[PSUBS-MAILIST] Drawing of my 2-man sub

[Alec Smyth via Personal_Submersibles]

Hi Andre,

Very nice drawing and concept, I like the simplicity and it looks balanced.
I would have the following observations:

- Check that you can actually get those hemispherical heads for a
reasonable price. Hemispherical heads are far less common than elliptical.
I was once shopping for endcaps and got the following quote: "The
elliptical is $300, the hemispherical is $300 plus $4000 in tooling setup
costs".

- Regarding the coning tower design (K250 in this case) it depends what you
want the sub for. The problem with that tower is the low freeboard, which
is fine for lakes but insufficient for open water. You cannot open a K250
hatch in the ocean in anything but flat calm conditions. Also, visibility
out of a K250 dome hatch is not good, even though that might sound
counter-intuitive. You are looking through the side of a dome, which means
poor optics. The bow dome visibility will be wonderful, because you're
looking through the apex. Or, of course, visibility *of the surface* will
be good from the coning tower, but one only uses that upon surfacing.

- I would not worry too much about the boat being top heavy. In general,
between low drop weights, low batteries, and high MBTs these little boats
are extremely stable. You should be able to carry a significantly taller
tower than that one given the hull beneath it. I'm not saying you should
skip the stability calculations, I'm just saying I think you will find that
the calculations prove you can carry a higher tower that will allow for
flat viewports and increase freeboard. Another option is to put a
cylindrical viewport on the K250 tower to bump it up. I haven't done that
myself, but it could be done.

Best,

Alec

On Fri, Jan 30, 2015 at 11:42 AM, André Eriksen <
personal_submersibles at psubs.org> wrote:

> Hi guys!
>
> Finally I can start building. Just rented a nice location outside town.
> This is the drawing of the sub. I want to have 400meters (1300ft) of max
> operating depth. The hull is 10mm (3/8") S355J2 steel. The ABS hull
> calculator is giving me 431,8m (1417ft) of depth, and 638,4m (2094ft) crush
> depth. Still have som FEA to do. Have to learn to use a new software since
> Autodesk Inventor don`t simulate buckling. Any thoughts on the design?
> Do someone want to confirm my calculations?
> Very excited to get started!
> Sorry for the metric dimensions for you who are not custom to them.
>
> I had a hard time figuring out the conning tower. I wanted it to go in one
> piece, but I want all the freeboard I can get and not get it too top heavy.
> Was thinking about going 20mm thick nozzle all the way up, but thinking I
> might get in trouble welding in the hatch seat ring. With 30mm I could do
> without welding in a seat ring, but it would be too top heavy. So decided
> to go with the Kittredge design, any thoughts on this?
>
> Domes in top and front and saddle tanks.
>
> *Emile:* If you still want to press domes for me, can you give me the
> exact measurements I should have for the bow ring?
>
> -André
>
>
>
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>
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