Model Boat Mayhem
Technical, Techniques, Hints, and Tips => GRP & Epoxy => Topic started by: MCAT on June 10, 2006, 08:21:00 pm
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Good evening all I have senn on here somewere but can not find now about the use of Resin to seal woden hullls.
I need to stop leakage on my puffer its a wood hull
and from time to time the joints move. would using some resin on the inside do the job of sealing the inside after dealing with the outer hull.
do you just use resin or do you use a hardner as well. not sure it would set without hardner or if you get enough time to seal the joints
more so wiyh this heat.
cheers Mick
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I mix some resin with hardener and pour it into the hull firstly tapeing up any moveing part i.e.propshaft,couplings etc and then just keep moving it around the hull so that it flows into all parts then as the resin beghins to gell put the hull in its cradle and leave to harden I have used this method for some time now and it works well for me
Cheers
Bob B
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I usually use resin plus a little fine matting.
I get my resin from yacht chandlers, much cheaper and in decent quantities.
Bob
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Cheers Gents I will give it ago this weekend sounds like it should do the trick, must remember
to tape up all moving parts.
All the best enjoy the weather
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Hi. Dont forget the amount of catalyst to be added to resin should not be more than 2% by weight. To much catalyst makes the resin getting very hot indeed and it will crack when set. Add some shavings of fiberglass with the mix or use thin tissue inside the hull. Hope this helps. Regards from the north.
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That last suggestion could be a bit misleading, assuming you're using a standard polyester laminating resin to coat the inside of your hull, 2% is far too much catalyst for a job like this, especially if you are using resin bought in a small pack from somewhere like Halfords, which are usually faster setting than the kind of thing that professional moulders would use. Working conditions are very important, not too cold and not too hot, and also not too humid. At this time of year, it's a good idea to get up early to do the job in the cool of the morning before your workshop temperature rises. After taping up any gaps on the outside, removing prop shafts & taping up the end of the tube, same with the rudder, add no more than 1% catalyst to the resin, mix really well, and use a stiff brush to work it into every nook & cranny inside the hull. With most resins you can use as little as ?%, which has two advantages. It lengthens the working time, and allows the stuff to soak well into the wood, which is what you want. I hope I don't need to tell anyone that resin won't do any good at all on areas of the hull that have traces of oil or grease in the wood. As always with anything like this, two thin coats are much better than one thick one, and if you see any traces of runs or puddles, you've applied too much. If it seems to be taking forever to harden you may have gone a bit too easy on the catalyst, but leaving it outside in hot sun, or taping it up in a plastic bag & bringing it into the house next to a radiator (in winter) will usually do the trick. When all traces of tackiness have gone, which may take a day or so, then you can apply a second layer, and with this one you can add strips of glass tissue or thin mat, cut neatly to fit between bulkheads etc. With this layer add about 1% catalyst, and unless you're an expert laminator, mix up small batches of resin at a time, don't try to do the whole job in one go, and if the resin starts to thicken, throw it away and mix a fresh batch. Because of the oil & grease adhesion problem, this kind of thing is always best done on a new hull, preferably one where the deck hasn't been fitted yet, access will always be a big problem on a finished boat. And the best of luck!
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Just a hint, for what it's worth, and I have to say it isn't worth a lot.
I'm building a 'lobster' boat, wood, sheet planked. Got it together okay, did some 'smoothing' of dents, bulges, etc, with 'plastic' wood filer. Also did the 'normal' priming to see any areas that needed more work. (Used a 'new to me' primer by a name brand company over here, doubt it you guys have it over there). Then proceeded to do the fibreglassing using epoxy resin. You would not believe the mess I ended up with, resin reacting with the primer (I think). Then again, knowing how bad I am at fibreglassing, you might believe it! Tried sanding the ridges off (looked like the 'diamond' shaped openings of some metal grill work). Started with 120 grit paper, no luck at all. Changed to 60 grit and an electric hand sander. Spent half a day, still has the same 'diamond' raised pattern on the hull. I give up! Figure enough paint over it should hide it and do some ballasting too.
The 'hint' part of all of the above is to try your resin on any applied primer/paint/wood/plastic/what ever before doing the boat. Wish I had...
- 'Doc
PS - Think I'll say I planned it that way! It does look like a well used boat. :)
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Take a look at CFS web site ]http://www.cfsnet.co.uk/ (http://www.cfsnet.co.uk/[/color). They have a full and interesting manual on their site that may be of use to you.
Their service is 72 hours but my order took only 23 hours to arrive.
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No website to that link RC John !
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sorry my mistake - works without " http:// "
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sorry my mistake - works without " http:// "
Not for me, it doesn't.
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Try? this link? http://www.cfsnet.co.uk
The problem was caused by trying to change the colour of the text in the link? ;)
mike
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For the ebayers out there I can also recommend TOMPS Mould making and casting supplies for both GRP supplies and also RTV silicone mould making rubber and casting resin. Their ebay shop is at the link below.
TOMPS Ebay Shop (http://stores.ebay.co.uk/Mould-Making-and-Casting-Supplies)
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Many Thanks to you all for the info. and to you Kayem as all you spoke about nearly happened
got the mix wrong but caught your mail in time while waiting for it to set . and then did a second
coat. I brought the resin from Halfords only a small qty but a little goes a long way
it has done a good job I will do the whole of the hull in the winter when I hope to give the
puffer a complete overhaul. ( Ive said that before ) Again many thanks all.
Mick