Fore Hatch for a Wooden Boat
How do you build a fore hatch which never leaks?If I knew that my friends, I would patent it and make millions.
Wind and spray have a habit of seeping through even the narrowest of crevices.
Of course it all depends on the type of boating you intend doing and on your local weather patterns.
Another consideration for the DIYer is, will it be reasonably easy to build.
If the fore hatch is likely to be walked on it will need to be strong and the top non-slip.
You will also need to be able to dog it down tight when at sea and to make it burglar proof.
My personal preference is for a forward opening fore hatch which will funnel air below when at anchor and lying to the wind.
The forward edge tends to be
the worst for leaks, however
it is easier to seal the opening edge than the one with the hinges. 
The
top covering can be made from tongue and groove or
laminated with plywood.
If you are using just tongue and groove, be sure that the wood is reasonably stable so the joints don’t open and close as the wood wets and dries.
On Mignonne’s hatch I used tongue and groove covered with plywood which was then painted with non-slip.
It is fairly simple to let an acrylic panel into the top to allow light below.
However, if this is likely to be walked on it will need support, such as brass rods underneath .
The acrylic will be slippery for walking on and will be a source of condensation underneath.
Rounded corners of the overhang will be both varnish and shin friendly.
And a curved top will always look so much better than a flat top.
The
outer sides of a hatch opening should never be within the
carlings as this is sure to lead to leaks getting into the beans and
below the
deck covering.
The outside rim of the opening should be fastened through the deck.
The corners of the hatch frame can be rebated however, these do need to be strong to prevent warping, they can be strengthened with doweling.
A box or finger joint will be stronger and look better.
I use a dovetail jig.
There are several types of hinge available however, piano hinges are fine.
There are also numerous types of stays for holding the hatch open, but some of these will extend below the lining when the hatch is closed, consider if these are likely to be a hazard.
The hatch flange should have an overhang with a drip groove on the under side.
The
hatch design shown has Weather strip, the sticky backed
sponge seals are fine and they are cheap and easy to replace.
The facing of the opening, inside carlings extends above the level of the outer rim, these need to be well sealed to prevent any water which does get passed the outer rim from seeping behind them.
I have shown the scuppers as being on the side however this will depend on the slope of your deck.
Scuppers are best placed on the trailing rim and certainly not on the front edge where green water might be forced through them.
I can’t guarantee that this fore hatch design will never leak but so far it has worked well on Mignonne.
