Shorter shaft

Go to www.Sumora.com You just pinpointed an advantage of Rail guns.

There seems to be an optimal amount of mass a spear needs with certain power from bands for distance. Many times a high power shorter gun will have a longer shot with a longer spear, because of the extra weight (mass) of the shaft. I believe it is the density of the water that creates the drag that will slow down a lighter shaft faster. Sometimes a light shaft will be pretty fast and accurate, but toward the end of its range it has little power left to penetrate a fish.

Also if your shooting with a line, some times a lighter shaft will be more effected by the drag of the line and veer more than a heaver shaft. Too heavy of shaft will tend to drop too fast which will make your shots low or you have to compensate more by aiming high and arching the shot. Another draw back of a heavy shaft is the increased kick back when fired.
don

Well put Don,

The word that come to my mind is "momentum". The heavier a shaft (from extra length or thickness), will increase a shafts momentum and with that, the "resistance" or "friction induced by the shaft", or "drag produced by the spearline" (mono or cable) is then of a smaller value to the shaft thus affecting its (the shafts) travel or energy loss by a smaller amount.

I remember Iya (gotta give credit where its due, its not quite the same though) going over this in one of his may posts that its like a Honda Civic driving 20mph tied to a dumpster (big metal one like behind most of your houses) with 40ft of stack, verse say a 1 ton diesel pickup. When the Civic hits the end of that slack its speed is most likely going to be reduced and it's line of travel maybe comprimised, as where the 1 ton diesel pickup probabley wouldn't be affected at all. Now imagine that theres a house 200feet infront of both cars; which one is going to go into the house further (considering they hit areas on the house of similar build)?? :duh

Kinda wierd way to imagine it but I think it covers it.

Hope this helps or at least makes your day more interesting in trying to figure it out .

Good Hunting,
Justin

To answer the original Q; I don't believe that accuracy, or range would improve with a shorter shaft. It would make the gun swing better, but thats all I could see it doing.

As to how much of ones accuracy or range would be lost with a shorter shaft.....I don't really know. It, most likely, wouldn't be a whole lot, and in all reality it's relative to how much shorter the shaft is made.

You should give it a whirl as I imagine I'm not the only person who'd like to hear about the results.

I hope this helps....

Good Hunting,
Justin

Originally posted by drkebs
To answer the original Q; I don't believe that accuracy, or range would improve with a shorter shaft. It would make the gun swing better, but thats all I could see it doing.

As to how much of ones accuracy or range would be lost with a shorter shaft.....I don't really know. It, most likely, wouldn't be a whole lot, and in all reality it's relative to how much shorter the shaft is made.

You should give it a whirl as I imagine I'm not the only person who'd like to hear about the results.

I hope this helps....

Good Hunting,
Justin

Click to expand...

I've gone through this in my tinkering several times.
Here are my personal observations:

Shorter shafts:

Harder to sight down shaft
Faster lateral tracking
Quicker shots
Less prone to bending


Longer shafts:

More accurate (easier to aim for me)
More penetration at range
Tracking slightly hindered
Shafts have higher propensity to bend
Seems smoother (opinion)

Longer shafts are more hydrodynamic & travel through the water better, also carrying more intertia. A fantastic spearo Abri who used to frequent here mentioned that he uses the shortest shafts he can on his railguns. This makes a deal of sense since the less overhang, the easier it is to track & the straighter the shaft will be at rest since the weight of the overhang causes a slight arc to it.

Personally, a longer shaft helps me aim well & I prefer thinner shafts. I'd rather have a 140cm 6.5mm shaft (910*pi) or a 130cm 6.75mm shaft(877.5*pi) than a shorter 120cm 7mm shaft(840*pi). As you can see, the mass of the slightly longer shafts more than makes up for the thickness & the longer length helps hydrodynamics.

Some Picasso guns like the Fibertek come with 140cm shafts on 90cm guns. This is how they explain that rationale(from PicassoAmerica.com FAQ's):
Why is the Picasso Century 90 equipped with a 140 cm and not a 130cm spear?
The reason why we equip our spearguns with a spear that is 10cm (4") longer than the other brands is that because you can aim better with both eyes open, like with a shotgun (think "skeet"), by aligning the pin on the muzzle to the tip of the spear. It is a lot easier and more accurate to aim at the fish with both eyes open and the speargun placed below your face, so that you can track your prey at all times, no matter how it moves, even if it suddenly goes down, below your aiming line. If you aim with one eye shut and straight, fitting the "aiming" pin on the muzzle inside the groove on the top of the gun's handle (like aiming a riffle on a small and distant target), then should the fish move down, it will disappear from you field of vision and you will have to move the gun away from your face to track it which may be too late.

For Bluewater guns, it's a whole new ball game... you want the weight & thickness of the shaft to help carry it & provide punching power. If you take a 9/32 shaft, at the extent of the range, you can hit a fish, but the shaft may not go all the way through. With a 5/16" or bigger shaft - if you hit the fish, the inertia of the mass will push the shaft through.

In the end, it's all about hunting styles & what you're using your gun for. If I'm playing around shooting tiny fish(I like frying some of the small 6-10" reef fish in Hawaii up crispy), I'll use a small gun with a short thin shaft & 1 14mm band. For other small/medium fish, I prefer thinner shafts either 40-50cm longer than barrel length. For bigger fish, I prefer thicker shafts as I no longer think of them as sniper rifles, but more as canons :hmm: It's all relative.

I've been through so many configurations with my guns that in the end, I've realized that whatever you get used to & are comfortable with, is the best configuration. There's a point where you have to stop making the gun fit your style & learn how to effectively use your gun the way it is.

Happy hunting!

The more you know... the more questions you come up with. It's a vicious cycle.