Need help adjusting weight from fresh to salt water

Please register or login

Welcome to ScubaBoard, the world's largest scuba diving community. Registration is not required to read the forums, but we encourage you to join. Joining has its benefits and enables you to participate in the discussions.

Benefits of registering include

  • Ability to post and comment on topics and discussions.
  • A Free photo gallery to share your dive photos with the world.
  • You can make this box go away

Joining is quick and easy. Log in or Register now!

Iceguy4

Iceguy4

Guest
Messages
54
Reaction score
1
Location
upstate New York
# of dives
200 - 499
24 lbs............. = ...............X
_____________ _______________
62.4 Lbs/ft cubed.....64.0 Lbs/ft cubed

Above is the equation I used ..My fresh water weight over unit weight of fresh water equal to the variable (X) over the unit weight of sea water.. when I solved for X I cane up with 24.61 Lbs. does this sound right or is my Physics failing me?
Thanks in advance for your time
Don
 
Iceguy4:
24 lbs............. = ...............X
_____________ _______________
62.4 Lbs/ft cubed.....64.0 Lbs/ft cubed

Above is the equation I used ..My fresh water weight over unit weight of fresh water equal to the variable (X) over the unit weight of sea water.. when I solved for X I cane up with 24.61 Lbs. does this sound right or is my Physics failing me?
Thanks in advance for your time
Don
Click to expand...

Your on the right highway but you took the wrong exit....

You need to consider your total density versus the water's density or specific gravity. Your volume is the same as is your weight. Salt water is 2.6% (S.G. 1.026) denser than fesh in general. You need to identify the entire dry weight of you the diver, you, weight, gear, even the air in your cylinder to be technical. Take this total weight and multiply by .026. This will be the swing weight, between 5-7 pounds in most cases. Don't worry about going fresh to salt or salt to salt, it's such a moinority percentage that the discrepancy is just a rounding error. More weight for salt water, take it off for fresh.

Pete
 
Iceguy4:
24 lbs............. = ...............X
_____________ _______________
62.4 Lbs/ft cubed.....64.0 Lbs/ft cubed

Above is the equation I used ..My fresh water weight over unit weight of fresh water equal to the variable (X) over the unit weight of sea water.. when I solved for X I cane up with 24.61 Lbs. does this sound right or is my Physics failing me?
Thanks in advance for your time
Don
Click to expand...
If your weight belt was going diving solo, you would be right. :)

Take your overall weight in air fully geared up and divide by forty.

Add that much weight to go from fresh water to salt water.

For example, if you hit the water at a total weight of 240 pounds in fresh water, add six pounds to dive in salt water.

Since salinity is not always what you expect, I would add two more pounds for a total of eight pounds added and check trim at the end of the first dive.
 
Don Burke:
If your weight belt was going diving solo, you would be right. :)

I am going to accompany my belt...LOL My weight is aprox 220 lbs(muscular build) with no gear. Short of suiting up I would guess-ta-mate (a very techinical term) my weight to be 270lbs fully suited up. I use a pro QD B.C. with 4 lbs total at my sholders and 10 lbs each in my drop weights (no belt) in fresh water. Should I add a belt ( I have one) or add it to my B.C. ...and where? maybe 1lb or 2 in my sholder pockets(Non release-able) and balince in my drop weights,.. as I like the way I'm weighted in fresh.
Thanks again Guys
Also I'm kinda nervous about this as its my first Boat dive as well as my first ocean dive (captin rob's outta N.H. to a seal Island to see seals) How about sharks...don't they eat seals??
Click to expand...
 
spectrum:
Your on the right highway but you took the wrong exit....

You need to consider your total density versus the water's density or specific gravity.

Just a thought.....I think you refer to the waters S.G. and density as the same thing...

Specific Gravity is = to dencity of fluid (salt water 64 lbs/ft cubed) over the dencity of water @ 4 degrees C (62.4 lbs/ ft cubed) or the unit weight of the fluid (salt water 2.00 slugs/ft cubed) over the unit weight of water @ 4 degres C( 1.94 slugs/ ft cubed) Since the units cancel out leaving a unit-less specific gravity as it should be. specific gravity, dencity and specific weight (unit weight)...three different things.

Thanks for putting me back on the right road.
Don.
Click to expand...
 
Iceguy4:
My weight is aprox 220 lbs(muscular build) with no gear. Short of suiting up I would guess-ta-mate (a very techinical term) my weight to be 270lbs fully suited up. I use a pro QD B.C. with 4 lbs total at my sholders and 10 lbs each in my drop weights (no belt) in fresh water. Should I add a belt ( I have one) or add it to my B.C. ...and where? maybe 1lb or 2 in my sholder pockets(Non release-able) and balince in my drop weights,.. as I like the way I'm weighted in fresh.
Thanks again Guys
Also I'm kinda nervous about this as its my first Boat dive as well as my first ocean dive (captin rob's outta N.H. to a seal Island to see seals) How about sharks...don't they eat seals??
Click to expand...
270 would mean to add about seven pounds for neutral. I would add two more for the first dive.

Adding a belt on a dive you are already nervous about would probably not be a good idea.

I think you are on the right track with two pounds or so at your shoulders and about seven in the drop weights for a total of nine added or a total of 33 pounds of lead.

I would definitely go for the couple extra pounds on a dive I was nervous about. One of the manifestations of nervousness is to not exhale fully and starting off a dive having trouble submerging can make it worse.

Be sure to check your weighting at the end of the first dive.
 
It's probably obvious, but it should be noted that all of the above assumes, that all of your equipment remains the same, in particular that you are not using a different (kind of) suit or totally different tanks.
 
So, if I weigh about 300lbs with all my gear on, and only need 8lbs in fresh water with an AL80, I would need around 7 - 8lbs of additional weight (double what I had before) just going from fresh water to salt water?
 
You must log in or register to reply here.

Similar threads

The Cosmicist
Advanced Beginner Gear Grab - Helpful for others too?
3 4 5
Replies
41
Views
7,220
BoatingDave
BoatingDave
RayfromTX
Blacktip Scooter- Limited To Weighting, Buoyancy and Trim
5 6 7
Replies
67
Views
11,347
crofrog
C
Brian Huff
New diver and new to BP/W - my first time in the water with one
3 4 5
Replies
46
Views
8,578
Brian Huff
Brian Huff
TMHeimer
Simple salt/fresh wt. questions
2
Replies
15
Views
1,065
MichaelMc
MichaelMc
arcticat99
weighting between fresh and salt water
2 3 4
Replies
31
Views
1,797
archer1960
A

Back
Top Bottom