One of the mantras in small boat design is "Space
is a premium, and to save space, everything should have more than
one purpose." To this end, many boat designs use the seats
and internal bracing to create empty spaces that, when closed
off, become flotation chambers - aka air boxes.
There are a couple of problems with making closed
off places in your boat: 1) They take up space - sometimes a lot
of space. 2) Water is insidious, relentless, and persistent -
it will get into any space it can. Left to it's own devices, water
will rot your boat.
The easy solution is to put an inspection port in
your air box - a hole big enough for you to reach in with a sponge
or towel and get any moisture out. If the inspection port - and
the air box - is big enough, you can use it as a storage space
and get a little bit of your boat's real estate back.
Lots of people like to seal off these inspection
ports with a hatch - something as simple as a board covering the
hole, held in pace with a bungee cord or as complex as a hinged
and gasketed window.
Here at the Boathouse, we usually use 1/4
Turn Deck Plates from Duckworks as our hatches. They are cheap,
effective, and come in useful sizes. They have two pieces - the
lid and the flange
The biggest drawback to using these hatches is that
they are fairly easy to goober up the installation, slightly deforming
the flange, making it nearly impossible to open or close the lid.
There are three main reasons an installation gets
Make sure to use lots of caulk (non-silicon, usually
labeled as "paintable") and make sure you clean up the
excess before it cures and becomes an unsightly, un-removable, blob.
The structure is much more rigid when the lid is in
That's it - if you can keep your installation loosey-goosey
and let the caulk do all the work, you should be golden.