Re: [PSUBS-MAILIST] My current submarine design: Specs and picture

[Christopher Graca <cgraca2@gmail.com>]

Emile, thanks for the pointers. I was originally looking at 10-20kW with the thought that I would normally be running the main prop at part load while cruising, and having additional overhead if needed. Maybe I'll look for between 5-10kW instead.

Jon, I've attached a new picture showing dimensions. I mis-typed 10' 4" when it is actually 1' 4". With regards to adding weld build-up to dissimilar thickness parts, does it need to be a 1:4 gradient? Also, the ABS spreadsheet shows 1136.2psi allowable working pressure for 5/8" 40" OD hemi-sphere (39.375" mid-plane diameter) with a .67 usage factor. Is there something that i missed doing in the calc?

-Chris

On Sun, Jun 17, 2012 at 4:57 PM, Jon Wallace <jonw@psubs.org> wrote:

Hi Chris,

Recommend more specifics when describing your sub, for example giving distinction between length of pressure cylinder and heads.  Keep them separate.  You said 10 feet 4 inches for overall length of pressure hull and I assume that includes the hemispherical heads.  Deducting 40 inches for the heads it looks like the pressure cylinder is 84 inches in length.  At .625 inch thickness with .5 inch thick ribs at 24 inches on center the ABS hull calculator on our web site is showing me a max depth of 1526 feet.  It is also showing me you'll need .875 inch hemi-heads which would provide 1575 feet.  So one inch hemispherical heads are not out of the question especially if 7/8 inch is hard to find, but you'll be looking at some welding build-up to match the heads to the pressure vessel.

Jon




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