Salt water weight requirements

[alcina]

#1 - have a great time in Hawaii!
#2 - let the guides know you are a new diver and they will help you...if they don't, find another operator for your next dives!
#3 - all salt water is not created equal...so what you use this time in Hawaii may not be the same as what you will use in Cozumel or Australia or Fiji etc. Our first time in Cozumel a month or so ago DH had to add 6 lbs to his belt. We use the same size tanks and dive here in salt water all the time. He is a very experienced diver. We were both surprised. I didn't add any weight but definitely felt the difference when my tank hit about 70 bar...that only happened twice so it wasn't a big deal.
#4 - have a great time in Hawaii!!

 

[lostinspace]

gotta agree with alcina - check & see if you are near any rivers with +/- 50km, as the fresh/salt water mixing can really play havoc with your bouyancy.

 

[Buoyant1]

I'm 290, but in good shape (I've earned a beer gut over the years, but pretty toned otherwise)

I do a half hour of good cardio 4+ days each week at the gym, and a bunch of weight training...

 

[lostinspace]

I'll have one heck of a time...I did some "resort" dives in Key West in July wearing 26lbs (no suit) I did my OW dives in freshwater using 28lbs with a 3mm full suit (and my instructor thought that I was probably over weighted by the time we got through to our last dive)

So NOW I'll be going back to KW in November, and taking the suit, how the heck much should I wear? hahaha!

I'm thinking that if in fresh water with the suit I was over weighted, I would probably be about right in salt water with the 28 lbs.

sounds about right then ~ 10% of total body mass for salt water + suit

For your first dive back in KW I would if I were you wear 30lbs on your try-out dive and let the instructor/guide/marshall know that you might need help.
If you feel overweighted - eg you keep sinking slightly - then drop a couple of pounds per dive until you feel comfortable.

 

[ScubaDadMiami]

You can calculate how much weight you need if you know how much you plus the same equipment (only works with the same equipment) weighs in either one, salt of fresh water. Of course, this also assumes that you are properly weighted for the known medium (salt or fresh).

Let's say that you get on the scale with all of your equipment (including the amount of weight you wear in salt water--we will use the example of ten pounds in this case). You weigh 300 pounds. Remember that Archimedes stuff from your dive class? This is where it comes in.

Okay, you know that you weigh 300. That means that you and all of your equipment are displacing 4.688 cubic feet of salt water (which weighs 64 pounds per cubic foot). How do we know this?: 300 / 64 = 4.688 cubic feet of salt water displaced. Now let's convert that to fresh water: 4.688 (you will still displace the same amount of space when you are properly weighted; that part doesn't change) * 62.4 (the weight per cubic foot of fresh water) = 292.5. This is how much you plus all of your equipment should weigh to be neutral for fresh water.

How much weight do you remove? 300 - 292.5 = 7.5 pounds. So, how much weight should you wear in this case? Since you are originally carrying 10 pounds, 10 - 7.5 = 2.5 pounds of weight to carry.

Let's double check (or pretend that you weigh 292.5 pounds with 2.5 pounds of lead in fresh water): 292.5 / 62.4 = 4.688. 4.688 * 64 = 300. 300 - 292.5 = 7.5 pounds to add. Starting with the 2.5 pounds you are carrying in fresh water, add 7.5 pounds of lead = 10 pounds to carry of lead.

 

[DandyDon]

This is why I always carry a couple of 1# soft weights and a couple of 2# softs. Boats often have plenty of larger weights, but not the smaller ones. 'Course, it's another 6# in my dive bag. :11: They sure come in handy, tho'

Be careful about just dropping them in your BC pocket, tho'. I've seen them fall out many times. Secure them well.

Another trick is to use cable ties to connect bolt clips to a couple of 1# weights, and clip thse to the bottom rings on your BC. When you're at 500 PSI in your tank, you can take one or two off to pass to the boat, and see if you're still heavy enough. I often pass these to others struggling to do their safety stops on the first dive underweighted. :shades: