Carrying extra weight - why shouldn't we?

[Lazlo]

I was in the pub last Saturday talking to some club members about why it is that you sometimes hear other divers say

"You must not wear any more weight than you absolutely need!"

There are some reasons that are often given for this:

1) Extra weight to lug around out of the water

2) You have to put more air in your suit/BC to compensate, and this causes extra drag

3) You will use more air putting air in & out of your suit/BC.

Now I'm ok with the first reason. Fair enough kit is heavy enough without carting around more than necessary - especially if you occasionally have two tanks and a dodgy back (like me ). But the second two reasons IMHO are at the very least somewhat exaggerated.

Take reason number 2. It's true to some extent, but how much effect does this actually have in real life? Say you put an extra 2kg on your belt. That's 2 litres of fresh water extra you're displacing in order to maintain the same buoyancy (a bit less if it's seawater). Now spread that 2 litres of water around the surface area of the suit or BC. How much difference is that going to make - especially on an entire dry-suit? Naff all. Also, I don't know what kind of diving people are doing, but if I'm fighting the kind of current where I'd notice the difference I'd most likely cut the dive short anyway. 99.9% of the time a dive is bimbling about in a nice relaxed hover, expending as little effort as possible.

As long as you're not being silly about it, and you keep your trim about right then I don't see there would be that much extra drag.

Reason number 3: WTF! Where does this come from? I can fill up my single-tank BC (large Scubapro) with 1 or 2 decent breaths. Once I've got the right amount in that's it - I just hover like any other diver. It's not as if I can watch my SPG dropping in real time as I'm pushing the power inflate.

Sometimes I think we just like to make things difficult for ourselves. I'm as guilty as anyone - I teach the buoyancy check procedure same as any other instructor - float at eye level with a full breath and empty suit/BC, breathe out to descend, add a bit if you're doing it with full tanks. Naturally, you should be able to remain comfortably above the surface if you dump your weights.

I reckon that a bit of extra weight does no harm at all. It can even be a good thing.

1) In a dry suit, it keeps you warmer cos you can put more air in the suit. (You wouldn't want to put too much on as the air does slosh around a bit especially in a membrane.)

2) It makes safety stops easier (there I said it ). You don't have to contort yourself trying to get the final few cc's out just because you can only stay neutral with no air AT ALL in your suit/BC. If a bit of surge pushes you up a metre, you can get back down all the more easily.

This whole argument is a bit like the one about ankle weights. I say so what - wear them if it makes you feel more comfortable, similarly with extra weight. Also, in the same way as ankle weights (and air use), there is a minority element who view it as a "macho" thing i.e I'm a better diver because a) I use less air then you, b) I use less weight then you, c) I don't use ankle weights.

Discuss

[Woz]

Bloody hell. Pull the pin out, throw the grenade and run...

Extra air in your suit does NOT spread evenly around the suit but collects in a bubble behind your head screwing up your trim and making you seahorse. And causing extra drag.

Dumping all that extra air adds to the task loading and is one of the primary causes of an uncontrolled buoyant ascent- if you have 2 litres of air extra and can't dump it fast enough that 2L expands sharpish and makes the problem exponentially worse.

Frankly if you were a better f'in diver...

[MATTBIN]

OK cards on the table.
I'm with Lazlo on this one, I often swap between twin 10's and 12's and I know that I should drop/add an extra couple of kilo, I often dive inland one week the sea the next so I should drop/add a couple of kilo, do I? Do I bollox. Cant be arsed. Does it affect me - a bit but not that much.

Matt

[IanRMartin]

Hi,

It would be the accent which would worry me the most especially the last 10m when the air would double in volume an extra 2L would make a big differnece IMHO.

I did start off by doing this when i was very new to diving in a dry suit thinking the extra air was keeping me warmer but all it did was make my dives uncomfortable and hard to control, my boyancy was all over the place and i was putting it down me needing more experience with a dry suit but several dives later and a Dive leader handing my weight belt over on the rib and nearly giving him self a herina i dropped 2kg and the improvment was dramatic! and i didn't find my self any cooler but enjoyed my diving so much more and my bouyancy was much better!

Ian

[kuki9591]

I agree with everything Woz said.

If your used to diving properly weighted and then add a couple of kilos, you do notice the difference and you can't wait to dump the extra weight.

I dive with a membrane suit, using my suit as my BC, compensating for the extra weight is a big deal and very uncomfortable.

I cannot comment on a neoprene dry suit as I have never used one.

Mike

[Mark Powell]

Originally Posted by Woz

Dumping all that extra air adds to the task loading and is one of the primary causes of an uncontrolled buoyant ascent- if you have 2 litres of air extra and can't dump it fast enough that 2L expands sharpish and makes the problem exponentially worse.

Spot on. That's the main reason for not carrying extra weight.

Many divers are worried about rapid ascents and so add extra weight thinking that it will stop a rapid ascent. Unfortunately by adding the extra weight you are more likely to have an uncontrolled buoyant ascent as the extra gas to offset the extra weight taskes longer to dump and expands faster than a smaller volume of air.

[wreckferret]

I find I have to use an extra 4LBS so I can put more air into my suit too keep warm.
When the water is warmer I remove it.
I use a weezle extreme plus and it works best with extra air.

Ref the ascent if you know what you are doing you shouldn`t have any problems.

[mixdiver]

Totally agree with the above - don't take the weight unless you need it- I took some ankle weights for the first time in about ten years even felt soooo uncomfortable I nearly chucked them off mid dive! - However they did not belong to me so had to return them to owner after dive. Moral of the story just take what is required to carry out all your stops no more and no less!

Mixdiver

[MATTBIN]

Originally Posted by Mark Powell

Spot on. That's the main reason for not carrying extra weight.

Many divers are worried about rapid ascents and so add extra weight thinking that it will stop a rapid ascent. Unfortunately by adding the extra weight you are more likely to have an uncontrolled buoyant ascent as the extra gas to offset the extra weight taskes longer to dump and expands faster than a smaller volume of air.

On ascent I open the auto dump fully (if I havent dived fully open already) then as I ascend it takes care of itself, the extra gas in the wing is easily got rid of by little and ofetn dumping and remaining neutral, the extra gas really isnt much of an issue I find. I concede for someone using new kit etc it might be.

Matt

[yellowduke]

Have to agree with the more air keeping you warmer theory. Two dives on the same day, dive one to 30m max total 58 minutes, dive two to 7m max for 32 minutes. Toasty first dive cold second simply because I was weighted to hold a 6m stop with little air in suit and empty wing.

Jim