totally watertight hatch

Here is a plan for a totally watertight hatch for yachts going into the high latitudes, it is a fact that 100% of companionways hatches can be made to leak if a high pressure hose is played upon the hatch, thsi means in a knockdown water will ingress the boat
The hatch here will never leak, , but you climb over the cockpit forwards coaming to get below In lesser lats, you could build another sealing door so that you do not have to climb over Drawn here for metal, but boats built of timber can easily adapt the hatchway coaming by using hardwood coamings of aluminium fabrication bolted to the cabin
i built the smallest yacht to be overseen by Lloyds in NZ, sure enough they turned a hose on all apertures, I did not use this hatch but the one I designed had metal tubes running fromn the hatch channels to the outside
the hatch here, was designed by an old friend who indeed sailed from NZ to UK via the Horn in a 32 footer, they steered by vane all the way and checked things through the bubble

[MikeJohns]

Stu

One concern would be that it should be able to be opened under pressure or unexpected load.

2 part hatches are safer in this regard, so I'd go for your suggestion of a vertical door or drop board in company with this. Just thinking of a dis-masting with the shrouds over the cabin-top , then if the fore hatch was similarly indisposed you'd be really sweating.

At least with drop boards you can use the axe in a real conundrum and they are easy to rebuild.

Do you know of any really reliable low profile Self sealing ventilators ?

[timgoz]

Interesting design. Looks inheirently stronger than a tarditional hatch. Would definetly work well for steel constrution. Do like Mike's idea of wooden door or drop boards & axe. Would have them extra stout.

Tim

WELL mIKE, this is a submarine type thing, and there would be hatches of the other type on the deck, Weaver NZ make a good one, the Volvo boats used with success, I dont know what the open 60,s use, think just a w/t door and no sliding hatch

MAKING egress as tight as possible
thing is most people go to sea neevr encounter a storm, but when it happens, stock builds are often in trouble