Re: [PSUBS-MAILIST] Re: Preliminary calculations, please check me

Yes sir, as I told Rick in my little dissertation there, the idea may prove impractical at that size for that very reason. I am sure I can build a hull and systems but I can't make the gas laws do what I want.

I am still playing with ballast and control issues

Joe

From: Myles Hall <myles.h@sasktel.net>
Reply-To: personal_submersibles@psubs.org
To: personal_submersibles@psubs.org
Subject: Re: [PSUBS-MAILIST] Re: Preliminary calculations, please check me
Date: Sun, 30 Oct 2005 12:45:44 -0600

Joe,

   It appears to me that if you are considering an ambient design that also has large ballast capacity, you are going to have to carry a ton of on board compressed air. That seems to be the issue with ambient designs.

Myles.

----- Original Message -----

From: Joseph Perkel

To: personal_submersibles@psubs.org

Sent: Sunday, October 30, 2005 11:50 AM

Subject: [PSUBS-MAILIST] Re: Preliminary calculations, please check me

Myles,

I am sitting here trying to make sense of some numbers but you may be interested in this as you are interested in the same basic dimensions I am.

According to the NAVPERS manual a Gato class fleet boat had a surface displacement of 1,750 tons and submerged 2,228 tons at neutral trim. The MBT were 16% of trim at 359 tons, not counting fuel tanks which were always full of either D.O. or seawater. There is a difference of some 28% between surface displacement and neutral.

I do not yet know how this scales down but I am trying to figure out some basics here, like tank size and air requirements. I see widely varying numbers in different submersibles.

If I have to double the cabin air to maintain a dry ambient boat @ 33', I may have to rethink an open bottom design.

I am finding lots of stability considerations as well.

Joe

From: Myles Hall <myles.h@sasktel.net>
Reply-To: personal_submersibles@psubs.org
To: personal_submersibles@psubs.org
Subject: Re: [PSUBS-MAILIST] Re: Preliminary calculations, please check me
Date: Sun, 30 Oct 2005 11:11:19 -0600

Joe,

   I'm sure it's all dependant on what you want the sub to do. For me, I want something with decent surface running so that I can drive the thing to the dive location. With this in mind, I am looking for quite a bit of ballast bouyancy to get as much of the boat out of the water as I can to reduce the drag. I am looking to have my dive planes up high on the hull so that they clear the water as well when in surface trim.

   However, I figure if you just want enough ballast to get you sufficient free board, you could get away with considerably less than 40%.

Myles.

----- Original Message -----

From: Joseph Perkel

To: personal_submersibles@psubs.org

Sent: Sunday, October 30, 2005 6:38 AM

Subject: [PSUBS-MAILIST] Re: Preliminary calculations, please check me

Thanks Paul and Myles,

30 to 45% is quite a bit, I am still working the numbers to see if this is doable.

Joe

From:  Paul Kreemer <paulkreemer@gmail.com>
Reply-To:  personal_submersibles@psubs.org
To:  personal_submersibles@psubs.org
Subject:  Re: [PSUBS-MAILIST] Preliminary calculations, please check me
Date:  Sat, 29 Oct 2005 18:50:07 -0700

Yes, using 63 lb/cf of seawater gives about 16cf needed to weigh 1000lb.

I think a WWII style boat which was more on the surface than submerged
would have 30% or more reserve buoyancy. Like Myles says.

On 10/29/05, Myles Hall <myles.h@sasktel.net> wrote:

Joe,

   My design calls for about 45%. I
want to get that thing out of the water when surface running. Also, I
figure a guy needs all the bouyancy he can get when launching the thing so that
you don't need 6' of water. I'm going for the "better to have too much
than not enough" concept. Hopefully I'm not overlooking
something.

Myles.

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