Replies to This Discussion

Permalink Reply by mlwebb on October 26, 2010 at 12:58am

I'll chime in, the experienced folks can correct me. (just finishing my first boat)
I think traditionally they floated, and I suspect, not for a lot more reason than any fastener in that spot would be likely to do more harm than good if the boat flexed a lot (ie split a frame). I bedded mine only to limit water intrusion in the joint. The downside of bedding them (particularly w/ 5200) is more mess - and any with that stuff is rather annoying. I did my bottom/frames with it because it was readily available - then ordered some Sikaflex 291-LOT in mahogany color and was happier with it. - not a lot easier to cleanup, but handled better and I buy the argument that its greater elongation trumps the 5200's greater tensile strength. I would bed them, but careful not to have excess 5200, and clean up before it sets. I guess it might depend some on your choice of interior finish.
Michael

• ▶ Reply

Permalink Reply by lhedrick on October 26, 2010 at 8:16am

Hope there is still time.

You really don't want to use 5200 on the outside chine and the messy issue is a small part of why. While I don't build with chine caps I do know that you will want to be able to remove them. 5200 is about the strongest bonding adhesive I have ever used. If the chine gets banged up over time you will want to replace it. If you have already put it on then it's too late. If you ever need to replace it you will need to use saws, chisel and rotary grinder. I'm not kidding.

Hope other framed builders will add input on this. I believe they use polysulfide compound for setting the chine. In addition I would seal the end grain of the plywood with epoxy.

Since the inside chine strip is not removable it might be reasonable to use it there.

5200 is amazing stuff so only use it for items you want bonded forever. I delaminated some plywood last year trying to dissemble something glued with 5200. Even the bonds of 5400 are strong.

• ▶ Reply

Permalink Reply by Randy Dersham on October 26, 2010 at 4:32pm

I recommend that you use the method that was first used on your boat.


There are two schools of thought about bedding chines. One is to use a poly-sulfide like 3M 301. It is flexible and a great bedding compound that will fill all gaps and can easily be removed. The chine batten is bedded using stainless screws. This is the tried and true. It is also the method that accounts for 90% of the boat bottom repair that we do. Too many boaters do not remove and re-bed the chine batten when it begins to leak.

The second is to permanently attach the chine using 3M 5200 and ring nails. We use that method at McKenzie Driftboats for two reasons. 1. We round the outside chine and tape the seam with 10oz fiberglass tape before we attach the chine. A pre-drilled hole through that tape will insure it the glass has a great bond and the ring nail is a tight fastener that damns against water intrusion. 2. Since the chine is a "permanent attachment we use 3M5200 because of its fantastic adhesion. It will protect that chine area with a flexible bond that lasts much longer. It is more difficult to remove. We do not remove the fasteners. They are bronze and easy to cut through. We use a metal blade in a jig saw to cut the chine within 1/8 to 1/16 from the joint. Then belt sand the final bit with 60 grit sand paper. This takes about 30 to 45 minutes per side and we feel is well worth the extra protection to this joint when you are on the water.

• ▶ Reply

Permalink Reply by Randy Dersham on October 26, 2010 at 4:33pm

Forgot to answer the first question. We bed the notches because it protects the chine log and the frame from future rot of water getting in that joint.

• ▶ Reply

Permalink Reply by Dave Z on October 26, 2010 at 4:49pm

Inside chine logs- mine are only bedded with Sika 291 to the plywood. No nails, screws or caulking to the frames. My interiors are oiled.
Chine battens on the outside- 1-1/4" Si bronze screws, Sika 291.
My exteriors are varnish over epoxy or paint over epoxy.

Lots of ways to do it, non are wrong I suspect.

• ▶ Reply