Tender hole

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oakleyb

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My tender has developed a few holes on the underside that i would like to repair myself. Having never done any fibreglass repairs before i'm open to suggestions - has anyone come accross idiots guides on web or can anyone spare the time to explain what i need to do
 
You're a real wag. That will have us all chuckling for a week. The idiot's guide was asked for not the idiot.
 
Suggest you go along to a boatyard or other firm doing grp moulding work and go equipped with two cleaned 1 gallon plastic oil cans (5 litre) and a glass jam or coffee jar. Buy from their bulk supplies - much cheaper, filling one can with resin, the other with acetone for cleaning up, and the jar with the hardner. Buy a couple of yards of chopped strand mat, the old 2 oz weight. You probably won't need any tissue unless the inside of your hull is super smooth (unlikely). Buy a sacrificial 2" paint brush to stipple the resin into the matt and some latex gloves to keep the stuff off of you!

Hardner is usually added at a few c.c's per pound, ask the yard man, and buy a 20p baby syringe from a chemist to measure it. Don't overdo the hardner, the resin gets bl**dy hot if you do and has caused fires. Work in a warm place if you can or it'll take forever to go off at this time of year. You need about 50-55 deg F (showing my age) minimum.
Sand off the inside of your dinghy hull with a coarse grit, put parcel tape over the holes on the outside and back that up with some hardboard or old stiff "L" plates to support it gaffer taped on and lay up a couple of layers of matt on the inside. The resin won't bond to parcel tape or Selotape. (It will bond to masking tape though!)

I assume you are going to have to paint the outside if it's that bad, presumably with a 2-pack polyurethane or similar, so after you've made your repairs you'll have to really clean off the outside with wet & dry for a good key. Use a layer or so of matt and resin over the outside of your holes, and reinforce any otherwise damaged areas like the moulded keel band which gets most wear. Then sand the resin glass back is my counsel rather than body filler like P38 which can take up water. Applying a layer of resin over sanded repairs will seal any exposed strands of glass, and gently wet and drying that gives a key for the paint. Good luck!
 
Cliveshep has described very nicely how to repair large holes ina fibreglass dinghy with polyester resin.

If they are quite small holes then you need much less resin and possibly don't need fibreglass. The F/g makes a strong matrix to bridge over large holes and certainly holds more resin in place to make a better repair.

Epoxy resin generally sticks better to old GRP and certainly wood. you can buy small quantities in the two tube pack Araldite is a common form. The hardener is either equall quantities to the resin or 50% of the quantity of resin. The amount sold in the pack will easily show how much to use.

You need an ambient temperature above 15 degrees C for the whole hardeninng time. Or you can heat the job with heat lamps etc.

Clean the area a round the repair to good strong base material free of moisure and paint.

Many hardware stores will sell a fibreglass repair kit which con tains some woven glass and the resin althougyh this is usually polyester resin. Motor parts shops sell a kit for body repair of cars. One product has glass strands mixed into the resin (again polyester) which can work OK.

You will probably want to sand the repair down to smooth and paint it when finished. You can cut the resin and glass when it is nearly hard with a knife or chisel but you can't sand ituntil it is really hard.

It is all very easy but messy. Buy some disposable gloves at your supermarket. good luck olewill
 
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