A couple doubles questions

[Badger7]

Started diving double HP100s the past couple weekends to get a feel for them. No issues with valve drills and starting to get trim dialed in. Of course I started out with what felt like a foot heavy configuration, and made some poor adjustments till realizing that I was only stable in a head up trim because it brought center of mass in line. After forcing neutral trim and relaxing, I'd continue going head down like you'd expect with all that extra brass behind my neck.

So, a pound of lead in each drysuit thigh pocket helped quite a bit on my first dive today. Dropping those and going with 3 pounds of tail weight felt even more stable, almost to the point of nice stable trim without having to work for it too much.

1) Continue going that route? Play with tail weight between the bottoms of the tanks till finding a good trim compromise between empty and full tanks? Only one hole position in my BP and only one set of grommets in my current wing, so can't play much with wing position other than further tightening crotch strap, and it's already pretty tough getting buckled up.

2) I'm already negative with just empty HP100 tanks, AL BP and standard kit with no lead. If I'm going further negative adding lead, should i look into changing tank sizes? Like would double HP120s which are slightly more bouyant empty, trim out better without having to add as much tailweight since they're longer? I would prefer to stick with 7" diameter tanks, as I'm rocking a 40lb wing and I can fit four 7" tanks in the bed trunk of my Ridgeline, but can't fit 117s or 130s nearly as efficiently. Up here in the midwest, getting LPs overfilled isn't really an option either.

3) Is lead zipped into drysuit pockets cheating? It seems like pound for pound it might be more efficient to move balancing weight further rearward to my thigh beyond the base of the tanks?

Thanks, any thought/advice welcome, trying something new to me and would love your perspective.

 

[crofrog]

I wrote about some of this here

Trimming for a leg heavy diver

Are you 100% certain that you’re feet heavy? A lot of times people find themselves in a head up position because they’re head heavy and if they go actually flat they end up head down.

scubaboard.com

double 100s are head heavy for everyone I know.

Some 120s are much better for trim but are heavy in the water.

I would consider doing the following in this order.

1. Move your tanks as far down your back as you can. I tighten the crotch strap and lengthen the shoulder straps. Keep going until you can barely do valve drills and then maybe a bit farther and work on your shoulder mobility.

2. Consider using dry gloves and a thicker hood if the water is cold an 11mm hood contributes a lot of buoyancy and dry gloves do some as well

3. I’d prioritize effortless trim over being slightly overweighted in a drysuit.

4. Weights in the pockets is kind of an open secret among some GUE communities in the NW. if yiure going to do it. I’d cave line the weights to a tiny bolt snap so you can clip them in.

5. Weight belts are under appreciated. It’s a really good place to add weight in doubles.

6. Everyone likes to hate on them but double 80s are preferable to double 100s from a trim standpoint because you get a lot more leeway in placing weight. There are some GUE instructors like Bob Sherwood that prefer them because of their trim characteristics.

 

[Badger7]

I wrote about some of this here

Trimming for a leg heavy diver

Are you 100% certain that you’re feet heavy? A lot of times people find themselves in a head up position because they’re head heavy and if they go actually flat they end up head down.

scubaboard.com

Thanks for that! It was your post with the illustrations back in Sept that I remembered reading that helped me figure out last weekend why lighter fins and a heavier light were making the head up trim worse, not better!

I use a waterproof h1 5/7 hood and dry gloves with 2mm liners. I might try a dive holding a short length of pool noodle to see what a little additional bouancy up front feels like. I did notice that closing my exhaust valve a couple clicks and getting some gas in the arms felt pretty comfy too.

You don't think longer tanks would be a silver bullet and I should focus on trimming these 100s as best as I can? 5'9, 200 lbs, medium build in case that's pertinent.

I'm not in any hurry, taking some tech classes next year, but thinking about doing a fundies upgrade between now and then so just trying sneak up on a nice stable trim that doesn't require much input to maintain.

 

[rjack321]

4. Weights in the pockets is kind of an open secret among some GUE communities in the NW. if yiure going to do it. I’d cave line the weights to a tiny bolt snap so you can clip them in.

I have never heard of this other than on a temporary basis like borrowing gear that needs extra lead to sink

 

[rjack321]

Thanks for that! It was your post with the illustrations back in Sept that I remembered reading that helped me figure out last weekend why lighter fins and a heavier light were making the head up trim worse, not better!

I use a waterproof h1 5/7 hood and dry gloves with 2mm liners. I might try a dive holding a short length of pool noodle to see what a little additional bouancy up front feels like. I did notice that closing my exhaust valve a couple clicks and getting some gas in the arms felt pretty comfy too.

You don't think longer tanks would be a silver bullet and I should focus on trimming these 100s as best as I can?

I'm not in any hurry, taking some tech classes next year, but thinking about doing a fundies upgrade between now and then so just trying sneak up on a nice stable trim that doesn't require much input to maintain.

What kind of undergarment are you in?

 

[Badger7]

What kind of undergarment are you in?

250g merino wool baselayer tops and bottoms, and Waterproof Meshtec thermal layer tops and bottoms, trilam suit.

 

[crofrog]

I have never heard of this other than on a temporary basis like borrowing gear that needs extra lead to sink

I just know what I’ve seen while doing some diving up there

 

[crofrog]

Thanks for that! It was your post with the illustrations back in Sept that I remembered reading that helped me figure out last weekend why lighter fins and a heavier light were making the head up trim worse, not better!

Glad it helped.

I use a waterproof h1 5/7 hood and dry gloves with 2mm liners. I might try a dive holding a short length of pool noodle to see what a little additional bouancy up front feels like. I did notice that closing my exhaust valve a couple clicks and getting some gas in the arms felt pretty comfy too.

Just let a little bit of air get into your dry glove / sleeve to feel it out.

You don't think longer tanks would be a silver bullet and I should focus on trimming these 100s as best as I can? 5'9, 200 lbs, medium build in case that's pertinent.

I owned a set of PST120 doubles, I’m about your height. I found that the 120s trimmed out nicely but they were sitting on top of my ass and hamstrings a bit and that made them tiring to dive compared to something a bit shorter.

In my experimentation with tanks I tried faber 100s, hp80s, gensis 100s, pst100s, pst120s, lp98s, lp108s, faber 133s al80s.

I’ve standardized entirely on 133s/108s and al80s.

I found them to be the most useful sizes and the easiest to trim out for my wife and myself.

I'm not in any hurry, taking some tech classes next year, but thinking about doing a fundies upgrade between now and then so just trying sneak up on a nice stable trim that doesn't require much input to maintain.

The stiller you’re able to be in the water the easier everything else will be.

Eventually you’ll be able to dive anything more or less and make it work, but making it effortless makes it possible to learn how to do that imo.

 

[Deco Nico]

Started diving double HP100s the past couple weekends to get a feel for them. No issues with valve drills and starting to get trim dialed in. Of course I started out with what felt like a foot heavy configuration, and made some poor adjustments till realizing that I was only stable in a head up trim because it brought center of mass in line. After forcing neutral trim and relaxing, I'd continue going head down like you'd expect with all that extra brass behind my neck.

So, a pound of lead in each drysuit thigh pocket helped quite a bit on my first dive today. Dropping those and going with 3 pounds of tail weight felt even more stable, almost to the point of nice stable trim without having to work for it too much.

1) Continue going that route? Play with tail weight between the bottoms of the tanks till finding a good trim compromise between empty and full tanks? Only one hole position in my BP and only one set of grommets in my current wing, so can't play much with wing position other than further tightening crotch strap, and it's already pretty tough getting buckled up.

2) I'm already negative with just empty HP100 tanks, AL BP and standard kit with no lead. If I'm going further negative adding lead, should i look into changing tank sizes? Like would double HP120s which are slightly more bouyant empty, trim out better without having to add as much tailweight since they're longer? I would prefer to stick with 7" diameter tanks, as I'm rocking a 40lb wing and I can fit four 7" tanks in the bed trunk of my Ridgeline, but can't fit 117s or 130s nearly as efficiently. Up here in the midwest, getting LPs overfilled isn't really an option either.

3) Is lead zipped into drysuit pockets cheating? It seems like pound for pound it might be more efficient to move balancing weight further rearward to my thigh beyond the base of the tanks?

Thanks, any thought/advice welcome, trying something new to me and would love your perspective.

Started diving double HP100s the past couple weekends to get a feel for them. No issues with valve drills and starting to get trim dialed in. Of course I started out with what felt like a foot heavy configuration, and made some poor adjustments till realizing that I was only stable in a head up trim because it brought center of mass in line. After forcing neutral trim and relaxing, I'd continue going head down like you'd expect with all that extra brass behind my neck.

So, a pound of lead in each drysuit thigh pocket helped quite a bit on my first dive today. Dropping those and going with 3 pounds of tail weight felt even more stable, almost to the point of nice stable trim without having to work for it too much.

1) Continue going that route? Play with tail weight between the bottoms of the tanks till finding a good trim compromise between empty and full tanks? Only one hole position in my BP and only one set of grommets in my current wing, so can't play much with wing position other than further tightening crotch strap, and it's already pretty tough getting buckled up.

2) I'm already negative with just empty HP100 tanks, AL BP and standard kit with no lead. If I'm going further negative adding lead, should i look into changing tank sizes? Like would double HP120s which are slightly more bouyant empty, trim out better without having to add as much tailweight since they're longer? I would prefer to stick with 7" diameter tanks, as I'm rocking a 40lb wing and I can fit four 7" tanks in the bed trunk of my Ridgeline, but can't fit 117s or 130s nearly as efficiently. Up here in the midwest, getting LPs overfilled isn't really an option either.

3) Is lead zipped into drysuit pockets cheating? It seems like pound for pound it might be more efficient to move balancing weight further rearward to my thigh beyond the base of the tanks?

Thanks, any thought/advice welcome, trying something new to me and would love your perspective.

I like your methodical self-assessments! It seems to me you are moving in the right direction in finding your comfort zone. There have been some good suggestions in this thread, too.

I took note of your use of a 40-pound wing. When I started with 100 HP steel doubles, I was surprised at -- what I considered to be -- the inadequacy of a 40-pound wing to "float" my kit. Please be sure you have enough lift to sustain you.

 

[rob.mwpropane]

I dive with a Halcyon tail weight / V weight thing in between the tanks. I think I have 6# soft weights at the bottom. I have 2 more Highland weight attachments on either shoulder strap at the bottom and can change weights or remove altogether. I dive heavier Hollis F1 fins. This works for me and I was able to play with different weights pretty easily to find what works.

Trilam ds, steel bp, HP 100's or LP85's.