weighting question

[TigerDiver8]

I just got a brand-new 5mm wetsuit that I'm using on a 3 day dive trip this weekend. With my old 7mm I used 14 lbs of weight. I am 155 lbs. Will there be a change in my weighting?

 

[Agility]

That depends on how old your 7mm Wetsuit is ;-)
If I were you, I would use the same amount of weight as with the 7mm for the first dive and do a weight check at the end of this dive (5m, 50bar, no air in the BCD).
If you change other parameters as well (fresh water/salt water, different BCD, Alu tank insteads of steel, etc.) you will have to take these changes into account, too.

 

[Steve_C]

Agree with Agility.

It depends not only on the age of the wetsuit but the materials. I had a 5mm semidry which had a material that did not compress much. I switched to a henderson hyperstretch 7mm. Henderson fit better and was easier to put on. Weighting stayed about the same.

 

[Rich Keller]

If the only change you are making is the suits you could put the old suit in a mesh bag with just enough weight to sink it then do the same with the new suit and make your adjustment on the difference between the two.

 

[DivemasterDennis]

With a new exposure suit, there is more positive buoyancy than with one that has lots of underwater hours. Going 7 mil to 5 mil will reduce weight, but as noted, if your 7 mil was used heavily, you may in fact end up adding a pound. Either way, plus or minus, the change should be minimal.
DivemasterDennis

 

[TigerDiver8]

Thanks everyone. My 7mm was very very old. Early 90`s wetsuit someone gave me.

 

[freewillie]

I'm trying to do this off top my head, but actual formula is in PADI OW and AOW manuals for Peak Performance Buoyancy.

3 mm = 3-5% body weight.
5 mm = 8-10%
7 mm = 10% + 4 lbs.

If diving Aluminum tanks the may add additional 3-5 lbs. to compensate for extra buoyancy at end of dive. Keep in mind that by default you will be slightly heavy at start of dive to be neutrally buoyant at the end.

You could either dive the same weight and adjust afterwards. Personally I'd take off at least 2 lbs. to start, but have either the extra weight at the end of the boat or give it to the deck hand ahead and tell him you may need the extra weight. Then, try be first in the water, see how easily you get under water, then get the extra weight if feeling too buoyant and/or having hard time getting underwater. You only need to get the first 15 feet to get the air bubbles in the wetsuit to crush enough to decrease their buoyancy effect.

 

[Jeff Scott]

If the only change you are making is the suits you could put the old suit in a mesh bag with just enough weight to sink it then do the same with the new suit and make your adjustment on the difference between the two.

+1, but I would do it wearing my wetsuit with my mask and fins on. I just did the UTD Extreme Scuba Makeover and that's how they had us do it. Get a bunch of weight together and keep adding until you start to sink underwater and you are able to stop your descent with a breath hold and remain neutral for a few seconds. My 5mm took about 10 lbs to sink with mask and fins in a pool...but that also factors in with your body's buoyancy as well, so that's why I recommend you do it while wearing your wetsuit. Hope I could help.

 

[kmurray719]

I'm trying to do this off top my head, but actual formula is in PADI OW and AOW manuals for Peak Performance Buoyancy.

3 mm = 3-5% body weight.
5 mm = 8-10%
7 mm = 10% + 4 lbs.

If diving Aluminum tanks the may add additional 3-5 lbs. to compensate for extra buoyancy at end of dive. Keep in mind that by default you will be slightly heavy at start of dive to be neutrally buoyant at the end.

You could either dive the same weight and adjust afterwards. Personally I'd take off at least 2 lbs. to start, but have either the extra weight at the end of the boat or give it to the deck hand ahead and tell him you may need the extra weight. Then, try be first in the water, see how easily you get under water, then get the extra weight if feeling too buoyant and/or having hard time getting underwater. You only need to get the first 15 feet to get the air bubbles in the wetsuit to crush enough to decrease their buoyancy effect.

I know that's the "formula" but for me at least it's WAY off from my weighting requirements. It would put me in the water with a 7 mil wearing 10 lbs more than I need. I know people need a starting point, but an actual weight check is much more accurate.

 

[Tony387]

I agree with kmurray719. Weighting formulas are rarely accurate. A weight check is the only way to know for sure. I'm 5'8, 175 and dive with 8-9 lbs in a 5mm with hood and gloves, not 14-17lbs as the referenced formula would suggest. A one size fits all formula tells you almost nothing about YOUR actual weight requirements.

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