Positively buoyant Jet Fins?

[Midwesterndvr]

Scubapro twin jets are positively buoyant in fresh water. I'm not sure if this still applies but black rubber was negatively buoyant.

 

[JamesBon92007]

Also, I have been using Scubapro Jet Fins for 43 years. They are hard to beat. If I knew I was making a dive with a lot of current, I would take my Jets instead of the Novas until I have a lot more time using the Novas than I do right now. Since you have the industry standard already, take your time and look for something a little different. My recommendation is to keep diving your jets and gain more experience and when you get the chance ask other divers if you can do a quick vertical test with their fins. A good time to do this is when between dives waiting out surface interval.

IIRC when they first started marketing the original ScubaPro Jet Fins they said they had the same density as salt water (sea water). I realize that does not necessarily mean that they are neutrally buoyant but I've never noticed them being negative or positive so I guess I assumed they are neutral. Do you happen to know if the newer ones are negative and possibly that the original ones were neutral? Mine are Made in USA from the late 60s or early 70s. I guess I'll have to take one off on my next dive and see if it sinks

Do you dive with the original originals or with the lightnings? I'm thinking there might be a difference there too since the lightnings are a bit more flexible.

 

[trpltongue]

The scubapro twin jets I used were definitely positive in the saltwater that I dive in (Arabian Gulf). It made the dive so much easier to stay level. Not quite neutral with my feet, so I still had to do some work to keep my legs up, but sooo much less than before. Only problem of course was the lack of power from the split fin.

As for my weighting. With 14 lbs, at my 5m safety stop with all the air out of my BC I was slightly negative. A big breath and I was neutral again, so I'm pretty comfortable with that setup as it puts me in control for my safety stop and able to breath normally

I've been reading up a ton on the Depp Six Eddy fins and they look like a great alternative. I may try to sell my Hollis F2's and pick up a pair of the Deep Six.

 

[Qdivers Ramona]

I know I'm a bit late, but I can probably help you to get some neutral bouyant yet fins in Qatar .
Let me know if you're still looking.

 

[Kazeone]

Do you add air to your bcd when reaching the bottom? If so you have to much weight. Jacket style bcds make your upper half light if they are not completely dumped. You should do better with your friends bp/wing set up. I dive in warm water just a rash guard and board shorts. 1kilo on the tank strap with a fully dumped bcd and sp jet fins perfect trim absolutely neutral. To go up fin up. To go down fin down. Frog kicks of course. Less weight equals better air consumption. Wear some neoprene booties if you need to. Hope this helps. Enjoy your new obsession.

I've tried to put an illustration together to highlight what I'm experiencing.

A divers trim can be broken into three sections: 1) Upper body to Hips, 2) Hips to knees, 3) Knees to feet. It is split into 3 sections because each section is separated by a rotating joint.

The first diver is neutrally buoyant in each of the three sections. 1) Upper body due to BCD and trim weights, 2) Hips to knees due to wetsuit and body composition, 3) knees to feet due to wetsuit, fins, and body composition. This diver can maintain any position they like underwater with no continuous effort required.

The second diver is neutrally buoyant in the upper body only, and negatively buoyant everywhere else. This diver will ALWAYS experience a downward moment of inertia around the hips and knees. The only way for this diver to maintain correct trim (without kicking) is to lock the hip and knee joints to prevent rotation AND to add weight in the front of their body to counterbalance the negative weight from their lower body preventing a "seahorse" position. This can be done, but it is tiring.

Alternatively, you can make the knee to feet section positively buoyant with fins/boots/etc., such that it counterbalances the negative buoyancy of the hip to knee section and makes the lower body neutral overall.

My wife and daughter are like the upper diver, naturally neutral in the water. I am like the second diver.

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[RainPilot]

Do you add air to your bcd when reaching the bottom? If so you have to much weight.

Depends on the amount. If you are wearing a wetsuit and are correctly weighted for empty tanks at the safety stop, then you will need gas in the BCD at the beginning of the dive equal to the gas weight and wetsuit compression. That’s around 6 lbs for an AL80 plus around 60-80% of the buoyancy of the wetsuit depending on depth.

 

[Kazeone]

Depends on the amount. If you are wearing a wetsuit and are correctly weighted for empty tanks at the safety stop, then you will need gas in the BCD at the beginning of the dive equal to the gas weight and wetsuit compression. That’s around 6 lbs for an AL80 plus around 60-80% of the buoyancy of the wetsuit depending on depth.

Interesting. No wetsuit. Thanks for the info.

 

[RainPilot]

Interesting. No wetsuit. Thanks for the info.

No worries. The 6 lbs of gas weight is independent of exposure protection.