More Folbot notes - seats, longerons, plywood

The seats were modified by some prior owner, maybe because they wore out or mildewed.  The renovated seats have that terrible cheesy open-cell yellow foam rubber--the stuff that absorbs water like a sponge.  A seat that doubles as a sponge doesn't seem like a terrific innovation to me; sitting down on a seat with an unexpectedly soaked cushion is only fun for the spectators, not for the poor dork who has to use the seat.

The just-plain-stupid foam cushion in one of the Folbot's seats.

The seat has a passable (but poorly glued on) vinyl cover, so what it needs now is some kind of closed-cell, durable, cushiony stuffing that will remain buoyant in all circumstances.  Some PFDs--maybe all of them, who knows--have sheets of white closed-cell plastic foam inside, and it seems like this stuff could be cut and glued to make a passable seat cushion.  Another alternative would be to use pool noodles or pipe insulation, maybe cut into a bundle of strips to make the seat less lumpy.

Foam sheet from a PFD.

PeteS on the Folbot forum suggested a boat cushion--which could be a Type IV PFD, which is a useful thing to have on any boat.  It could be held in place over the plywood seat bottom with (for instance) some simple clips on shock cord, in such a way that it could be easily and quickly detached if necessary.

The bottom of the seat and the brace.

I think the seat plywood is original, and I'm not sure about the braces.  If the brace is original, it may have come off when the glue failed from old age--which is a problem that affects the paddles and the boat's wood frame--and the screws pulled out of the plywood.

The bow assembly.

The longerons are the aluminum tubes that run the length of the hull and support the skin and the sides of the deck.  The flattened ends of the middle longerons are cracked where they attach to the bow and stern assemblies, maybe because they need to be shortened; page two of the Folbot Super assembly manual at John Burch's site says something about shortening the tubes if they are so long that they aren't in contact with all the frames.

The forward end of a middle longeron from the bow assembly.

I suppose the best solution would be to replaces the tubes; the next best would probably be to weld the crack shut.  I don't consider replacement an option, and I don't know how to weld (yet), so I sanded the cracked area inside and out and put epoxy putty around both sides of each crack in the forward tubes.  When I get around to the stern tubes I'll clean with a solvent after sanding and then work some liquid marine epoxy into the crack and add the putty when that's dry.  Wrapping the tube end with fiberglass tape and epoxy might be another option if it doesn't add too much bulk to the tube.

The longerons are supported at the bow and stern by bolts that runs thru the wood and thru the tubes. Rather than try to shorten the tubes I might try move the hole forward by drilling a new hole for the bolt a bit forward of the old one at the bow, and epoxying a hardwood dowel into the old hole to fill it.  If that doesn't seem to make it harder to get the bow into the skin, and if the tubes are still too long, I could try the same thing at the stern.  This trick is reversible--the old holes can be drilled out and the new ones filled--but it would be harder to lengthen a shortened tube.

The edges of the tube at the flattened end seems a bit sharp, and I'm going to sand these down so they won't be able to gouge the inside of the skin.  It seems to me that if the tube ends had a slick surface that didn't cause friction with the skin then assembly might be just a bit easier--but maybe not enough to justify the effort.  Or maybe it would help a lot; I'll just have to try it to find out.

The end of the stern assembly. 

The stern assembly looks like the bow assembly (pictured above).  There's a rotten spot on the stern, maybe from a damp garage floor.  In the lower left you can sort of see where the lamination of the plywood is uneven.  I think that this is caused because wood shrinks as it ages less in the direction parallel to the grain than it does perpendicular to the grain, and since the grain of each ply in the plywood is at right angles (or at least at a different angle) to the grain in the surrounding plies, the odd plies are either higher or lower than the even plies.

I suppose the edges could be filled with epoxy instead of being sanded down and then sealed with epoxy or oil or whatever.  They ought to be sanded when the wood is re-varnished every n years anyhow--plywood edges can look really good if they're sanded properly before being finished. If the boat's skin has shrunk (I hear that's a common problem) then sanding the edges, and some extra off of the foremost and aft-most extremes, should be mandatory.

The rotten spot ought to be cut out and replaced, preferably with some more marine plywood, since it looks too deep to just sand away.  It would be nice to have some kind of abrasion-resistant patch under the ends of the longerons so that the varnish wouldn't be scraped away.  (Or maybe the longerons could be fixed so they don't scrape.)