frequent divers need less weight?

[TMHeimer]

Aviyes, Chairman, Ah, Aviyes, You've took -- trips for -- years and weight then was OK. Ok I can agree that can happen.

Chaiman-- Unless you do everything right in OW - in 2005 and am a Greek God!

Pete-- Hope to some day meet you-- but the Canada-US border will probably be closed until 2021. My thoughts on that got me in trouble politically with one of my Clarinet Forums.

 

[Luca Brasi]

How does age of wetsuit effect weighting

 

[BlueTrin]

How does age of wetsuit effect weighting

Neoprene is fairly buoyant because it has a lot of bubbles of gas which also gives it its thermal properties.

When you go at depth the neoprene compresses.

Over time it compresses and stay thinner as it loses its performance.

Because it is thinner it occupies less volume for neary the same weight so it is less buoyant.

(edit: that’s my understanding from reading some posts here)

 

[ofg-1]

The little bubbles of gas in the neoprene rupture over repeated compression cycles. The old G231 Rubatex was more resistant to this, but was stiffer.

 

[ATJ]

The article was mostly focused on respiration and physiology, not trim and removing air from BC.

I personally haven't found this to be true. I dive 2-3 times a week and my average dive time is 2 hours. While my SAC has definitely improved over the years I see no evidence in my own experience for needing to carry less weight. At the end of the dives on my safety stop my wing is empty and my drysuit is very tight.

 

[TMHeimer]

I personally haven't found this to be true. I dive 2-3 times a week and my average dive time is 2 hours. While my SAC has definitely improved over the years I see no evidence in my own experience for needing to carry less weight. At the end of the dives on my safety stop my wing is empty and my drysuit is very tight.

We are in the same situation and you have more dives and frequency of diving than me. I don't really know if my SAC has improved. Seems it's always been regular-- exert more on a dive, consume more air, etc. Being old, I watch the needle drop when donning fins in the water....But I think that was true 15 years ago too.

 

[stretchthepenn]

Searching to find this “in print” somehow lends validation?

If you're writing a research paper of any sort, then finding a citable source for a factual claim, whether the claim is true or false, is kinda...um...required.

 

[wetb4igetinthewater]

1. I don't think we did OW weight checks--maybe due to diving wet in Nov. in Nova Scotia, and that takes time when you may wind up frozen.

Were you in wetsuits or dry suits? If the former, one can determine the negative buoyancy of the BCD with nearly empty cylinder and regulator assembly using a fish or luggage scale and a row boat, the positive buoyancy of the wetsuit an unworn wetsuit (mesh bag with wetsuit inside connected to a weight bag where you slowly add weight until it is about neutral - mind you this will be a bit high as when worn, the neoprene is stretched and therefore less buoyant - but it gives a good starting point), and in the pool, you can figure out how much it takes to sink the student in the pool with just a swim suit. This isn't too course, but at the end of each open water dive after the safety stop, each student can drain their cylinder down to 500, empty their BCD and see what happens. I've never been off by more than 2 lbs. With dry suit, one can also take the same BCD with nearly empty tank (obviously the instructor does this some other day) and subtract that amount of weight from how much is needed to get a student to sink in just a mask, fins, and breathing from a long hose from a BCD floating at the surface.

 

[Angelo Farina]

When working for a 3-months summer season at diving resorts I also noticed this.
It was due to the wet suit.
On day one it is brand new, thicker and entirely air filled, giving you a lot of buoyancy.
After a couple of months during two dives/day and leaving the suit always wet, it becomes thinner and heavier (as some cells in the Neoprene foam are filled with water).
So it is much less floating, and also less thermally insulating...

 

[TMHeimer]

Were you in wetsuits or dry suits? If the former, one can determine the negative buoyancy of the BCD with nearly empty cylinder and regulator assembly using a fish or luggage scale and a row boat, the positive buoyancy of the wetsuit an unworn wetsuit (mesh bag with wetsuit inside connected to a weight bag where you slowly add weight until it is about neutral - mind you this will be a bit high as when worn, the neoprene is stretched and therefore less buoyant - but it gives a good starting point), and in the pool, you can figure out how much it takes to sink the student in the pool with just a swim suit. This isn't too course, but at the end of each open water dive after the safety stop, each student can drain their cylinder down to 500, empty their BCD and see what happens. I've never been off by more than 2 lbs. With dry suit, one can also take the same BCD with nearly empty tank (obviously the instructor does this some other day) and subtract that amount of weight from how much is needed to get a student to sink in just a mask, fins, and breathing from a long hose from a BCD floating at the surface.

We were in 7 mil farmer john wetsuits. Appreciate the process described. Have read of a variation or two of it.
Still to date always diving wet, the 4 years I assisted on OW courses weight checks were done at the ocean at the start of OW dive 1. But, I only assisted in Aug.-Oct. when cold water was no issue. I did assist once in Nov. as a DMC and can't recall if checks were done. Either way, I would be surprised to see a shop follow this procedure for each student--you know, the old "time constraints".
I have heard the shop has begun a bit of offering the OW course in drysuits. Don't know how that is decided/rented, etc.