Re: [PSUBS-MAILIST] Free Flooding Spaces

Bill,

That very thought has occured to me, but with a welded supurstructure instead. It goes beyond the original intent but it is a potential option if I find myself retired before I ever start construction.

As it is I am finding myself with the "incredible shrinking sub" anyway, so real boat ramp trailer ability becomes more attractive. if you missed the post, here are the specs for that drawing, just remember that the drawing does not "scale" to the specs. These specs fit a much shorter boat.

Specifications

120 cf total flood able interior space = 7680 lbs displacement

1000 lbs external structures = 8680 total displacement

Target dry weight = 6076 lbs

Soft Ballast Capacity = 325 gals seawater in 40.68 cf of tanks

It would be nice to have a nice long waterline for surface speed, long and narrow like a sharpie hull, but control issues become a problem. I suspect a long skinny sub would need her planes most whereas short and squatty is multiple thruster territory.

Joe

Specifications

120 cf total flood able interior space = 7680 lbs displacement

1000 lbs external structures = 8680 total displacement

Target dry weight = 6076 lbs

Soft Ballast Capacity = 325 gals seawater in 40.68 cf of tanks

From: "Akins" <lakins1@tampabay.rr.com>
Reply-To: personal_submersibles@psubs.org
To: <personal_submersibles@psubs.org>
Subject: Re: [PSUBS-MAILIST] Free Flooding Spaces
Date: Thu, 17 Nov 2005 03:25:56 -0500

Oops! I accidently sent this the first time without typing anything.

Hi Joe.

I was thinking the same thing as Paul. Keep your cabin just large

enough for a few people and flood the rest of the superstructure. Easier to take

a smaller bubble under than a large one. You could even build floodable storage

areas into the floodable superstructure to hold things that you needed, like deck

chairs, etc. Then when you surfaced you and your crew could enjoy the deck area.

That way if you want a submersible version of that S boat replica, you get the look, but not the

interior bubble space unless you flatbed and tractor trailer it. The smaller the bubble displacement

the less weight you need. I like the idea very much though. The first time I saw that S boat replica

like you I thought how cool it would be to have a real sub like that. You mentioned you would only

use it to submerge shallow and not for long periods. If you did that perhaps you could minimize the

pressure hull volume to a very small space just big enough to comfortably seat 3 or 4 crew with no

extra room left over, then when things began to feel a bit cramped, you could surface and use that

big deck. Since you have realized you have to go smaller with the hull, how much room would you

need for say 3 or 4 people to just sit comfortably in it for a hour or so, and once you calculate that

how much weight do you need, and will that allow you to trailer it on a regular trailer? I had another

idea for you Joe. Looking at Paul's drawing made me wonder.....why not just build a kittridge sub and

build a plyood/fiberglass superstructure on it to look like an S boat? Your superstructure put over the

kittridge sub would create more weight so you wouldn't need as much ballast weight too. You would have

to calculate the weight of the normal kittridge sub WITHOUT your S boat looking superstructure,

and then add the superstructure's weight to that, to calculate how big to build your ballast tanks

which you might have to make a bit larger possibly because of the extra weight of the superstructure,

but then again, you might not have to modify their size at all and simply use less ballast weight.

Does that sound interesting to you? Since you realize you are not going to have the room in the

pressure hull that the replica had with it's spacious accomodations, why not just use an existing

sub kit and dress it up to look like the S boat? Just a thought.

Bill.

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

From: Paul Kreemer

To: personal_submersibles@psubs.org

Sent: Wednesday, November 16, 2005 2:09 PM

Subject: Re: [PSUBS-MAILIST] Free Flooding Spaces

Joe, I think we need some drawings! I've been following this message thread but am not sure the kind of boat you're after. Here's a rough layout sketch of a sub that I spent a few minutes on. It looks maybe a little like a fleet boat, but I didn't try to do much with the free flooding spaces (in white). I also didn't try to apply any scale to it - so it may be way off.

But there's a lot of floodable space here, like you described earlier. This first sketch of mine has a lot of problems: usable viewports, access to and use of free-flooding space, overall size and power requirements, lots of stuff.

Regarding your surface buoyancy question, my impression was always that you had loads of buoyancy and maybe had issues more with just getting it to sink and having adequate propulsion and control with such a large amount of free-flooding volume. But hopefully some more experienced designers can comment.

Paul

On 11/16/05, Joseph Perkel <joeperkel@hotmail.com> wrote:

Paul & Dan (ref: your reponses below)

I need to cut total interior floodable space by at least half. What everyone's been telling me has sunk in, the numbers aren't lying. Myles was correct, it's either a sub or a glass bottom boat.

If one where to consider the free flooding fairing idea more closely, how do you provide sufficient surface buoyancy for the structure without running into the same problems all over again?

These WWII boats do not "scale' down well and a short and stubby "caricature" shape would actually be easier to control. Damn problems keep rearing their ugly little heads!

Joe