Monofin Bend

[ADR]

Originally Posted by BennyB

Who wants to put a wager on that Andy is in the shed tinkering as we speak?

Just came in from the shed from working on the underwater scooter project with a kick arse trolling motor.


....but already on the monofin tinkering as well Benny and ordered 2 fins and a blade only from Bogdan last week and plan to cut the top out of one and build it up internally with a secret Dave Goldie mix that is both non compressive but neutrally bouyant.....as I hate how rubber sinks an neoprene compresses

[Mullins]

Originally Posted by trux

That sounds like the fin is not reinforced under the footpockets and you bend the blade with your feet. Or the reinforcement (often a metalic plate) is bent or broken, or simply too weak. However, when gliding, the V-bend is not bad at all - in fact it stabilizes you. It is only bad when the fin is in action.

Yes, I think there is something unusual going on. As you say, it's not a problem during the glide itself, but it would make the blade more predisposed to folding if it's bent even before the kick starts.

[Walrus]

Hi Dave,
I was thinking about the v-bend when you are gliding and I can think of one cause. I think even when the reinforcement between the footpockets are working properly these newer style fins are much more prone to movement between the footpockets at many angles, including "roll" for want of a better word.

For example you put your feet in the footpocket, then bends your knees out apart from each other, compared to bringing them in touching. That will be putting a stress on the fin and forming a v shape. Would imagine this action would be worst when the blade is flat, ie gliding. Maybe try next time at the pool get someone to watch you glide with your legs straight and roll your knees inwards, then roll them outwards and see if there is a difference. If it does make any difference and provided there was room in the footpocket you could put material in to change the angle, perhaps build up the arch ?

Perhaps the footpockets are at the wrong "roll" angle for your feet/legs hips. They could just be at the wrong angle full stop, not just for you. I think when I glide I do tense certain muscles, arch my back, no idea what I'm doing with my legs. Everyone's feet, legs hips are different, theoretically should be the same but maybe this slight difference combined with swimming/gliding style can put a bit of an V angle in the blade. Just the shape of your foot, if you have a high or low arch for example would effect the angle your feet sit in the footpocket. More and more I'm thinking they need to really beef up the fibreglass at the base of the blade, and come up with a very secure way to attach the footpockets.


Cheers,
Wal

[salibandy]

About the footpocket bend issue. I wanted to ask, is it possible that it was meant to be? I was told that hyperfins (i shall use giperfins so as not to confuse between brand names) were designed around their footpockets, not the blade. The footpockets are 'springs' that absorbed energy and then gave it out. This is a known fact about gipers. Or maybe the question in this thread that I'm missing, is whether the footpockets should bend that much.

[trux]

Not speaking about the v-bend, the bending in foot-pockets is not a problem as long as the blade maintains the optimal angle of attack, which is definitely not the case in the picture of Ben's fin, where the blade is almost at 90 degrees to the axis of motion. In contrary, the photos of your fin look just right.

Both, bending in one point (at the foot-pockets), or continuous sinusoid bending of the entire blade, have their advantages, and I think it is difficult to tell which principle is better without making very complicated measurements.

[stergios]

can we use the monofins for spearfishing applications?

[salibandy]

If you really really want to. Otherwise a pair of stereos are more maneuverable.

[Mullins]

I use a mono for spearfishing sometimes. Only when it's deep though.