why 20mm, not shorter 16mm? | DeeperBlue.com Forums
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why 20mm, not shorter 16mm?

Thread Status: Hello , There was no answer in this thread for more than 60 days.
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Griff

Certified SCUBA Rider
May 7, 2002
557
60
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hi spearo's
is there any reason that you go for a 20mm rather than just shortening a 16mm. i would understand if to get the same force exerted by a 20 with a 16 meant that it is stretched past its elastic properties, but does it?

cheers
mark
 

ivan

looking for deeper water
Jan 26, 2002
1,503
48
0
hi

Griff 20mm rubbers seem to last a lot longer for me then 16mm. On my 150 I have 16mm bands and they are wearing out fairly quickly cos they are over stretched. With 20mm you would have to be like Arnie to over stretch them.

cheers
 

loopy

Deeper Blue Hypoxyphiliac
Oct 24, 2002
719
51
0
39
Yup

If you shorten the 16mm too much, it loses it's elastic properties. Also having 'standard' leangths means that companies can mass produce rubber of the same size.
 

Griff

Certified SCUBA Rider
May 7, 2002
557
60
0
40
i also feel that it has to do with durability. a 16 lasts for 1 season but a 20 much longer. i'm toosing up which to use.
i read on the freedive list's description of rubber. they guy said that good rubber should have 800-900% elongation, so we really do underuse the potential. there is a test that these guys did on rubbers and they encountered soak-down, where the rubbers loose a bit of elasticity first off, but this flattens out. so maybe once could prestretch your rubber. website is http://www.rocknfish.com/Rubber_Test.html
here are my 20/16 pro's cons. some may be negligible, but i'll list them anyway

16mm cheaper fisrt off (thinner and shorter), lighter? easier tracking? less momentum/recoil? easier to load, longer lenght of thrust. less pain :waterwork

20mm more durbable because its way understressed

this is assuming that you stretch them to the same pulling force.
 

ivan

looking for deeper water
Jan 26, 2002
1,503
48
0
hi

Griffster remember that when you have a 20mm you feel like more of a man when you haul it back, and the fish sure respect that rubber when they watch how fast it slings that shaft into their mates.

BTW Do you know where our other Sa friend is, it sucks without him I want to ask him some stuff.

cheers
 

Griff

Certified SCUBA Rider
May 7, 2002
557
60
0
40
no idea about abri, but youre right, his input is missed.

btw, andrew, with regards to an earlier question of yours, i have done a 40m dive once, actually 42m. it was 1m down, 20m to the other side of the pool, 20m back and 1m up. didnt spear anything though:hmm
 

ivan

looking for deeper water
Jan 26, 2002
1,503
48
0
hi

Nice one Griff, I like those sort of dives as well no lung squeeze :D Speaking of a dynamic attempt the water is freezing at the moment but I may pluck up the courage to get in the pool this arvo and try some dynamic without fins for the first time in about a year :hmm

On abris last post ( Yeah I check his posts regularly) he says that his internet access was being restricted but arrangements were being made but that was almost a month ago :waterwork Where are you mate. My family gets sick of me telling them about this guy from Sa who spears Marlin and hunts the 40m range :duh

cheers
 
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