Re: [PSUBS-MAILIST] Free Surfaces solution!

Hi Rick,

"Hi, Joe, et al . . . I'm curious about the foot-well thing and the nasty buoyancy thing. Could you elaborate a bit?"

Sure thing Rick. If I want the ability to touch down "softly" on a sand patch and stay there with my design as is sans thrusters, I will need to vary the buoyancy slowly to negative and balance on the keel with short bursts to the saddle tanks. The foot well is nothing more than a variable tank then. It's the only place I can use because of the battery box.

Here's the potential nasty part. A 1 atm design never changes anything in the crew cabin when playing around with the variable tank. I'm not worried about sinking into the abyss because I'm never going to be in deep water but, I do worry about running hard aground with 2000 lbs + of internal lead ballast and things could break. That crazy Newton inertia thing.

Overcompensate because your now worried about slamming into the bottom now, and you could take the fast track back to the sun with Boyles Law now becoming a bit of an issue.

My design may not be appropriate for ever trying to touch down, I'm still looking at this and various options....I just don't know yet.

Joe

From: "Rick and Marcia" <empiricus@telus.net>
Reply-To: personal_submersibles@psubs.org
To: <personal_submersibles@psubs.org>
Subject: Re: [PSUBS-MAILIST] Free Surfaces solution!
Date: Sat, 4 Mar 2006 00:49:02 -0800

I am contemplating flooding the pilots foot well as a variable tank but, as Dan pointed out, things can get a bit nasty buoyancy / control wise in an ambient.

Hi, Joe, et al . . . I'm curious about the foot-well thing and the nasty buoyancy thing. Could you elaborate a bit?

The only reason I can see for flooding a footwell is to reduce the amount of required compensating air into the cockpit, in other words, to save compressed air. Many moons ago, before I decided on the reg compensation scheme, I considered using a kayak skirt to keep the wet sloshing surface in the cockpit from splashing around (unlike the Sportsub, I wanted my boat to incline like a "real" sub). Everything up to the skirt would be wet, everything abouve would be dry. Kent Markham with a kayak skirt.

There seems to be a widespread feeling in the list that ambients will have buoyancy issues. Boyle's Law will only come into play if you have an open bottom in your cockpit.

Maybe I'm missing something here.

Rick L

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

From: Joseph Perkel

To: personal_submersibles@psubs.org

Sent: Thursday, March 02, 2006 7:31 PM

Subject: Re: [PSUBS-MAILIST] Free Surfaces solution!

Bill,

I see what you are saying. Sportsub is clever that way and even smarter in their placement of the entry. But, I will be lucky to have a few inches under the keel dockside at most ramps here.

If I land on the bottom, I have to balance her on her keel with little bursts to the saddle tanks like a BC. This makes ever leaving the boat an absolute no no. I won't be doing twin keels because of increased wetted surface...that and the lower hull peppered with limber holes as is, would be a bit much to ask of any decent surface running.

Also, the discussion regarding "fine tuning" of the numbers has me re-thinking things a bit. My deciding to design in the ability to leave "snorkel depth" also leaves behind the hydrodynamic / energy advantage of the 14 hp diesel, and its hull effect. That gives me the reserve to force her under even if the boat were significantly positive, how much positive?...(me not know). I lose that advantage as soon as I would break away from the surface and that makes things a bit tougher for me.

I am contemplating flooding the pilots foot well as a variable tank but, as Dan pointed out, things can get a bit nasty buoyancy / control wise in an ambient.

Let's see what develops.

Joe

From: "Akins" <lakins1@tampabay.rr.com>
Reply-To: personal_submersibles@psubs.org
To: <personal_submersibles@psubs.org>
Subject: Re: [PSUBS-MAILIST] Free Surfaces solution!
Date: Thu, 2 Mar 2006 21:00:49 -0500

Glad to help Joe.

See how the exact same "center board trunk" idea can be used to create an open bottom hatch that the water level is under by a few inches

and therefore would not slosh into the ambient boat? No need for a hatch if you want to cut down on time and costs and don't plan to be

sitting outside atop the sail. Just use your trunk hole to enter and exit the sub. One thing to remember if using this for going out diving from the sub.....

remember you were already pressurized at whatever depth the sub was at and for that time. Now if you go outside and dive deeper as a diver,

you must calculate your previous compression pressure and its time and then treat your outside dive just like any other repetitive scuba dive so

you will not require deco. Even if you did decide to put in an upper sail hatch, or deck hatch, it would still be very nice to have a big hole in the floor

that you can just jump out of the ambient sub thru.

Bill Akins.

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

From: Joseph Perkel

To: personal_submersibles@psubs.org

Sent: Thursday, March 02, 2006 6:40 PM

Subject: Re: [PSUBS-MAILIST] Free Surfaces solution!

Yes you did Bill but, I didn't put 2 + 2 together at that moment! I was still thinking of a flat plane.

Thanks so much!

Joe

From: "Akins" <lakins1@tampabay.rr.com>
Reply-To: personal_submersibles@psubs.org
To: <personal_submersibles@psubs.org>
Subject: Re: [PSUBS-MAILIST] Free Surfaces solution!
Date: Thu, 2 Mar 2006 17:30:03 -0500

Hi Joe.

Remember when I told you to partially enclose the ballast tanks to prevent not only burping but also to aleviate your free surface problem and just leave a small hole in their bottoms for ambient operation?

Looks like you came to the same conclusion.

Bill Akins.

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

From: Joseph Perkel

To: personal_submersibles@psubs.org

Sent: Thursday, March 02, 2006 12:08 PM

Subject: [PSUBS-MAILIST] Free Surfaces solution!

I really did not want to seal off the soft tanks completely in my ambient design to keep the "free surfaces" in check. I found the solenoid flood valves unnecessarily complex for my application, plus the issue of access and maintenance.

This is truly bizarre and a testament to the function of this list. Not to encourage off topic discussions but...

The rocket discussion made me think about the pyrotechnics of solid rocket motors, which made me think of flares, which made me think of the time years ago, Freddy got drunk and set his sail cover on fire one July 4th with a hand flare.

That boat had a centerboard trunk!!

Hmmm, centerboard trunk!!....led me to this solution in five minutes!

http://www.frappr.com/?a=viewphoto&id=269116&pid=1473286

You guys are just bursting with design ideas!!! :)

Thanks

Joe

************************************************************************ ************************************************************************ ************************************************************************ The personal submersibles mailing list complies with the US Federal CAN-SPAM Act of 2003. Your email address appears in our database because either you, or someone you know, requested you receive messages from our organization. If you want to be removed from this mailing list simply click on the link below or send a blank email message to: removeme-personal_submersibles@psubs.org Removal of your email address from this mailing list occurs by an automated process and should be complete within five minutes of our server receiving your request. PSUBS.ORG PO Box 311 Weare, NH 03281 603-529-1100 ************************************************************************ ************************************************************************ ************************************************************************

************************************************************************ ************************************************************************ ************************************************************************ The personal submersibles mailing list complies with the US Federal CAN-SPAM Act of 2003. Your email address appears in our database because either you, or someone you know, requested you receive messages from our organization. If you want to be removed from this mailing list simply click on the link below or send a blank email message to: removeme-personal_submersibles@psubs.org Removal of your email address from this mailing list occurs by an automated process and should be complete within five minutes of our server receiving your request. PSUBS.ORG PO Box 311 Weare, NH 03281 603-529-1100 ************************************************************************ ************************************************************************ ************************************************************************

************************************************************************ ************************************************************************ ************************************************************************ The personal submersibles mailing list complies with the US Federal CAN-SPAM Act of 2003. Your email address appears in our database because either you, or someone you know, requested you receive messages from our organization. If you want to be removed from this mailing list simply click on the link below or send a blank email message to: removeme-personal_submersibles@psubs.org Removal of your email address from this mailing list occurs by an automated process and should be complete within five minutes of our server receiving your request. PSUBS.ORG PO Box 311 Weare, NH 03281 603-529-1100 ************************************************************************ ************************************************************************ ************************************************************************