: it has no bulkheads so i would like to add some, and then some hatches, will
: also have to relocate the rudder slides as my long legs push them off the
: rails

: so my question is what materials would make the best bulkheads and how best
: to seal them to the polyplastic hull, then how would i best waterproof my
: jigsaw cut hatches and fill the holes left when i move the rudder rails

I'm not aware of any glue that works reliably on polyethylene boats, so i would say that your two options are to use mechanical fasteners or a plastic welder for pluging holes and adding new fittings.

Harbor Freight has a plastic welder (www.harborfreight.com) which has a 500 watt heating element and uses compressed air at about 3 psi. It comes with a regulator, so you could attach it to an air tank or a small air pump.

The basic writeup on this tool is at:
http://www.harborfreight.com/cpi/ctaf/Displayitem.taf?itemnumber=41592
and its picture is at:http://www.harborfreight.com/cpi/photos/41500-41599/41592.gif

The instruction book for this is available online as a .pdf file at:
http://www.harborfreight.com/manuals/41000-41999/41592.pdf

I was looking at mcmaster-carr (www.mcmaster.com search for "hole plug") for some plugs and washers, and I was struck by the similarity of some of them to the rubber plugs sold for repairing tubeless auto tires.

I find them in the auto section at discount stores, complete with a tube of rubber cement and a tool for inserting them into the tire. Those parts you can save for when you et a nail in your tire and want to patch that hole. If your local repair shop has these they should be fairly inexpensive. Poke the thin end of one through the hole and grip it with a pliers. then pull the fat part into the hole. as you pull it stretches and gets thinner. when you stop pulling it widens again, and it should plug any hole very nicely. Carefully cut off most of the excess part of the plug and it should stay there until you decide to force it out.

A bolt (aluminum, brass, bronze or stainless) with a flat or oval head can be used. If you use one thich is slightly larger than the existing hole it may thread itself in, cutting its own threads into the plastic hull, and seal without the need of any gasket. Otherwise, you would insert the bolt from the outside, and on the inside force a rubber gasket or washer over the threads, then put on a washer and a nut. Tighten gently. You just need to slightly compress the gasket or rubber washer. You can cut gaskets or rubber washers for this from an old bicycle innertube. Or, you can make some from silicone sealant, or an acrylic plumbing sealant applied to the bolt and allowed to cure before the metal washer and nut are threaded on to compress this.

For a bulkhead you can use minicell foam as suggested by others.

I want you to think about why you would want bulkheads, though. If your intention is simply to reduce the amount of water that gets into your cockpit, then why not consider making airbags, floatbags, drybags, or cargo bags which would fill the space. A piece of waterproof material rolled into a cone and with a base glued on can be assembled in far less time. Just a suggestion.

To hold the inflated float bag in place you can add some brackets to the inside of the kayak, and criss-cross a rope between them. attach the brackets with bolts inserted through the hull. Again you cna thread them in and the should be self sealing, or you can insert them and add a resiliant internal gasket. On top of that place the bracket and tighten it down with a nut. You won't need the internal metal washer if the hole in the bracket is a fairly close fit to the bolt.

If you attach several of these around the perimeter of the boat you'll find them useful to hold a wood or plastic bulkhead in place. I'd seal around the edge of a stiff bulkhead like this with some minicell or other closed cell foam -- even home insulation -- as you won't find any way to really bond the bulkhead to the inside of the kayak other than welding it in. teh compressible foam should work as a good seal, though.

Use the same technique to attach brackets or fittings for your new foot pegs. If you are "large" then consider using several mounting points so that you spread out any stress you might apply over as large an area of the hull as you can. The worst case scenario would be if you pressed down too hard, forced the foot pegs out of place, and ripped the bolts right through the polyetylene hull, leaving you with small geysers of water coming into your cockpit from each neat hole.

If your foot rests have only one or two mounting points, then consider inserting a piece of wood or plywood and bolting that to the inside of the hull as a base. Use this to spread any stresses and strains over a larger area of the hull and mount your foot rails to this.

You may be able to use the existing holes for mounting those bases, and then you would have one less hole to drill, too.

As for the hatch on the deck.

Before you cut out the plastic for the hatch I think you should buy a plaster "insurance policy". This is nothing more than 5 to 10 pounds of plaster
of paris. Decide on where you want the hatch and outline the area with a grease pencil or china marking pencil, or put on some masking tape and draw a line on that. Two inches out side of that area tape a 1 inch high "form" to the deck. You can make this of cardboard or thick paper. Grease or wax the area inside the form with some vegetable oil or auto wax. Mix a smooth batch of plaster of paris and pour it evenly into this form. It doesn't need to be a full inch high, but at least half an inch would be good. When the plaster has hardened, remove the form and tap the plaster gently to free it from the deck. You now hav a mold of the curvature of the deck over th area where you want to put your hatch. You cna use this to make a fiberlglass hatch cover should the original hatch (cut from the deck material) either not work, or be lost. If you are making two hatches ( bow and stern) repeat the process for the second hatch.

10 pounds of plaster is not very expensive -- about US$5 so your "insurance" costs are very low. You can use these molds to make new hatch covers simply by waxing and oiling them, and then laying up several layers of fiberlass cloth and epoxy or polyester resin, covering with a sheet of saran wrap and maybe putting some weight on it (sand or a bag of water?) to help compress the layers of fabric and give a smooth interior finish. The polyester resin is readily available at auto repair stores and is less expensive than epoxy. While we use a lot more epoxy when working with wood boats, I think in this case the polyester resin may be a better product. When the fiberglass deck hatch has cured a day or so, remove it from the mold and trim it to fit.

Otherwise, the installation of hatches shuld be nearly the same as on a wooden boat. Mark the location, CAREFULLY cut out the hatch, make and insert a lip that sits 1/8th to 1/4 inch under the deck, and cover the sealing area with a rubber weatherstripping material, or other gasket which is 1/8th to 1/4 inch thick (a little thicker than the drop of the internal hatch lip) and drop the hatch back on.

The problem of designing good latches to hold that hatch closed is more involved than I want to cover here, but it is well treated elsewhere on the bulletin board. You'll have a lot of choices.

Hope this helps

PGJ
is