garden for several years. I don't think it needs grinding back and re-filling, which is why I wondered if a light sanding down and filling with something like isopon might do the trick.

 

[VicS]

Avocet there are no holes, just hairline cracks or pin pricks, which is why I was surprised to find water in the forward tank. Nothing immediately visible. When turned on it's side it emptied from one corner where it was attached to the hull, so it might be just a small detachment that needs filling. It had been stored upside down in someone's garden for several years. I don't think it needs grinding back and re-filling, which is why I wondered if a light sanding down and filling with something like isopon might do the trick.

For small cracks and pin holes a car body filler such as David's Isopon P38 will probably do the trick

For larger cracks Isopon P40 , which contains glass fibre to bridge any gaps, would be better.

For even bigger gaps or if the joints are coming apart use a liquid resin, such as David's Fastglass and strips of glass mat or glass tape.

All the above are available from Halfords ( except maybe glass tape)

In some cases ( the liquid resin ??) the hardener may be separate... if so make sure you get the hardener.

Sand the surface first to remove paint or other comtamination and make sure it's dry. Rake any muck out of holes or gaps,

A light sanding and a coat of paint will hide the repairs.