DB want to give me tools for research...WOW...Thanks
One of the reason ( I think ) Riffe made the overhang of the shaft that long is for aiming. In the high power Riffe-s, you can't aim zero degrees flat on the shaft cause of some muzzle kick. I aim my JBL straight down the front muzzle. Since the muzzle of the JBL is quite high above the gun barrel, don't you think this is also indirectly a modified aiming ?? People may say that they aim just straight on JBL, they do but the use the enclosed muzzle as a reference. This is not straight aiming, this is elevated aiming. A Riffe, a Wong or an ALexander has nothing above its shaft to use as a reference aiming, so we elevate our aim by trying to see more of the spearhead, which mean muzzle up-butt down. This is more so on the high power models.
I shoot target board often so, I see the difference clearly. When you spend all ur shots shooting fish...especially big ones..it will be hard to tell. I am a land based hunter before I shoot fish, so I carry over the discipline of "zeroing" a gun before hunting with them. However speargun is more complex in its own way but being a close range gun ( say max at 7 meter s/23 feet effective ) many inaccuracy are not obvious cause you need range to open up the "grouping" circle.
The definite reason why Riffe has the same overhang for its threaded shaft on its entire range is that it is designed to ACCOMODATE the Riffe Ice Pick, that uses a slide ring to attach its cable. That overhang equals to the length of the Ice Pick cable.
Some people have shorten the overhang and get better result. Until I shoot target board with modified settings, I personaly can not claim anything I do results in better accuracy. How to define increased accuracy if there is no reference or measurement to use ?
I think longer overhang being better or not, depends on how each gun is suited to that overhang. If you can keep away shaft whip/oscillating, I suppose u can have the longest overhang possible if that benefits you. Don't think that overhang is a useless design. As long as you gun shoot well, it works.
An open muzzle like Riffe, has the simplicity of being able to use all kind of shaft diameter without much hassle of different slide ring/s size. At higher power Riffe, hitting a slide ring like a JBL set-up will be a disaster, this is why all high power guns will not use slide ring to attach a shooting line.
One thing we must understand on all projectile being fired out of a gun is that it will have a parabolic trajectory......some is more some is less. Depending on shaft weight and powerband used. I am not talking of muzzle kick induced low shots, strictly gravity related trajectory. The moment the shaft exit the gun, gravity acts upon it and the longer the shaft's flight time, the more it will head down. Let's not calculate the extra drag caused by various spearhead or thick shooting line and so on, just gravity. If a gun can shoot effective 7 meters /23 feet ( meaning it will be quite useless at 9 meters ) and the owner tell you that it is flat shooting, that is a ton of bull shit. There must be some few inches trajectory involved.
As far as trajectory is concerned, it is difficult to accurately measure on high power guns like 3 x 5/8 rubber ( or more ) Riffe or any other brands. I mean if you ask me to measure trajectory by 0.5 inch increment or by shooting a target board per 1 foot increment, I might have problem cause there is no fix or accurate sighting system to use. Practice is the key cause shooting a speargun is more by feel eventualy. The only kind of grouping you want to avoid on any guns is the erratic shots going left and right, this is inaccuracy. Consistent low on a fix distance is trajectory. Untill someone come up with a "smart shaft" that has some kind of steering control, trajectory is something we must live with.
What I foud out is that high power guns ( as long as recoil can be managed ) using thin shaft has better/flatter overall trajectory. It is not to say thin shaft is better, it juts move faster in water and means less time in flight, thus less gravity effect. I am still trying to find out the best shaft set up for each of my guns. The problem with fast shaft is that water drag increase (can't remember the exact formula ) tremendously for speed increase , so much so it become inefficient. I mean energy required versus shaft speed produced.
I recall the rule of thumb to double speed on boats require quadraple horsepower and that is applicable for up to certain speed, later the underwater gear ( propellers ad brackets ) will produce cavitation and can not push the vessel much faster efficiently in terms of power applied. I just surf around some NAVY submarine info and it seems 80 knots/ 92 MPH is about the critical speed any underwater object/projectile can do most with efficiency. The next step is to produce super cavitating torpedos where they introduce an air bubble to envelope the torperdo and eliminate water drag......some fancy physics. If anyone has a boat with step hull, this is similiar in concept but probably 100 times more advance.
Don't we wish one of us spearo works in a naval research facility and can "steal" some simulator time...Wha ha ha ha.
