Frank, I know that you have put an awful lot of thought and effort into this project so I cannot wait to see your success. Depending on the angle and the amount of water flowing past your lower angled ballast tank ports, you may find that a vacuum gets pulled on your tanks. R/Jay From: owner-personal_submersibles@psubs.org [mailto:owner-personal_submersibles@psubs.org] On Behalf Of ShellyDalg@aol.com In a message dated 10/25/2009 2:18:41 P.M. Pacific Daylight Time, bottomgun@mindspring.com writes:
I think I know which boat. It's got some nice innovations. Hope to see some info as it progresses in design. If we take a heavy pressure hull, encase it inside big ballast tanks, we can make it float well above the surfaced water line of the hull alone. Just how big the ballast tanks need to be depends on how heavy the pressure hull is. Of course, it takes a LOT of air to blow out the tanks.....I've got 320 cu.ft. of onboard air for ballast blow. That should give me 11 blows at/near the surface. I can hardly wait to finish welding the tanks to see exactly how much they hold. I'll use a 5 gallon bucket and fill 'em up with water to get a real number. One concern for me was when towing, the ballast tanks might fill up with water just by virtue of the water piling up against the openings. Again, another trade-off. The open ports to my ballast tanks are short tube sections of 2-1/2 stainless pipe cut into the bottom of the tanks, ( two each tank ) and angled backward so the water flow when towing will be rushing past the openings. The trade-off is maybe slower to fill when getting ready to dive, and possible over pressurizing the tanks if I dump too much air into them too quickly. I can always increase the size later if these two events prove problematic. The air side of the tanks is 1 inch so I'm hoping the water can get in and out without stressing the tanks. Frank D. |