cont'd from 8/13:

Here's a couple more wierd ideas

Opposing Coves:

1) Wierdo 1 - worth a chuckle anyway:

After hatch cut out, run cove edge around hatch edge. Take a short length of 1/16" wire and attach to end of 1/4" rope ( as long as the perimeter of the hatch).

To close, place hatch in place and put 1/4" notch somewhere along the seam line. Thread in the rope by pulling on the wire , and pull the wire all around the seam. To remove, pull the wire back thru the notch. Simple, quick - but will it work?

Downside

- you must use vented bulkheads

- hull flexure could compromise

- one continuous rope is probably too much, but the idea is such a hoot! Try using bungee rope pulled taut, when you let go, it swells up to bind. Or 1/4" surgical tubing as it prob thins out more and seals better.

2) Wierdo cont'd further

Take a small bicycle inner tube ( I assume 1" diam. x-sect). Place it on uncut deck. Draw any shape hatch profile whose perimeter matches that of the c/l circumference of the tube. Flip deck. On underside of deck, glue 1" thick x 4" wide ethafoam (or minicell or urethane etc.) centred on the profile drawn above (poke thru pins for alignment). Flip deck back. Cut out hatch - cutting ethafoam at the same time.

Apply flange to u/s of the deck ethafoam. Route out a 1" diam cove in hatch and deck ethafoam. Drill 1/4" hole where you want the valve to stick up.

Deflate tube, mount it around hatch, put hatch in place. Blow up tube! If lung pressure is +3psi or more it may even be enough to be secure. Maybe use fitting on the hand pump? Maybe slight cove offsets to give more sealing pressure?

Nigh on invisible, too!

3)Small Airbag: (another stretch)

- assumes hatch w/ flange

Under flange, attach 2" wide strip of 1" wide ethafoam all around and flush w/ the opening. Sand or rasp this edge back 45 deg. On underside of hatch, mark w/ pencil the extents of the flange. On bottom of hatch, glue (or attach w/ webbing) on a small airbag that is just larger than the hatch. Poke valve up somewhere thru hatch (pretty fitting or minimal). Put hatch in place, blow up airbag - it's stuck - and you won't sink either!

Well maybe, at least you'd be using airbags!

another type of hatch on dwg 10/13