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Staples in plascore
Staples in plascore
April 12, 2017 06:50PM
Curious if anyone has stapled plascore on to wood successfully.

Now​ that my strong backs are done i want to staple my panels to the strong backs, lay my bottom on the inverted boat, and then glass over the staples.

I would disassemble the strong backs, pull them out, clip the staples and then glass over them on the inside.

Would this work with the honey comb?
Re: Staples in plascore
April 12, 2017 10:30PM
For all Plascore construction I use 1" inch or 2" inch squares of scrap 1/4" plywood with a sheet rock screw going through the scrap plywood, then through the Plascore and into what ever temporary wood former is on the inside. Those hold the Plascore tight to the form. Then I glue the Plascore edges together with epoxy putty. You could probably use 3M 5200 instead of resin putty, the stuff that comes out of caulking gun. I haven't experimented with that yet.

Once the Plascore edges are fastened together you can remove the temporary 1/4" plywood scraps and fiberglass the outside.
When I built with plywood I fastened plywood sides directly to chip board trapezoid shaped temporary ribs.

The few times I've built all Plascore I built a real plug first with AC construction plywood fastened to the temporary ribs, with 4mil visqueen over the plug and Plascore on top of that. I like the plug because it helps me see the shape of the boat before I commit to cutting Plascore. But it isn't required. Larry Hedrick built his all Plascore Rio Verde (a stretched out 17' foot Honky Dory) with Plascore fastened directly to chip board temporary ribs, as if it was funny looking plywood.

Larry used 1/2" Plascore. I've always used 3/4" inch. I'm using 3/4" now because I had a half a dozen sheets on hand. But if I had it to do all over again I'd at least consider 1" Plascore for the bottom. Jeremy Christensen built a Briggs with a 1" inch Plascore bottom.

The stiffness of Plascore panels increases as the square of the thickness of the honeycomb core while the weight of an additional 1/4" inch or 1/2" inch of plastic honeycomb core is not much. Lots more stiffness with only a tad more weight is hard to argue with.
Re: Staples in plascore
April 13, 2017 02:25AM
Ok, but i don't understand how the form doesn't move once the screws are taken out. I'm ready to epoxy my transoms on, then lay the top on it and weigh it down, once the epoxy dries and the bottom and ends are glued on, what keeps the boat in place once the screws come out? None of my panels are fiberglassed yet if that matters.

Also im just using 2x4 as temporary ribs. I've got some ideas how to do it, just looking for opinions/direction.
Re: Staples in plascore
April 13, 2017 03:50AM
If you build a plywood plug with AC construction plywood over temporary frames the core covering, which is either Plascore or more expensive plywood on top of visqueen on top of cheaper plywood, there is no problem. Once the edges are glued together the core just sits there. Glass the outside pop it off the plug or mold and proceed with straightening and glassing the inside.

I you want to make it simpler and cheaper by skipping the plug you can fasten Plascore or plywood directly to temporary rib like formers. In that case you don't remove the screws that hold the core to the frames. Press some bar soap or wax into the screw slots and glass right over the screw heads. Use an exacto knife to dig the screw heads out a few days later. Back the screws out then. Putty over screws holes.

For a bright finish where appearance matters you can make those screw attachments close to the chine and underneath what will later be covered by a gunwale. For a paint finish it doesn't matter where the screws go.

I started making cheap male plugs with AC plywood back in the late '80s when I made end grain balsa wood hulls. Plascore is much the same but an order of magnitude better. Balsa core is no good below the water line--"encapsulating" it in fiberglass is great. For a while. But it doesn't last.

I recently patched a Plascore chine that was ten years old. It had been split open and dinged for years. I just ignored it. There was no price to pay. Fixing it was a snap. I ground the cracks open a bit. Let it dry for two days and patched. If it had been plywood or end grain balsa under the split fiberglass (on the chine) drying out the core material would have been a giant pain the grinder/heater/fan. With lots of cussing and teeth grinding.
Re: Staples in plascore
April 13, 2017 09:41PM
Here's the plug I built the blue Dayak on.....pictured a few posts away in a slightly different thread.
AC plyood sides, chipboard ribs.





The side panels were about 10' feet long. The bottom about 54" That's wide for such a short boat. It's really stable. Lots of side flare too so it rides up instead of dipping down--when I suddenly get sideways to a fast current. If I had it to do all over again I'd make even more side flare (which requires a serious dish in the chine, else the rocker gets out of hand).
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