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Old 11-13-2019, 04:54 PM   #1
AKSandman
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Question Cracked Fins

I purchased a pair of plastic freediving fins earlier this year. After about a half dozen dives, the blades on both fins developed cracks about 2” from the end of the rails. (2” toward the foot from the tip of the rail)

Obviously this isn’t “normal”, but I don’t know if I caused this, or if the blades are defective.

I never stood up on them, jumped into the water feetfirst or bent them in transit. They do have some scuffing on the ends of the blades from diving on the reef, but no substantial gouging.

I did notice that when they looked like they bent a LOT when I was kicking. Perhaps they are too soft? Even if they were soft, can fins break from kicking too hard?


Thanks in Advance!


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Old 11-14-2019, 04:53 AM   #2
Mikel_24
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Re: Cracked Fins

I guess that the exact location of the crack is showing exactly what the problem is... Those blades and the rails are not a good match. Rails seem to be too rigid and instead of allowing the blade to curve gently from right under your toes all the way to the tip, they force a sharp bend on the blade at the very tip (or almost) of the rails. Stress concentration.

Did you buy the fins new? Any chance those fins had been sitting in the store for a long time and the properties of the rubber/plastic have degraded (for the worse)?

Anyhow, I would contact the store and letting them know about it. Maybe they can replace it. If not, switch brands/makers.

My first long fins were Sporasub's green round shaped tip ribbed blade fins with adjustable pockets. When I finally switched to something else, they had developed white spots at the very end of the rails, where the rails ended. Same problem, stiff rails, soft blades.

Next fins where Beuchat Mundial fins (high tech plastic, almost sounded like metal if you smack them with a coin or something). Comfy footpockets but ended splitting them at the top and while I was using them with duct tape all over(waiting for replacements) the blades cracked. Pretty much in the same place. One cracked while I was about 10m deep... quite interesting experience to surface with only one usable fin!

Then I switched to Cressi Sub Gara 2000 HF... and the only reason I changed them was because I wanted to try carbon fins. Those Garas are damn indestructible, and the pockets (bimaterial) are very comfortable. But you need to have legs to move them!

Just my own three examples to show that having pockets/rails matching the properties of the blades is just as important as having the very best blade material. Sporasub and Beuchat failed, Cressi Sub was king of the hill (I still have those fins in two different sizes that I lend to friends who come diving with me once in a while). Fantastic fins.

Again, contact the seller!

Mikel
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Old 11-14-2019, 01:13 PM   #3
DNAPL
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Re: Cracked Fins

Quote:
Originally Posted by AKSandman View Post
I purchased a pair of plastic freediving fins earlier this year. After about a half dozen dives, the blades on both fins developed cracks about 2” from the end of the rails. (2” toward the foot from the tip of the rail)

Obviously this isn’t “normal”, but I don’t know if I caused this, or if the blades are defective.
Brand of fin? I had a similar problem with Mares Razor
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Old 11-20-2019, 03:44 PM   #4
AKSandman
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Thumbs up Re: Cracked Fins

Mikel, thanks for the detailed examples of rail/blade pairing importance. The brand is JBL. I got ahold of the manufacture and explained my issues with the fins. I was told that there was some issues with the injection molding on a run of blades. They took care of me and sent out two new sets of blades on the house! Two thumbs up for customer service at JBL!
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