In a message dated 11/5/2002 12:23:04 AM Eastern Standard Time, storm@intas.net.au writes: << Don't know wether you have seen this one or not. Meant for model submarines but the theory is sound. All different styles of ballast tanks plus a good description of dive planes and the relationship between for and aft planes. http://www.heiszwolf.com/subs/tech/tech01.html Storm >> Very good. Vance