Model Boat Mayhem
Technical, Techniques, Hints, and Tips => GRP & Epoxy => Topic started by: BlueWotsit on August 01, 2006, 10:02:06 am
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It was suggested to me that a good way of affixing things to GRP Hulls, would be to use Fibreglass resin as sold by people such as Halfords.
It was said that to "pad it out" I should also use car plastic putty, from the same source.
What experiences of this have people had, and what sort of quantity of putty needs to be added to the resin mix ?
thanks
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I would use epoxy or polyester resin depending on if your hull was laid up with epoxy or polyester. I find West Systems products excelleant and they produce a range of fillers and thickeners too. Deluxe Materials do a good Polyester resin and sell microballoons to thicken it as well. So do Z-Poxy.
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fibregalss resin will be fine though I would agree with Mankster Micro balloons to pad it out or you could even use some stands of fibreglass see a previous thread re a place Southport that will do mail order I cant think of their name better value than Halfords
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Glasplies
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Best way to secure stuff into a grp hull, first tack it in place with Araldite Rapid, then work in a mushy mix of resin and fibreglass strands around it.
Pour some lay-up resin (same type as that used to make the hull) into a jam jar, then pour in a bit of gel-coat resin to thicken it up. Break up some fibreglass mat and mix the strands into the resin. When you need to use some, scoop the required amount out and put it on a suitable palette. Mix in some catalyst and away you go. Use a scrap of ply or plastic to work it in around the item you're fixing in.
I've used loads of this stuff for fixing hardware into multi-race boats and it gives a good solid fix.
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Try David's Isopon P40 if you can't be bothered to chop fibreglass etc. It's a polyester resin already mixed with chopped strands, and works wonders around prop and rudder tubes, servo mounts, bow-thruster tubes etc. Halfords sell it, sometimes together with an equivalent tin of P38 filler paste at an offer price.
CAD2
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I'd say that BlueWotsit had it pretty much right at the start of this thread, as long as the hull is made from polyester resin and not epoxy, all you need is resin mixed with some filler, P38 is good, Plastic Padding very similar, and I use the one sold under their own brand by motor factors Brown Brothers. You add enough filler to the resin to get whatever consistency you want for the job in hand and the amount of gap-filling that's needed. As with any job of this kind, the most important single factor is surface preparation, if you don't do a good job here, you're wasting your time whatever material you use. I know that there are other fillers, glass-filled, microballoons etc, but I've never used any of them. With good surface preparation and ordinary filler or a filler/resin mix, I can get a good enough bond with a propshaft/hull joint to break the fibreglass before the joint gives way, what more could anyone need? There's no need for any complication here, just keep it simple.
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Just one little thing to remember though.
Most car body fillers are porous, so a good coat of paint is needed.
Bob
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Hi
Just been reading this topic with interest about polyester or epoxy, can someone tell me what material and old caldercraft "Marie Felling" is constructed off have a need to repair one.
Lionel
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grp, [ glass reinforced plastic, aka fibre glass] ;)
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Thanks nhp651
What I meant is the hull made of Polyester or Epoxy, it appears that there is different products to repair each type or have I misread the details which is more like me.
Lionel
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It will be polyester resin. However, you will not be able to make a chemical bond to the existing cured resin so you can use either polyester or epoxy based products to make the repair provided you abrade and key the existing surfaces first. If you can tell us what sort of a repair you need to make, e.g. split, puncture, scrape etc. we will be able to give you more specific advice on how to proceed.
Colin
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Colin
"O" thanks for getting to the next problem for me, I have a hole about 1" long and 1/2" high which I unfortunately made trying to remove old fibreglass and lead weights. Will post some photo's tomorrow but wonder also how to match up plates and rivits that where originally cast into the hull.
Ideas welcome on above but I thought about filling proud the dremel down to give plates but no idea how to form the rivits.
This should be fun, hope someone can help
Lionel
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the best way to tackle that wee problem would be to;
mask from the outside of the hull, the hole and about 3" square all around the hole, completely covering the hole and area around with a good few layers of masking tape so you dont get any leakage..
if the hole is in an inaccesible position from the inside, use the glass repair mat supplied in a polyester repair kit and Mash it up.ie pull the strands apart. mix it with an amount of the polyester resin until it is a pulp and then (after adding the requisite hardener(catylist) position the hull until the damaged area is lying flat, and pour in the mix, leving until it is set.
Then tape off and sand and fill finely on ther outside of the hull before painting.
If the hole is accesible from the inside, just use the repair kit as discribed in the instructions.
neil :-))
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Thanks, but excuse my lack of knowledge, but where is the best place to get the polyester kit.
Lionel
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Halford's or any car accessory shop will stock a kit, monarch, but make sure it is the one with fibre glass matting AND NOT steel mesh patch,( there are two types of kit) as that is not the road to go down.
alright for patching car wings but not boats
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This is the sort of thing you want: http://www.halfords.com/webapp/wcs/stores/servlet/product_catalogId_10151_storeId_10001_partNumber_711317_langId_-1#dtab
Colin
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Thanks so much for all the great responses what a wonderfull forum.
I'm sure that without such help would make a real mess of things, mind you that may happen anyway.
What I still need to know is how to form the steel plates and rivet heads in the new repair as per photo
Lionel
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once you've backfilled it by masking from the outside and filling from the inside, you'll find you'll be able to sand in the line of the plates. then a blob of glue [superglue gel type or waterproof pva administered with a cocktail stick] plopped on to represent each rivet will restore the plating.
neil. :-))
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Great, thanks somuch to everyone for your help. Its nice to have such helpful people on the forum.
Maybe I'll become and exspert one day ha ha
Thanks again all
Lionel :-)
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once you've backfilled it by masking from the outside and filling from the inside, you'll find you'll be able to sand in the line of the plates. then a blob of glue [superglue gel type or waterproof pva administered with a cocktail stick] plopped on to represent each rivet will restore the plating.
neil. :-))
For rivets.....
The little glass beads found mixed in with the charcoal in water softener cartridges are useful too.
drill a little dimple.....add S-glue and a little bead.......jobs a good'un!
Rex
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Hi All
Managed to fibreglass the hole in the side of my hull, but now need to fill the lower part of the hull which is over 1" deep (see photo) which shows the problem better than I can explain it.
Any great simple ideas on the best solution :P
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so long as there isn't a hole there. Monarch, I wouldn't bother doing anything with that at the moment, as sooner or later you will want to add some balast, and this area will be probably be covered with ballast and resin which will fill it in. :-))
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Hi nhp651
I removed to large lead weights from this area and now need to fill and level to fit 2 x 12V 12amp/h batts which I think will just about give me most or maybe to much ballast.
So if any ideas out there please lets hear from you. O0
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Hi nhp651
I removed to large lead weights from this area and now need to fill and level to fit 2 x 12V 12amp/h batts which I think will just about give me most or maybe to much ballast.
So if any ideas out there please lets hear from you. O0
Just pour in fiberglass resin until the hole is level. If you need to mount the batteries on a platform, make the battery base, pour in the resin, then set the platform into the resin while its setting.
John
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...but don't pour a big pool of resin in one go. It gets very hot and could distort the hull.
Andy
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...but don't pour a big pool of resin in one go. It gets very hot and could distort the hull.
Andy
Good point.
John
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as simple as oldiron has said.
It's not really rocket science, just a self belief in what you are doing feels right to you.
Basically how we all learn. Bit of trial and error, but making sure you can rectify those errors.
If you feel that when you put into the hole some resin it might be too much, a simple tip.....greese with vaseline the areas you are going to fill, blanking off at the front and back of the hole with plastecine modelling clay.
Put into the area to be filmed and onto the grease, some cling film.
Pour into the area covered with cling film, your resin.
Once hardened, the resin block mould can be removed and trimmed down if too heavy...Latteral thinking. :-)) :-)) :-))
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Thanks, but you mention not pouring in to much a one go being a newbie what is to much 1/2", 1" or more?
Also will the old fibreglass foundation need cleaning first
Confused Monarch :embarrassed:
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the secret to ballasting your boat is to put it in the bath and weigh it down to where you want it to sit in the water with lead shot, or small pieces of lead, or sand (all put into small freezer bags), but not forgwetting that such things as batteries, engines r/c gear all also weigh. Ballast where you want the boat to sit, and then deduct from that weight the r/c gear and batteries and such. what you are left with is the ballast weight. then take it out and weigh it. substitute any weight that you take out for resin by also weighing this.
Once you have the items weighed you can then put them back into the places you need as you did in the bath.
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nhp651 is right on.
I just weighted my Smit Nederland this weekend. The only difference I did (as a matter of personal preference) is to install the radio gear and battery, then put in the weight in the seal able freezer bags, so I didn't have to continually pull the bags in and out of the hull, I placed them on the deck to check the hull was down to the water line. I adjusted the amount of weight in the bags accordingly. Then I placed the bags in their home in the hull, along with all the rest of the bits to make the boat run, including the superstructure. It took me longer to get water into the bath than it did to weight it.
After I've done a sea trial I'll pull the bags, pour in some resin and reinstall the bags.
John
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Thanks all but I need to know how much fibreglass to pour in in one go, 1/2", 1" or more then when do I add the second layer whilst tacky or completely dry. Don't wish to distort the hull.
Also do I need to know wether to clean the fibreglass first before pouring the first layer.
Monarch
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i don't honestly understand what you're wanting to do, monarch.
perhaps you can tell us.
but if you are just trying to fill an area to level it off, then just mix an amount and pour in, keeping the boat on a level and even keel,
it's just trial and error as to how much you pour in, and if to little, ,mix some more and pour in.
setting time is on how mch hardener you put in, but if you keep to recommended amount on instructions you won't distort the hull.
but don't forget, your ballast must be as low as possible. ie, under the resin you want to pour in.
you can pur in one amount on top of another without the first lot having gone off.
as for cleaning, remove any grease with warm soapy water and then sand the area to be filled for a key.
neil. :-))
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Hi nhp651
Just what I needed, I will check ballast first and build batt boxes in as low as poss.
Just left with the bath tub test after the hull is repainted and where nearly there.
Thanks so much for all the helpful advice.
Monarch :-)