Re: [PSUBS-MAILIST] RE: glassed-in ballast tanks

I have no idea why this was just resent. I wrote this about a week ago?

-----Original Message-----
From: Alec Smyth [mailto:owner-personal_submersibles@psubs.org] On Behalf Of Alec Smyth
Sent: Wednesday, April 27, 2005 10:42 PM
To: personal_submersibles@psubs.org
Subject: glassed-in ballast tanks

Hi Dan,

I remember you making that comment some months back about the bleed holes, and it made me think about this issue. Snoopy carries two SCUBA tanks for blowing ballast. Since one of the tanks also blows the VBT, it tank empties considerably before the other. I presume the most likely cause for doing a buoy impersonation would be if you blew ballast and one of the SCUBA tanks was empty while the other was full. Lets say for sake of argument you successfully blew the forward tank and the rear one remained flooded, thus putting the sub severely nose up. If you found yourself in that predicament, what one would do is switch tanks, to blow aft ballast with the remaining air. I presume the issue is that depending on the location and depth of the aft tank lower opening, you could find that air injected into the aft tank would escape through the bottom of the tank rather than rise inside it. That would prevent the stern from rising. Plan B would be to lower the bow, but you couldn't do that either because the vent is at the rear of the forward tank. Thus the buoy attitude would become permanent. If I had the small vent holes in the forward tank, it would slowly flood, and I could switch tanks in the meantime, waiting until the angle was a little less radical before blowing aft ballast. I presume this is the reasoning behind the Captain's comment, and I can't see any gaps in it.

However, perhaps Kittredge was not thinking of stovepipes that protrude downwards from the tanks. If the stovepipe were located such that I can blow tanks even with an extreme angle on the boat, then I would rather like to switch tanks without losing any of my scarce air. For this reason, when Snoopy is back together I'm planning to conduct a simulation before drilling those little holes. The test is to blow one ballast tank only, and see if at the greatest angle possible I can or cannot still blow the second tank. This obviously would be done with someone standing by to assist. If the stovepipes do the trick, I think I'll keep the tanks un-drilled.

I really appreciate your having made that comment, because it was a scenario that had not occurred to me, and led me to think about the placement and depth of the stovepipes. D'you think my reasoning is sound?

I'm planning on being in FL from July 18th to 28th. Let me know if you'd like to convoy down with two subs, that would be terrific.

thanks,

Alec

-----Original Message-----
From: Dan H. [mailto:jmachine@adelphia.net]
Sent: Wed 4/27/2005 5:48 PM
To: personal_submersibles@psubs.org
Cc:
Subject: Re: [PSUBS-MAILIST] towing requirements

Alec,

If it helps, my 350 has a 3 Hp aft thruster and two 3/4 Hp side thrusters and it moves along. Exactly how fast is just a guess but I'd say about five MPH. Total 4 1/2 Hp. As you probably know 9 Hp won't move you twice as fast.

A note on glassing in the under side of the soft tanks, I was talking to Captain Kittredge when I was doing mine and her mentioned to be sure to drill a few holes in the most forward and aft ends of the tanks to insure any trapped air would bleed out if you ended up nose of tail straight up like a buoy. I drilled two 5/8 holed in each end of mine. They don't burp out at the ends anyway.

Where in Fla. are you going and when? I'll be near Fort Myers in a few weeks but I won't have the opportunity to take Persistence. :-(

Dan H.

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

From: Alec Smyth

To: PSUBS

Sent: Wednesday, April 27, 2005 11:12 AM

Subject: [PSUBS-MAILIST] towing requirements

Hi all,

I?m planning a trip to South FL, and have run into the issue of finding a tow boat for a K-250, since I would need to do tows of 4 to 7 miles each way in open water. One option is to purchase an inflatable, and they come in a huge range of sizes and engine capacities. Smaller is better for me, but only so long as it?s not TOO small. Any little tender with a whimpy motor will move a K boat to some extent, but for those who have ?been there done that?, what do you consider would be appropriate for open water use, for example getting home against the Gulf Stream? If I can decide on 35 HP, 50 HP, etc. I can work that back to a matching boat.

The sub itself, BTW, I have modified for towing by glassing in the ballast tanks and using stove-pipes, so that they don?t ?burp? as much.

Thanks,

Alec