Electric vests inside drysuits

[CAPTAIN SINBAD]

So does anyone have any experience with heated vests inside drysuits? How much layering are you able to reduce with heated vests? Thanks.

 

[Jack Hammer]

I dont reduce layering with mine, it is a normal layer when turned off. Basically, you still need to have enough insulation to account for a vest, battery, cord, etc, failure. What is nice is being able to turn it on/off as needed or adjust the amount of heat. That saved my butt once.

 

[Gareth J]

I have found that the thermal vest makes a very efficient layer in itself. I suspect that its internal reflective layer works very well, on keeping heat in.
As stated above, I haven't reduced any of my normal layering since using the vest.

You should also be aware that the risk of DCI can increase if your vest fails towards the end of the dive. As you cool the off gassing efficiency reduces. I tend to use the vest towards the end of a dive to improve (or at least maintain) the efficiency of off gassing towards the end of the dive. This also makes the dive more comfortabel.

I would also strongly recommend having the battery OUTSIDE the suit and the controls on the outside. I have seen a number of people with quite bad burning, they all have one thing in common, the controls and battery where inside.
If you do have some sort of issue you can either disconnect the power or at worst cut the cable. Not that I have ever had an issue.

Gareth

 

[mmadiver]

I have found that the thermal vest makes a very efficient layer in itself. I suspect that its internal reflective layer works very well, on keeping heat in.
As stated above, I haven't reduced any of my normal layering since using the vest.

You should also be aware that the risk of DCI can increase if your vest fails towards the end of the dive. As you cool the off gassing efficiency reduces. I tend to use the vest towards the end of a dive to improve (or at least maintain) the efficiency of off gassing towards the end of the dive. This also makes the dive more comfortabel.

I would also strongly recommend having the battery OUTSIDE the suit and the controls on the outside. I have seen a number of people with quite bad burning, they all have one thing in common, the controls and battery where inside.
If you do have some sort of issue you can either disconnect the power or at worst cut the cable. Not that I have ever had an issue.

Gareth

What heating garments were these people using when they were burned?

 

[Miyaru]

Mine has a 7V battery which lasts for nearly 4 hours, and I keep it inside my wetsuit.
I never really notice the heating - I just don't get cold. As for burns: never happened. I know other divers who use heating vests with elements based on carbonfibers, none of them ever experienced skinburns.

 

[victorzamora]

What heater are you using that's 7V and inside your wetsuit? Are you using it in salt water?

 

[tbone1004]

What heating garments were these people using when they were burned?

typically the motorcycle heating vests that most people and realistically most manufacturers use can be prone to shorting. Carbon fiber is quite brittle and when it breaks it will arc across the fibers which will cause a burn. Have to be careful.

The other important one is you have to have some sort of variable controller, preferably one with constant output. Things like DUI BlueHeat, Light Monkeys Pitkin controller etc. will all lose heat as the battery pack wears down because they are 11v systems driving 12v vests. They a. won't get fully up to temperature, and b. will have the temp fall off during the battery life since they don't have boost drivers in them. Issue here is that towards the end you are getting less heat, which leads to less efficient offgassing. The UWLD solution is quite expensive, but it has constant output, is designed to work with 7v or 12v vests *user adjustable for that*, and has 5 output options.

You want the vest over your layers if at all possible to keep heat from escaping and to somewhat assist your body in generating heat to be most effective. Having it against the skin will still allow heat to go outwards to the suit and create a heat barrier on the outside of the suit. In terms of removing layers, it depends on how cold tolerant you are, how cold the water is, and how long the dive is. 3 hour ice dive? I'm not reducing any layers. 5 hour cave dive? Probably willing to sacrifice a bit of layers because I'll be sweating like a pig for the first 3 hours if I don't.

 

[Miyaru]

When using a battery inside your drysuit, the risk is flooding. In freshwater, nothing will happen. In saltwater, the battery will short and nasty things could happen. Usually the battery swells up and starts forming gas. Exploding batteries only seem to have happened in I heard of a diver that stories.

It's a matter of selecting a solution that works for you. My winter dives are usually around 1 hour long, doing max 2 dives a day. My heating jacket came with 2 batteries and for me it's a cheap solution that keeps me from getting cold.
Having a suit with external heating is for sure better in ways of regulating the amount of warming, using additional battery sources (eg. scooter), and being able to turn the heating on or off. However, the costs will be 6 times as high for the whole system (heating garments, cable passthrough, external battery pack).

 

[Bison]

This research talks about thermal protection. Interesting discussion regarding physiological stress and risk for Decompression.

 

[TrimixToo]

typically the motorcycle heating vests that most people and realistically most manufacturers use can be prone to shorting. Carbon fiber is quite brittle and when it breaks it will arc across the fibers which will cause a burn. Have to be careful.

The other important one is you have to have some sort of variable controller, preferably one with constant output. Things like DUI BlueHeat, Light Monkeys Pitkin controller etc. will all lose heat as the battery pack wears down because they are 11v systems driving 12v vests. They a. won't get fully up to temperature, and b. will have the temp fall off during the battery life since they don't have boost drivers in them. Issue here is that towards the end you are getting less heat, which leads to less efficient offgassing. The UWLD solution is quite expensive, but it has constant output, is designed to work with 7v or 12v vests *user adjustable for that*, and has 5 output options.
<snip>

The Blue Heat suit runs at 6V, not 12V, and the battery is nominally 12.8V so it uses some sort of voltage regulator or inverter/converter system in the battery case's head to get down from 12.8V to 6V. I can assure you that it gets up to temperature quite well, a lot like an old-time electric blanket (not the wimpy ones sold for the past 20 years or so). It also does quite a good job of keeping the heat constant at the selected level (there are three) until the battery is nearly flat. If you have the primary light cable, it will reduce heat in favor of keeping the light alive for as long as possible, which I truly appreciate when I'm diving where it's dark (deep, or in overhead environments) because it's one less thing to keep track of. Are there things I'd change about the system? Sure! But these things are not among them.

I have not tried the UWLD system from Bobby Franklin, which is considerably *less* expensive than the Blue Heat. After drooling over his lights for years (good thing they're waterproof) I got one last year and finally met him this year at BTS. The build quality is impressive and I would expect the same of all his products.

I also know people who use the Santi vests extensively, and like them a lot. I've no experience with those systems, either.

I completely agree that internal batteries are evil. I too have seen divers with severe burns from such systems that shorted for one reason or another. It's got to suck to have a significant deco obligation in cold water and get burned while you watch...the...TTS...clock...wind...down. If it's warm enough to be able to open the suit and unplug, you wouldn't be using heat! I want a system I can unplug if necessary, which means an external battery.

Full disclosure: DUI is a sponsor for a project I've been involved in, as are DRIS and UWLD.