fresh /saltwater formula

[LI Diver]

Ok guys what was that formula again?? If it takes 5LBS of weight to sink my new wet suit in fresh water then how much do I need to sink it in salt water??? And this does work right ??? If I know exactly how much weight I need in a bathing suit alone and then put on this wetsuit with the weight needed to sink it in my pool plus the salt water differential I should be dialed right in.... or pretty close anyway right?
Thanks guys!

 

[SteveFass]

Sounds right to me, assuming you are doing the pool test correctly (e.g., no air pockets in your ... pockets) and your gear doesn't change between your bathing suit test and actual usage. There's a fancy formula, but it basically works out to 6 lbs differential, plus or minus a half lb. So 5+6=11. Just noticed you're in NY, so you're diving with 7 mil at least,right? 11 lbs with a 7 mill doesn't sound like nearly enough. There's something I'm missing here.

 

[The Kraken]

ES,

There's more to it than just making a change based on the buoyancy of your wet suit.

The rule of thumb formula is to take your gross weight for a proper fresh water dive and add approximately 3% of that weight to compensate for the increased buoyancy of salt water.

IE: If geared out for a proper fresh water dive you weigh in at 250# (completely geared up) then you will need an approximate additional 7.5# of weight to be properly weighted.

the K

 

[Thalassamania]

Sea water is a little more than 3% heavier that freshwater. You should be able to handle it from there.

 

[LI Diver]

Steve, Yes.. 5lbs is to sink the 2mm shorty in size 2x in my pool without me in it. I know I needed 16lbs diving with my bathing suit in Curacao last summer. So I figured if I added the weight needed to sink my wetsuit and wore it over my bathing suit in bonaire then add that amount of weight and VOILA! The heaviest thing I have is a 5mm full so I have yet to experience diving in NY. However until this trip became immenint I was very close to doing a shallow dive here in NY with it! So if 2.5% is the differential that should be based only on the 5lbs needed to sink the wetsuit and is really insignificant.......right??

 

[LI Diver]

Thanks K, I just wanted to use my bathing suit (salt water) wt as a given or constant and then get the "add" for the wetsuit. I didn't want to get everything on and have to go rent a cylinder to do an actual pool test. Or drag everything to the lds and use their pool. I just wanted to get in the ball park and fine tune on my orientation dive.
Ed

 

[LI Diver]

Is anybody else having issues with a lot of functionality on the board or is it just me????????????????? It's really aggravating!!

 

[spectrum]

You, your suit, cylinder and other gear are all part of the buoyancy equation. Common ocean water is 2.6% denser than than freshwater so that's where the 3% rule of thumb comes from.

You take the total diver weight just prior to entering the water an multiply by .026. For most divers the answer is between 5-8 pounds. Another quicke trick is to divide by 40. A diver that dresses out dry at 280 pounds would add 7 pounds for the ocean.

Any other incidental relationships are just that.

Pete

 

[LI Diver]

WOW I must be really dense or am not expressing myself properly! I already know how much I need to sink myself and gear in saltwater.(dive in my bathing suit I guess was misleading). I now want to add a 2mil shorty. Instead of driving down to the beach I sunk the wetsuit alone in my fw pool, it took 5 lbs. So in salt water it should take the (5lbs + the weight of the wetsuit) x 1.025 to sink said wetsuit. Therefore if I am already dialed in with full diving gear in saltwater bathing suit for exposure protection only and then put on said wet suit I should have to add the product of the above equation to stay dialed in........right or are you guy's messing with me?

I understand all of the above but I am not saying I need x amount in fresh how much do I need in salt.

 

[Charlie99]

Therefore if I am already dialed in with full diving gear in saltwater bathing suit for exposure protection only and then put on said wet suit I should have to add the product of the above equation to stay dialed in........right or are you guy's messing with me?

We're only messing with you when we point out that for practical purposes 5 * 1.03 = 5.

In other words, if all you are changing is adding the wetsuit, then just add 5 pounds to what you used in saltwater with just a bathing suit for exposure protection.