Blocking on plywood boat

[cs]

I've gotten so used to using epoxy that I almost forget that you don't have to use it.

I was working on my weekender last night. I'm doing a different seat than what the plans call for. The plans call for a boxed in seat and I'm going to make it open.

But beyond that I was having to put some cleats (or blocking if you will) underneath the deck to hold the vertical of the seat backs. I was thinking that I would epoxy these in and than fasten them with screws.

I dry fit the cleats on last night and after thinking about it, there should be no need to glue them on with epoxy, right?

Chad

[Bert Langley]

Great place for rot to start if you have uncoated wood to wood. Moisture will get in there. If you don't wnat to epoxy them in place be sure that both surfaces are well sealed.

Also I built a Pocket Cruiser, which is similar to the weekender in construction. The seats provided significant stiffness to the hull sides, serving as a full lenght stringer. Others have gone to the open seating and had no problems, but think about how you attache this, since the seating serves as a significant structural component to the hull.

[cs]

A quick image to illustrate what I'm doing.

http://a3.cpimg.com/image/81/A9/46700673-f3b8-025801E0-.jpg

Bert I will coat it with epoxy, I was just wondering whether or not it need to be laminited up with epoxy. I'm thinking that screwing the cleat to the deck will provide plenty of support.

Chad

[cs]

Mike, when completed the edges will be sealed with epoxy and thus hopefully reducing the chances of moisture getting in and around.

Chad

sorry I missed your call yesterday, give it another shot.

[JimD]

The seats provided significant stiffness to the hull sides, serving as a full lenght stringer. Others have gone to the open seating and had no problems, but think about how you attache this, since the seating serves as a significant structural component to the hull. Like Bert says. So Chad, have you asked Stevensons? If they say glue the seats in place because the hull needs it for strength, then you must glue. If not, then you can fasten only for the convenience of being able to remove the seats down the road, but then you'll still have the problem of moisture getting in the screw holes so they would all have to be bedded. At the least I would be inclined to glue the cleats to the inside of the hull sides, and then fasten the seats to the cleats without glue.

[Dave R]

Chad, my seats are open slats. They are screwed to cleats on the cabin bulkhead and on the laz. I have had no issues in three years of sailing. I've not seen any issues relating to a lack of stiffness even when I stand on the side decks. I do have several layers of wood forming a coaming around the inside edge of the side decks and an additional layer of plywood screwed to blocks on the hull sides. These pieces of plywood cover up some fltation foam although the space is open top and bottom for ventilation.

[Bruce Hooke]

Chad,

I agree with you that once you have coated the whole works with epoxy there is little chance of moisture getting into the unglued joint (assuming the epoxy covers everything, including the screws). However, I do have to say that if you are going to seal up everything with epoxy then I would probably glue down the cleats just because it is so easy to do and because they will effectively be glued down anyway once you've coated everything in epoxy. The best practical justification I can offer for this is that if the part is just screwed down and sealed with epoxy it is possible that under stress it could move slightly and crack the epoxy "seal" and let water in. Of course given that the cleat is right up under the deck the chances of much water getting up there regularly are pretty small.

[Bob Smalser]

I'd epoxy them like called for in the design.

But for future reference, Chad, you have two choices for faying surfaces....either epoxy followed by poison primer of poison primer followed by bedding compound.

http://pic3.picturetrail.com/VOL12/1104763/6791366/92273655.jpg

The oak replacement frame on that dory is epoxied to the plywood hull like was done originally....but unlike the original it was primed with red lead after the epoxy cured.

The frame end brace above it, however, was got out, the faying surfaces coated with red lead, and bedded in bedding compound before screwing it home. After the bungs/plugs are trimmed it'll get more red lead followed by alkyd paint.

Some members that need maximum "give" like plank to frame are an exception...but not many.

[ 04-08-2005, 05:53 PM: Message edited by: Bob Smalser ]

[Bruce Hooke]

I would be cautious about using bedding compound on parts that will later be coated with epoxy. I'd want to do a bit of testing to make sure the bedding compound does not interfere with the epoxy's curing processs.

[cs]

Just to add. The seat back will go from the deck all the way down. The only part open will be under the seat. This should provide the strength and stability needed.

Chad