[PSUBS-MAILIST] FW: Casper 2

Tue Jul 31 09:02:23 EDT 2018

Hi Graham,

I had a similar problem initially with my new sub. It comes down to adding
buoyancy up high and weight down low. I too have batteries inside
cylindrical pods. One of the cheapest and easiest ways to add low weight is
to cut long steel bars and slide them into the V shaped spaces between the
batteries and the sides of the pod. If you weld a nut to the end of each
bar you can easily slide them out using a bolt as a temporary handle. Make
sure the bars don't have a way to jump up and short out the battery
terminals when bouncing along on a trailer. In my case the upper edge of
the batteries is touching the wall of the pod so there is no way for the
bars to get on top of the batteries. A cheap way to add high buoyancy is
using trawl floats.

Best,
Alec

On Tue, Jul 31, 2018 at 8:40 AM, Alan via Personal_Submersibles <
personal_submersibles at psubs.org> wrote:

> Graham,
> firstly I am assuming you meant diameter not radius with regard
> to the new pod.
> I did the calculations for fresh water & with carbon steel.
> Old end caps in air 24lb in water 20.9lb x 2
> Old cylinder in air 429lb in water 190.32.
> So 190.32 + 41.8 = 232.12 heavy for the old pod in water.
> Am ignoring the battery weight as you say they are the same in both pods.
> New end caps in air 21.8lb in water 19lb x 2
> New cylinder in air 229lb in water -189.71lb
> So -189.71lb + 38lb = -151.71lb buoyant for the new pod in water.
> You need 151.71 + 232.12 = 383.83lb ( difference of weight in water
> between old
> & new pod) extra lead to get you to the neutrally buoyant state.
> Hope that's right. See if anybody else comes up with anything different.
> Cheers Alan
>
>
>
>
>
>
> Sent from my iPad
>
> On 31/07/2018, at 11:31 PM, graham bayliss via Personal_Submersibles <
> personal_submersibles at psubs.org> wrote:
>
> Hi Alan
>
>
>
> The original pods are as per plan 57 -3/4" twelve inc sched pipe I have
> built mine six feet long and fourteen inches radius out of 1/4" steel plate
> my end caps are flat plate 1/2" thick  I carry three leisure batteries 18
> kgs each plus I have added 150 lbs of lead to the out side of the cases .I
> made them longer to carry extra batteries for extra power.
>
>
>
> Graham
>
> *From:* Personal_Submersibles [mailto:personal_submersibles-
> bounces at psubs.org <personal_submersibles-bounces at psubs.org>] *On Behalf
> Of *Alan via Personal_Submersibles
> *Sent:* 31 July 2018 12:08
> *To:* Personal Submersibles General Discussion
> *Subject:* Re: [PSUBS-MAILIST] FW: Casper 2
>
>
>
> Graham,
>
> to do this accurately we would also need the dimensions of the
>
> previous pod & it's battery weight to see what positive or negative
>
> effect it was having. Ie. if it was 20lb negative then that is our
>
> target with the new pod to get your sub back to neutral buoyancy.
>
> Alan
>
> Sent from my iPad
>
>
> On 31/07/2018, at 10:14 PM, Alan via Personal_Submersibles <
> personal_submersibles at psubs.org> wrote:
>
> Graham,
>
> what is the wall thickness of the battery pods. Is the 14" the outside
>
> diameter. Is the length you quoted to the ends of the end caps?
>
> Are there reinforcing rings in the pods. If so what dimensions.
>
> Also what is the weight of the batteries. You should be able to get
>
> that spec off the internet.
>
> I have the program " Under Pressure" that gives weights & buoyancy.
>
> I would have to put hemispherical end caps in the equation as thats
>
> it's limit.
>
> You might get a better offer from someone with a better program but
>
> I am sure I could get you in the ball park.
>
> Cheers Alan
>
>
>
> Sent from my iPad
>
>
> On 31/07/2018, at 9:48 PM, graham bayliss via Personal_Submersibles <
> personal_submersibles at psubs.org> wrote:
>
>
>
>
>
>
>
>
>
>
>
>
>
> Hi
>
>
>
> my name is Graham Bayliss I  have been building Casper 2 for many years
> and now find my self frustrated by science I have craned my sub into the
> water three time only to be frustrated by buoyancy problems I have
> redesigned my battery tubes to carry more batteries. this has meant they
> are very buoyant and being on the bottom my boat they tend to want to turn
> her on her side. My housings measure six feet long by fourteen inches I can
> not calculate how much weight I need to make these negative buoyancy I have
> three leisure batteries in each housing plus one hundred and fifty pound of
> lead on top. this does not counteract the upforce which each housing is
> subjecting my sub to. I am lost as to how I can over come my problem  as
> she is determined to roll . can some one help me please.
>
>
>
> regards
>
>
>
> Graham
>
>
>
> Pictures  of Casper 2 being built are on the site if you need to look at
> what I have built.
>
> _______________________________________________
> 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/20180731/648d3cb4/attachment-0001.html>