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All About Guns What's your weapon of choice, and why? Discuss the beloved speargun here!

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Old 08-15-2017, 07:37 AM   #16
Castronova
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Re: how heavy is too heavy?

Quote:
Originally Posted by Red Tide View Post
I used to like my guns to be slightly nose heavy like Phil described. Now I like my guns to float with the shaft in. Once you dive to any depth the balance of the gun changes. I like the neutral feel when aiming and shooting. A heavy muzzle at 100 feet is not easy to swing, aim and shoot.
The other advantage of a floater is you only loose guns 5% of the time. Hahaha!
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Old 08-15-2017, 07:32 PM   #17
Hahalua
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how heavy is too heavy?

Quote:
Originally Posted by Impaler Spearguns View Post
ok - but how do you determine what % negatively buoyant IS?

it is quite subjective and unmeasurable

5% of what? the overall weight out of the water? in the water?

see the problem here?



I didn't mean that I was going to ignore his request - it must have sounded that way- I just meant that I didn't know HOW to determine an exact percentage .

Myabe it IS possible somehow? Idk - I just took his 5% and took that to mean - just barely negative by 40 to 60 grams - which is nothing



You can give the buoyancy in terms of weight but not percentages

or can you ? idk not 100% sure on that




as far as % ballasting, I think you could quantify it like this:

if weight in air = 10 kg

5 % neg = 0.5 kg negative in water

5 % pos = 0.5kg positive in water

0% = perfectly neutrally buoyant



if weight in air = 20 kg

5 % neg = 1.0 kg negative in water

5 % pos = 1.0 kg positive in water

0% = perfectly neutrally buoyant

(substitute units of choice - a 20 kg spear gun doesn't really sound right, but you can get the picture)



The difference in density of ocean water is on the order of +/-0.1% pretty much across the globe. Of course there will be a few outliers, graph at end of paper below shows what i mean.



(here is a paper regarding ocean water density variatiability:

http://www.geo.cornell.edu/ocean/p_o...2_Density1.pdf)



if you wanted to set up a ballast tank in your shop you could add a measured amount of pool salt to a tub big enough to float your gun and measure the wet weight using a small hanging scale (i.e. fish scale for really small fish)



I don't know if that helps- hope it does.

Last edited by Hahalua; 08-15-2017 at 10:03 PM.
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