Post by surflung on Mar 4, 2015 7:43:43 GMT -8
Vintage Divers are Buoyancy Masters!
- I noticed that PADI offers an "advanced" certification in Buoyancy Control. And it made me think about all of the considerations I've put into managing my buoyancy without a BCD. Here's what I learned.
- #1 is Wetsuit thickness... If you wear the thinnest wetsuit that will still keep you warm, you will deal with much less suit compression and therefore much less buoyancy variance in your dive. I found the easiest buoyancy control with a cheap Stearns 2-3mm suit but I got cold. I upgraded to a BARE semi-dry Elastek 3mm... Got the same buoyancy but was warm even down to 37 degrees at 100 feet in Fortune Pond.
- #2 Tank and equipment weight. The heavier your tank/equipment... The thicker the suit you have to wear for buoyancy and the less you can adjust with weights on a weight belt. I've put together three sets of double tanks. USD 1800 psi 38s, Sportsways 1880 psi 42s, and army surplus 1800 psi 38s. With the 1800 psi 38s, I can float with the thin 3mm BARE wet suit and I'm neutral at the surface with 8 lbs on my weight belt. With the Twin 42s, I'm neutral at the surface with no weight belt and I sink at all depths deeper with my 3mm suit. (A thicker suit only fixes this until you get deep enough for suit compression to allow sinking again.)
- #3 Weight yourself for the depth you will be diving... Plan for buoyancy. Somebody told me the Cousteau divers often hung a basket with weights so that divers could discard weights going down and add weights coming up. At Fortune Pond and Wazee there are always rocks on the bottom to pick up if you are under weighted. I've installed a D-Ring on my weight belt so that I can clip on/off an extra 2 lb. clip weight. But here's an example, of my experiments in buoyancy at Fortune Pond:
- Surface to 20 Feet: With 6-8 lbs I float on the surface and am ~neutral from 12-20 feet.
- 20 to 60 feet: 6lbs is pretty neutral for this entire region.
- 60 to 120 feet: 4 lbs is pretty neutral for this entire region.
A Word About Wetsuit Compression...
- At 33 feet the suit is compressed to half it's original thickness. At 66 feet it's compressed by only 1/3rd of the remaining thickness. At 99 feet it is compressed even less... By only 1/4th of the remaining thickness.
- In other words, the deeper you go, the less variance you will see in buoyancy due to suit compression. So, it is VERY worth your while to plan your weights for the depth you'll be diving.
- This is worth noting for BCD diving as well... You shouldn't have to keep adding and venting to compensate for suit compression at these depths.
- I noticed that PADI offers an "advanced" certification in Buoyancy Control. And it made me think about all of the considerations I've put into managing my buoyancy without a BCD. Here's what I learned.
- #1 is Wetsuit thickness... If you wear the thinnest wetsuit that will still keep you warm, you will deal with much less suit compression and therefore much less buoyancy variance in your dive. I found the easiest buoyancy control with a cheap Stearns 2-3mm suit but I got cold. I upgraded to a BARE semi-dry Elastek 3mm... Got the same buoyancy but was warm even down to 37 degrees at 100 feet in Fortune Pond.
- #2 Tank and equipment weight. The heavier your tank/equipment... The thicker the suit you have to wear for buoyancy and the less you can adjust with weights on a weight belt. I've put together three sets of double tanks. USD 1800 psi 38s, Sportsways 1880 psi 42s, and army surplus 1800 psi 38s. With the 1800 psi 38s, I can float with the thin 3mm BARE wet suit and I'm neutral at the surface with 8 lbs on my weight belt. With the Twin 42s, I'm neutral at the surface with no weight belt and I sink at all depths deeper with my 3mm suit. (A thicker suit only fixes this until you get deep enough for suit compression to allow sinking again.)
- #3 Weight yourself for the depth you will be diving... Plan for buoyancy. Somebody told me the Cousteau divers often hung a basket with weights so that divers could discard weights going down and add weights coming up. At Fortune Pond and Wazee there are always rocks on the bottom to pick up if you are under weighted. I've installed a D-Ring on my weight belt so that I can clip on/off an extra 2 lb. clip weight. But here's an example, of my experiments in buoyancy at Fortune Pond:
- Surface to 20 Feet: With 6-8 lbs I float on the surface and am ~neutral from 12-20 feet.
- 20 to 60 feet: 6lbs is pretty neutral for this entire region.
- 60 to 120 feet: 4 lbs is pretty neutral for this entire region.
A Word About Wetsuit Compression...
- At 33 feet the suit is compressed to half it's original thickness. At 66 feet it's compressed by only 1/3rd of the remaining thickness. At 99 feet it is compressed even less... By only 1/4th of the remaining thickness.
- In other words, the deeper you go, the less variance you will see in buoyancy due to suit compression. So, it is VERY worth your while to plan your weights for the depth you'll be diving.
- This is worth noting for BCD diving as well... You shouldn't have to keep adding and venting to compensate for suit compression at these depths.