Question on Transom bonding

[Nismoron]

I just picked up an 86 Starcraft Mariner 210 that haas a COMPLETELY rotted transom and no floor. The transom is going to completely fall apart when I take it out. So I am going to have to make a template to put it back. Oh joy?

When replacing, is the wooden transom somehow bonded to the metal outer skin. Or is it just bolted in place. Mine is so degraded that I cannot tell. I've been searching here as well as the vast starcraft rebuild resource on iboats, but cant seem to find anything on it. Lots of pics and people saying "finished installing transom", but no details.

 

[lckstckn2smknbrls]

No need to bond it to the hull.

 

[Nismoron]

Thanks for the quick reply.

I didn't think that it was, but it just seems un-natural. haha
I've only worked on glass boats. They are bonded.

 

[surfman]

They are not bonded but unlike a glass hull there is no protection for the wood with the glass, therefore you will need to seal the wood with either epoxy (the best alternative, not polyester resin!) or a good quality spar varnish. Depending on the exposure the boat will get, depends on how long it lasts. Another alternative since you are used to working with glass is to glass over the wood, then you could use polyester and glass, just don’t use the resin alone it will not hold up. All holes need to be completely sealed as well. Do not use PT wood unless you seal it with epoxy or glass.

 

[Natedog57]

Nismoron » 20 Aug 2014, 20:43[/url]"]The transom is going to completely fall apart when I take it out. So I am going to have to make a template to put it back. Oh joy?

When replacing, is the wooden transom somehow bonded to the metal outer skin. Or is it just bolted in place. Mine is so degraded that I cannot tell.

Regarding the "template"... lay the plywood up against the outside of the transom, and trace the cutout. You may in fact get a better fit piece than the original.

If your old transom wasn't covered with aluminum sheet on the interior, I would highly recommend adding this, it will last SO much longer, regardless of finish applied to the wood.

 

[bobberboy]

surfman » Today, 07:20[/url]"]They are not bonded but unlike a glass hull there is no protection for the wood with the glass, therefore you will need to seal the wood with either epoxy (the best alternative, not polyester resin!) or a good quality spar varnish. Depending on the exposure the boat will get, depends on how long it lasts. Another alternative since you are used to working with glass is to glass over the wood, then you could use polyester and glass, just don’t use the resin alone it will not hold up. All holes need to be completely sealed as well. Do not use PT wood unless you seal it with epoxy or glass.

Can you explain why the resin with glass will work but the resin alone won't? I don't understand what the glass does as it doesn't (at least I don't think it does) change the chemical nature of the resin. I am at a point in my project where I'm about to install my resin-coated transom and floor and I don't want to think I've gone to all that work for nothing. I'm not all that schooled on the 2-part materials and want to get it right.

 

[lckstckn2smknbrls]

Polyester resin without fiberglass cloth or mat won't last.
Epoxy resin without fiberglass cloth or mat is just fine.

 

[surfman]

The resin is way too brittle (I assume) and will just crack flake and peel, I don't know why but I tried it once and within a year the stuff was flaking off like crazy, add a layer of glass to it and it is there forever.

 

[surfman]

Fiberglassing is kind of an overkill though, I like ND57's suggestion of covering with a sheet of aluminum.

 

[Nismoron]

I am doing this in a Starcraft Mariner 210. It's a 21ft Aluminum Center console with a splashwell.
I'll be laminating two sheets of 3/4 Marine ply using Epoxy resin. I will then cover all sides of it with 6 or 8oz glass cloth and epoxy resin. It should last a year or two. haha I just needed to know if the wood was bonded to the transom skin or just through bolted.

 

[acabtp]

surfman » 21 Aug 2014, 08:20[/url]"]Another alternative since you are used to working with glass is to glass over the wood, then you could use polyester and glass, just don’t use the resin alone it will not hold up. All holes need to be completely sealed as well. Do not use PT wood unless you seal it with epoxy or glass.

just don't use PT wood at all on an aluminum boat.

lckstckn2smknbrls » 21 Aug 2014, 13:51[/url]"]Polyester resin without fiberglass cloth or mat won't last.
Epoxy resin without fiberglass cloth or mat is just fine.

polyester resin won't last with or without mat because it is not UV resistant. sunlight will break it down unless it is covered with a UV stable coating like gelcoat or paint. epoxy is not as bad with this.

bobberboy » 21 Aug 2014, 11:07[/url]"]Can you explain why the resin with glass will work but the resin alone won't? I don't understand what the glass does as it doesn't (at least I don't think it does) change the chemical nature of the resin. I am at a point in my project where I'm about to install my resin-coated transom and floor and I don't want to think I've gone to all that work for nothing. I'm not all that schooled on the 2-part materials and want to get it right.

you're right, no chemical changes; the addition of the glass makes it a composite so the surface is a bit stronger and resists chipping longer than it would otherwise (especially if you say, drop something heavy like the anchor on it). but eventually, if you used polyester resin and it's not painted, varnished, or otherwise protected from UV, it will fail. just a matter of time. i'm not just talking out my *** here, a few years ago when i was redoing my starcraft, i let myself get talked into using poly resin by reading posts on here saying it'd be fine. DON'T DO IT! i got less than three years out of poly coated panels and i really wish i had just done it right with epoxy. on the panels without glass the finish just chips away, and on the glassed ones the whole glass/resin layer separates from the wood.

really polyester just resin sucks. it's 60s technology. epoxy resins are superior in every way except cost, and are what pretty much all commercial composite fabricators are working with these days. and when it comes to the cost, what is more in the long run, doing it right once with epoxy and not worrying about it for the life of the boat? or doing it multiple times with poly resin?

I am doing this in a Starcraft Mariner 210. It's a 21ft Aluminum Center console with a splashwell.
I'll be laminating two sheets of 3/4 Marine ply using Epoxy resin. I will then cover all sides of it with 6 or 8oz glass cloth and epoxy resin. It should last a year or two. haha I just needed to know if the wood was bonded to the transom skin or just through bolted.

sounds like a solid plan. you should get many years of good use out of it.