I'm in the progress of building a "guillemot", is it advisable to prepare for a rudder on this design? Or is that just to ruin something that has reached completion? Unfortunately I haven't had the opportunity to try this design.

I recently stumbled across a product that looked just right for a previous posting about venting a closed compartment(I have searched the archive but is unable to find it again :( It is a membrane-ventilator from Gore called Gore-polyvent/PG7, that is used to ventilate electronics enclosures, it can withstand an outside water pressure of 0.6 bar. And when not under pressure ventilate vaporized water from the inside. Cost is 61 SKR about 8 US.