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Re: [PSUBS-MAILIST] How heavy can I go?

One way to find out the "dead displacement" of your entire sub (that should be the displacement of all solid part without any air bubbles trapped in any hollow spaces):

call a local company to rent a auto crane for a hour ore two rent or buy a good balance (I mean the devise to measuring the weight..)

hang yout boat on the hook. Weigh it in the air and then  sink it complete into the water. (have a look that there are no air filled spaces left. Add lead if nessary) Then weigh it again.  The difference is the bouyancy off your solid sub. Measure the density of the water (you can use an devise that is common for lead batteries in German: ANEOMETER or something like that or you put exactly one liter water and weigh it. (or 10 liter )

actual bouyancy divided by the water density gives your the solid volume of your sub. this volume is a fixed value until you add or remove some staff.
(later it is sufficient if you only "twice-" weigh the extra stuff.)

The extra bouyancy from all later air filled spaces can be determined if you fill the space with water and measure the quantity. (maybe you have to put your sub on there head or have to seal it temporary)

The quantity of water is your later volume of air.

If there is air there canīt be water at the same time. (because the water donīt like to be displaced by anything then water itself it is fighting for his natural right. This force gives your the bouyancy. It is like a battle: the water fight with his density against all other stuff penetrate there homeland. The rule is - man against man means 1 cubicmeter water against 1 cubicmeter "enemy". The more heavy wins. But have to pay there tribute to the enemy.  will say:  If you have water with the density 1 t/cm and an "enemy" with lets say 2 t/cm then the "enemy" "wins" the battle but "lost" (its a fair fight) 50 percent against the water. so the remaining "fightingforce" of the "enemy" is only 1 t/cm. (in this case the remaining uplift)
sorry, I do not want to teach you like a child but I like clear and dramatic physic ... .-))

hope you enyoy my "epic battle tales"

A.



In einer eMail vom 09.04.2002 06:16:32 (MEZ) - Mitteleurop. Sommerze schreibt jeffpost@rawbw.com:


You'll need to calculate the total volume of the hull ( measured from the outside of the hull), and subtract the interior volume of the ballast tanks. Figure out how many gallons of water that volume displaces ( V / .13368 ) and multiply that number by the weight of one gallon of water (different for fresh and salt water). That is how much your sub needs to weigh. Any more and it won't float, any less and it won't sink.

JP


----- Original Message -----
From: Gregory Snyder
To: personal_submersibles@psubs.org
Sent: Monday, April 08, 2002 6:53 PM
Subject: RE: [PSUBS-MAILIST] How heavy can I go?


Exactly my point.
I have a modified resortsub (sportsub II)  but how do I calculate the weight once I close the cabin off, capturing that bubble?
Thanks-
G

-----Original Message-----
From: owner-personal_submersibles@psubs.org [mailto:owner-personal_submersibles@psubs.org] On Behalf Of AndrePevestorf@aol.com
Sent: Monday, April 08, 2002 7:18 PM
To: personal_submersibles@psubs.org
Subject: Re: [PSUBS-MAILIST] How heavy can I go?

Hi Greg,

Which one do you mean ? SportSub No. I or II ?
generally speaking you have to compensate the extra bouyancy with extra wight.
The extra bouyancy is given by the extra volume ( of air in this case) and considering the salt content.
The extra wight is equal to the extra wight of the displaced water but keep in mind that the wight of some steel or lead blocks are not the same under water as on air. (because the displace water themself)

A