This is the second time I have reviewed the inspection port requirements for the Dorade boxes.
The drawings say to install 4" inspection ports in bulkhead 2, to provide access to the boxes. So I duly purchased a pair, and set them aside. As mentioned in a previous post.
Now, as I started to build the Dorade boxes I thought about their final fitting out.
I retrieved the ventilator cowls from the hull hardware pack to check them out, and re-discovered that they have a hefty screw-in flange inside the Dorade box to seal them off securely and completely from the outside when not in use.
This flange does not fit through the 4" inspection port. That would mean it would be imprisoned permanently inside the box when unscrewed, rattling and banging about while sailing or on the trailer.
That's no good.
The only practical alternative is to switch to a 5" inspection port, with sufficient room to remove the cowl sealing flange completely when sailing.
So I duly purchased two more inspection ports.
Now I had to make a new pair of gaskets as well.
First I scribed out the hole using a compass on some scrap ply.
Then I cut out the hole with a Japanese keyhole saw, which made short work of the task.
I cleaned up the inside edge of the gasket with a Spiraband abrasive wheel ...
... resulting in a perfect drop fit.
Then I cut out the gasket with a jig saw ...
... and cleaned it up with a rasp.
Lastly, here is the pair of new 5" gaskets, ready to fit when required.