20mm or 16mm

Well I would be using the Rob allen with double 16mm rubbers... come to think of it... I am using Rob Allens with double 16mm rubbers

If your after smaller fish and want quick loading just use the single 16mm band... if your after the bigger fish or longer shots where you require a bit more penetrating power I would put the 2nd 16mm on and away you go... if you have a 6.6mm shaft and a 7mm shaft you have your bases covered! RA also has a 7.5mm shaft these days but I prefer the 7mm shafts so far... I have only used the 7.5mm shafts on 1 trip however... I feel they could have a place if shooting Dogtooth Tuna ect.

Why buy a gun if another gun outperforms it in all area's?

Their again I could be biased I am sponsored currently... if only I could get out spearing a little more I would be a happy camper... it's been 8 weeks and I have either been sick... had boat problems, or had weather problems...

As I say every week... hopefully next week I will get out and spear

Oh... and I am having trouble logging into Deeper blue from home... so sorry I am not on more often!

Take care
Rob

Hello Fuzz, I am also using an excalibur,104 cm wood,wih 6mmor 6,5 mm shaft,and one 18mm sling rubber. One month ago A friend of mine used the same composition only with the double 18mm power,and after 15 seconds of loading the two rubbers the excaliburs mechanism failed and failed. Then he now changed the Excalibur with T-20 handle and no problems..

its better to start spear fish again so i can make every shoot count instead of missing target everytime

Twin 16mm vs single 20mm RA

After being tormented by the possibility that twin 16mm rubbers must be more powerful than a single 20mm ( 2 x 16 mm is more rubber afterall ) i did a test and for once and for all put the matter to rest in my mind.

I used 1.4 RA. Fitted with standard 20mm rubber and loose 7.5mm shaft.
I braced the gun over the wall @ 45 degrees. Pulled the trigger.

Recovered the spear from 98m pegged in the ground.
Replaced the 20mm rubber with twin 16mm rubbers and repeated the test.
Recovered the spear from the same hole in the ground 98m on.

Results. Twin 16mm rubbers thow the 7.5mm spear no harder than a single 20mm.

Why not ?

The rubbers do not accelerate infinitely. They reach terminal velocity before reaching the end of their travel. This happens with both the 20mm and the twin 16's. ( similar acceleration )

Conclusion.

New theory: The heavier the spear the better twin 16's will probably begin to perform, but the 7.5mm is light enough to accelerate to a similar max speed before leaving the muzzle with either combination of rubbers.

7.5mm spear is therefore too light for twin 16mm rubbers.
So,

I prefer 1 x 20mm rubber. same result, harder to load but simpler, quicker to load and less accuracy questions.

Unless i could not pull a 20mm rubber, i would not bother with twin 16's on any euro gun. It's a WOT.

*Multiple rubbers therefore have a place on big wood guns shooting whopping heavy shafts with great inertia so posing a challenge to the rubbers.

Skin.

You have my respect Skindiver just for shooting a spear 98m out in the open after which I imagine your neighbours are spending most of their time indoors.

I accept the results of your experiment with some reservation. You used RA's for it and there is a marked difference between standard euro guns in that you use sling rubbers while euros mostly use circular bands. So you have more rubber in the 16mm RA than the standard 16mm bands of your average euro.

I consider double 16 deliver a "sweeter" shot. This is because the spear is released more progressively than with single 20mm. Im not talking about softy 20mm like some picasso circulars released in the past which were complete flops, but hard 20mm like the G20 that can rival in power the double 16's. Specifically with the G20's I found the shot too explosive. Agreed the power was there but accuracy was greatly affected.

RA has the advantage that it does not use circular bands (screw ons) so the rubbers are comparatively at a wider distance from the muzzle hole from a standard euro gun. Some euro guns have a narrow muzzle and fitting 20mm causes the crimps or the shaft itself to be deflected by the rubbers again affecting the accuracy.

Now purely on the issue of power a standard aluminium euro gun with a single 16mm sling will not shoot as far as a wooden gun with a 16mm sling of the same size. This is because in wood all of the force discharged by the rubber is harnessed while in alluminium it is absorbed to a degree by the movement during the shot of the different components (vibrating barrel, shaking muzzle and handle). So multiple rubbers are not a necessity cause wood naturally delivers a longer shot.

Specifically on wood and double 16mm's Ill have to get back 2 u when my Totem Tahiti 120 arrives.

Happy and Safe Hunting

OMER guns are the best.

I've used numerous Omer guns over the years. They really are the best Euro guns in my opinion. Just to give you an idea of how well designed these guns are and correct some misconception that changing or adding bands and shaft length or thickness may offset the balance or design. I will list below one of the modifications that I've done on my Omer Alluminum 130cm. Almost all of my guns are modified, but this one is pretty interesting mod.

Gun: Omer Alluminum 130cm
Sear/mechanism: Cast alloy
Bands: Dual bands, 21mm screwed to muzzle and 20mm circular
I use steel or dynema wishbones directly tied into the rubber, no articulated wishbone or screw-on wishbones.
Line: one loop of 400lbs black mono, single double-sleeve crimps
Shock cord: Rob Allen with bluewater swivel and quick release
Shaft: 6.3, 170cm. Yes, you read it right ..

The gun is still extremely accurate, very fast and the kickback is not too dangerous. It does make a much louder BANG after I shoot it. I'm quite impressed with how little change Omer guns feel after dramatic modifications like this. Most of my other Omer guns are modified as well.

Disclaimer: If you modify your gun like I did above, it may mis-fire or cause breakage to your gun or even death... I don't think Omer will be covering the gun under warranty if you modify it that much either. Just had to make it clear, this is not a typical mod.

Dive safe,
Rabih

Trial and error

Got a chance to use a friends 90 cm Sporasub Aspic. He made a couple of modifications. First He changed the shaft from the 6mm stock to a 17/64 shaft (6.5mm?). Next he took off the stock 16 mm band to a single 20 mm band. Last and probably to best thing he did was mount a Beauchat reel to the gun. I must say that this gun was pinpoint accurate. I took a couple of reef fish to get the feel of the gun then ran into a couple of Uku (jobfish). Made a drop and in they came. After a short wait. I lined up on the smaller one (the larger one wised up 10 feet ago) and let the shaft fly. I wish I could say I got it but due to the short gun, single wrap of line, and my inexperience with this set up, I simply tapped the Uku's side. It went circling away then came back to stare at the shaft as I pulled it up. The coolest part was how the front half of it's body was still silver while the back half (from the spot I tapped) was barred black and silver. To say I was impressed with the setup is an understatement. The single 20 has enough oomph to stretch the single wrap and then pull a few inches of line out of the reel. I think this helped me decide on a single 20 on a 110 cm with a double wrap of line with the slightly larger shaft and a nice little reel. Thanks for the input gang. Happy hunting.

Brad

it is possible for both 16mm and 20mm to deliver the same power, you just need a shorter 16mm. the problem is that the 16's loose their stretch quicker than the 20mm's, so after time they deliver less power. from a energy delivery point of view, 16's are better than 20's cause they are pulling over a greater distance(cause they are shorter).
for these reasons, i'm going to go for a 18mm when i replace my rubber. may give the best compromise between performance and durability.