Re: [PSUBS-MAILIST] Heads up for those needing batteries

[Carlos Del Valle <carlosd072657@gmail.com>]

Hi James, me again, just to let you know, the sub I'm designing is for shallow water

use only, max 30'. At that depth and with a relatively small airspace ( the dome and maybe an inch or two below hatch level) would I still be safe with a 1/4"or do you think I'll have to go up on the dome thickness. As for electrical components, all switches and lights

will be potted, and from what I've read, at that depth batts should be OK for sealed

AGMs as is, without a water tight compartment, or did I read wrong? If not, what

is the easiest way to make a watertight box for the batt?

Thanks again, Carlos

 

On 6/25/10, Alan James <alanjames@xtra.co.nz> wrote:

Hi Carlos,

Here's a link to California plastics, who advertise that they do domes thicker than 1/4".

http://www.calplastics.com/custom/hemitemp.html

From what I can gather they have standard molds they vacuum mold into.

If the dome is 1/4" it's probably about 1/3 of that at the apex (top of dome).

The pressure on the dome will be all from the inside & the pressure will be dependent

on how you set up your ambient equalizing system. Depending on the depth of your hull

& where & how the ambient equalization system is set up, you could see 500lb internal

pressure over the area of the dome. There is a guy who has just built a wooden replica

sub with a bottom hatch for diver exit. When the internal pressure reaches the point

where the bottom hatch is able to be opened, his 20"x20" top hatch will be seeing 900lb

pressure.

I'm not an ambient expert, but from what I've seen, there's two ways of doing the life

support. You either dive with a regulator in your mouth (all of the dive) or flow through air

at 3 times your respiratory minute volume. So three x what you calculated.

Not sure what you meant by using your air space as buoyancy.

Here's a link to the "Fugusub" home page. It's an ambient & there is a lot of information

on the site.

http://www.fugusub.com/index.php

Regards Alan

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

From: Carlos Del Valle

To: personal_submersibles@psubs.org

Sent: Saturday, June 26, 2010 2:40 AM

Subject: Re: [PSUBS-MAILIST] Heads up for those needing batteries

 

Alec, I'm finally starting to build my 1 person ambient sub after the completion of

my ROV. For my top dome I plan on using 1/4 thickness in Acrylic for a 24'' diameter

by 12" high dome. Do you think this would be adequate. Also, I plan on using a

calibrated flow meter set to deliver 12.5 liter/min of air based on my calculations

for my "minute volume" at rest, and, should I use "my airspace" for buoyancy or

should I go with an exterior ballast tank? Let me know what you think,

Thanks, Carlos

 

On 6/23/10, Smyth, Alec <Alec.Smyth@compuware.com> wrote:

Snoopy is about to get four new AGM batteries, and I've been shopping around quite a bit. I usually avoid West Marine at all costs, because they're super pricey. Yet for AGM batteries in particular, for some reason they're highly competitive. Elsewhere I'm seeing group 24 AGMs typically priced around $300 and in one instance $420. At West Marine they're going on sale tomorrow at $170.

Cheers,

Alec

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