I am sorry but you did not see how mine works it is a non presurized tank system ,see diagram,real one way valves are used,that way the pump and lines are not stressed or amprage increse.I fully acknoledge the system you areusing,before as mentioned at first you said no valves now you say you use valves,even if its just a smaller line it will still alow water to return into the bag simi flexable or not,this has all been tried before.
It might be ok on small subs but on larger ones there is going to be problems especialy in the freeboard aspect and at depth.
This system is very similar to others posted.
I guess most of your concerns derive of your lack of precise acknowledgment about my system. It is not a standard pump and tank system, where, yes, the pump drains more and more amps when filling the tank, due to the air inside raising pressure NOT MY CASE. As I fill the bag, the air escapes through a hose which has a one way valve, that valve prevents water to enter again when "blowing" the tank, maybe a few drops through the tiny hole in he hose, while more "gallons" are pumping out through the pump, this way making the sub emerge.
Dave Amur Sub Yard
