Vance would know more about how common it is but fighting for space inside is a common thing. Moving the water with air pressure is fine but what do you do with the exhaust air as to get rid of it would mean fighting against outside water pressure or compressing it inside the transferee tank. I believe it is better to have access outside as then you can compensate for different weight of passengers and also compression of the vessels, difference in temperatures, fresh to salt water options etc. Easier to use a manual bilge pump to transfer if you are having it inside and then air into one tank equals air out. I am following the Comsub HBT system with the motorized pump and 2 tanks with a relief valve on each tank so if the pump fails I can blow with air to remove the water against the relief. My penny’s worth. Hugh From: owner-personal_submersibles@psubs.org [mailto:owner-personal_submersibles@psubs.org] On Behalf Of ojaivalleybeefarm @dslextreme.com Hi, I'm thinking of having my hard ballast located inside my pressure hull and controlling it's contents with air pressure. So I guess it will have to be rated equal to my pressure hull. One reason for doing this is simply for logistics as far as how my sub is laid out and how I have to locate things. I could change this in the future to have the hard ballast outside if I can find a good place for it.. I was toying around with the idea of having fore and aft trim tanks using hydraulic fluid as the medium for transferring weight fore and aft. That way I wouldn't have to worry about corrosion in the pump, even though the oil would not have the weight of water. Is locating a hard ballast inside the pressure hull a common thing to do? Hugh, any thoughts? Brian __________ Information from ESET NOD32 Antivirus, version of virus signature database 6925 (20120229) __________ The message was checked by ESET NOD32 Antivirus. http://www.eset.com __________ Information from ESET NOD32 Antivirus, version of virus signature database 6925 (20120229) __________ The message was checked by ESET NOD32 Antivirus. http://www.eset.com |