HEIDI SKIFF,building question

[bob goeckel]

I'm at the stage where the plan calls for epoxy tapeing the chine/bottom seam (plywood bottom). This seems the wrong thing to do seeing as this is a traditionally built boat, and i worry about trapping moisture which may find it's way behind the chine from inside the boat. any advise? thanks

[ 04-14-2003, 11:15 AM: Message edited by: bob goeckel ]

[Bruce Hooke]

I'm not familiar with the design but in general plywood is very vulnerable to edge troubles because of all the exposed end-grain, so IMOOP it is almost always a good idea to cover ply edges with epoxy and 'glass cloth. I think you are more likely to have problems if you don't cover this joint with epoxy and 'glass cloth than if you do.

- Bruce

[bob goeckel]

bruce, i can see your point but what about all the clinker built Lymans and Thompson etc. that have lasted all these years. with just the outer seam taped you are not encapsulating the wood so water seepage behind the chine log would be trapped wouldn't it?

[Bruce Hooke]

Bob - Certainly lapstrake boats built with plywood are a major exception to what I said, and they clearly can last, so plywood edges do not have to be sealed with epoxy. Here are some points to consider:

If you are using top quality hardwood marine plywood you are in a much better position to leave the epoxy off. If, on the other hand, you are using douglas fir marine plywood then I would definitely use the epoxy because I have seen that stuff come apart if the edges get too much water exposure.

The plywood edges on lapstrake boats are protected much better than edges of the plywood bottom on a typical hard chine hull. The chine can take quite a beating so it is very hard to keep paint on this edge so epoxy is often recommended and commonly used to protect this edge.

Unless you are planning to let the boat sit on shore with water inside it, the interior of the boat should always be drier than the outside, so water will want to migrate towards the inside and into the air rather than the other way around. Put another way, if the water can get from the inside of the boat to the outside, underneath the epoxy, then it can do the reverse and the reverse is what it will want do.

BTW - If the boat will be stored under cover and only put in the water when it is being used then you can do darn near whatever you want :D because the boat will never stay wet long enough to rot. However, if that is the situation I would still use epoxy just to give the chines some extra abrasion resistance.

- Bruce

[Bruce Hooke]

Of course you could try the handyman's secret weapon...duct tape! Hey, we might be onto something here - an instant, removable replacement for epoxy ;) :D

Sorry, when I saw your 'signature' I just couldn't resist. :D

[bob goeckel]

i thought that's what they meant by taped seams anyway. duct tape forever! thanks

[Bruce Hooke]

LOL...

For those who don't know what Bob and I are referring to, visit this site... http://www.redgreen.com/

[ 04-14-2003, 06:12 PM: Message edited by: Bruce Hooke ]

[capt jake]

If you are using top quality hardwood marine plywood you are in a much better position to leave the epoxy off I think this is the point that is very valid. Most of those boats were built when you 'could' find 'quality' plywood!! smile.gif

If I were in you shoes, I would epoxy the edges of the plywood. Why take a cvhance?? smile.gif IMHO smile.gif

[imported_Steven Bauer]

How about tape and epoxy on the inside also? Wouldn't that strenghten the joint and address your concerns about water penetrating from the inside? My John Gardner skiff has external chine logs, maybe to address that issue.
Steven

[bob goeckel]

steve, i'm not sure about trying to lay tape and epoxy over the chine logs inside. i received a reply from rich kolin and he suggests tape over the chine outside for abrasion resistance.

[Bruce Hooke]

If this boat did not have chine logs then I would agree with Steven's suggestion. Since there are chine logs, I agree with you, Bob, that trying to wrap the chine log with epoxy and glass cloth would not be a good way to go. If nothing else it would just get really messy trying to lay in 'glass cloth around chines, frames, etc.

[imported_Steven Bauer]

Chine logs? I didn't know there were chine logs! If you are still worried about water getting in there how about a little 1/4" radius fillet of thickened epoxy? One at the top of the log, one at the bottom. Or maybe just not needed and you're worrying needlessly.

Steven

[bob goeckel]

steve, in my original post i was wondering about the call for tapeing the outside of the chine since the boat is traditionally built not stitch and glue. i was worried about trapping water between the chine and outer plywood bottom. i'm not worried about leaks (hey i am perfect!). i still think epoxy fillets are the wrong way to go here. thanks smile.gif