My friend made one up himself. Get a high pressure inflatable dinghy pump (4-7psi), connect a long flexible plastic conduit (used for wiring) to a snorkle, Tee-off near the snorkle top to another short length of conduit and end with a plastic throttling valve. With this throttling valve, you can adjust the bleed-off pressure slightly so that you won't be over pressure by the pump and yet can throttle in if you go deeper. Do not understand estimate water pressure at 4-8 feet below. The snorkle must have an over-pressure one-way valve. That's your safety device in event you shut the bleed-off too much and pump pressure is coming in. You won't want to puncture your lung. Any decent snorkle should have this feature.
This arrangement is good for cleaning even the keel. Depth is depandant on the pump pressure.
There is always an element of risk, its up to you to manage that.
7 feet of water is approx 3.0 psi
2002 Hunter 326, SV Millennium 2
1999 Macgregor 26X, SV Millennium
Last edited by trantor12020; 09-29-2008 at 10:40 PM.