PocketShip.net

Had a test sail after sanding the centerboard back, and it was still sticky, but at least I could get it down with some fiddling through the inspection ports. I'm thinking of putting a drainplug fitting on the top of the CB trunk (cockpit deck just forward of the mainsheet fitting, so I can stick a round stick with a notch on the end down and use it to push the back of the CB down. Thoroughly frustrating, I must say.....
Cheers,
Bob in Sydney

Silly me.....I missed the 3rd page of this post, and everyone else had already come up with same idea about a push stick. By the way, Dana, re lifting Sandpiper with the gantry, I think it would be too unstable to use two slings on the same gantry, but lifting it with two gantries and slings would be the best way.
Cheers,
Bob in Sydney

What's the cause of the stickiness? Or, is it a mystery?
Thanks,
Bob

Hate to ask this, but is there any chance that the CB is warped? I ask because my first CB warped on me. I think it was because I used lamps for warmth durring the laminating process so both sides were not the same temp. Thankfully I caught it before pouring the lead and made another. With only 1/4 inch clearance it wont take much. If not laminated on a perfectly flat surface it could pick up a slight warp that would not readily be detected.
Herb

Warped?!! That's the last thing I needed to hear I've got my CB lying flat, but it's sitting on some 2x4 scraps to keep the edges off the table, and I have not been all that particular about their placement. I guess when I get home tonight I'll check the board for any warping. Meanwhile I'm keeping my fingers crossed--the board is almost finished--just another coat or two of graphite/epoxy on one side and some sanding left to do.

I'm mighty surprised to hear about a piece of 3/4" marine plywood warping that easily. One main advantage of plywood is that you have layers of grain going in at least two directions so the possibility of warping is greatly reduced, and marine plywood doesn't have any voids, so there's that too. I'd like to know if this has happened to others. It sounds like you are building from plans--any chance you got cheated on some less-than-ideal or non-marine plywood that was touted as marine?

It might be a dumb question, but do you remember how the board felt when you dropped it in initially? Did it go in without rubbing? I mean it seems unlikely that glassed plywood would actually warp. It seems more likely that a bend could be overlooked or even accidentally introduced while laminating the two pieces (like Herb mentioned in his post).

Virtually all plywood has some curve to it. Careful lamination can often correct that. I laminated mine on the flattest place I have, my table saw. I did a dry run with clamps and checked for flatness with straight edge across many angles looking for cupping and bowing. I cut 2 inch pink foam board insulation to the shape of the centerboard minus a couple inches in each direction to leave room for the spring clamps. I set that foam cut-out on the table saw, then set the ply pieces on top of that, placed a 2nd identical foam board cut-out on top of that, followed by a bunch of bricks and clamped all around the perimeter. Even then, there was probably some luck involved. The wood was pretty flat to begin with as I recall (I'm building the kit).

I guess if I was you, I'd try to take some (little) comfort in the knowledge that if the board is the problem (not debris), then at least you can rectify it with another centerboard. If you've already determined that debris isn't the cause, then it would seem that it must be a bent or swollen board. There just aren't that many variables, and, "gravity isn't just a good idea, it's the law."

For what it's worth,
Bob

John Harris mentioned in an earlier post the possibility that water infiltration could have occurred, resulting in swelling of the board. I hope that's not it, by the way, but is it possible that you struck something jagged under the water that scraped away the epoxy? If so, then the swelling would be near the bottom of the board and once you get it started out the remainder should drop out easily. That would perhaps mean you could sand down that section and apply a glass/epoxy patch. Maybe some dynel cloth and graphite/epoxy too, as long as it doesn't make things too thick.

I only use top quality okoume and have built enough boats to know the difference. Any plywood can warp if not properly cared for. When laminating it will tend to take the shape of the underlying surface. The illustration in the manual, showing the pieces on scraps of 2x4s to provide clearance for the spring clips can lead to problems if one is not careful to ensure that not only are the 2x4s exactly the same thickness but that the surface they are on is perfectly flat. Nice thing about building boats is even if the wood is slightly warped you are almost always forcing it around some sort of a bend so its ok anyway.

Herb

Seems like I always learn these things after it's too late. I couldn't detect any warpage, but the true test will come when I try to insert the board into the trunk. If there is a problem I'll just have to fabricate a new one at that time. Thanks for the advice.

Uh-oh, after a more careful check with a good straightedge I see a very slight curvature. It drops about 1/8" at the center. Not too bad but may be a problem with the narrow trunk. My plan is to turn the keel upside-down sometime soon and dry fit the board. If there is any rubbing I will wait for the hot weather and place the board outside with 50# weights on each end. (Might put it in direct sun with a tarp over it for UV protection.) I had thought of putting a shim in the middle, but then I might run the risk of creating a curve in the opposite direction--so will place it on a flat surface and hope for the best.

If anybody has a better idea, please let me know. Is there anything about this in the manual? I have noticed this manual seems to be aimed at the more experienced builder--there's not a lot of hand-holding. I have built a kayak and a sailing dinghy, so have some experience, but obviously not enough!