Re: [PSUBS-MAILIST] Joe's sub and Boyle

Hi Rick,

All of these issues, particularly structural ones, are partly the reason I have taken up a course in CAD Naval Architecture. I say partly as I have other motivations and areas of interest in marine design besides the sub. To answer your questions for both emails, I expect the design to be a completely dry ambient with a small VBT and removable weights to compensate for changes in occupants.

There is a general rule of thumb in boatbuilding regarding costs in the neighborhood of $4 to $6 dollars per pound of displacement. Mind you, that rule is for boats with various degrees of machinery and accommodations however, for my "Octopus" scheme there is no reason not to expect, at a minimum, the lower end of the range for about 6K lb displacement.

The very broad strokes of the design process for this project are done. (Dry weight) +/- (variable buoyancy) = dive/surface. Throw in some previously proven systems and there is no reason why this cannot work...with a caveat.

Caveat: I could build myself a 25 to 30k white elephant if I don't know what I'm doing. Somewhere in the NTSB accident reports, there is a fellow who built himself an airplane and forgot to include wing attach bolts or some nonsense like that......oops. It sure did look like an airplane but,.....He be dead now.

At this point in the game where structures, materials and construction are concerned...I'm just guessing. I have to try to be as objective as possible and apply the Scientific Process to keep emotions and judgment in check in order to increase my chances of producing a viable end product. Realistically, I will never have the time for experimentation with simpler structures and systems. When I carve that first stone, this particular pyramid is going up!

Ironically, I expect this to be under less stressors while submerged then when underway in surface wave action. But one thing is for certain. Every detail of this project will be spelled out, proven and drawn out to the point where I am convinced of 100% success prior to ever starting.

So the bottom line is that I am convinced this is viable but, I just have to learn how to go about it to the last detail.

Joe

From: "Rick and Marcia" <empiricus@telus.net>
Reply-To: personal_submersibles@psubs.org
To: <personal_submersibles@psubs.org>
Subject: Re: [PSUBS-MAILIST] Joe's sub and Boyle
Date: Wed, 26 Apr 2006 23:17:35 -0700

Once in a while I wonder about questions asked on the list. I had a "moment" commuting to work.

Joe - are you still at odds regarding the design of your cockpit and sloshing water and Boyle's Law?

Magical Child will be admitting water into the cockpit just like your boat. I realized that the easy way to answer your dilemma may have been to point out that MC's trim water will be admitted into the cockpit BEHIND a bulkhead behind the pilot's seat. A simple vent (hole) at the top of the trim tank/cockpit bulkhead will allow displaced air to flow back and forth to and from the cockpit and the tank.

The water will simply be behind MC's pilot rather than at his or her feet. Why doesn't Boyle affect the trim tank? The cockpit is sealed from ambient water (not pressure). There IS no water being admitted or expressed from the cockpit (except for initial trim adjustment just under the surface).

The cockpit regs compensate the cockpit AND the variable trim tank, which is merely a physical extension of the cockpit.

Rick L