Today, my husband and I were in a LDS talking to the owner about BP/W set ups. We were checking out the OMS comfort harness and were quite impressed by it (fit, comfort, quality, etc). The owner suggested that my husband (being 6'3" and 250 lbs) get the 60 lb wing. From the research we have conducted, this seems to be a little excessive. Are we wrong to think this?
We are going to buy the OMS comfort harness with SS back plate (which is 6 lbs.).
We both have the Pinnacle 8mm wetsuit with hood.
We will be diving with single HP 100s, and plan venture out on the occasional dry-suit trip in Alaska.
From all the research we have done on this board and other sites, a 32 lb. wing with wetsuit seems to be sufficient. Is this just our naivety rearing it's ugly head, or should we go with the 45 or 60 lb. wings?
Thanks in advance!
Kate
Kate,
Any BC needs o meet two criteria. It needs to offer enough lift to float your rig at the surface with a full tank if you ditch it, and it needs to be able to compensate for the maximum change in buoyancy of your exposure suit.
In cold water the buoyancy of your exposure suit will likely determine the wing size, and could also impact the maximum negative buoyancy of your rig.
The size / weight of the diver plays no part in wing selection, other than how it impact the size of the exposure suit.
How buoyant are your exposure suits? Roll them up and put them in the water and add lead until it just sinks. Weigh the lead. That the "initial" buoyancy of the suit.
Your exposure suit cannot loose more buoyancy due to compression than it starts with at the surface.
****This is just an example, your numbers will likely vary****
I'll
assume that your husbands "8mm" suit is 25 lbs buoyant. I'll assume you are using PST E7-100 tanks. These tanks are -1 lbs empty, and -9 full. If you are using other tanks find out what their buoyancy is. Google "Scuba Tank Specifications"
A SS back plate and harness is about -6 lbs. A regulator is about -2 and we have assumed your tank is -9 full. That means your rig will be about -17 with a full tank, and will provide about -9 lbs of ballast with an empty tank.
If your exposure suit is +25 and your rig provides 9 lbs of ballast you will need another ~14-16 lb of lead. You can put this 14-16 lbs in a weight belt, or put some of the weight on the rig. I'll assume you choose to put 8 of the 14-16 on the rig via weight pouches on the harness or weight plates, or a "P weight" etc.
Now your rig, with a full tank will be 17 + 8 = 25 lbs negative.
To float your rig you need a wing bigger than 25. A ~30 would work fine. To compensate for a fully compressed wetsuit you need a wing bigger than 25 lbs also, here again a ~30 would work fine.
How buoyant would your exposure suit have to be to need a 45 or a 60 lbs wing?
Over sized wings add drag, and are more difficult to vent than a well designed wing of appropriate size. Buying a huge wing will negate many of the advantages of using a BP&W.
Go test your suits, and research your tank's buoyancy. Be prepared when you shop for your next BC.
Tobin