Jim,
Snoopy can do roll control because she has sufficient metacentric height to start with, and is improving on what she already has while surfaced. For the uninitiated, MH is the distance between a center of gravity and a center of buoyancy. Due to the stock fore and aft tanks, Snoopy (like all K-boats) tends to be roly-poly. But even without the side tanks, they won't roll over (or at least won't stay rolled over) because there is a good solid MH integral to the design. Brian, I suspect, has the other problem. His MH is too short, and that simply won't work. Also, it's good to keep in mind that the metacentric height changes (shortens) as and after you submerge. There are a whole bunch of fun calculations that have to be done to prove to ABS (for instance) that the boat will retain sufficient stability in whatever trim she is in, surfaced, diving, and submerged. There just ain't no substitute for MH in that game. As to Brian's problem I'd say that if he does have sufficient payload capacity to add lead down low, then he could easily lower the sub's CG without altering its CB, which would improve the MH. Is that enough acronyms for now? In any case, if he actually does have the payload for another 500# of lead (or whatever), I'd be prone to strapping that under the hull and try again before going to work with the edge grinder, just to see if it works.
Vance
-----Original Message-----
From: via Personal_Submersibles <personal_submersibles at psubs.org>
To: personal_submersibles <personal_submersibles at psubs.org>
Sent: Thu, Apr 14, 2016 11:21 am
Subject: Re: [PSUBS-MAILIST] more Esmae video
Brian,
Alec imparted some education to me one time on roll control. When he added side ballast tanks to Snoopy, I asked why he had mounted them so they were partially above the waterline when surfaced. He explained that when the vessel rolls to one side, the tank on that side then becomes more submerged and provides more "lift." Simultaneously the tank on the other side rises and provides less lift. The net effect is automatic roll dampening.
Jim T.
In a message dated 4/14/2016 9:18:04 A.M. Central Daylight Time, personal_submersibles at psubs.org writes:
Hi Alan, Going to add a lot of weight to the bottom of the concrete ballast , at the very bottom. Need to cut an access hole in that area so I can put lead bars in there and bolt them in.
Brian
--- personal_submersibles at psubs.org wrote:
From: Alan via Personal_Submersibles <personal_submersibles at psubs.org>
To: Personal Submersibles General Discussion <personal_submersibles at psubs.org>
Subject: Re: [PSUBS-MAILIST] more Esmae video
Date: Thu, 14 Apr 2016 19:17:46 +1200
Another interesting video Brian.
I see what you mean about the stability.
Pity you couldn't have sunk her completely to see how stable
she was once that big conning tower was under the water.
What's the next step?
I am not sure I am getting all the posts so apologies if I'm doubling
up on any one else's comments.
Alan
Sent from my iPad
On 13/04/2016, at 10:19 am, Brian Cox via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
Hi All,
Here is some additional video made by a friend of mine:
https://vimeo.com/162570037
Brian
_______________________________________________
Personal_Submersibles mailing list
Personal_Submersibles at psubs.org
http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles
_______________________________________________ Personal_Submersibles mailing list Personal_Submersibles at psubs.org http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles
_______________________________________________
Personal_Submersibles mailing list
Personal_Submersibles at psubs.org
http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles
_______________________________________________
Personal_Submersibles mailing list
Personal_Submersibles at psubs.org
http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://www.whoweb.com/pipermail/personal_submersibles/attachments/20160414/28b55a8c/attachment-0001.html>