I have a 48 Biller. I've never had any problem with power, plus I live in the North East so I can't see anything more than 10 or so feet away so hitting it isn't really a concern for me. I use two 9/16th inch bands with the gun, and I have been wondering if using a single 5/8th inch band on the last notch of the spear would provide as much power as the two 9/16th bands? Also would it change the accuracy of the gun? And finally, would using a 5/8th in band on the last notch and a 9/16th in band on the "middle" notch ruin the flight of the spear?
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Mixing diameter bands?
- Thread starteralexrom1207
- Start date
Thread Status: Hello
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How do you like the Biller?
I use an RA railgun & the idea of using 2 different bands has occurred to me too. My thinking was that you could use, say, 18/20mm alone for normal use, a single 16mm band for closer work/poor vis. and both for bigger fish/longer shots. However, a single band is simple & quick to load. Also lighter, less drag, cheaper to maintain,....
I can't comment on your exact configuration but doing a quick calculation (2.54cm in an inch) sounds like you are using 2x 14mm band and thinking of a single 16mm band. I suspect the 16mm band will be slightly less powerful - but it would be quicker to load. The reason I think that is that for RA railguns the power order seems to be 16mm < 20mm < 2x16mm.
If your gun has a rail supporting the entire length of the spear upto the muzzle, then I doubt if it would adversely effect accuracy - provided you have a thick enough spear (6.5mm should be fine for a 16mm or 20mm single band) and a trigger mech. rated to handle any increased power. I was happy with a single 16mm, 10 feet is no problem. Are you shooting big fish (stripers perhaps?). Why don't you try a 16mm/ 5/8" band & if it is not powerful enough, either add a second or one of the 14mm. The double 14mm sounds like an interesting combination -- I've never seen that offered in the UK. I would think it would be quite powerful yet easy (but slower) to load.
I use an RA railgun & the idea of using 2 different bands has occurred to me too. My thinking was that you could use, say, 18/20mm alone for normal use, a single 16mm band for closer work/poor vis. and both for bigger fish/longer shots. However, a single band is simple & quick to load. Also lighter, less drag, cheaper to maintain,....
I can't comment on your exact configuration but doing a quick calculation (2.54cm in an inch) sounds like you are using 2x 14mm band and thinking of a single 16mm band. I suspect the 16mm band will be slightly less powerful - but it would be quicker to load. The reason I think that is that for RA railguns the power order seems to be 16mm < 20mm < 2x16mm.
If your gun has a rail supporting the entire length of the spear upto the muzzle, then I doubt if it would adversely effect accuracy - provided you have a thick enough spear (6.5mm should be fine for a 16mm or 20mm single band) and a trigger mech. rated to handle any increased power. I was happy with a single 16mm, 10 feet is no problem. Are you shooting big fish (stripers perhaps?). Why don't you try a 16mm/ 5/8" band & if it is not powerful enough, either add a second or one of the 14mm. The double 14mm sounds like an interesting combination -- I've never seen that offered in the UK. I would think it would be quite powerful yet easy (but slower) to load.
I have mixed bands for years and didn't notice any problems. Be very careful about shooting a gun with an unloaded band attached. There was an accident where the shaft shot forward against the unloaded band and then came backward and broke a diver's mask. He was lucky there was no real damage done, there have been a few eyes lost in shooting accidents.
To calculate the relative strength of bands, use the square of the diameter. It's accurate enough for comparison.
eg 9/16 divide 1/2 squared = 1.27. 3 9/16 have 95% of the power of 4 1/2 inch bands. Rubber varies a lot more than that and they label 12 or 13 mm as 1/2. Let's not get into the 2 mm hole in the centre.
To calculate the relative strength of bands, use the square of the diameter. It's accurate enough for comparison.
eg 9/16 divide 1/2 squared = 1.27. 3 9/16 have 95% of the power of 4 1/2 inch bands. Rubber varies a lot more than that and they label 12 or 13 mm as 1/2. Let's not get into the 2 mm hole in the centre.
Hi Bill, I wonder if that formula should be (diameter x 1/2) squared, rather than (diameter / 1/2) squared?
The latter is the same as (2 * diameter) squared. The former is the same as (radius) squared -- i.e. the power is proportional to the cross-sectional area of the rubber; I've never heard this before but sounds viable.
e.g.
16mm: r^2=256
20mm: =400
2x16: =512
e.g.
9/16: = 0.079
5/8: = 0.098
2x9/16 = 0.158 <-- Suggests you might be better off staying with this set up
It looks like it might be a useful rule of thumb. Although, I doubt if the difference between 16 & 20mm range is anywhere near that large in practice, not least because 20mm rubbers will be cut longer (to allow loading!) & therefore stretched less. I found 1x16mm more than enough for all the fish I have encounter -- fish in the UK are mainly less than 10lb & usually less than 5lb - bar two instances. Both gill area shots on large fish, & one was with a 20mm band: spear just bounced off. Apparently just something that happens from time to time (that area is very boney).
[BTW I like imperial measurements for some things but -- metric makes a life simpler for rubbers, wrenches, nuts & bolts.
]
The latter is the same as (2 * diameter) squared. The former is the same as (radius) squared -- i.e. the power is proportional to the cross-sectional area of the rubber; I've never heard this before but sounds viable.
e.g.
16mm: r^2=256
20mm: =400
2x16: =512
e.g.
9/16: = 0.079
5/8: = 0.098
2x9/16 = 0.158 <-- Suggests you might be better off staying with this set up
It looks like it might be a useful rule of thumb. Although, I doubt if the difference between 16 & 20mm range is anywhere near that large in practice, not least because 20mm rubbers will be cut longer (to allow loading!) & therefore stretched less. I found 1x16mm more than enough for all the fish I have encounter -- fish in the UK are mainly less than 10lb & usually less than 5lb - bar two instances. Both gill area shots on large fish, & one was with a 20mm band: spear just bounced off. Apparently just something that happens from time to time (that area is very boney).
[BTW I like imperial measurements for some things but -- metric makes a life simpler for rubbers, wrenches, nuts & bolts.
]
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It's a very good rule of thumb, pretty accurate as a comparison against rubber of the same quality. I would prefer to use PI.D^2 (rubber) - PI.D^2 (hole) to give a better indication of the differences. The relationship to the band length is inverse obviously but it's not linear, Hook's law does not hold with rubber. So the amount of power gained by increasing the stretch ratio diminishes by some factor of the rubber. So within the normally accepted stretch ratio's a long 20mm band will give more punch than a short 16mm.
mixing bands may be a good idea if youre hunting conditions vary...for example youre diving for reef fish but occasionaly a big pelagic could be cruising by and you dont want to carry two guns, so you use one of the 2 bands on the reef fish and load the other band if you see an opportunity for something bigger...i never tried it though so not sure how practical that would be....
"Hi Bill, I wonder if that formula should be (diameter x 1/2) squared, rather than (diameter / 1/2) squared?"
I'll have to be more careful. I was comparing bands. The equation was specific. Formula is. (D1/D2)^2. Hole in the centre makes the difference a little more.
I'll have to be more careful. I was comparing bands. The equation was specific. Formula is. (D1/D2)^2. Hole in the centre makes the difference a little more.
Thanks a lot guys. I will definitely try the two bands. I shoot in the North East, in Rhode Island, so I may be shooting blackfish or trigger fish (yes we have them up here, they follow the gulf stream up...i was shocked the first time I saw one) but then I may run into a striper so having the power there when I need it is nice. However, I am usually reluctant to shoot at blackfish too close to the rocks because I don't want to break my spear, or break my tip.
Mr. X, I love the biller. I bought a sporasub 55 first, with one band. It was WAY TOO WEAK, and I wasn't really shooting anything big. So I bought the biller used, with two new bands for $100. Since then I've been landing fish instead of wounding them.
Mr. X, I love the biller. I bought a sporasub 55 first, with one band. It was WAY TOO WEAK, and I wasn't really shooting anything big. So I bought the biller used, with two new bands for $100. Since then I've been landing fish instead of wounding them.
Alex, I saw a great website on spearing around Cape Cod area a year or so ago. Unfortunately I no longer have the URL but it had some good info. on striped bass & gear. From what I recall, the size of guns the author used is similar to those we use in the UK (similar visibility). The striped bass are much bigger than anything we get though.
I agree, I think your best bet is to set up a stationary target, measure off some distance and shoot away!
Yeah Mr. X, The strippers here get huge; 2 years ago someone caught a 60lb (27.27 kg) bass with a rod and reel. I've never seen any that big, but a lot of the more experienced spearos here shoot them upwards of 45-50 lbs (20.45 - 22.72 kg) within 70 meters of shore. I usually don't use a float and I don't have a reel on my gun so a fish like that would either mean it would be my last spearfishing trip or I'd lose my gun. Although this summer I'm looking forward to gearing up properly and going for one. I'll post pictures, if I'm luck enough to hit one.
In the UK what is the average size of the different species of fish you guys shoot?
Just a note to everyone: I just joined the forum and all the advice and expertise is so nice. Since I can't go into the water from October through mid June, I'm usually on Youtube watching spearfishing videos, and annoying my friends because I'm the only one who really understands how much fun it is. So this forum has been a great outlet. Although it may hurt my Criminal Law grade in lawschool, but I think it's a fair payoff. Thanks again everyone.
In the UK what is the average size of the different species of fish you guys shoot?
Just a note to everyone: I just joined the forum and all the advice and expertise is so nice. Since I can't go into the water from October through mid June, I'm usually on Youtube watching spearfishing videos, and annoying my friends because I'm the only one who really understands how much fun it is. So this forum has been a great outlet. Although it may hurt my Criminal Law grade in lawschool, but I think it's a fair payoff. Thanks again everyone.