Відео

The small rubbers at the top are necessary to achieve the preload necessary on the lower rubbers.. otherwise there is simply no geometric option to achieve that: this is why the top rubbers are filled with dyneema to transfer the initial energy from the lower rubbers to the spear... the top rubbers come into action later. They are also very useful for easy loading. I think the setup you mention is called "invert" in Italy and as far as I heard (I never tried it myself) from friends, it is not as brilliant.

Honestly I have no idea... A pragmatic approach to the matter is probably the easiest option... Basically just give it a try

Hi. I put the glue on the mask mount to lock the screw in place... Once I have found the right position, then I can go rough on it without being worried about it changing position if I hit something or into the gear bucket in the car. EIS...it is under development... I don't know more.

The loading force when the rubbers are fully stretched is the same... but a standard speargun starts from 0% until ~320% , while a Fusion starts at 200% until ~320%. In short, it is harder from the beginning... but besides that, it is the same strength that you need to pull it back til the pin.

@@ragnaroksub1442 Thank you for your answer sir. Much appreciated. Is there a chart somewhere where you can get the exact length of each rubber to cut according to the length of the speargun ?

Not for sale anymore... Sorry

Calibration depends on the geometry of the speargun... There are too many variables to draw an algorithm to simulate the finished product... It's easier to do it time by time. The preload can be increased by adding a dyneema line inside a pair of top rubbers to limit the stretch... So you decide the min-max load below and adjust on the top.

Yes, an 8mm shaft is heavy... That is why the barrel is a carbon tube 26/30 and sometimes 30/32 with the two ends double-walled with a 26/30 reduction. Basically you increase the volume of the barrel to match the spear weight. Personally, in a demultiplexed system, I prefer to use a spear 7mm powered to the upper limit to maximize the speed... 8mm are slower and I don't need that added range here. For me, the ultimate speargun for the Scandinavian waters is a FusionK1 90cm with 6.5mm spear, 2 passes of monoline Asso Supersoft 0.9 followed by a good quality reel.... In other waters you'll need to find your balanced range/speed/power

@@ragnaroksub1442 The geometry of the speargun is simple. It’s a 90cm carbon Fusion inverted roller gun. The preload is the amount of pretension in the rubber bands (each) with the wishbone at the end of its travel. The notch load is the load at the shark fin when fully tensioned, per band. What is complicated about that? Energy imparted to spear launch is the average of these values x travel from notch at trigger to where it stops at the roller head

It is not complicated at all... and the empirical method is straightforward. And by the way, if you like to be accurate, the energy is not calculated by an "average" but by the equation K=1/2*m*v^2. You can see the graphical demonstration of two systems with the draft of the integral of the function (pretty much linear) of load and distance between the two extreme wishbone positions.... But it is pretty much a scholarly discussion without real application. Ha... I forgot... The "Invert roller" is a completely different system... composed by two pair of sheaves: a pair of wire sheaves on the muzzle and a pair of round rope sheaves on the proximity of the handle where the rubbers go around... I guess the confusion in terminology comes because of the rushed translation of the spearfishing tradition in English when the social media brought the many different rubber-systems to the other side of the ocean a few years ago.... rollers, invert, invert roller, Demo(s), Fusion(s), Vela, Volcan, Mach... and a few more like G-roll etcetera nowadays disappeared.... No wonder that the internet is full of misunderstanding.

Thanks very much for your replies. Yes, I agree that the energy (of the spear leaving the muzzle) is 1/2 mv^2 I.e. kinetic energy equation but you have to know the terminal velocity to calculate that as well as mass of the spear. I am intrigued by your reference to the spear accelerating faster than the wishbone due impulse loading rather than a simple linear imparting of rubber bungee energy from notch load to the end of the travel at the muzzle. This invalidates the assumption of the average energy summation and is more driven by the impulse at notch load. This is good news because it removes the requirement for preload at the muzzle. Could you please comment on this?

For the kind of video I take, it is perfect: a fish at 3-4 meter distance looks like its real size... and not like a sardine as it does with all other action cams also in narrow mode. For more cinematic scenes instead, an additional wide angle lens is giving excellent results, but it is an expensive accessory and I suggest it only if you are into videos hobby. The visibility here has been constantly under- standard, so I haven't been able to produce any decent footage... But next week I'll be in the Med and I hope to find the time for a dive and to take some footage there with the various lenses.

​@@ragnaroksub1442 Thanks for the reply! I am still waiting for the camera to get delivered and will test it first, but will probably end up getting the wide angle lens too.

how is this better than a normal roller or inverted roller

Definitely yes. The camera is a solid hardware platform made to last technological-ageing much longer than ordinary multi-purpose action cams. Because of the Covid19 delays in production, the latest firmware version (February 2021) is still lacking some features like EIS and few small things, but Paralenz is working hard to catch up... and what they have in the pipeline is absolutely amazing. In my case, diving in the northern seas of Europe, it is the only camera that can actually show what I'm filming in all visibility conditions: its low-light performance is amazing.

@@ragnaroksub1442 sry what exactly do they have in pipeline coming up to make it better?

Hi. Yes... with a full moon, some species will be hunting at night and will be resting in daytime... the opposite goes with new moon. Depends on the species and locations of course...

The fusion split the rubbers in two segments (upper and lower), the rubber start from the handle, goes around the head and comes back on the spear. Inverted roller (the classic at least) start from the front, goes around sheaves at the handle, goes back to the head and return with a line. Depending on prestretch, the start point can be moved with another pair of sheaves in the head. Both systems are wildly abused by manufacturers that have few but confused ideas... but when well made, both systems are good... I prefer Fusion because is much more simple.

@@ragnaroksub1442 Thank you! Finally I understand it! 👍🏽

I use Paralenz cameras... the accessory is called "Third Person Viewer"

@@ragnaroksub1442 thank you i will check it out 😁 Buon Natale 🎅

Non sono sicuro che in Germania sia legale la pesca subacquea (il possesso del fucile si, ma l'uso non saprei)... Per quanto riguarda il pesce, credo che ad ovest di Rostock ci siano pure i merluzzi nei relitti. Comunque credo che sia terra di trota salmonata... molto divertente all'aspetto ed un po si comporta come la spigola. Se la visibilità è buona, perché non provare?

Not exactly. Tests made with high-speed cameras show clearly that the hydraulic losses in the rubber (elastomers behave partially as liquids) cause a slow-down of the rubbers in a roller. This make the wishbone speed topping at around 3/4 of the barrel... definitely more efficient than a standard circular rubber but less effective than a Fusion despite the loss of "barrel lenght". We tested it several years ago with 100 fps... nowadays the new 240fps cameras will be even clearer. Furthermore, the real difference-maker between roller and roller or roller-fusion or whatever, is the less visible pre-stretch: if you have a roller, try two sets of rubbers with the same final elongation but different pre-stretch%... The pre-stretch change completely the K equation raising the start point and increasing greatly the integral of the K(lenght) available to the wishbone point. Basically, higher is the pre-stretch, more is the kinetic energy that is transfer to the spear: the same principle is applied to pneumatic spearguns, and is the reason for the need of high pressure in the tube.

@@ragnaroksub1442 OK i made a little bit of research. So let's take for example a 90cm speargun. We have 90cm to accelerate our shaft as much as we can. Using a pair of 30cm rubbers on a classic gun stretched at 300%, acceleration occurs only at 200%-300% elongation because water resistance, friction and other losses. Our usable acceleration length then would be 30cm. In the most efficient scenarion we would like to have a prestretched band of 90cm at 200%, in order to accelerate the shaft for the whole distance of 90cm, but that would need a length of 270cm rubber. Using roller guns we use band lengths that would normally fit into a longer speargun. A classic roller has long rubber but great losses from the bands on the pulleys, an inverted roller has losses on the pulleys and is not using the bands at their sweet spot (200-300%). A fusion setup on a 90cm speargun would have a 30cm bottom band prestretched at 200% and a 20cm upper band with no prestretch. That's a usable accelerating force length of 50cm that normally a 150cm gun would use. Hope this view is better than my previous. :) Thanks for your reply

Are you speaking of a demultiplied or invert roller? There is a lot of confusion on the matter on the Internet... I have seen system called in miriads of ways, most of them wrong, especially in the US where it looks that they are still struggling with the definition of "kilometer" :-/

The old ferry harbour pier...

Most of the standard reels are quite bad... special reels instead have adapters for mounting it on several speagun models.

Ragnarok Sub thanks!

This is a Paralenz DC+... GoPro is obsolete ;-)