what causes yoyo motion while drysuit diving?

[admikar]

OK, so in your belief, there is no extra drag if you try to move with body pointed up 30 degrees?

 

[Celt]

OK, so in your belief, there is no extra drag if you try to move with body pointed up 30 degrees?

in my belief underwater topography, be it reef, wreck or shore is not flat and a diver needs to change and adjust to the conditions they find themselves in.

 

[admikar]

OK, I agree with that, but I still understand your statement that trim is not important?
In that video, level trim is important because bottom is level and diver is moving allong the bottom

 

[Celt]

OK, I agree with that, but I still understand your statement that trim is not important?
In that video, level trim is important because bottom is level and diver is moving allong the bottom

It’s simulated, but in reality a diver is more likely to find a rock or other obstacle in front of him. In real life would he stay horizontal and swim into the rock or change trim and swim over or around it. Flexibility is what a diver needs to practice not an ungainly stiff posture.

 

[Curious_George]

In real life would he stay horizontal and swim into the rock

In our fresh water lakes there are constant obstacles such as rocks, bluffs, trees, fishing line, or you name it. And the obstacles often appear relatively quickly due to not that good of visibility. There is no need to come out of horizontal trim to avoid them. One can easily move over, under or around by breathing a little fuller or shallower so that depth increases or decreases. Use a back kick if you are too close, turn left or turn right before advancing but don’t come out of trim. Pretty easy to spot where someone came out of trim because it raises huge clouds of silt and all visibility is lost.

Did you ever follow another car on a dry dirt road? Not too much fun.

There are situations where coming out of trim is appropriate, I don’t mean to speak in absolutes. Just saying that in most situations where I dive it is best to stir the water behind you, not below you which is what happens when out of trim. Same problem with scissor kickers, but will leave that for another time.

 

[Celt]

In our fresh water lakes there are constant obstacles such as rocks, bluffs, trees, fishing line, or you name it. And the obstacles often appear relatively quickly due to not that good of visibility. There is no need to come out of horizontal trim to avoid them. One can easily move over, under or around by breathing a little fuller or shallower so that depth increases or decreases. Use a back kick if you are too close, turn left or turn right before advancing but don’t come out of trim. Pretty easy to spot where someone came out of trim because it raises huge clouds of silt and all visibility is lost.

Did you ever follow another car on a dry dirt road? Not too much fun.

There are situations where coming out of trim is appropriate, I don’t mean to speak in absolutes. Just saying that in most situations where I dive it is best to stir the water behind you, not below you which is what happens when out of trim. Same problem with scissor kickers, but will leave that for another time.

I’d roll to one side and swim around it. No change to my buoyancy.

 

[admikar]

It’s simulated, but in reality a diver is more likely to find a rock or other obstacle in front of him. In real life would he stay horizontal and swim into the rock or change trim and swim over or around it. Flexibility is what a diver needs to practice not an ungainly stiff posture.

If you go back, you will see that no one said that you MUST remain level at all times. We tried to find a reason why OP is yoyoing when doing frog kick. It's not a point being level, but finning along body axis. In that case, if you want to maintain depth, you have to be level.

 

[Celt]

If you go back, you will see that no one said that you MUST remain level at all times. We tried to find a reason why OP is yoyoing when doing frog kick. It's not a point being level, but finning along body axis. In that case, if you want to maintain depth, you have to be level.

Maybe the so called perfect frog kick don’t suit the OP and he should try something else.

 

[stepfen]

Ok, back to the point.
I did 2 dives with my new suit (d7x nylontech) this morning.
First of all the yoyo motion is almost gone. And I say almost because depending on the conditions it comes back, although to much lesser extend than before.
More experimenting is definitely needed, but I noticed that it is probably happening when my legs are light (more air in the boots). So probably by feeling my legs light I try to compensate by pushing them down during the kick, which in turn is pushing my upper body up and so it goes. All these happen more or less unintentionally of course.
On the other hand, I noticed that when air is more uniformly distributed to my whole body, this yoyo thing stops entirely.
I think, my fins (mares avanti quattro) don't help as they are neutral (actually very slightly positive), so legs tend to float even with small amount of air in the boots. But, before I start making equipment changes I need to experiment more and see how it goes.
Thanks for all the help. Keep it coming if you wish

 

[Lorenzoid]

Good to hear it is working out. You are going to need heavier fins.