Skip Asay's "T" valve - a new(?) twist on an Old School idea

[roedj]

This question is probably intended for HeWhoCannotBeShamed but anybody's free to answer and thank you for your time.

While scrounging through my shipyard misc. boxes I came across one of Skip Asay's "T" valves (see the attached picture). I even ran one of these subs - a Marlin, I think - many, many moons ago. It was not sophisticated but it was simple -KISS all the way- and fun. The only problem with it was that it didn't work too well if you couldn't drive the sub tower, and thus the air intake, above the water line.

Before you get your knickers in a twist, let me explain the word "problem". It was not a problem with Skip's design which I view as genius but only a problem for me and my intentions. OK?

But then I thought what if I attach one of DM's SNORT valve to the air intake so that I can more rapidly achieve an increased positive buoyancy driving the boat to the surface quicker where the air intake can actually take in air - what a concept. I wouldn't have to suck much air from the dry sections of the WTC to achieve my goal - I think - just enough to add some positive buoyancy to a sub that is already slightly - and I do mean slightly - positively buoyant.

With asbestos girded loins,

Captain Cantankerous

[trout]

Just my < 2 cents worth, what will a slight vacuum produced by the blowing of the tank have on this design?
Peace,
Tom

[Bob Gato]

I guess the air from the dry WTC goes to negative pressure then gets equalized after surfacing but then stays at atmospheric -I don't see how exess air from the ballast tank could be stored in the dry area with that lower check ball closing and all the ballast tank air goes overboard when the tank is filled? -I must be missing it...

[roedj]

Just my < 2 cents worth, what will a slight vacuum produced by the blowing of the tank have on this design?
Peace,
Tom

Technically, you don't blow the tank.except if you're forced to use the gas (Propel, air, CO2,...) for an emergency ballast blow.. Ordinarily, just pumping water out of the ballast tank creates a low pressure area at the top of the tank and air is drawn in from the outside if the air intake is above the water. Therein lies the rub. If the air intake is below the water line then turning on the pump to expel water just brings more water in and nothing happens. In this case, you're at the mercy of the positive buoyancy you hopefully built in to raise the sub until the air intake is above the water. My idea (and I don't really know if it's truly my idea) is to scavenge some air from the dry parts of the WTC to give the sub some additional positive buoyancy to surface more quickly.

BUT...

Bob (see below) may have identified a gotcha in my idea - please read below.

[roedj]

I guess the air from the dry WTC goes to negative pressure then gets equalized after surfacing but then stays at atmospheric -I don't see how exess air from the ballast tank could be stored in the dry area with that lower check ball closing and all the ballast tank air goes overboard when the tank is filled? -I must be missing it...

Bob,

Good catch.

Normally air that is expelled from the ballast tank is pumped overboard and is not stored anywhere. If I scavenge air from the dry parts of the WTC it does NOT get replaced unless...

unless, unless the SNORT valve opens up a passage to the dry parts of the WTC - and thus equalizes the pressure - when it also opens up a passage to the outside air. If the SNORT valve does not work like this then my idea is pretty much verkacht. I could draw air from the WTC maybe once or perhaps twice but then then the low pressure area created in the WTC would be a leak just waiting to happen.

I have zero experience with DM's SNORT valve. Does anyone know how it works? Does my idea still have some merit?

Captain Concerned