16mm RUBBERS..VS..20mm

[Hamrrhed]

Some comments and testing of bands

Scroll to the lower half of the page for the info regarding the 16mm~20mm debate

 

[sickbugs]

i bought some dessault 16mm bands, and i must say im completely impressed with them, seem to have about as much power as my beuchat 20mm bands, or maybe more? but the spear leaves the gun different, i dont know if its accelerated different or what, but its more accurate, and packing plenty of power (of 4 fish ive hit with it, 2 shots put the spear straight through, from close range, and i felt a pretty solid tug when the spear reached the full length of the shooting cord, single wrap)

 

[Old Man Dave]

Thanks for the link Hamrrhed ( http://www.freediver.net/freedivelist/faqstuff/faq_bandtesting.html ).

Very interesting, however, all the tests were in air and while it makes for good reading I'm not sure the test results are "scientifically" valid. Seems to me that water resistance would slow the spear considerably and the increased static stored energy of the larger bands might create more thrust to accelerate the spear against the added resistance of the water.

This guy working on roller guns built a device to measure speed of spears in water. Perhaps if mark reads this he could get in touch and repeat the experiment using a similar device. http://www.roamingsolutions.net/niko/index.htm

Dave

 

[spaghetti]

i bought some dessault 16mm bands, and i must say im completely impressed with them, seem to have about as much power as my beuchat 20mm bands, or maybe more? but the spear leaves the gun different, i dont know if its accelerated different or what, but its more accurate, and packing plenty of power (of 4 fish ive hit with it, 2 shots put the spear straight through, from close range, and i felt a pretty solid tug when the spear reached the full length of the shooting cord, single wrap)

As I posted above, Dessault rubbers are the best for me too. Apart from any techical testing, that's my clear impression as a user along many years. Also had a positive inmpression by the Omer power 18 and Top Energy, Cressi S45 and Demka 17,5mm (Demka is a greek high quality brand, surprised it's never mentioned here on DB).

 

[sickbugs]

never heard of the demka, but when i switch to a hammerhead muzzle, i'll be using omer bands

that is, unless dessault makes loop bands? i havnt seen any, but it would be nice

 

[greendiver]

Killo Mike, the secret generally lies at the strech. If you can strech 16mm and 20mm rubber by same amount obviously 20mm will unleash more power. (of course we consider same latex) So if i were you, i would have changed the rubber lenght.

Que pasa picha!!, yep I understand that, but..if you read HAMRREADS link, ( 2 posts below yours), you will see what I mean.
Does this mean that, in this case smaller rubbers are better?

 

[Spaniard]

never heard of the demka, but when i switch to a hammerhead muzzle, i'll be using omer bands

that is, unless dessault makes loop bands? i havnt seen any, but it would be nice

Dessault do indeed make loop-bands;

http://www.dessault.com/site/arbalu.htm

Good luck

 

[Hamrrhed]

Greendiver,

If memory serves me right it took less effort to load the smaller band and in the end there was a negligible power difference.

Then again it seems as though we are just splitting hairs, Id much rather be in the water........drat the wind!

Anthony

 

[sickbugs]

mmmn.. double dessault loop bands... might be just what the african pompano ordered

 

[Mr. X]

...I wonder if the gun had a rail it would make much difference. ...

Dave, I reckon the rail does make a difference. I fitted a 20mm band to my railgun this season. It has a 6.6mm spear (I measured it with a vernier caliper to be sure). It shoots fine. I've had my best week & my best day spearing with this set up. It is hard to judge power & accuracy - I can say that it did not have any noticeable detramental affect though. However, as you may have read, I had some teething problems (broken dyneema wishbones & loading bruises) - but I think those are resolved now (by using a thick supplementary loading pad & taking care that the rubbers are even with the wishbone toggles pushed deeply into the rubber while the cinch knots are tied very tight).

I believe the RA spears are made differently to some other brands (e.g. galvanised spring steel rather than stainless), which might also be a factor.

Dessault 16mm bulk rubber sounds very interesting although RA 16mm rubber always struck me as plenty powerful enough for any UK fish. The extra power of the 20mm seems to have been as much of a liability as a benefit to me!rofl I've twice had to dive to recover my spear after it went right through a fish. Once it wedged very tightly between 2 rocks 6 or 7m down & another time it got somehow entangled in rocks on the bottom. I thought I had somehow lost the fish (hard to believe as it was a good solid hit in a large fish) but after freeing the spear & line from the rocks I found the fish a couple of metres further up the spear line! (My speargun is attached to my float-line, so I just leave float if I have to dive for the spear)