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Dean, I think your on the right track. The Alicia and R300 both have the ability to release there drop weights with a hydraulic hand pump. The Alicia has a ram that looks like a custom version of the Porto-Power Ram in the below link. http://www.northerntool.com/webapp/wcs/stores/servlet/product_6970_126175_126175 Here is a link for a 2 and 4 ton ram and a 4 ton pump. http://www.toolrage.com/prodView.asp?idproduct=4422 http://www.northerntool.com/webapp/wcs/stores/servlet/product_6970_382413_382413 http://www.northerntool.com/webapp/wcs/stores/servlet/product_6970_382415_382415 You could install an exterior check valve in the hydraulic line as it comes out of the hull for extra safety. I never did figure out exactly how they configured the Alicia's drop weight to be released by the ram pushing off one side of the drop weight. Perhaps there was some heavy duty resistance springs on the other end of the drop weight from the ram. Paul Moorhouse explained only part of it by showing the ram coming out. I can see a much easier configuration that does not require the springs, by having the ram push on the end of a lever, of which will rotate a dog, thus releasing the drop weight, basically how the K boats do, but with a added lever arm added to the rotating dog for the ram to be attached to and no shaft through hull. But since that type of configuration cost a lot more then a the way Dan H. built the Persistence, I would ask him if he has had any sealing trouble with his drop weight through hulls... If you want some extra protection for that through hull, just add a second O-ring to the shaft or add on a flange that is lathe turned as apart of the shaft on the exterior of the hull with a O-ring in it or the mating surface that is apart of the hull. As for me I would install two O-rings in that flange and grease them so you can rotate the shaft easier. The shaft would have threads cut into it on part of the area of the shaft that is on the interior of the hull, for a bolt to be used to tighten the exterior flange with it's O-ring(s) against the flat surface of the welded in through hull lathe turned part. The end of the shaft that is inside the sub can be machined to be a square with a threaded hole in the end, so you can first slip the main through hull tightening bolt down the shaft and then add a bolted on handle. Now look what you made me do Dean. I have to make another model now. ;)' Thank goodness for cabin fever. We got another foot of snow dumped on use in the last 24 hours, so we now have at least five feet of snow with no end in sight. Regards, Brent Hartwig
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