Tech 40 Trim and buoyancy

[Windmutt]

I'm an experienced diver (Master Diver with 100 dives per year for the last 4 years) and have been able to establish perfect trim and buoyancy in my recreational kit. During the last two sessions of Tech 40, I have been unable to keep my head up in a horizontal position. Its as if someone put 20 pounds on my head. My instructor says my trim sucks. We have made no adjustments to my kit with the exception of switching my Apex RK3 fins to ScubaPro Jetfins.

Note, the training is taking place in FRESH WATER. My kit consists of: Hollis Drysuit, Twin steel 100's, 40 bailout bottle, Hollis stainless backplate, Hollis DT 50, OrcaTorch canister light, extra mask, DSMB, manifold, spool, 2 knives, two additional backup lights, fourth element 7mm hood, three reg setups.

The only instruction I am getting is to keep my head up. I have my head touching the manifold knob and still I will angle down unless I put air in my drysuit. The fins (my idea) helped a little. Is it really my technique or do I need to adjust my rig (we never made any adjustments, move the tanks etc...)? Do I need a larger wing. My instructor says their is no need to adjust and it is all about technique.

 

[boulderjohn]

I have my head touching the manifold knob and still I will angle down unless I put air in my drysuit.

I don't know what this means. You have to have air in your drysuit.

Managing the air in your drysuit is a skill that creeps up on you a little at a time. How long have you been using a drysuit?

 

[Windmutt]

I’ve been diving regularly in a dry suit for 2 years with no issues. No corking, legs up etc…My point is, the only way I have found to keep from angling head-down is to add air to my dry suit. Something I have never had to do before. Normally I only add air to prevent squeeze and add air to my bcd to control buoyancy. Is this clear enough for you?

 

[sea_ledford]

Were you diving in doubles before your tec 40 class? A manifold and two regs adds about 10 lbs of weight, so if you were trimmed out in a single and made no other changes I would expect you to be head down.

You also might be foot heavy and are subconsciously going head down to counteract that. It also might be the drysuit as John mentioned. Lots of options...

If the doubles are new to you, what I have found helps students adjust to them more than anything else is to think of yourself as hanging from your rig, rather than wearing it. Picture yourself as a blimp with your body being the cockpit and your tanks and wing as a single unit supporting you.

 

[Windmutt]

New to doubles and renting them from the instructor. No adjustments have been made over two days of diving. I adjusted my single to maximize trim. Just being told to hold my head back and not getting anywhere with my head held back and legs extended out arms forward.

 

[tursiops]

New to doubles and renting them from the instructor. No adjustments have been made over two days of diving. I adjusted my single to maximize trim. Just being told to hold my head back and not getting anywhere with my head held back and legs extended out arms forward.

Change your instructor, not your rig.

 

[jlcnuke]

Change your instructor, not your rig.

Yeah, while technique can help with a lot of things, if your rig isn't setup to properly trim you out there isn't much you're going to be able to do. In my Intro-to-Tech course we spent 3 dives making small adjustments between wing and backplate adjustments for the tanks before finding the hole positions that worked best for trimming me out naturally. Most backplates have 3 hole positions you can run the tank's bolts through. If you're in the top, move it down one. If you're using the middle, move it to the bottom. Similarly, many wings can also be positioned in multiple places. These adjustment options exist because they need to for proper trim. Not everyone will trim out in the same way using the same adjustment positions.

An arched back, head up, and feet and arms out can only do so much. Sometimes the answer is to fix the gear. If your instructor doesn't understand that I'd be worried about what else they don't understand.

 

[inquis]

The manifold, 2nd valve and 2nd regulator put a lot of mass up high (headward), compared to your singles setup. Make sure the upper band is right at the crown on the tank. I also put the wing as high as it will go (posts through the bottom set of holes) and the tanks as low as they'll go on me (posts through the lowest holes in the backplate).

Ensure there are no issues reaching valves, though. There is technique to that, however -- elbow should point forward, not out.

 

[macado]

There are a lot of variables to consider. First - What is your height and build?

My personal experience is HP100s are shorter doubles and tend to make people very head heavy. A lot of people unconsciously dive heads-up position to try to offset this. When diving doubles you now have the weight of the manifold + 2 first stages at the top of your head.

For me a tail weight as low as possible is absolutely essential. it's literally the only way I can trim out HP100s. How much weight might be a function of how head heavy you.

Before trying that you should also try loosening your harness to drop tanks lower on your back and make sure you're using the bottom bolt position on your backplate (this raises the plate but drops the doubles lower on your back). I've found a lot of people have their shoulder traps a lot tighter than they need to be. Mine are pretty loose which you compensate for by cinching down the waist strap and snugging up the crotch strap.

Also already mentioned but make sure the top band is right at the crown/break of the tanks. This will also drop the doubles lower on your back.

 

[rongoodman]

Before you start moving things around you might try just adding a couple of pounds at the bottom of your tanks to see it that helps. Doubles will make you head heavy, and there've been a lot of discussion here over the years about people diving head-up to compensate, which confuses the issue even more.