I’ve been getting some water in my amas. Not a lot, but enough to worry about it if I go on en extended expedition. The prime suspect was water entering in through the bolt hole where the ama is attached to the wing. I had been putting silicon sealant there to minimize seepage. I should have that fairly well closed off.
I just did the experiment, though, of unscrewing the cap for the drainage hole and blowing in the ama with my lips sealed around the drainage hole. To my surprise, lots of air escaped from below the base of the drainage plug that is screwed on the ama. This might have been the main problem all along.
(Note this picture taken with a wide-angle lens which makes the ama look shorter and fatter than it really is).
When I unscrewed the drainage cap, I verified that there is no gasket providing a seal between the cap and the ama. This should be easy to fix. Fifteen cents worth of silicon sealant applied to the right place.
When I blew in the drainage hole after unscrewing the drainage plug (as shown above) the ama was air tight except for a tiny bit under considerable pressure being forced out through the bolt-hole.
I think the ama was acting like a lung and while sailing various forces where causing the ama to expand and contract causing an inhalation and exhalation around the base of the drainage plug. On some of the inhalations water sucked in. Over time a lot of water can suck in especially if you are burying the ama or if waves are crashing over it.
In conclusion, I need to add a bit of silicon under the drainage plug insert.
[Edit: It was pointed out to me that the amas need to be able to vent some to handle hot air expansion while sailing. Be sure not to seal things up too tight. Let it breathe a little and tolerate a little water getting inside. Otherwise, any built-up air pressure could cause other unwanted failures.]
[Edit: Be sure not to block the small hole at the base of the plug. This is actually where the water will drain out. If the hole is blocked, water will only be able to drain out through the end of the shaft that inserts into the ama and you will never be able to get it all out. It might be a good idea to drill some extra holes at the base of the shaft.]
[Edit: I drilled a 2nd hole on the other side of the plug to allow the water to drain out twice as fast. I only put silicon on the plug away from the holes to not cover up the holes and also to allow a little air to vent at that location on the plug. The idea is to add some silicon to prevent some water from entering but not so much that it also prevents any necessary venting to avoid air pressure issues within the ama.]
