Jets and double tank diving

[Ed Palma]

I recently tried my twin LP72 tanks in OW. For my single tank diving previously, I had been using large jet fins. No problem with them, fits great, good power. Now when I tried them out with my dubs, I was still able to move forward, but I was having a hard time keeping up with my buddy. I've read threads where size L jets had a noticeably shorter fin length than the next larger size, the XLs. At this point in time, double 72s are as far as I care to go.

1. Will shifting to a larger fin help me, or is a performance decrease like this expected and something I just have to live with?

2. Is the foot pocket of the XL fin proportionally larger as well, or will my foot still fit well in it? (given that my size 8 foot with 5mm booties fit great in the large fin).

 

[tstormdiver]

They will probably be a bit large on you. I wear XL Jets with my drysuit Rock Boot & insulation, when diving my double LP 108's & they're almost too big for me (women's size 9). There is plenty of power to move myself through the water. In neoprene booties,... probably too big. Yes, the XL Jets are longer & wider, giving more surface area in contact with the water, thus more potential power.

 

[knowone]

XL Jets. 22" long 9 1/2" wide. Foot pocket 4 1/2" wide 3 1/2" high 8 3/4" deep.
Flexible rubber at the mouth, narrows off then broadens which is a dumb design for back then when people wore neo socks or with a thin sole. Splits have a crap small pocket and crap buckle setup.
If you get a bootie with a heavy walking runner type sole should fit. Half my foot pokes out looks like I'm missing half a pocket.
The secret is mild constant wetting with stainless brush in circles and blending.

 

[PfcAJ]

Was your buddy diving a single tank?

 

[Ed Palma]

Was your buddy diving a single tank?

Well, he was diving my singles rig His fins were my Mares Plana fins.

Actually, I am able to move about, but its just a lot slower. I was wondering if the performance decrease when shifting to dubs was this much, or can I improve this performance using different fins?

 

[Jim Lapenta]

Actually what happened here is your buddy screwed up. I would not expect to swim as fast in doubles as in a single or expect my buddy to when starting out. Before trying to solve the problem with new gear have a talk with your buddy. The slowest diver sets the pace. Period, end of discussion. I have heard several times from people who dive with me for the first time that they have never swam so slow. They are used to trying to keep up with people who fly from one place to another. It is not a race down there.

 

[String]

Twinset you're carrying twice the mass as a single. It takes more energy to move that mass through the water. For the same effort you are going to swim slower in twins than singles.

 

[gsk3]

Also consider that your first dive in doubles you may have been out of trim (often head-heavy), and since drag in water is a killer of efficiency, that may have slowed you down quite a bit. Before you buy new fins, consider working on trim and eliminating danglies. You can also try a frog kick if you're currently using a flutter; I find it hard to get much power out of Jets with a flutter kick (which is more about my bad technique on the flutter than it is about the Jets).

 

[Ed Palma]

Also consider that your first dive in doubles you may have been out of trim (often head-heavy), and since drag in water is a killer of efficiency, that may have slowed you down quite a bit. Before you buy new fins, consider working on trim and eliminating danglies. You can also try a frog kick if you're currently using a flutter; I find it hard to get much power out of Jets with a flutter kick (which is more about my bad technique on the flutter than it is about the Jets).

I was head heavy! Initially, I was unable to even look up completely. My manifold kept getting in the way. My trim was totally screwed up from the get go. Moved the entire rig down one hole on the plate, and it was all better.

Currently have no danglies. All stuff stowed and bungeed either to my plate, or in my pockets. Currently use frog kick (or try to), but because of my totally screwed up trim, I had to make constant adjustments to try to stay level that I was occasionally kicking up silt. Not my best day.

I guess I'm not one of those who takes to twins like a duck to water.

 

[String]

Most people in a twinset for first time do head first silt plummets. Are you using the evil abortion aluminium tanks as well which will make things worse or rather saner steel?