Weighting advice

[catalyst81]

Just finished my OWC and I've done some research and will be picking out a DSS BP/W thanks to Tobin's help figuring out wing size. I have a question about estimating the amount of weight I'll need. I know the best way to get there will be a buoyancy check when first diving my new gear, but to get me close I'm attempting to calculate it. Do I need to account for wetsuit compression at the safety stop depth in my weighting calculation? Around how much buoyancy loss will there be in the wet suit at that level? If I don't account for it will I likely be a little heavy the first buoyancy check/dive?

 

[nolatom]

You're being very thorough and precise. But since it's better to be slightly heavy than slightly light while trying to "hang" at 15 feet, personally I would disregard compression in the wetsuit. It's only half an atmosphere at that depth, so if you're heavy because of it, it'd be (I guess) only a pound or two (I'm thinking here of my 3mm full suit).

Then you can fine-tune after the actual event. But you can fix heavy. You can't fix too light, beyond exhaling, once your wing is empty.

When you test this out, it's better to have an anchor line or ascent line, just in case.

 

[decompression]

The buoyancy loss at depth can be "compensated" for by the wing. However, if there is a wing failure and you drop weight or you're wearing enough weight to get you deep in a thick wetsuit, you are gonna have problems.

At 15' there wont be very much compression.............
easy way to guesstimate is put all your gear (wetsuit, gloves hood etc) into a mesh bag and see how much lead it takes to sink it. If fresh water (pool) then add 4 lbs on top of that number.

Add or subtract if using steel or Al tank.
Minus Backplate/regs/light or other negative items.......that number gives you the lead you need.


Many agency's don't advocate deep diving in thick wetsuits as it can be near impossible to swim to the surface even after ditching weight at depth (if there is a wing failure).

 

[catalyst81]

You're being very thorough and precise. But since it's better to be slightly heavy than slightly light while trying to "hang" at 15 feet, personally I would disregard compression in the wetsuit. It's only half an atmosphere at that depth, so if you're heavy because of it, it'd be (I guess) only a pound or two (I'm thinking here of my 3mm full suit).

Then you can fine-tune after the actual event. But you can fix heavy. You can't fix too light, beyond exhaling, once your wing is empty.

When you test this out, it's better to have an anchor line or ascent line, just in case.

Thanks for the replies. I had a feeling I was being a little anal about it.

Many agency's don't advocate deep diving in thick wetsuits as it can be near impossible to swim to the surface even after ditching weight at depth (if there is a wing failure).

I could definitely see that. What depth is typically viewed as deep diving?

 

[decompression]

60 fsw.......after that its drysuit.

 

[george_austin]

The buoyancy loss at depth can be "compensated" for by the wing. However, if there is a wing failure and you drop weight or you're wearing enough weight to get you deep in a thick wetsuit, you are gonna have problems.

At 15' there wont be very much compression.............
easy way to guesstimate is put all your gear (wetsuit, gloves hood etc) into a mesh bag and see how much lead it takes to sink it. If fresh water (pool) then add 4 lbs on top of that number.

Add or subtract if using steel or Al tank.
Minus Backplate/regs/light or other negative items.......that number gives you the lead you need.


Many agency's don't advocate deep diving in thick wetsuits as it can be near impossible to swim to the surface even after ditching weight at depth (if there is a wing failure).

Can you direct me to written documentation which states 'many agencies don't advocate deep diving in thick wetsuits" - near impossible to swim to the surface even after ditching weight? That is unqualified BS if I've ever heard it. Shame on you for saying that to some new diver with less than 25 dives. We've been diving for 45 years as deep as you want to go on air and in thick wetsuits. I have never seen anyone find it "near impossible" to swim up - thousands of dives. We consistently dive to 130-150 - 180 fsw in thick wetsuits and no BC. For that matter, when was the last time you witnessed a "wing failure"?
I have seen PLENTY of dry suit failures and I for one consider them a dangerous piece of equipment - especially in use by people that aren't experienced enough or confident enough to be using them. The OP is in southern California, not the Arctic - a 1/4 inch wetsuit with hood and gloves is all that's needed here even in the winter months. In summer, its trunks and a T shirt.

 

[decompression]

Can you direct me to written documentation which states 'many agencies don't advocate deep diving in thick wetsuits" - near impossible to swim to the surface even after ditching weight? That is unqualified BS if I've ever heard it. Shame on you for saying that to some new diver with less than 25 dives. We've been diving for 45 years as deep as you want to go on air and in thick wetsuits. I have never seen anyone find it "near impossible" to swim up - thousands of dives. We consistently dive to 130-150 - 180 fsw in thick wetsuits and no BC. For that matter, when was the last time you witnessed a "wing failure"?
I have seen PLENTY of dry suit failures and I for one consider them a dangerous piece of equipment - especially in use by people that aren't experienced enough or confident enough to be using them. The OP is in southern California, not the Arctic - a 1/4 inch wetsuit with hood and gloves is all that's needed here even in the winter months. In summer, its trunks and a T shirt.

Apologies,..... I meant near impossible to swim up with a wing failure.......you can swim to the surface from depth after ditching your weight belt.....you can't however control your ascent.
Most agencies that teach a balanced rig don't advocate deep diving in thick wetsuits, including 2 that I've been trained by.
For all my dives in La Jolla and Scripps canyon it was sure nice to be dry, I think a 1/4" wetsuit would be pretty cold at 180', certainly at the deco stops.
I've seen a few wing failures, inflators screwed on incorrectly, hoses cracked, bladder faults etc.
I've also seen a lot of leaky drysuits but never one that couldn't hold air somewhere. It sure is nice to have a redundant means of bouyancy though.

The things you've mentioned that you do; diving without a bcd, diving as deep as you like on air etc, are certainly not what I would consider "best practices". Any piece of equipment, not just drysuits, can be dangerous if the user isn't "experienced or confident".

Here's a video showing why deep diving in thick wetsuits isn't "optimal". Enjoy....

 

[cmrangel]

I agree that with a 3mm suit, it is minor. However, I see you are in CA. I am also in CA and dive with a 7mm. In that case, can easily lose 5 lbs of buoyancy at 0.5 ata. While I agree that you many not want to account for all of that until you do a weight check, you should be prepared and not be surprised if you end up dropping 5 lbs or more.

 

[boulderjohn]

Most agencies that teach a balanced rig don't advocate deep diving in thick wetsuits, including 2 that I've been trained by.

Could you be specific? I have never heard of this either.

 

[John Carroll]

There are so many things to account for. I dive in Monterey CA and I am 5'9 at 220lbs. Calculations say I should dive with 26lbs but I only use 14 to 16lbs, depending on gear.
I recommend getting the peak performance buoyancy book and using it to get your weighting correct. Or better yet, take a course.