Horse Collar

[rstofer]

I am looking at a horse collar with reasonably modern features: Great deal on SEA ELITE HORSE COLLAR from Divers-Supply.com I don't know that I will use the power inflation. It's pretty clear that I would need a longer hose if I tried to run it from the hookah port of the RAM. With the PRAM (DA AM conversion), I probably will use it.

One thing that concerns me is how to get geared up. Sure, the weight harness goes on first. Then I assume the scuba kit with retro cotton harness. But how do I deal with the horse collar waist and crotch strap? How are they physically routed?

I am willing to consider alternate methods: route the crotch strap from the scuba harness to the BC or route the front crotch D ring of the BC to the scuba harness waist belt, connect the BC waist belt D tings to the scuba harness waist belt, things like that.

Any thoughts on how buoyant I should be on the surface with a full tank (HP 100, -10.5#) with an empty BC? Tobin at DSS recommends eyeball level with full tank and empty wing. We're talking cold water with a 7/8mm one-piece wetsuit.

Richard

 

[cool_hardware52]

Any thoughts on how buoyant I should be on the surface with a full tank (HP 100, -10.5#) with an empty BC? Tobin at DSS recommends eyeball level with full tank and empty wing. We're talking cold water with a 7/8mm one-piece wetsuit.

If you understand why I recommend eye level at the surface with no gas in the BC and full tank when diving in thick, buoyant exposure suits you will have your answer.

How much buoyancy can your 7/8mm suit loose at ~15 ft.? Quite a bit, remember teh pressure is doubling from the surface to 33 ft.

How much lighter will you be at the end of the dive? Not more than the weight of your gas.

If the suit compression is equal to or greater than the weight of your gas you will be able to hold that shallow stop.

Keep in mind that any part of your BC that is out of the water provides no lift, as it is not displacing any water. A large portion of a horsecollar is out of the water when the diver is at the surface.

Tobin

 

[rstofer]

If you understand why I recommend eye level at the surface with no gas in the BC and full tank when diving in thick, buoyant exposure suits you will have your answer.

I've got that part down pretty good. I haven't verified that I actually achieve that condition but that's due to a lack of time in the water. The task lists for the rest of the herd have left me with little time to correct my own situation. I figure that I am at least 5# heavy at the moment.

Keep in mind that any part of your BC that is out of the water provides no lift, as it is not displacing any water. A large portion of a horsecollar is out of the water when the diver is at the surface.

That is certainly true, especially when laying on my back. I don't remember horse collar training with a degree of fondness.

I would like to use my LCD-30 wing but the elbow collides with the regulator housing. I could buy a different wing but I thought I would try to mess around with the semi-retro concept of the horse collar. It's really just an experiment. I don't envision using a horse collar as a permanent solution.

It'll be a couple of week before I can get back to Montery and try some of this stuff.

Richard

 

[captain]

I do the horse collar first, than the scuba rig than the weight belt. I guess if you are using a weight harness and can dump weights without the dumping the whole harness then you can go harness, horse collar and scuba last. Either way the collar goes on before the scuba.

 

[simonbeans]

I do the horse collar first, than the scuba rig than the weight belt.

Ditto

 

[rstofer]

OK, but this would mean I couldn't use the scuba harness chest straps. Or, at least, I would have to buckle them underneath the collar. I'm not sure what omitting them would do to the stability of the tank. Reproduction Vintage Harness by Allan Klauda [AK-RVH] - $36.00 : Vintage Double Hose!, Your online source for all things related to vintage diving

I am using the DUI Weight & Trim Classic harness and the weights are easily dumped without removing the carrying harness. DUI - Weight & Trim Systems

Richard

 

[Nemrod]

Horsecollar BC goes on first, then the scuba harness and then the weight belt, that is per all texts from the day and all of my instruction.

The LP hose may be just fine with a PRAM, perhaps a touch short if you run from a T swivel on the hookah port.

For vintage diving where the BC is just an assist to providing the neutral buoyancy you should weight to achieve. I would try to set up for to be a few pounds negative with a full tank at about 20 feet depth. You will become buoyant as the dive progresses, safety stops are not a vintage profile. You will have to add a bit of air at the beginning of the dive once at depth but by the end of the dive your BC will be sucked flat and you will want to be positive. At the beginning of the dive you will need to pike dive (bend at hip), and SWIM down until your suit compresses. This is not how it is done now but you asked in a vintage board so that is my vintage answer, lol .

Weight belt always last in vintage.

We swim down, we swim around and then we swim up.

N

 

[captain]

I buckle the chest strap under the BC and have the end routed out through the head hole to be able to easily pull it for quick release. You do know how to thread the D rings for quick release I hope?

 

[Walter]

You're mixing gear from different time periods. The harness you're using is from the time before BCs. The back pack with no chest strap is what is generally used with a horse collar. With the two rigs you're planning to use, you have a couple of problems. First, they both have crotch straps. You won't be able to rig the horse collar crotch strap (remember to adjust it with the BC fully inflated) with the tank already on your back, so the horse collar has to go on first. With the tank harness you'll find it much easier to rig the chest strap prior to donning the BC. I'd suggest either using a back pack designed to use with a horse collar (no chest or crotch strap) or use the harness without a BC.

The correct order is horse collar then (not than) tank, then weight belt.

As for weighting, you should be neutrally buoyant at the surface with NO air in the BC and a near empty tank. With a 100 cu ft tank, you can weight yourself with a full tank, then add 7.5 lbs to compensate for the air you'll breathe during the dive. The problem with weighting yourself as you described is you'll be underweighted at the end of the dive. While you may (I wouldn't bet on it) very well be able to hold your safety stop, you'll be hard pressed to ascend slowly from your stop to the surface.

 

[cool_hardware52]

As for weighting, you should be neutrally buoyant at the surface with NO air in the BC and a near empty tank. With a 100 cu ft tank, you can weight yourself with a full tank, then add 7.5 lbs to compensate for the air you'll breathe during the dive. The problem with weighting yourself as you described is you'll be underweighted at the end of the dive. While you may (I wouldn't bet on it) very well be able to hold your safety stop, you'll be hard pressed to ascend slowly from your stop to the surface.

Wetsuits compress and 7/8 mm wetsuit compress a lot. A suit with 25 ~30 lbs of buoyancy will have easily lost 7-8 lbs at 15 ft. You are moving from 1 ATA to about 1.5 ata at 15 ft. A 50% increase in pressure does have an effect on the buoyancy of the neoprene.

This is easy to verify. Just get neutral at the surface in a thick suit with no gas in your BC and descend to 15 ft. It will necessary to add gas to your bc to stop the descent. Why? Wetsuit compression of course.

If you start a dive in thick wetsuit negative by the weight of the gas in a modest sized single cylinder you will be over weighted for the entire dive.

Compressed neoprene does not "snap back" it rebounds fairly slowly, a well compressed suit can take hours to return to it's original volume.

One of my favorite things is the slow gentle ascent from 15 ft to the surface in a thick wetsuit and empty bc. As there is little or no gas left to vent from the BC one is only subject to the rebound of the neoprene, a slow gentle ride to the surface.

One still of course has their lungs available to make small adjustments.



Tobin