what is the difference between BCD for cold and warm water?

[Junzhe Davy Zou]

Hi all

I am looking to replace my BCD. I keep coming across some travel BCD that says its for warm water, and a few that says its for cold water. I am just wondering if there are any differences between the two. I dive in both situations so like if I take a warm water BCD and use it for cold water will it fail? In what way would it fail?

Mostly the reason for replacing it is because when I started I diving I didn't want to invest too much money. So I bought everything 2nd hand and promised myself that if I got really into it I would go ahead and buy myself a nice BCD.

Currently I have a dive rite trans pac II. It's perspective replacements are
Dive Rite travelPac (cause my current dive rite bcd)
Halcyon Traveler BC (LDS recommended)
[h=2]Hollis Ride Wing Travel BCD[/h]
Thanks guys

 

[divad]

The difference is Marketing.

 

[chrisch]

I've never heard of a warm water BC. Also I wouldn't replace a functioning Transpac as it is modular and you can replace those bits that are worn out (none of it at a guess) or where you want a different wing for singles or doubles. If you want to go to a steel backplate then the DR one fits the system. Your "new" BC will look tired and second hand in a year or two.

 

[Junzhe Davy Zou]

why do people get a backplate? my current one doesn't have a backplate and it is fine.

 

[Lorenzoid]

A BC that has more lift or buoyancy might be marketed as being more suitable for cold water because divers need to wear exposure suits that provide more thermal insulation, which are therefore more buoyant. A thicker wetsuit or a drysuit worn with thick undergarments is more buoyant than a thinner wetsuit, etc., and a thicker wetsuit loses a lot of buoyancy as depth increases. Remember, the purpose of a BC is to compensate for changes in buoyancy that occur during the dive, which for a diver wearing a thick wetsuit can be substantial. A BC with a bigger bladder provides more buoyancy. Conversely, a BC that has less buoyancy might be marketed as being suitable for the tropics because divers tend to wear thin shorty wetsuits, rash guards, boardshorts, etc. Since those kinds of garments do not lose much or any buoyancy as depth increases, a diver can get by with a BC that provides less buoyancy. So, in general, a BC with a smaller bladder might be marketed as suitable for the tropics. Since traveling divers like to travel light, a BC that is compact in size might be marketed as suitable for tropical diving in an effort to appeal to those people. But these are totally generalizations. How much lift or buoyancy a diver needs really depends on a number of factors, and it's pointlessly simplistic to categorize them into "warm water" and "cold water."

In other words:

The difference is Marketing.

 

[divad]

Lol...

 

[Junzhe Davy Zou]

Yeah I just weighted my bcd, it is at 7lb, when you consider most travel bcd advertise at 6lb it is a very small difference.

 

[divad]

why do people get a backplate?

So they can turn it into a doubles BCD or single-tank BCD in 1 minute or less using the same already-custom-fit-for-them webbing, thereby eliminating
two piles of useless padding, fabric, and stringy straps with crappy buckles.

 

[Buoy_A]

As warm water divers require less insulation (wetsuits), they require less ballast (lead) to allow them to sink. So warm water BCDs generally have a smaller capacity for ballast. For instance, the Aeris Jetpack or Sherwood Ventura can only carry 14 and 16 lbs of ballast respectively and are physically smaller for easy transport. However, the more versatile Scubapro Knighthawk and Zeagle Ranger can carry up to 34 and 36 lbs ballast, respectively.

I should also add that ever since airlines started getting strict about luggage weight, scuba companies have really been trying to emphasize the "lightness" of certain BCDs (IIRC the Jetpack was specifically designed to target this concern). However, if you are diving both conditions and are only buying one BCD, you'll want to buy one based on cold water diving as it will have adequate capacity for ballast.

 

[Neilwood]

why do people get a backplate? my current one doesn't have a backplate and it is fine.

So they can turn it into a doubles BCD or single-tank BCD in 1 minute or less using the same already-custom-fit-for-them webbing, thereby eliminating
two piles of useless padding, fabric, and stringy straps with crappy buckles.

When diving with a thick wetsuit in particular, a lot of lead needs to be worn to overcome the buoyancy of the suit on the surface. If the BCD has inherent buoyancy as well, that is more lead that is needed. Using a stainless steel backplate and wing design means lower inherent buoyancy from the wing and also allows some of the lead to be moved onto the BCD (the weight of the plate is substituted for the lead) and off the diver's belt/harness.

Also to eliminate the needless bulk of a lot of the modern jacket BCD's. Between the padding, the additional straps and the buckles I feel quite restricted by a jacket type.