Proper Weighting while using Drysuit

[TSandM]

Most of the boat dives I've done have not offered the opportunity to spend time doing a weight check, beyond the simple one of whether you can descend or not. They want to get the group underwater, and often, conditions aren't great for spending any significant time on the surface and expecting to keep a group together.

 

[Bubbletrubble]

Is it really uncommon for people to do weight checks from/during a boat dive?

It entirely depends on the circumstances.

If you are on a boat in Cozumel, there's probably going to be current present and, to keep the group together, DMs often instruct divers to descend immediately. If you want to have a chance to do a weight check under those conditions, then you need to speak up in advance and arrange to be the first one in the water hanging off the back of the boat with a DM helping you get your weight situation sorted out. Once you do your weight check, then everyone else can enter the water. Since it's common for the dive boat to follow the group's bubbles, I suppose it would be possible to do the weight check while hanging onto the boat after everyone else descends and begins the dive. However, you're taking the chance of not being able to meet up with the rest of the group underwater. For this reason, I'm not sure that most dive Cozumel ops/DMs would be OK with a plan like that.

You would encounter the same problem in Florida, Galapagos, California, etc., if the site features significant current.

For boat dives arranged through commercial recreational dive ops, a diver should make every effort to have his weighting issues sorted out before even boarding the boat. This is done as a courtesy to the other divers on the boat. If it means going out of your way to do a simple shore dive weight check beforehand, so be it. That's probably the best option in a place like Cozumel.

If the dive site doesn't have any current, then a dive op would probably be more flexible in accommodating how/when the weight check is conducted.

If you're diving off of a friend's boat, you could probably take all the time you need to do the weight check.

On a side note, I've encountered a significant number of people who exit basic OW class without a clear idea of how to do a proper weight check. Pretty sad.

 

[packeteer]

yeah, go jump in the local pool and do your checks. Get comfy and then do the math for salt water.

I did not do this, and had a very scary 20m dive off a boat! VERY bad idea!

 

[CAPTAIN SINBAD]

Thanks a lot folks. This is all very helpful and I have learnt a lot that the drysuit class did not cover.

Cheers -

Sinbad

 

[captain]

Here is a good video of dry suit buoyancy control.

Hydroglove! on Vimeo

 

[boxxstudio]

Other than the suggestion above about checking weight while swimming upslope at the end of a dive, the traditional weight check guides suggest checking weight at the beginning of the dive. This seems strange to me. Shouldn't the standard be to check weight for the end of the dive? In full gear, I bleed my tank to 500psi. With drysuit and BCD completely deflated and standing in shoulder deep water, I test my buoyancy. If I sink when I exhale and rise when I inhale, I'm properly weighted. Is this not a better way to do a weight check vs checking with a full tank? Appreciate input.

 

[mmerriman]

No the weight belt does not prevent the air movement

but it does keep a suit with extra space it in more streamlined....

 

[NAM001]

That's how I do it....

A note of caution. doing this is a pool when you are using some thicker undies usually results in lead on the belt. So much so that you need a wing that has extra lift at the belt. The problem is when you go to lighter undies and you don't need the weight on the belt and are stuck with the lift at the belt fromt he wing and you end up, feet up. I had to get a separate wing for the lighter undies. dui's 300g undies needed the belt with 38# on it. My lighter 100g undies needs 19#s . Those figures were just for buoyancy needs. trim was inpossible with the wing used for the 300g set of undies while wearing the 100's.

If you have access to a pool set up a weight belt with a good assortment of weights starting with 5's and 6's finishing with 3's and 2's. Put about 40lbs on the belt. Lay the belt on the bottom of the pool and attach a floating line to the end with the heaviest weights. Get in the pool beside your floating scuba rig with your suit and undies on. Burp it well and while breathing on your rig start pulling up on the line until you sink below the surface. The amount you pull up off the bottom will be the weight you require to sink you and your suit. It is interesting to watch while doing this test how much the weight changes between empty and full lungs. Now weigh your submerged rig (with empty tank) using a fish scale. Hopefully it does sink with an empty tank (it might not with an Alu). The weight of the rig submerged is the weight you can deduct from the weight you observed on the belt. If your rig floats add weight to it until it sinks. In this case add this weight to what you found in the first step. For salt do as Bubbltrubble said...use your total weight (diver and rig) and multiply by 2.5%. This will be what you need to add for the sea.

 

[DaleC]

If you are diving an Al 80 you can roughly figure 4-5lb's for the air in the tank. If you do a weight check at the beginning of the dive just compensate for that by adding 4-5lb's after you find the sweet spot. For best results try to keep 2-4 lb's lose (able to easily ditch) and at the end of the dive just tweak it a bit. If I am doing a weight check I'll clip a couple of ankle weights to my belt for this task. Easy to undo.