This morning the cramps came off the pot recess.  A little bit of trimming and sanding and I'm happy with the result.  The bottom of the recess is curved so water will run out easier when the yacht is heeling and the overall oval shape keeps the volume down whilst allowing the lid to be easily removed.

This part will be glued to the underside of the deck which will have a matching oval aperture removed

Here is a photo of the BOR's miniature pot which only housed the RX.  Again the canted sides is to allow water to drain out and gain access to remove the lid

Checking the size and location, the BRC winch will be located on the Port side of the fin case.  The rudder servo (futaba 3050) will be located on the starboard side and the 3S LiFe battery and rx will be in the pot.  I think it's really important to keep the  weight as close as possible to the Centre of Balance or put another away make the bow and stern as light as possible.  The circular disc in the bottom of the photo is to stiffen the joint between the mainsheet post and hull.