Does Size Really Matter?

[Coralina]

Hey, it got your attention, right?
I've finally saved up enough dinero to buy my first BCD and I could use some advice. I've rented an Extra-Small Sea Quest Diva QD quite a few times and have no complaints whatsoever about the fit and the lift. That is, while wearing it over a 3 mm suit with a aluminum tank. My friendly neighborhood dive shop guy was encouraging me to get a Small because local diving is cold water and the extra lift I'd get from upping the size might come in handy. The time I used a Small BCD it was with a steel tank and over a 6mm suit and I felt rather wobbly in it. So I've been researching all over the internet about how big of a variation there really is in lift between an XS and an S. Per Boyle's Law this would be a reasonable assumption, but I'd think that the designers would account for that, right? So...does size really matter?

 

[ERP]

According to the Seaquest site the XS has 18lbs of lift and the S 23lb.

whether either would have adequate lift, depends a lot on how much weight your going to be wearing, and the dive conditions (waves etc).

 

[Coralina]

Where did you find that on their website??? This site is like magic!! Thanks a bunch!!! I thought I was just going to have to experiment in the dive shop pool, but the chlorene turns my hair green and now that Xmas is over, looking like an elf isn't trendy...
5 pounds is a pretty significant difference though, isn't it? And Lake Michigan can get quite choppy.

 

[ERP]

It's in one of the PDF's.

www.sea-quest.com/pages/choose_equip/ce_pdfs/SQ_GUIDE_BCs.pdf

Yes 5lbs is significant, extra lift is nice if the water is choppy.

I did my open water dives with insufficient lift and it wasn't much fun, I'd talk to people locally and see if they think 23lbs of lift is enough.

 

[canuckdiver]

5lbs of lift is a signifigant difference!

IMHO 18 lbs is not really enough lift, depending of course on how much weight you are wearing.

you want to have enough lift (in the great lakes anyways) to get your head above the waves.

just my .02$

 

[stiebs]

Coralina once bubbled...
The time I used a Small BCD it was with a steel tank and over a 6mm suit and I felt rather wobbly in it.

I ran into a similar problem a couple of weeks ago when I purchased my SQ Balance. I tried on a medium in the LDS with no suit on, and it fit quite snuggly. With a 7mm on, it still fit alright.

The owner urged me to go for the ML, which fits a lot better with the wetsuit on, but it is still a good fit with no suit on (for my occassional warm water trips).

I would suggest to find a size that is just small enough with your thinnest exposure suit, and just large enough for your thickest suit.

If you are concerned about lift, the only real way to make sure you're comfortable, is to hire that XS when you're diving a 6mm.

 

[Walter]

Yes, it matters. Most people wear BC's that are too big. You'll be comfortable with a better fitting BC. If the extra small fits, go with the extra small. You should be weighted so you are neutrally buoyant at the surface with no air in your BC at the end of your dive. You'll need enough lift to compensate for the air in your tank and the loss of buoyancy from your wet suit compressing at depth. Unless you are huge, this will not total 18 lbs. If you are huge, you won't fit in an extra small BC anyway. Try on the xs BC with the thicker wet suit. If it fits, that's the one you want.

 

[Bubble Boy]

For all the reasons Walter mentioned above.

 

[Zept]

I'm not sure you're going to like this suggestion, but... if you go for the Diva LX, rather than the QD, you'll get 29lb of lift in an extra small. The downside is you'll have to carry on saving.

I have a Diva QD in XS. The fit is great and for the diving I do (tropical, recreational, 3mm or 5mm wetsuit), it has more than enough lift to compensate for buoyancy changes underwater (see Walter's post). However, when I'm floating around at the surface afterwards, waiting to be picked up, I have to have it fully inflated to be comfortably buoyant. I sometimes wish it had more lift... if I were starting over, I'd give more serious consideration to the LX.

Another thought: when you tried the S, did you have the cumberband on the tightest setting? The Diva QD has fittings in the back that let you adjust the length of the cumberband.

Hope that helps,


Zept

 

[Coralina]

Allow me to commend you on your excellent marketing skills...you've managed to convince me to spend more cash all the way from Singapore!! Not that I needed too much encouragement, I was sighing over the LX but couldn't mentally justify the extra expenditure. But since I'll have it for a really long time (since I'm not planning on becoming huge, thank you Walter!), I might as well splash out!!!

Thank you all very much for your sage advice.
c