Fish Hunter Thanks. You are correct there is some energy loss going around the rollers. And the calculations I am using could in many cases have a 10% difference. However no matter which way you put it, a well set up roller giving the same (actual) penetration as a conventional gun. Will be shorter and have less recoil. Your other issues are all solvable with right equipment and setup. I will be covering all of these.

@@CoatesmansSpearfishingI'll keep my eye out for the next video, you might persuade me to give rollers another go! Do you find bridles get frayed quickly?

Badly designed rollers cause that lifting on the notch which causes the wear on the bridle.

@@CoatesmansSpearfishing I haven't tried the rob Allen roller head and I notice it has a little Ridge on the ramp/stopper. Is this to slow the bridle down and let the spear exit without lifting tail? Very interesting and well designed head which I need to try.

@@fishhunter348 Yes the cut out was made to do exactly that. If you have a good shaft with no sharp edges on the notch your bridle should outlast your rubbers.

Stoked

Thanks 😊 Will definitely have to bring up inverted rollers. Many pro's and con's

What kind of inverted roller do you use? The one with pulleys? If so, the calculations would be not as straight forward as in this videos

Hey Noah, yes there is a certain amount of inertia traveling backwards. But by spreading the energy out over the length of the gun, is by far the greatest reducer of recoil.

@@CoatesmansSpearfishing thx for your great knowledges !

Roland, thanks. I have only seen the Fusion guns online, but have not actually used one. From what I have seen they looked well put together.

for inverted rollers you work out each rubber , from rest to full load x the drive length and add them together. This only gives you an idea of the kg/cm energy as there is loss around pulleys, just like rollers and that needs to be factored in. Will have to do a vid on this

I use a test bench with a digital scale and pulleys. I guess you could somehow attach a scale to the handle and load onto scale hook?? Bit of a dodgy idea tho, safer on the bench.

1100 with 57cm 16mm (386%) x 2 using the same rubber metrics is: 4797 kg/cm This gun will have greater penetration than both the guns discussed in this video. But if you have used a roller for any amount of time, and then try use a std double rubber gun. It won't matter how strong it is, it's just horrible to shoot.

Absolutely, mass is key. So with rollers go thicker and shorter so you can put more power.

@@CoatesmansSpearfishing I would love to see some side by side tests of rollers in a pool like madjq8 does. Maybe we can set up a gofundme to send you to test guns with him when the COVID situation has normalised. kzfaq.info

This is something I have in the pipeline. Even contemplating building a long pool :-D

Hey Blue Dog Gum Have a look at @RobAllenSpearfishing video where they compare the two kzfaq.info/get/bejne/fMyerLRzprPIfo0.html Maybe not the exact same setup but similar

Hey Paul. Yes you add the total area below the line.

@@CoatesmansSpearfishing Hey Chris would you mind explaining why that is the case? What you have explained is the Potential Energy which I am understanding. I'm confused Like Paul on how much of the PE is converted to KE? With a standard set up you release all the PE and convert it to KE. With the roller that is not the case as you only release some of the PE which partly is why the recoil is much less than the standard set up. I'm thinking to understand fully what is happening here is you want to see the rate of acceleration the shaft is under and how even that is over the distance and what the velocity of the shaft is as it leaves the gun. By this I mean the shaft is being accelerated more evenly aka more force over the assigned distance of acceleration in the roller than the standard set up. Simply put, when the shaft leaves a roller muzzle it is still under force from the band and being accelerated. When the shaft leaves the muzzle of a standard set up it is not under force and acceleration. There are cameras that can capture this for you for fun and games :) Hope this helps

You could go with a 70cm 14mm which will have 17kg on the muzzle. It will drive a 7mm shaft real smooth, but this is not a great setup as far as power goes.

Hey Alan, I have pool tested most different variations. The thickness definitely increases the drag. But this is sum what balanced out with the additional weight / inertia of the shaft. Shaft flexibility is also very important, especially with more powerful guns using 16mm etc. This why it is important to use high grade carbon steel shafts. I talk a little about this in the 110 & 120 videos. Penetration is something guys also miss. Like sliptips, they have a lot of drag going through a fish and require massive shafts with big guns to penetrate through the fish.

@@CoatesmansSpearfishing Thanks very much for this reply. It gives great insight into what works and what doesn’t, from your many years of experience. It brings back great memories of swimming in Durban, Natal way back my younger days! Has Rob Allen got an inverted roller conversion in the works to reduce drag of the bands squeezing around the rollers (through the holes) by using dyneema vs bands with eg 3 x 14mm short inverted bands underneath? This would improve the launch force, make more efficient use of the potential energy and make it much easier to load. 3 x 20kg vs 1x 60kg for 16mm bands?

Not won- should say I own

2 x 14mm (3183 kg/cm) 73cm the same length provide more power with less recoil as the 1 x 20 x 73cm (3132 kg/cm) And is easier to load. This was my go to before I found rollerguns. Most tests I have used this gun as a yardstick to compare against.

Jedidiah, you are right a 140 with 2 x 16mm bands would have way more power than a 110 single roller with a 14mm band. I was not comparing power or the performance of the two guns. But rather illustrating the length of drive a roller has compared to a conventional gun. A 120 single roller with 16mm bands and 7.5mm shaft would be a good gun to compare to the 140 conventional band gun.

@@CoatesmansSpearfishing ahhh I see thanks for the response !