First time of tech doubles, had a bit of trouble...

[Aaron Harmon]

To be perfectly honest double HP117s are absolutely beasts of tank system without a wearing drysuit or thick wetsuit. Personally I would not use these tanks with a wetsuit but that's another debate all together..

My suggestion for you with your harness is to make sure your crotch strap and waist straps are tight. Both of these will help stabilize the rig on your back. Believe it or not, shoulder straps can be a lot looser than most people realize.

Does anyone have a set of double AL80s or LP85s you can try to at least get used to having doubles on your back? You can learn how to use doubles and do value drills with a smaller set of doubles. HP117s are REALLY heavy without wearing any exposure protection. That's just a really sh*tty* setup to dive in a pool with just a bathing suit.

I suggest wearing a full 5mm or 7mm wetsuit (these won't compress too much in a pool environment, using an AL plate, anything to make that setup more manageable..

Yeah, Instructed recommended 117s. He dives 100s and plans to change to 117s. I plan to go on wreck dives with him and didn't want to be unprepared when he changes, so I started with these.

He has double 100s and if I asked, I'm sure he'd let me use his while training together for the sake of practice.

The shop only has Steel 80s but I don't think they have any doubles rigs laying around for rent/use (though I heard they are buying some).

I am going to use a Hogarthian set up guide I found to work on fitment of harness and plate so that I can see it I can tweak it a bit

 

[decompression]

If you are average height, don’t use the steel 80’s......the steel 100’s however are a fantastic tank. That’s what my students transition to from the 80’s. I’m weary of the recommendation for 117’s.......unless you are 100% sure to move on to tech 2/ extended range/ trimix. Or you plan on 2 tech dives in one day. When you run some dives and find the gas requirements you’ll find 240 cuft (2x100+40 deco) does a wide range of tech dives, besides next level adds another bottle so + 80 cuft.

Anyways, borrow the 100’s, learn as much as you can and have fun.

 

[Aaron Harmon]

If you are average height, don’t use the steel 80’s......the steel 100’s however are a fantastic tank. That’s what my students transition to from the 80’s. I’m weary of the recommendation for 117’s.......unless you are 100% sure to move on to tech 2/ extended range/ trimix. Or you plan on 2 tech dives in one day. When you run some dives and find the gas requirements you’ll find 240 cuft (2x100+40 deco) does a wide range of tech dives, besides next level adds another bottle so + 80 cuft.

Anyways, borrow the 100’s, learn as much as you can and have fun.

Yes, my plan is to move on to advanced extended range and deco

 

[NothingClever]

If you are average height, don’t use the steel 80’s......the steel 100’s however are a fantastic tank. That’s what my students transition to from the 80’s. I’m weary of the recommendation for 117’s.......unless you are 100% sure to move on to tech 2/ extended range/ trimix. Or you plan on 2 tech dives in one day. When you run some dives and find the gas requirements you’ll find 240 cuft (2x100+40 deco) does a wide range of tech dives, besides next level adds another bottle so + 80 cuft.

Anyways, borrow the 100’s, learn as much as you can and have fun.

I dive metric so I had to do the math.

A pair of 100s yields 5735 liters of back gas and twin 117s would provide 6670 liters.

Since I dive a dainty set of AL80s every week, the contrast in quantities (4400 liters for AL80s) is impressive. The long bottom times either steel config would yield are impressive.

Aaron, I think you’re getting good advice here. Pick one bit of kit to get used to first, get comfortable with it and then introduce the next complexity. Since you have access to the twinset now, it seems logical to focus on buoyancy and trim reps at the pool while you’re waiting on the dry suit to come in. If the pool is deep enough, practice “elevator drills” in the deep end.

 

[michael-fisch]

Don't agree. Diving really heavy tanks with a bathing suit/thin wetsuit/thick wetsuit is hell on the diver. Having to readjust the straps on the backplate with each suit change is also hell on the diver - there is no way you are ever going to get it exactly right.
I'd get the drysuit with the right thinsulate ASAP, then learn to dive it with lighter doubles, backplate and wing.
Now rig the backplate for your drysuit without the tanks, if properly rigged you should be able to get your wrist lower than your neck (shoulder area) while reaching back over your head n shoulders without any problems. Waist and crotch straps should be snug, and shoulder straps should be loose enough that your hand, while making a fist, easily fits under the shoulder straps. If you are not using a single piece strap, tape the shoulder straps with duct tape so they cannot shift in length after you get the adjustments right.
Now you can finally attach the D117s, wing and regs to the backplate and learn how to use it. Weights are something that you will never need again!

Michael

 

[NothingClever]

Having to readjust the straps on the backplate with each suit change is also hell on the diver - there is no way you are ever going to get it exactly right.

I don’t dive a dry suit so I defer to your experience about them. However, I’d hardly characterize having to adjust the shoulder straps on a BP as “hell”. One can use a ruler and white paint marker or tailor’s soapstone to index the shoulder straps where they enter the BP for incremental adjustments. I don’t think that rises to the level of being overly burdensome when adjusting for different exposure suits and dialing in your kit. Au contraire, I think it’s part of becoming a proficient diver.

 

[NothingClever]

I bought a new 117 CF doubles setup along with back plate, webbing redundant 60lb wing etc. Basically everything I'd need to take the TDI intro and beyond.

Currently I am taking TDI intro to tech.

My dry suit will not be here for 4 to 6 weeks but my doubles came in and my instructor wanted to get my rig set up and get me comfortable in it.

Since he is near a SCUBA-friendly pool, already bought the 117 tins and his instructor is coaching him to get used to the rig, I thought it best to focus his energies on one bit of kit right now.

If Aaron has the money, time and forbearance to rent or buy another set of smaller twins and wait on the dry suit, then more power to him.

Perhaps I’m not the brightest bulb in the house but I’d just commit my focus and energies to getting good at driving those 117s around the pool and some OW dives and then back to the pool when the dry suit comes in.

 

[Aaron Harmon]

I think that I found the issue, or at least one among several last night. I pulled everything out and test fitted it based on a guide I found online. As it turned out, the shoulder straps were a bit too loose. Moreover, one of them was twisted a half turn which made the whole thing feel a bit wonky and dig into me, but I couldn't find the issue, because, looking at it, it was subtle. Standing still, out of the water, you wouldn't have noticed it without a keen eye. Once in the water, I suspect that it twisted the whole rig to a degree. In any case, I have it all re-put back together and readjusted. I needed to order a few bits and bobs to make everything work (a hose or two was a tad too long, another a hair too short). In any case, I will probably get back in the pool once I get everything setup just to see if these little adjustments make a difference. I suspect that they will. I also know that getting my drysuit will change my buoyancy dramatically which will change things.

I talked to one of the owners at the LDS today (not my instructor) but he told me that it took him 20 or so dives to get comfortable in a big set of doubles. He's a good diver and I have a lot of respect for him so that made me feel a bit better.

I will keep you all posted.

Thanks for all the help so far.

Aaron

 

[Compressor]

Good Luck @Aaron Harmon. Good things come to those with patience.

 

[ToneNQ]

.............snip.............I talked to one of the owners at the LDS today (not my instructor) but he told me that it took him 20 or so dives to get comfortable in a big set of doubles. He's a good diver and I have a lot of respect for him so that made me feel a bit better.......................Aaron

For what its worth Aaron, I did my first AN/DP dives with steel LP117s, felt like a rank amateur. On the second day the instructor took those tanks and made it look effortless. I went to steel LP100s and it felt effortless. One thing you may note is that long-term tech divers have a room full of gear. Many own multiple backplates because different materials have different buoyancy characteristics. Those tanks and that wing and an SS backplate is hard work. If you had an AL backplate, 45lb wing and LP100 tanks, you'd be having a very different experience.

We learn a lot from adversity so enjoy the challenge. Hopefully your adjustments help, if they don't just remember this is not an easy thing that you are attempting. For me the shoulder straps don't do much once I'm in trim, my backplate and waistbelt do the work. There is a lot of inertia in your rig so don't fight it, try to feel it and counter it. Get your arms out in front, pull them into your chest, feel how that changes things. Follow your instructor around the pool, watch him like a hawk, how quickly or slowly he moves, how his breathing changes, then question him about it. He'll role model good technique, see if some of those work for you.