Universal wing to backplate fit?

[Flycaster]

@Flycaster
HP100-100*.08=8lbs
28lbs of floaty+8lbs of gas=36lbs

To float the entire rig at the surface with a full tank, and all of the ballast on the rig, you need a 40lb wing.
If you move some of that to the belt, and don't dive terribly deep, you may be able to get away with a 35lb wing.

The HP80 poses problematic for the Torus 35 because the short tank puts the wing at higher risk for pinch flats so I would recommend avoiding that tank if you can.

The ballast of the farmer john is what is killing you and a huge reason that you don't see recommendations for them on this forum. If you need that for the warmth, you are far better off biting the bullet and going dry.

You're stuck between a Torus 35 and a LCD30/40. If you get weight plates with the large plate it gives you 15lbs there, plus another 2 for the reg and you have another another 8-10lbs of lead to put somewhere. 8lbs if you have a Worthington HP100, 10lbs if a PST or Faber. I think the Torus35 would be better from a trim perspective due to the 14lbs on the belt, and if you don't get the weight plates, you'll want to get to the Torus for trim purposes in my opinion. Tobin's may be different. Risk with the Torus as mentioned is with that HP80 that could cause a pinch flat.

To hell with the HP 80 then.
It's no longer a part of my plans.

 

[tbone1004]

To hell with the HP 80 then.
It's no longer a part of my plans.

probably best. The HP80's are f*cking annoying tanks unless you are super short. They're very negatively buoyant and they cause all sorts of trim problems if you're a tall diver as well as being uncomfortable to sit down on the surface because you turtle backwards. HP100's are the bees knees and are in most of our opinion, the ideal tank for most people

 

[rhwestfall]

The only configuration I like an HP 80 in is on a double hose so I can wear it low. Outside of that, they are great door stops.....

 

[cool_hardware52]

Tobin,

We are finally there.

Steel HP 100 for my go to set-up.
I may at some point use a Steel HP 80 later down the road.

Most buoyant - Farmer John 15, Step through shorty 13, Total 28lbs.

Least buoyant - Shorty -Total 13lbs.

I have a neoprene weight belt which takes 1-1/4lbs To neutralize it but I think I may use ditchable weights to replace the need for it. Your suggestion on that please.

Thanks for the time you spent on this and my questions.

Glen

Glen, is 15 lbs and 13 lbs the actual buoyancy of the "Farmer John" and "Shorty" or does this represent the lead you used while diving with each?

If I assume it's the actual buoyancy of the suits I'd recommend a LCD 30.

28<30 so that covers the maximum possible change in buoyancy of your most buoyant suit combo.

Your rig will be about - 19 with a full cylinder, 7 for the plate and harness, 2 for the reg, ~10 for a full HP 100. Even if you add the weight plates your rig would only be -27. 27 < 30.

When would I recommend the Torus 35 instead of the LCD 30? If you had plans for more buoyant suits, i.e. new 7mm 2 piece, or a Drysuit. If you diving primarily cold water there is little penalty for going up a wing size.

Tobin

 

[Flycaster]

Glen, is 15 lbs and 13 lbs the actual buoyancy of the "Farmer John" and "Shorty" or does this represent the lead you used while diving with each?

If I assume it's the actual buoyancy of the suits I'd recommend a LCD 30.

28<30 so that covers the maximum possible change in buoyancy of your most buoyant suit combo.

Your rig will be about - 19 with a full cylinder, 7 for the plate and harness, 2 for the reg, ~10 for a full HP 100. Even if you add the weight plates your rig would only be -27. 27 < 30.

When would I recommend the Torus 35 instead of the LCD 30? If you had plans for more buoyant suits, i.e. new 7mm 2 piece, or a Drysuit. If you diving primarily cold water there is little penalty for going up a wing size.

Tobin

Yes. I put each piece in a barrel today and added weight until they were neutral so yes its the actual buoyancy.

I am puzzled by your comment on going up to a 35 if I used more buoyant suits?
Wouldn't the adddd buoyancy relieve the amount of bcd lift required?

I would think if I was diving warm water with a thinner suit would require more lift.

 

[cool_hardware52]

Yes. I put each piece in a barrel today and added weight until they were neutral so yes its the actual buoyancy.

I am puzzled by your comment on going up to a 35 if I used more buoyant suits?
Wouldn't the adddd buoyancy relieve the amount of bcd lift required?

I would think if I was diving warm water with a thinner suit would require more lift.

Buoyancy Compensators are used to compensate for things that lose buoyancy as you descend.

Would you need more or less lift capacity if you were diving in swim trunks with a rig that is a maximum of 10 lbs negative, or in a 2 piece 8/7 mm wetsuit that is 32 lbs buoyant at the surface?

Tobin

 

[tbone1004]

@Flycaster the wing compensates for two things. The one that never goes away is the mass of gas in the tank. I.e. if you use a HP100, you need 8lbs of lift to compensate for the gas as you use it no matter what suit you are diving.

The second thing the wing compensates for is changes in buoyancy due to compression at depth. The thicker the suit, the more air bubbles in the neoprene, which results in more loss of buoyancy at depth. Think back to basic OWT and Boyles law. If you have something that is 28lbs buoyant in a flexible container *your wetsuit in this case*, when you get to 33ft, or 2ata, then the bubbles will be at half the volume, which is roughly half as buoyant, in this case 14lbs. At 99ft, or 4ata, then they half again to 7lbs. What that means is that at 100ft, you need 21lbs of wing lift to get back to neutral if you were weighted for neutral buoyancy at the surface, PLUS the 8lbs of lift that you need to compensate for the mass of the gas in your tank.

Now, if you are diving a 3mm suit with say 8lbs of positive buoyancy, then at 33ft it is 4lbs, and at 99ft it is 2lbs so you only need 6lbs of lift to compensate for it.

You bring the amount of lead you need to stay neutral at your safety stop and that amount of lead is directly proportional to the thickness/size of your wetsuit.

By going to more buoyant suits, you add positive buoyancy at the surface, but you need to compensate for that with lead, and you also increase the amount of buoyancy that you will lose at depth which needs to be compensated for by the wing.

This math is a lot easier to do with wetsuits than drysuits when the buoyancy of the suit theoretically doesn't change based on depth, but is dependent on how much warmth you want from the bubble, but that is a discussion for another day

 

[scrane]

Measurements are not standardized, but you should be able to get an idea what fits what by comparing images.

 

[Flycaster]

@Flycaster the wing compensates for two things. The one that never goes away is the mass of gas in the tank. I.e. if you use a HP100, you need 8lbs of lift to compensate for the gas as you use it no matter what suit you are diving.

The second thing the wing compensates for is changes in buoyancy due to compression at depth. The thicker the suit, the more air bubbles in the neoprene, which results in more loss of buoyancy at depth. Think back to basic OWT and Boyles law. If you have something that is 28lbs buoyant in a flexible container *your wetsuit in this case*, when you get to 33ft, or 2ata, then the bubbles will be at half the volume, which is roughly half as buoyant, in this case 14lbs. At 99ft, or 4ata, then they half again to 7lbs. What that means is that at 100ft, you need 21lbs of wing lift to get back to neutral if you were weighted for neutral buoyancy at the surface, PLUS the 8lbs of lift that you need to compensate for the mass of the gas in your tank.

Now, if you are diving a 3mm suit with say 8lbs of positive buoyancy, then at 33ft it is 4lbs, and at 99ft it is 2lbs so you only need 6lbs of lift to compensate for it.

You bring the amount of lead you need to stay neutral at your safety stop and that amount of lead is directly proportional to the thickness/size of your wetsuit.

By going to more buoyant suits, you add positive buoyancy at the surface, but you need to compensate for that with lead, and you also increase the amount of buoyancy that you will lose at depth which needs to be compensated for by the wing.

This math is a lot easier to do with wetsuits than drysuits when the buoyancy of the suit theoretically doesn't change based on depth, but is dependent on how much warmth you want from the bubble, but that is a discussion for another day

It all makes perfect sense now. Got it

 

[tbone1004]

It all makes perfect sense now. Got it

spoke with @cool_hardware52 directly earlier about why his numbers came up a bit different than mine for wing lift recommendations and it stems on his more direct experience with weighting for divers in thick wetsuits. I don't usually work with wetsuits thicker than a single 5mm or rarely 7mm as I go straight to drysuits for anything colder than that. I am also usually diving doubles where the wing lift is usually already larger than I really need.
What he is advocating for is that you are weighted to be neutral at your safety stop with an empty tank so you will be positively buoyant at the surface. From a safety standpoint this makes perfect sense and I agree with him whole heartedly.

His recommendation for the LCD30 wing is also my personal wing and is quite good