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Re: [PSUBS-MAILIST] Dumb answer was Dumb Question
> Stuart schrieb:
> I am a Newbie to this sub stuff so bear with me. My friends and I were thinking of building a sub to go 20ft > or so. We thought of
> making it out of one of those galvanized drainage pipes 4ft tall and 10ft long. If someone could tell me if > this would work I would
> appreciate it and how I could seal stuff and ideas on how to sink it. If I am going to kill myself I want to > know.
>
> Well I guest that Idea got shot down. so if I were to find a hull of
> some short how do I figurer out how much it needs to weight. I checked
> out some web sites and they had nothing. So I tried the volume it
> holds times the weight of water and it came out extremely high is this
> equation right or am I just stupid or is my sub too big because I see
> must of these subs weight 1500lbs. If some one could answered this I
> would appreciate it.
>
> P.S. thanks for not letting me fumigate my self.
Hi Stuart -
4 ft with 1ft = 0,3048 m = 4 x 0,3048 = 1,219 m
with 10 ft long = 3,048 m
Outside Volume of that hull without the endcaps =
(1,219 x 1,219) x 3,1415/4 x 3,048 = 3,558 t
and right simillar to displacement in freshwater lakes.
Displacment in seawater = 3,558 x 1,025 (density of saltwater) = 3,647 t
with 1 lb = 0,453592 kg you get in this first round
3647 kg / 0,4536 = 8040 lbs weight before the cylinder dived.
But you have to add the displacement of the domes, batteries pods etc.
You displacement gets smaller if you put your ballast water tanks
inside this cylinder in a configuration like :
(Tank -bulkhead I crew comp. bulkhead I tank )
With a tank volume inside the cylinder
of say 30% the displacement gets in
the = 8040 lbs X 70 % = 5630 lbs with out dome , pods etc.
Normal small subs like the Kittredge single seater or simillar
double seater use smaller diameter in the 800 mm - 1100 mm
(2,62 - 3,6 ft) and much shorter pressure hulls in the
1,5 - 2 meter (4,9 - 6,6 ft) area.
hope helps a little , Carsten