Posts by Don Paul

  • Building a speargun

    Quote from tufual

    quick question , how much of the gun's accuracy is down to the shaft like the flopper , geometry of the tip vs the track on the gun , i would imagine the barrel isn't as important as the projectile .?(


    A lot... here's some of what counts: hydrodynamics, duration of of thrust of the projectile (rubber pull) cross section of the projectile, payload the projectile (in the case line wt and drag) and here's the big one...speed of the shaft through a liquid the density of salt water.
    More rubbers after a point don't equate to more shaft speed on long shots....more mass of the projectile retains more energy down range.


    I'll save more comment for another thread sometime on dynamics.
    Now I'm just drooling over the history of this fine teak.:thumbup:


    Cheers, Don

  • Building a speargun

    Quote from Deanmc

    Don, thanks for all the great information on enclosed tracks. Really good stuff.


    One of the only reasons I offered my thoughts are for other home builders that may be overwhelmed by the construction of what some guys preach i.e. 'The only way for a long gun to be built is the ET track system.' Not everyone has the skill to mill such a groove with just a drill press. Fine guns can be built with files/rasps, sand paper and planes.


    I've seen too many Tahitian marksmen as they shot their 6 foot long 6.5mm spring shafts propelled by two 16mm bands through the heads of small fish.


    Cheers, Don

  • Building a speargun

    Alexander on closed track guns shoot further and why one of his guns would have more range.
    Quote:
    This is a common question that I often get asked. First let me saythat if you hunt where there are plenty of fish and you can get all you want, then an enclosed track gun is not going to help you. However, if you go home empty handed too many times because the few fish you saw were just out of range, then an enclosed track may improve your odds. I started building guns with enclosed tracks about 13 years ago simply as a means to hold the shaft in place while hunting. This was a necessity with my
    over-and-under, dual-shaft guns, especially with the bottom shaft. Then, as more and more divers, following Terry Maas’ lead, started targeting the big Tuna, I saw a need for spearguns with more range to increase the number of opportunities to hit and land these fish. Like everyone else, I tried adding more power to my gun, but it became erratic as the shaft bowed when fired
    and the recoil increased drastically. My solution was to increase the gun weight and enclose the spear track. This resulted in a gun that would shoot a 3/8" shaft powered by 6 bands, over 30ft. with consistent accuracy.


    So how much of that improvement was attributed to the enclosed track? Not very much, I’m afraid. John Warren, a part-time gun builder in S. California has made several guns with up to 7 bands that have exceptional range and accuracy with only the slightest depression on the top of the gun for a track. These guns, however, are extremely heavy. I would have to say an enclosed track is beneficial under certain circumstances, that is, if the shaft is subject to very high band tension and the diver wants the gun to be reasonably light for handling purposes. On the other hand, an enclosed track is entirely a waste of time if the shaft is not being over-powered. So, at what power level does the shaft become unstable during acceleration? That depends on many variables, such as: tip weight and drag, shaft diameter, shaft length and hardness and how straight it is. Also as previously mentioned, gun weight, especially at the muzzle end, has an effect on recoil in the vertical direction, which can destabilize the shaft considerably. Underwater testing of your particular combination is the only simple way to tell for sure, but “generally” a 5/16" x 65" shaft in a close fitting, half round track, will handle about 300 pounds of rubber tension; and a 3/8 x 72"
    shaft is OK up to about 420 pounds. Shorter shafts can take more power, longer ones less. Again you may get away with more power if the gun is very heavy.


    There is another way to increase range without sacrificing accuracy; Increase the stiffness of the spearshaft by increasing the diameter. How about a gun with a half-inch diameter shaft and nine bands that shoots 45 feet? This may seem a little extreme, but you’re only limited by how much gun weight and size you’re willing to lug around and how many bands you’re
    willing to cock! Remember, the more range you have the more opportunities you will have. SA

  • Building a speargun

    From my empirical knowledge and history; I see closed tracks as something to use as:


    1. A scuba free shaft tool on a gun that has a extra shaft mounted to plug a hog fish with.
    2. A design I tried in 1984 on my over powered 50'' poured graphite track gun and after extensive testing with power and range,mounted the pretty gun in a Brigeport and milled the track open...
    retested...found deeper penetration @ 20' off the tip to the target and never looked back.


    3. Used as a tool by a guy with great mind and build skills;Steve Alexander to keep the bottom shaft in his double from falling out.


    4.A marketing tool Steve then used when coming out to compete with a Riffe Blue Water gun,followed by more Scuba lovers in Florida... see #1.
    But... now the cool ''state of the art'' factor motivates guys to order guns from Steve Alexander in closed track.Jay Riffe counters with a closed Metal tech that sinks...see #1. 1990's a dive mate of mine bought one(Steve's) and could no longer make the long shots he was used to. I pool tested the gun for distance and penetration, then told the gun owner I would buy the gun from him if it didn't shoot further after I milled the track open.....it did and the gun stayed with him and served him very well.


    In conclusion; lets look at the state of the art carbon guns in Italy and Greece in 2000 to 2004...
    no ETs. because they know how to design and match the power to the gun.
    I bet under their breath their saying ''those crazy Americans will even pay $110.00 for a
    Titanium knife that cuts like a laser, but will not hold a edge''.
    So the tail wags the dog and now we even have the Greeks and Italians on board with guns that ''shoot like a laser''. :rolleyes: But guess what... Americans will buy them along with their cross drilled brake rotors and painted calibers that they think look hot and stop better.


    Somewhere on the web Steve Alexander is asked about his closed track guns shooting further... he tells the truth saying to the effect that ''well mine don't, but when the gun is leaning up against a wall and falls the shaft stays in place''. Recently Mori was asked the same question.....guess what he replied?


    I believe owner peceived value and cool factor is what sells here, gives a guy something to talk about at the Scuba Store.


    Cheers, Don

  • 3 atm float

    Quote from LunkerBuster

    If you have a fish take all these floats away you should have taken a better shot ;)


    Some monster fish are just going Fleck you even with a spine chip.
    After I screwed the pooch with my black marlin loss I spent a few weeks hanging with a Cali
    sword fish harpooner. He showed me pics of a 350#er that took down 3 big red eyes for 2 hrs. They hooked a large penn to the last floating ball, before the fish sounded to 600 feet and pined itself into the mud for another 3 hrs before they planed it back to the surface.
    When the fish was boated and cleaned they found the Lilly Head had cut half the spine.
    Some big fish are hard to kill, and the same ones will roll over on the side with a gut shot in the right place. The depth where the fish is shot also makes a huge difference, some times just a flopper shaft bleeding wound will just let a fish tow around the float rig for 5 hrs before she tires or bleeds out. My buddy landed a monster blue this way with one riffe float.


    As we sit here on the keyboard we can design and re-desigh our gear....but every thing changes when a monster shows up...is pissed off and does not want to die.


    Sure a big one can be boated with a perfect shot and conditions but guys don't always get away with that.


    Cheers, Don