Looking for stiff, negative fins

[Brett Hatch]

Sounds to me like you have some significant air trapping, leading to over weighting, leading to over inflated wing and or suit. What suit do you have?

We are the same height, but I've got about 40 lbs of body wieght on you. Last time I dove dry in California, I think I had 14 lbs, plus a steel BP and steel 100 tank (I think? it might have been a weird steel 80 or old 72). So about 25ish lbs. I was wearing medium weight polypro undergarments and a compressed neoprene suit.

Unless you are wearing huge fluffy undergarments, you sound way over weighted.

It's a Seaskin trilam, and I'm using a thin Seaskin wicking layer and DUI DuoTherm 300 undies, which I believe are a poly fleece of around 500 gsm weight. Something like that, anyway. I also wore a thin-ish wool ski sock last time (on recommendation from @stuartv, actually). The numbers you and @Marie13 mentioned do suggest that I might be running around with too much lead, possibly to compensate for the skills issue of bubble management. However I can't just take your height and weight at face value, since I don't know whether your extra 40 lbs is all muscle, all fat, all bone, or what -- your body might be denser or less dense than mine overall, I don't have enough info to say. Right?

I went back and re-read the OP.

There are a lot of things I might agree with saying "wait on that until you get more experience". This issue of fins in your drysuit is not one of them.

From the details in the OP, I would say try the regular F1 fins ASAP. I suspect they will work well for you. At least, they will not make you foot heavy, I don't think. And if they do, that just lets you let a little air into your feet to compensate.

If they are comfy and work for you, then don't waste more time on the Deep6 fins. Get some F1s. If you really don't want all black, they have the Yellow Tip option.

Mine are all black, but I got red and white Scotchlite reflective trailer safety tape and put it on mine. It has stayed on, no problem, for years now. The red is still there. The white finally came off just in the last couple of months. The reflective white (on the bottoms) has definitely helped my buddies to keep track of me in very low viz water. The yellow tips do a similar job (I say after diving with buddies in the past that have those).

Thanks Stuart. I think we're up to 7 recommendations to try my buddy's F1s, so I'll definitely do that! Interesting idea on the reflective tape, I've never seen that before. Do you have any photos?

 

[stuartv]

Thanks Stuart. I think we're up to 7 recommendations to try my buddy's F1s, so I'll definitely do that! Interesting idea on the reflective tape, I've never seen that before. Do you have any photos?

Hrrmmm.... Well, no. Not where you can see the tape on the fins, anyway. I just put it crossways towards the tip of the fins. I used a heat gun to warm up the fin and the tape when I put it on, to help it stick well.

I need to put some new white tape on anyway. If I do that, I'll take a picture for you.

 

[flymolo]

stiff is not a word I've ever heard anyone use to describe turtle fins...

The turtles are pretty good w.r.t. stiffness. Similar to my old jets; maybe a little more flex but not much. They are plenty good fins. the jets really rubbed up on the tops of my feet and were very uncomfortable but I’ve never had any discomfort with the turtles even on longer dives, so a fair tradeoff overall.

 

[rob.mwpropane]

It's a Seaskin trilam, and I'm using a thin Seaskin wicking layer and DUI DuoTherm 300 undies, which I believe are a poly fleece of around 500 gsm weight. Something like that, anyway. I also wore a thin-ish wool ski sock last time (on recommendation from @stuartv, actually). The numbers you and @Marie13 mentioned do suggest that I might be running around with too much lead, possibly to compensate for the skills issue of bubble management. However I can't just take your height and weight at face value, since I don't know whether your extra 40 lbs is all muscle, all fat, all bone, or what -- your body might be denser or less dense than mine overall, I don't have enough info to say. Right?

Thanks Stuart. I think we're up to 7 recommendations to try my buddy's F1s, so I'll definitely do that! Interesting idea on the reflective tape, I've never seen that before. Do you have any photos?

I'm not sure that I would focus so much on weight as a number. I believe (at least for me) that kind of drops off when it drops off. I started with 24# because I didn't know anything and I was by myself and I REALLY didn't feel like going back to shore if I was too light. Since then it's dropped to ~ 16# and that's in a neoprene ds with heavier undergarments. I'm just saying I would do what feels comfortable until that feels heavy (as you get more comfortable)...if that makes sense.

 

[wstorms]

I'm up to 3 . And yes, I have found it to be easier every time. Buoyancy control, trim, gas consumption, everything. It is certainly the case that I have skills problems with skills solutions. I guess with that in mind, it's hard to say if I have gear problems as well at this point, so maybe I'm jumping the gun here w/ looking for new fins.

Spot on. Take some time and simply enjoy being underwater. Always do a number of dives (20 or so) before making significant gear changes. This ensures you become more familiar and learn the finesse of the equipment without being blinded by new challenges.
My advise would be to work out your weighting first, as this will affect your buoyancy. After that, focus on trim and swimming technique and you will soon notice a big difference.
Have fun!

 

[lexvil]

A few things, no need to burp out air for Monterey shore diving, by the time you get out far enough to get your fins on most of the air is out of the suit, when diving from a boat you’ll want to get the air out before corking.

For Monterey weighting is different if you want to stay warm, thick undies and not being squeezed require lead, you’ll have time to add or subtract as you get used to the suit. Proper placement for trim is important and I have the opposite problem with sinker legs, I have to work to get air in my foot area, I use the lightest powerful fins I can get, I wear my tank up high, and have 10 lbs on the top band and the rest on my freedom plate and high mounted pouches.

With a shell suit you do have to pay attention to the bubble and adjust accordingly. To much weight will compress the lower part of the suit and you may feel wet/cold on your front.

F 1 are nice fins and heavy do give them a try but also work on weight distribution.

 

[Boston Breakwater]

View media item 209694Hey, Brett. My experience with fins is actually limited. I dove U.S. Divers "Blades." along with U.S. Divers "Rocket fins for 20 years. (They were both great fins.) One pair of my Blades were Yellow, purposely bought for visibility working as a Divemaster in the early 2000's. I also had a pair of Scubapro Jet Fins for about ten years. I REALLY liked those.
I am currently diving Apeks RK3 HD's which are both heavier, and stiffer than the RK3's.
I bought a DUI TLS 350 Drysuit in 1999. It was suggested that I try ankle weights "Training Wheels." until I got used to the suit. The blades were fairly light, and I kept weights on my ankles for a long time. The "Blades were kind of light, and the weights balanced out perfectly. (Just a thought.)
Iv'e had numerous.....minor inconveniences I'll say, as far as, fin storage.
The Apeks fins have a hole in the center that you can you to hang them up, saving on damage, or distortion of the rubber.
I am a firm believer in "Diving." with what you are comfortable with, like most S.C.U.B.A. gear this may include "Trial and Error.
Cheers.

https://www.deepbluediving.org/jet-fin-vs-rocket-fin/

 

[Brett Hatch]

Update: Did a dive yesterday with the following gear config:
* DUI duotherm 300, Seaskin base layer, ski socks, trilam suit w/ compressed neoprene socks
* 3mm booties
* SS backplate, wing, harness
* Single HP100
* Borrowed Hollis F1 fins
* 16 lbs lead on belt
* 4 lbs lead on lower cam band
So compared to last config, I used thinner booties, denser fins, removed 3lbs ankle lead, removed 2lb from the belt, and moved 2lb from belt to lower cam band.

I spent a lot of focus on managing the bubble away from my legs, occasionally flattening them out and going slightly head-up to drain the air back to my upper body. It worked. It was easier to maintain good trim. I actually felt just a little leg-heavy, so next time I will either move some lead up to the top camband, or just dive my Deep6 fins again with same lead config.

At the end of the dive, I had no trouble holding a stop at 10 feet with about 1000 psi in the tank, in both vertical and horizontal trim. Original goal was to breathe the tank down a bit more. But by the 1-hour mark in 54F water my buddy (who dove wet) was cold, so we just thumbed it there. 500 psi of gas only weighs about a pound though, so a stop at 1k seems a reasonable test. I could probably dump a few pounds more of lead, since my suit was not fully squeezed and I was plenty warm at the stop. However I will work on dialing in the trim and fin selection before trying to get the lead down to a minimum. My SAC still isn't what it was wet, but is improving every single dive.

We had a long surface swim on the return. On the surface I kinda missed my light fins, especially when climbing through patches of giant kelp. So the jury is still out on whether I actually want negative fins or to stick to my neutral fins. The negative fins definitely worked in the water, so I might end up shelling out for them. But it seems that there are still gains to be had by simply improving my bubble management skills... maybe that will be enough, maybe not, time will tell.

Thanks everyone for all the pointers, I really appreciate it.

 

[stuartv]

It might be easier to just accept that you're going to get a little air in your feet and stick with the more negative fins. Easier than having to straighten out your legs and go head up periodically just to get the air back out.

I have found that my RMV is pretty consistently about 0.1 cu-ft/min higher in doubles and a drysuit versus single tank and wetsuit. Maybe even a little bit more of a difference, like 0.15 or so. It's never going to be the same between drysuit and wet. Drysuits are inherently more drag in the water, so you'll always burn just a little bit more gas in one. Not to mention if you use your back gas for suit inflation, that will show in your numbers as more gas burned, giving you a higher measured RMV just based on that.

 

[Brett Hatch]

It might be easier to just accept that you're going to get a little air in your feet and stick with the more negative fins. Easier than having to straighten out your legs and go head up periodically just to get the air back out.

That might end up being the case, I'm definitely open to it. I would rather buy dense fins than accept the reality of doing weird stuff like straightening out to move the bubble. Or possibly gaiters as @Marie13 suggested. On the other hand, this thread reminded me that when I have an issue, just how tempting it is to look for gear solutions, when there are still skills solutions on the table.

I have found that my RMV is pretty consistently about 0.1 cu-ft/min higher in doubles and a drysuit versus single tank and wetsuit. [...] Drysuits are inherently more drag in the water, so you'll always burn just a little bit more gas in one. Not to mention if you use your back gas for suit inflation, that will show in your numbers as more gas burned, giving you a higher measured RMV just based on that.

For sure. A few months ago I did a trip to warm water, wore a 3mm suit, and was floored by just how much time I was able to squeeze out of each AL80. And understand that gas consumption is a function of many variables, but the diver's cross section is an important one that just cannot be addressed with skills (once you have good trim, that is). Diving dry you'll have a thicker cross section, not to mention extra lead to drag around.

Yesterday I consumed about 500 psi more than my buddy (vs usually within 100 psi when both diving wet). That's down from a 900 psi difference on dive 1. I expect that trend to continue until our SAC is in the same ballpark once again, +/- a bit. It might even get to where my average SAC is better than it was wet, since the reason I went dry in the first place was that cold was the limiting factor, and of course my SAC would be higher in the second half of any given wet dive in cold water. Maybe. One can hope .