Re: [PSUBS-MAILIST] Variable Ballast Calculations

Bill,

The "hybrid" component of the Hunley is fascinating and would be interesting to consider. But as I told you earlier, I do not trust my engineering skills enough to design the hull in such a manner as to be able to "cycle" like that. But perhaps others would be able to incorporate precisely those ideas, the savings in space and air requirements would be well worth the effort.

Fascinating links...thanks!

Joe

From: "Akins" <lakins1@tampabay.rr.com>
Reply-To: personal_submersibles@psubs.org
To: <personal_submersibles@psubs.org>
Subject: Re: [PSUBS-MAILIST] Variable Ballast Calculations
Date: Sun, 13 Nov 2005 06:32:54 -0500

Reading the psubs posts about variable ballast calculations made me think of the things below.

Why variable ballasting made me think about them will become clear towards the end of this post,

but enjoy the links at the beginning of my below post first, then you will see the connection.

Four confederate submarines like the Hunley are buried in earth that once was covered by a river in Lousiana. A situation

similiar to the recovery site of the steamboat "The Arabia" in that the river changed its course from where the confederates

scuttled the subs to prevent Union capture. The four confederate subs are there to this day waiting for someone to dig them up

on DRY land! Check it out at this below link.

FIVE CONFEDERATE SUBMARINES AT BUILT AT SHREVEPORT

A while back I wrote a section/link there called... " How did the Hunley's ballast tanks work and how did she submerge?"

and was answered by this section link.... Michael Crisafulli ANSWERS who is a conservator archaeologist

currently working on the Hunley. Mr. Crisafulli supported my hypothesis that the Hunley was (TECHNICALLY) ambient WHEN

her ballast tank inlet valves were OPEN and water was filling her open to the hull interior tanks compressing her atmosphere.

Then when the ballast tank valves were closed and AFTER the water was pumped out of the tanks, she became a 1 atm sub again.

It appears my claimed theory that the Hunley was a hybrid of both systems is likely correct according to a conservator of the Hunley.

I may be a "Hunley Bunley" (whatever that is! Lol) but my theories were vindicated. It appears I wasn't a "candle waster" after all for

defending my theories to critics who claimed the Hunley was ONLY a 1 atm sub and NEVER ambient. Perhaps who called me that

might burn a few more candles of their own in studying next time before they cast dispersions. The Hunley conservator agreed with me,

even though he said it was TECHNICALLY ambient because of the smallness of the ballast tanks. Technically or not, Hunley was both ambient AND 1 atm.

A hybrid like I thought. He also agreed I may very well be correct that the Hunley was ALWAYS just slightly buoyant and that she may have pushed herself

underwater with her forward motion and dive planes and then when the water pressure was greater than the trapped interior atmosphere, her ballast tanks would

begin filling when their valves were opened. Similiar to the Holland sub which was previously thought to be the U.S. Navy's first sub until the existance of the

Alligator was discovered, wherein the Holland was ALWAYS slightly buoyant and kept under only by her forward motion and dive planes.

Here's the site's homepage main link below.

http://www.hunleystore.com/NEWSLETTER_58/NEWSLETTER_58.htm

Seeing that the Hunley's internal and open to the hull interior ballast tanks were very likely a hybrid ambient/1atm, I thought it might be usefull for some of our members who want to

construct their own small ambient subs to consider this... Imagine utilizing a system wherein your sub was ambient when the open to the interior ballast tanks

were filling, which compresses the air INSIDE the sub and you could pump the water back out WITHOUT having to have ANY compressed air

to do so. That would save space and weight since you would not need compressed air to blow your ballast tanks. Then you could close off the

ballast tank inlet valves to keep any more water from coming in once you were neutrally buoyant underwater. The beauty of this hybrid system would

be that although your sub would TECHNICALLY be ambient when the valves were open and the water was compressing the interior atmosphere, it would

not compress it very much if you made the sub heavy enough so that the ballast tanks did not have to be large. Also the small, technically ambient, compressed hull

atmosphere, would not be much of a concern for human body decompression at all even with the tanks completely full, and then you would close off the valves to prevent

further water filling the tanks and you could even go deeper (if your hull was strong enough and by forcing the sub deeper with your dive planes) without having to have your atmosphere further compressed

because you closed off the ballast tanks water inlet valves. So although your interior atmosphere was now compressed a small amount, you would not further compress your atmosphere

by going deeper. If you went deeper you would of course have to have attributes of a pressure hull. Remember however; you would have a small amount of pressurized atmosphere

inside the hull pushing outward a little which would help you some against the outside water pressure before your hull started to have pressure exerted against it from the outside.

This might be a good idea for a design that allowed you to go a little bit deeper than most ambient subs (because of no decompression limits) but still staying shallower than most 1 atm subs. Do you see what I mean here?

I mean you could go deeper than a typical ambient because you can CLOSE OFF the compression of the interior atmospere so your body wouldn't be under much compression like in a typical ambient

and therefore you could go deeper than normal no decompression scuba depths dive tables allow in a TYPICAL ambient sub.

This hybrid system is something that no one here at Psubs has ever built (or even discussed building) to my knowledge. With modern technology and construction and with more safeguards built in than the Hunley

had, this ambient/1atm hybrid system has real possibilities. After I finish my wetsub project and IF (BIG "IF" here) I ever build an ambient I might build consider building a hybrid design like this myself.

Who know? Maybe I could make it look like a mini Hunley. But I'd want a bit higher hatch tower. Too easy to be swamped otherwise. AND I'd want the interior ballast tanks to not have open tops that could

spill into the hull interior, but instead have the tank tops closed but with a valve on their tops that would allow the water pressure to pressurize the interior air. That way I could close off the valves on the tank tops

and never have to worry about the tanks spilling into the interior. The most they could do would be to squirt out the valve tops until I could close them if I forgot to close them to begin with. Much safer than total open

top ballast tanks open to the hull interior, but still allows the atmosphere to be compressed.

Bill.