Seat top hatches

After a bit of a break, I’m back to futzing on the boat a little bit every week. In thinking how to handle the larger custom hatches, I landed on a few points:

• I don’t want to try to perfectly recreate the old PT hatches, complete with routed groove for the gasket. This is a lot of work for something that will admittedly look clean but apparently not work in most cases

• I do want a clean hatch cover opening. This means hidden attachments and minimal visible crap on deck

I’m going to go with a kayak style bungie hatch. This uses bungies to hold the hatch cover down from underneath, at the cost of taking up some space in the actual storage area for running the bungies themselves. But it does provide a nice clean topside.

Also, I decided to go with a basic gasket around the lip edge, just affixed with something like double sided tape. This is simple, easy to apply and replace when needed, and works pretty well from my experience with kayak hatch covers.

Hatch locations

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I decided to start with building these hatches into the seat tops first, before cutting into the cabin sole. I’m a little more uncertain about putting these style of hatches into the cabin sole (there’s no really good drainage system with these style hatch covers - water is just meant to run off. That works for kayak hatches and seat tops, but in the cabin sole there’d be nowhere for the water to run), and so I wanted to build a few first (and as it is, I’m thinking I might go back to armstrong hatches for all access holes in the cabin sole itself)

Secondly was to decide how many hatches and where to put them on the seat tops. In argument for fewer hatches cut is the fact that your boat will take longer to flood, while more hatches makes getting access to storage space much easier.

Thinking about the starboard seat top, I eventually decided to put one small access hatch between b4 and b5 (so that I could access the centerboard pin if needed) and a larger one to access the large storage area between b5 and b6 (and, through the cutout in the frame, to also be able to store things between b6 and b7 via this same hatch cover).

I considered potentially doing something a little different on the port side, but eventually decided to just mirror the setup over there. So two hatch covers per seat top, a small one farther forward and a large one behind it.

Gasket space

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Using a gasket taped down on the lip does mean that I need a bit of spacer material between the underside of the deck surface and the lip itself, in order to provide a place for the gasket to compress and still have the hatch cover be level with the surface top around it.

I figured about an 1/8" thick would do it, and so after much searching I finally found a sheet of “door skin” plywood, which is basically just a single veneer of wood, thus 1/8" thick. This will be perfect.

Construction - cutting out

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First off I had to size the hatch covers (I used the old PT hatch covers as a rough guide for sizing) and figure out how to round the corners (I chose the radius of a nice tin of varnish in my shop - all the better for wrapping in sandpaper and then using to sand the corner once cut out!)

The best way I found to cut them out neatly (so the cutouts can be reused as the actual hatch covers) was to use an oscillating multi tool with a very thin kerf blade for the straights and a (very) small japanese pull saw for the corners. Worked great, although the corners took a while.

Construction - gluing

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With the covers cut out, next up was fitting the seat top back into the boat and then fitting the spacer (and after that the hatch cover lip) in prep for gluing.

With them flipped over I added a couple of marking lines to ensure the piece is properly aligned once glue is applied.

Then the steps were:

• Mix up straight epoxy, and put a coat on the bottom of the seat top and the gluing side of the spacers

• Mix up epoxy with silica thickener to a good peanut butter consistency, apply to spacers, and put back on seat top using the alignment marks made earlier

• clamp everything down making sure nothing moves as clamps are applied

Inevitably after the epoxy dries there’s some glue squeeze out on the inside edge (that’s hard to get rid of because the clamps are in the way). A rasp to the rescue!

With the spacers in place, next was to glue in the hatch cover lip itself. But before doing that, I wanted to round over the top inner edge to make this a bit of a soft edge for when I’m reaching through to grab gear. A quarter inch round over bit on the router table worked great.

And then finally back onto the boat, position the lips, clamp in place, off the boat for alignment markings, another coat of epoxy and then glued in place.

After this I applied one more coat of epoxy across the entire bottom of the seat top, including the bottom of the lip itself. The underside of the seat top is now nicely sealed (indeed I’ll have to rough up some sections of it before gluing the seat top down onto the boat itself).

The starboard and port seat tops are now done, so next up is building the bungie attachment system for each of the hatch covers.

My small time disaster

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So where was the disaster per se?

Up above I was very specific about ensuring you fit the seat tops to the boat and then position the spacer for gluing, clamping it in place then pulling the whole assembly back off the boat to actually glue in place.

You see, if you don’t do this, you might accidentally glue the spacer to the top of the seat, instead of the bottom.

Once I realized my mistake I tried to sand off the spacer, but that was taking too long, so I tried to grind it off, which worked better but i was digging into the seat top itself a bit, and so I just decided to buy a sheet of marine ply and cut a new seat top, which is what I did.

Marine ply is a lot more expensive now ($170/sheet) then it was when I started this project. An expensive lesson!