Saturday, June 28, 2014

Hatch hold-downs

I'm building eight plywood hatches into my boat.  One issue with hatches is how to latch them, with maybe the simplest answer being to put six or so turnbuckles around the perimeter.  I thought it would be more elegant if I could reduce that number to maybe two.  In order to attempt that, I've built in interior hold-downs for one side of the hatch.  This is an idea borrowed from another SCAMP builder.

Here's the proto-type.  From the top down, there is hatch cover, hatch stiffener, and then the latch made of three layers of 9mm ply.  Notice that the latch part extends out beyond the edge of the hatch, and this is key.  It gives you room to insert the hatch into the hold, and snugs down the hatch cover on the gasket as the hatch closes.

Here's the prototype being checked for fit

I laminated a bunch of stock and cut it to length.  The two longer pieces are for the seat hatches. The V-cuts are there to locate the hatch in the center of the hole on the latch side and the two adjacent sides.  I cut them to rough dimension with the bandsaw, and then made a little router jig to make sure they are all the same.

I then made a positioning jig to locate the latches side to side and at the proper distance from the edge.

After applying thickened epoxy, I held the latch in place and shot two 23-gauge pins in from the other side to hold it in place ...

... while I removed the positioning jig and applied a couple clamps.  I really like the stainlesss pins in an application like this because they keep the parts from sliding around while putting the clamps on.

Here's the set of them all glued up. 

Next I laminated some stock from which to cut the little triangle pieces.  I inserted each hatch into it's proper hole and shimmed them in  the center.  Then applied thickened epoxy to the triangles and shot them with three pins each to locate and clamp them.  No additional clamping needed for those.  I then removed the hatch covers and cleaned up the epoxy squeeze-out. 

Getting these little triangles installed under the cockpit sole was the piece of work that has been holding me up from getting the cockpit sole glued down. See next post...


  1. I'm anxious to see how this works out in practice

  2. Yes, I hope it works out. I figured that worst case I can revert to the typical system of having hold downs all around the hatch. I have one hatch in B3 that has a slight bow in it that I think will cause problems, I think a stiff, flat hatch cover is essential to get these to seal well.