Problems trimming out

[PfcAJ]

Step 1 is to have enough weight. Move on to step 2 (getting flat in the water) after you have step 1 down.

The cart must not go before the horse.

---------- Post added April 23rd, 2013 at 12:56 PM ----------

That's kinda funny. Here in the caves of FL, I don't know of a single cave diver adding weight to their LP104's. The diver is probably already negative about 20lbs without adding any weight in a drysuit.

I will poll 100% of the divers I see at Ginnie for the next month though and report back. I'll be shocked if I find a single person with 104's wearing weight. We should have about 50+ people to use for this research.

A bunch of people doing something doesn't make it a good idea. Do a weight check. See what happens.

This site (Scuba Cylinder Specification Chart from Huron Scuba, Ann Arbor Michigan) lists the E8-130 at a whopping -1lb empty w/ valve. I'll give you a few lbs here and there for bands and regs, plus 6 for the ol' backplate. Thats still no where NEAR enough to sink me with a 400g undergarment. Add in a light stage bottle or deco bottle, and you're struggling.

104s are listed as a little heavier (varies with year of manufacture, iirc), and the hauss Faber 121s check in a neutral when empty. Neutral!!

What it weights full doesn't matter. Gotta check that empty weight.

 

[rongoodman]

When I did my first cave classes in Mexico in doubles, the instructors were doing the same thing--wanting to weight me with full or nearly full tanks.

 

[rjack321]

That's kinda funny. Here in the caves of FL, I don't know of a single cave diver adding weight to their LP104's. The diver is probably already negative about 20lbs without adding any weight in a drysuit.

I will poll 100% of the divers I see at Ginnie for the next month though and report back. I'll be shocked if I find a single person with 104's wearing weight. We should have about 50+ people to use for this research.

I don't care what other people do or don't do (unless they are my buddies).

I can't believe as an instructor you'd propose this kind of "survey". A good chunk of those divers are doing visual jumps too, so are those "ok" now too?

Dump your own tanks down to 4-500psi and let us know if you can hold a deco stop. 'Cause if you get deep into your reserves at Ginnie you are almost surely going to have deco (unless you had a failure and lost a bunch of gas). Either way, you need to be able to stay off the ceiling while you exit.

 

[Pegger]

Who cares if you can or can't trim out right now? You shouldn't be diving underweighted - period. Once you get the total mass of lead right, then we can talk about moving lighter vs heavier things around to achieve proper trim. You are so drastically underweighted there's nothing to move or change right now anyway.

OK, this is where I need some further explanation. I'm dressed the same way I would be if i were diving in Lake Ontario, aside from my hood and dry gloves, with the same equipment including an argon bottle and canister light. I have 500 Lbs of air in my tanks and when I dump my wing, I sink to the bottom of the pool. Now I understand at the end of a real dive I would need to have some gas in my dry suit for warmth which will require some extra weight but how am I so drastically under weighted?

 

[rjack321]

OK, this is where I need some further explanation. I'm dressed the same way I would be if i were diving in Lake Ontario, aside from my hood and dry gloves, with the same equipment including an argon bottle and canister light. I have 500 Lbs of air in my tanks and when I dump my wing, I sink to the bottom of the pool. Now I understand at the end of a real dive I would need to have some gas in my dry suit for warmth which will require some extra weight but how am I so drastically under weighted?

What kind of undergarment are you wearing? What kind of suit? How heavy is your backplate?

For the Great Lakes a "normal" undergarment is going to be 400gm thinsulate or something equivalent. So compare with PfcAJ... In that type of undergarment he needs 8lbs on top of a SS plate to sink heavier doubles (pst 104s) in FL. I need about 10lbs to sink that undergarment in heavier tanks (hp100s) here. You need none. Hmmmmmm

Now I believe that people are going to vary and some will need more of less weight. BUT the fact that you think you need no lead at all, for diving in the Great Lakes with a fairly bouyant set of tanks (Faber lp95s are not the heaviest tanks by far) is way way outside the norm. Like 3 sigma+ less than what I've ever heard of.

And you need to check with gas in your suit. If you just hop in the water with 500psi in your tanks the water pressure will force everything out of your suit and pretty much anyone can sink. But if you were on an actual dive its not possible to shrink wrap yourself that much on deco (since you have to ascend to do it). And you'd freeze.

There are lots of good instructors in your area, most of these issues are best worked out with them in person.

 

[PfcAJ]

You might even end up with an even longer deco than you expect. Say you get delayed at depth, dip hard into those reserves, and not you're light, with a longer deco ahead of you. Are you prepared for that?

Imagine you're on a 250' dive. Planned BT is 20mins with a RT of 80mins. Your buddy gets caught up in some line or somethin goes sideways. You get delayed for 6 mins. 6. You just increased your RT from 80mins to 107mins. Nearly a half hour. Because of six minutes. Can you handle an additional 30mins with your suit squeezed down? Struggling to keep either warm or neutral, and you can only choose one. You've got light deco bottles that are getting lighter all the time. Sure you can hand off the empties or send them up the line, but you've got some 40mins on o2 to manage. No handing that one off. Heck, even if things DO go to plan and you're diving trimix, a few light stages or deco bottles at the end of a dive can make you too positive.

Guys, it pays to have a few lbs on you when you're doing dives like this. if you try and get too slick with your weighting, you're gunna have a bad time if things don't go to plan. I've struggled on a 250' dive in the ocean like that. It SUCKS. Its a mistake I won't make again. Its serious business, both cave and ocean.