cowl repair

[Diamond Geezer]

Hi Guys

Maybe some of you can help fitted a different engine to my cap 232, so the exhaust and needle valve are in a different place, I've laminated the inside with fibreglass and resin what would you use to fill the outer with?

[Tim Mackey]

I fear that whatever you use may end up loosening and cracking etc.

I assume its a glass cowl? - I think I would probably just build up with resin and chopped strand filler, ( its available for car body repairs ) then sand it all back down flush with the outside surface, perhaps finishing any small holes etc with flexible filler such as "Isopon" before primer and top coat.

[Marko]

hi D G if you rough up the surounding with 120 grit paper  you will be able to use

upol (car bodyfiller ) as its only going to be a thin scim it shoulnt crack

hope this is of some help

 

cheers ....................mark

[kc]

It is important to use polyester resin if the cowl is made with polyester resin or epoxy resin if the cowl used epoxy.  

Same with the filler so it all bonds properly.  Build up the surface and scrape level whilst still soft like cheese.  Then when hard, sand with ' wet or dry '  used wet.

 

For a filler you could use 'micro balloons' mixed with the resin to form a paste.  

 

For ABS cowls use the proper solvent glue ( plumbing stuff ) and some spare ABS offcuts.

Edited By kc on 30/06/2010 20:23:35

[Myron Beaumont]

This might sound a bit over the top but if you fill holes ( as per Timbo) ,whether it's Polyester or Epoxy resin that was the main constituent  of the original cowl, I would use clear gel- coat to re finish it (as used on boats) .It is normally the first layer to apply to your mould making a hull after release agent. You'll only be able to buy small quantities in a chandlers though. Normally it comes in drums for the trade.

It can be rubbed down with wet & dry . This will end up perfect ! As I said -a bit over the top for such a small job but you'll probably find lots of uses for what you havn't used later on. Don't ask me how I know - (Well alright then if you insist ! I had a cabin cruiser type boat which had a bad crack in the hull I had to fix )Otherwise I would just smear 30 min epoxy thinly all over it & rub down when cured

[Marko]

hello myron l will have to disagree with some of what you have said  1,clear gelcoat is harder than coloured it is used for mold making because it is tougher than coloured gelcoat by the time D G has rubbed it down he would have gone through the rest of the cowl .2 upol as i said will stick to both  ,most cowls are made using epoxy poliester will not stick for very long !!

 cheers .........in the trade...........mark!!!!!!

[Myron Beaumont]

Mark

  Only talking about what I've done My boat didn't sink !

[Tim Mackey]

I have some white coloured gel coat here, and on the rare occcasion I have used it on my gelcoated F/Glass fuselage ( Jart ) it set rock hard, and resisted pretty much all attempts to sand it.

I now use it  VERY sparingly and ensure its smoothed off as best I can before it cures.

I understand the clear gel is even harder

Edited By Tim Mackey - Administrator on 30/06/2010 23:37:42

[Myron Beaumont]

Timbo

I didn't realise that the pigment altered its hardness either

[Chris Bott - Moderator]

Gents, is there any way of telling whether the original resin was polyester or epoxy?

[Lazygit]

If you rub it with acetone or paint thinners, the polyester will start to dissolve IIRC. Epoxy will just sit there.

[Bob Cotsford]

you can usually smell polyester when sanded, but epoxy doesn't have any smell.  Polyester moldings are usually thicker as it seems more brittle than epoxy.

[Diamond Geezer]

thx for all your help guys

[Bob Cotsford]

Posted by Lazygit on 01/07/2010 06:06:39:
If you rub it with acetone or paint thinners, the polyester will start to dissolve IIRC. Epoxy will just sit there.

 are you sure about that? If that is the case, I'm wondering how does it survive painting, especially when used in car body fillers?