Body Weight / BCD sizing

[justin.strassfield]

Recently completed my open water cert, not being thrilled with rental gear went ahead and purchased my own. Based on comfort, purchased the same sized BCD used in class.

6'1"
180 lbs
31" waist
38" chest

Purchased a SMALL based on cummerbund comfort and didn't question the notion of lift capacity until trying to research after leaving the dive shop.

Based on weight alone, the sizing charts wanted me to go for a LARGE.

Is this an issue? I did not have any issues maintaining positive buoyancy on the surface utilizing (albeit a different BCD than that which was purchased) in my first four open water dives.

Much obliged.

 

[00wabbit]

Small may have plenty of lift but may hold it too high up on your back and make of difficult for you to achieve good horizontal trim.

 

[diversteve]

What did you buy? And where will you be diving?

A small likely has enough lift for warm water tropical diving with not much of a wetsuit. Add a full 7MM in cold conditions and that could change if you need to carry 30lbs. of weight to get down. There's also other factors like tank size/composition - Steel tanks are heavier than aluminum. Although the difference really just moves weght to your back instead of on the BC/weightbelt.

Some BCD's also use the same wing/bladder across the entire line so it's not an issue - I've noticed that on some Aqualung models. Some like the Zeagle line are modular so you can use small shoulders on a large BC etc. Or change the cummerbund between sizes.

Some trim issues can be solved if the BC has back weight pockets. Some mfr's also sell add-ons that go on the tank strap. Or that can be mounted higher on the tank with various methods.

If you didn't get it wet yet it's probably exchangeable if still in the original condition.

 

[justin.strassfield]

I bought a back inflate. Aqua lung Axiom i3 and I'll be diving almost exclusively in 84 degree water in Guam.

 

[diversteve]

I don't think you'll have a problem. There's only a 5lb. lift difference between the small/large and 31#'s lift is more than you'll need for single tank diving. Some people in the tropics dive with an 18lb wing and most travel BC's are in the 24-30 range.

It does have the trim pockets on either side of tank band so you can probably put up to about 10lbs. in there if needed to trim better. On my back inflate, I do about a 60/40 weight split but you probably won't need that much. Also if you ever did need to drop the front weights, having a little weight fixed in back makes it a slightly more controlled ride up.

An Axiom is actually a Jacket though. Back inflate means the entire air-cell is on your back. With yours, some of the lift is on the sides wrapping around towards the front.

The Axiom i3 is a feature-rich, jacket style BC that incorporates Aqua Lung’s patented i3 inflation / deflation system.

Look at the Dimension on their website to see the difference - notice that only the weight pockets are sewn onto the side material.