• Welcome to the DeeperBlue.com Forums, the largest online community dedicated to Freediving, Scuba Diving and Spearfishing. To gain full access to the DeeperBlue.com Forums you must register for a free account. As a registered member you will be able to:

    • Join over 44,280+ fellow diving enthusiasts from around the world on this forum
    • Participate in and browse from over 516,210+ posts.
    • Communicate privately with other divers from around the world.
    • Post your own photos or view from 7,441+ user submitted images.
    • All this and much more...

    You can gain access to all this absolutely free when you register for an account, so sign up today!

Mixing different band thickness on the same gun.

Thread Status: Hello , There was no answer in this thread for more than 60 days.
It can take a long time to get an up-to-date response or contact with relevant users.

Kodama

Well-Known Member
Jun 20, 2016
436
206
83
On several occasions, especially on the Italian forums i have read about spearos combining different band thickness on the same gun.
Especially with carbon guns like those of C4 this seems fashionable.

Does anyone have experience with this? I am interested in the philosophy behind it and even more so in any number if they are available.

For example i see 16 and 14mm bands combined on a 94cm gun.

Your thoughts?
 
Last edited:
Reactions: mariusshobo
Kodama said:
fashionable
Click to expand...
This.

Every manufacturer boasts about the 'research' going into their guns/fins/suits/etc, but in reality there's not really much research being done except for the few cracks on the different forums who like tinker with their stuff.

Perhaps by 'research' they mean using Google.
 
Reactions: mariusshobo and foxfish
I see no problem doing that.
But keep the thicker band closer to the shaft - if you are using dyneema wishbones; if using steel ones with different sizes that arranges bands parallel, does not matter).

As for theory (mine, at least, form the depths of my economist brain )), there is an example:
- a pipe speargun with a single hole to insert the two bands, so the bands rubs against each other when loaded;
- dyneema wishbones;
- two bands from the same range / manufacturer : 16mm and 14mm (the 16mm one is obviously thicker and stronger);
- same stretch factor for both bands;
- loading the bands on the same shark fin;

If the 14mm is closer to the shaft, the 16mm will push against the 14mm and tend to raise it, inducing an upward force that can ruin accuracy.
When the gun is fired; the 16mil will push against the 14mil band and tend to crush it against the shaft. Not good.

Any other thoughts?
 
Reactions: Kodama
But why would you mix them? The most valid reason I see is if you need to rig a gun double banded, but only have a little of both diameters left, and the stores are closed because of corona.

Of course you could mix them to go inbetween double-14 and double-16, but keep-it-simple gets you more fish.
 

That is an interesting line of thought.
Anyway it has to do with performance in That some users seem to prefer such a setup.

 
Planet Dive Store has the new 105 - 110 cm C4 Carbon "Gladius" models with 6.75 mm tabbed shafts and a 16 mm and a 14 mm band. The 85 - 95 models have a 6.5 mm tabbed shaft and one 16 mm band.
 
Reactions: Kodama
popgun pete said:
Planet Dive Store has the new 105 - 110 cm C4 Carbon "Gladius" models with 6.75 mm tabbed shafts and a 16 mm and a 14 mm band. The 85 - 95 models have a 6.5 mm tabbed shaft and one 16 mm band.
Click to expand...

I first noticed this setup on the spec sheets and afterwards learned more spearos do so on older models too.

My main concern would be a potential difference in retracting ratio causing the setup to be inefficient where one band is doing all the work and the other Almost nothing.
There must be a rational (and hopefully some sound physics) behind it that i would love to understand.
And only having access to a pool for test shooting once in a while i don’t feel like doing time consuming experiments.
 
Reactions: mariusshobo
1 band 16mil + 1 band 14mil will pull harder then a single 16mil band. So the theory that the 16mil band will do all the work do not stand IMO.
 
The effect of bands is cumulative, if you want to test this then try pulling both bands back at once. The use of different band diameters is to provide more energy without going as far as 2 times the larger size band.
 
Reactions: mariusshobo
popgun pete said:
The effect of bands is cumulative, if you want to test this then try pulling both bands back at once. The use of different band diameters is to provide more energy without going as far as 2 times the larger size band.
Click to expand...

So then one band just provides less force. If it is that simple why not adjust the bandstretch instead?
Use the same band thickness set one on 320% and the other on 280% and call it a day. There must be more to it i would think.
 
Reactions: foxfish
Kodama said:
So then one band just provides less force. If it is that simple why not adjust the bandstretch instead?
Use the same band thickness set one on 320% and the other on 280% and call it a day. There must be more to it i would think.
Click to expand...
No, there isn't.
 
Kodama said:
set one on 320% and the other on 280% and call it a day.
Click to expand...
There is this factor - 3.4 I think, no 100% sure - and stretching bands after that will not translate in increased shaft velocity anymore.
So, if you need faster shaft, stretch the bands more. But once both bands hit the stretch factor, it is senseless to do it over that.
You need more power, that means another band or a thicker band.
 
Check at 7:25.
“C4 decided to do this must have a good reason for it”......

Do they?


 

You could stretch bands further. However it is rather a question off wether you can somehow comfortably load them.
At a certain point you need to increase the diameter of the shaft to handle the increased force applied.
 

I've quote myself and challenge my theory.
Here is a screen shot with ARCUS G speargun, where the bands are stashed in top of one another. The fisherman is George Vasiliou (World Champion 2016).
And the way he twist his wrist during shot is in total contradiction with what I know and do, but he is doing just fine.


full vid here
 
Reactions: DivingNomad
Good shooting at around 40 m down, all fish hit in about the same place, just back of the head as they turn. Curiosity is their undoing. Knowing exactly how your shaft flies lets you pull off the same shot time after time.
 
You must log in or register to reply here.
Menu
Log in
Register
Cookies are required to use this site. You must accept them to continue using the site. Learn more…