Trimming for a leg heavy diver
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Moving weight down can have the opposite effect of what you expect. I didn't believe it would work the first time I tried it. . .
Since you're in Mexico, I'd suggest seeing if you can find someone to work with you from Under the Jungle. They're all pretty damn good at fixing stuff like this, and you'll waste a lot less time figuring things out with a second set of eyes.
mr_v
Contributor
How well does your drysuit fit you?
If the drysuit is reasonably snug around legs, tilt your head/torso down when inflating to move the gas bubble to the feet.
If the drysuit is reasonably snug around legs, tilt your head/torso down when inflating to move the gas bubble to the feet.
Everyone's different, but just in case, I was fighting trim issues in steeltanks/freshwater/drysuit for a while earlier this year too. I tried lighter fins, heavier flashlight, moved the tank up and down the band, moved the wing aft, all the little adjustments helped a little bit.
Once I settled on some consistent undergarments, and did a very precise weight check at 500psi at 10feet, I realized I had been diving significantly overweight. Dropping from 10lbs of lead down to 2lbs of lead essentially fixed all my trim issues to the point of being able to go back to stiff fins and not obsess about weight of minor accessories.
Before you really dial in your trim, are you 100% sure you've dialed in your weight?
halocline
Contributor
I dive in Mexico too, and I’m a bit leg heavy. I went through a few pairs of fins before settling on the eddys. Lots of people dive dry in MX caves, I wouldn’t rule it out. Oh one other thing, you can remove the spring straps from the eddys and replace it with bungee, that might help a little. Try to get your weighting down to the minimum.
This is bad advice.
Im almost every single person I've helped fix there trim in doubles. If they're trimmed out head up they're actually to head heavy and if you move the weight down towards their feet their problem will go away. You have to assess them by having them get completely flat in the water and stop moving and see which way they fall.
AeroSpartacus
Registered
I’m going to try to explain. Credit to gue.com for the image of the diver. Scribbling on it courteousy of yours truly.
• In this diagram, the diver’s Center of Lift (CoL) is positioned above their Center of Gravity (CoG).
• However, if the diver try’s to flatten their trim, the misalignment between CoL and CoG causes a downward head tilt due to gravity pulling on the CoG.
• the forces from CoL and CoG are no longer balanced because the bubble moves forwards the divers feet as they flatten out, I’m a dry suit gas starts to move to the feet exaggerating this effect. Thus resulting in the head dropping due to static imbalance.
• This diagram represents the other position of static stability where the CoG is directly below the CoL.
• In a dry suit this likely ends up with the diver hanging by their boots as the dry suit bubble shifts.
By moving the weights forwards the divers feet. You create flat static stability
And if this exist when the diver is flat the diver will always try to return to thus position versus falling through flat into a head down position.
With a manifold and 2 first stages. The cg is almost always to close their head. Loosening the shoulder straps and tightening the crotch strap. Tail weights and weight belts solve a lot of problems.
If you fail to diagnosis the problem correctly you keep adding weight higher on the diver and you just keep making them more head up it the water
• In this diagram, the diver’s Center of Lift (CoL) is positioned above their Center of Gravity (CoG).
• However, if the diver try’s to flatten their trim, the misalignment between CoL and CoG causes a downward head tilt due to gravity pulling on the CoG.
• the forces from CoL and CoG are no longer balanced because the bubble moves forwards the divers feet as they flatten out, I’m a dry suit gas starts to move to the feet exaggerating this effect. Thus resulting in the head dropping due to static imbalance.
• This diagram represents the other position of static stability where the CoG is directly below the CoL.
• In a dry suit this likely ends up with the diver hanging by their boots as the dry suit bubble shifts.
By moving the weights forwards the divers feet. You create flat static stability
And if this exist when the diver is flat the diver will always try to return to thus position versus falling through flat into a head down position.
With a manifold and 2 first stages. The cg is almost always to close their head. Loosening the shoulder straps and tightening the crotch strap. Tail weights and weight belts solve a lot of problems.
If you fail to diagnosis the problem correctly you keep adding weight higher on the diver and you just keep making them more head up it the water
justinthedeeps
Contributor
Can add more air to the wing or suit, and stop fighting the forward tilt that makes this actually neutral and trim. Does resulting neutral state have too much head down forward tilt? Then maybe yeah trim weights need to shift around?
Definitely keep verifying the real weight check by dumping all wing & suit then ditching some weights at the safety stop at the end of a typical dive, lay on the ground if you can stop finning during the check. (Detach stage tanks during check if you want them out of the equation)
Try ditching heavy fins, can tech dive and back kick etc in the light version of the RK3 fins, even in a drysuit packed for 7-10°C / < 50°F (I do). Some cavers go even smaller and lighter? Sump divers? The fin just needs to be stiff and wide for tech kicks. It can also be short and light if that's what works
Definitely keep verifying the real weight check by dumping all wing & suit then ditching some weights at the safety stop at the end of a typical dive, lay on the ground if you can stop finning during the check. (Detach stage tanks during check if you want them out of the equation)
Try ditching heavy fins, can tech dive and back kick etc in the light version of the RK3 fins, even in a drysuit packed for 7-10°C / < 50°F (I do). Some cavers go even smaller and lighter? Sump divers? The fin just needs to be stiff and wide for tech kicks. It can also be short and light if that's what works
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