I see below the waterline through hulls and hoses as potential boat sinkers. With a vented loop well above the water line, only that column of hose to the loop, the connections at both the thru hull and loop are the vulnerable areas. Without the loop, everything connected is fair game for boat sinking. The hoses, the bladder, the pump, and all it's connections. Plus, I wouldn't think a survey would allow that?

But I wonder the same about the pressure on the pumps check valve. I guess I'll just try it I don't think there's anything worse than it would pull the check valve through it's stop. Then again, this must happen in other set ups where the pump out has tested these check valves, I haven't heard of a problem. Mechanically, a stiff plastic flap against it's stop. It would have to collapse or otherwise break up to fail I guess. Then the vented loop would open.

I'm kind of testing the whole idea with the thought I would look into a better tank, hand pump in the future if it all works out. At that time, if a Y valve looks needed, I'll figure that space in.

Thanks.