Calculating Weights for Thicker Wetsuit ?

[NoFe2O3]

I'm planning a trip to the Galapagos later this year, and I have a custom 7mm wetsuit on order. But it looks like I may not have an opportunity to dive the new suit in seawater before I leave.

So here's the question - if I know these three things :
1) How much weight I need to be neutral in freshwater with my tropical wetsuit
2) How much weight I need to be neutral in freshwater with the 7mm wetsuit
3) How much weight I need in seawater for the tropical suit

Can I then calculate the weight neded for the 7mm suit in seawater??

Thanks for your insights!

 

[merxlin]

I use 22 lbs here in CA with my 7 mil, and used 26lbs there. Some was to stay slightly overweighted for negative entries off the pangas, and some was due to the higher salinity. Most boats if you are on a liveaboard will do a check out dive the first day.

 

[Diver0001]

If you can dive it in fresh water before you go then you're most of the way there. Assuming you'll be using the same tanks then you can work out a ball-park figure by adding about 3% of your total weight, including the gear, to the amount of weight you needed in fresh water.

The 3% is an average increase in buoyancy for sea water but some oceans have higher/lower salt contents than others. That's why it's only going to be a ball park figure. You'll still need to dial it in once you get there.

R..

 

[Bubbletrubble]

Your weighting requirements with a "tropical" wetsuit are irrelevant.

If you know your fresh water minimum weighting requirements with all of the gear you'll be using in the Galapagos, then you can simply add 2.5% of the dry weight of you + your gear (7mm wetsuit, lead weight, tank, BCD, reg, mask, fins, hood, boots, gloves, etc.).

For an average-sized person, this is about 6-7 lbs.

This will get you in the ballpark of proper weighting (assuming that you are conducting the weight check properly). If I were you, I would still conduct a proper weight check prior to Dive #1 in the Galapagos since this accounts for differences in water salinity, slight tank differences, etc. This can easily be performed with a full tank. Just make sure that you have worked out all the air pockets from your wetsuit and you compensate for the weight of the gas in the full tank.

Have fun on your trip!

 

[redacted]

Fresh water vs salt water is not significant when it comes to the buoyancy of neoprene. I simple measure and record the buoyancy of all my neoprene components using a mesh bag and lead weights to get each component to sink. And I know what my basic gear and I require with no neoprene in both salt and fresh water. The rest is a pretty easy adjustment. But you would need to get your new suit wet before you go

 

[aquaregia]

If you take the fresh->salt difference in your tropical and add that to the fresh weight for the 7mm, that should be within a pound. As previous posters have mentioned, it should be pretty close to fresh + 3%.

 

[mark01]

You might try this:

Assuming an AL80 and no other accessories which would create more negative or positive bouyancy.

Use 5% of body weight with a 3mm
Use 6% of body weight with a 5mm

Add 2% for salt water.

Should get you pretty close.

 

[NoFe2O3]

Thanks to all for the great info!

 

[Bossman]

What everyone above said.


You can calculate the difference in wetsuit buoyancy at the surface by filling your bathtub with water, fold up the tropical suit, and put your weight belt around it. Keep adding weight until it starts to sink. Take note of the amount of weight it takes to sink the suit.

Do the same for the 7mm suit. The difference between that number and the first number for the tropical suit is the additional weight you'll need when wearing the 7mm.

Get your buoyancy correct in fresh water, add 2-3% for saltwater, and then add the additional weight calculated above for the 7mm.

 

[Rich Keller]

If you can dive it in fresh water before you go then you're most of the way there. Assuming you'll be using the same tanks then you can work out a ball-park figure by adding about 3% of your total weight, including the gear, to the amount of weight you needed in fresh water.

The 3% is an average increase in buoyancy for sea water but some oceans have higher/lower salt contents than others. That's why it's only going to be a ball park figure. You'll still need to dial it in once you get there.

R..

Adding 3% from fresh to salt water is correct. If you are renting some or all of your gear though you are just going to have to check it on site.