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The Truth from Steve Alexander on enclosed track speargun

Iyadiver

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Apr 22, 2002
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Gentlemen & Ladies,

This is what I received from a good friend. The info was from Hawaiin SkinDiver Online but the website is out of action now.
Some of you might have read this but there should be plenty out there who is still in the blind.

ENJOY.....................


Do enclosed spear tracks improve
speargun accuracy? >> Jasmine


Jasmine > 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



Delrin vs. wood track: improved speed, range & durability?

Unless you just “gotta have the look”, a Thermoplastic track such as Delrin or Teflon is not worth the money or effort. The popular misconception is that since Delrin and other plastics are commonly used as bearing materials, they would make a great speargun track because of their friction reducing properties. The fact is there is no friction reduction advantage because there is no appreciable friction to reduce. For the same reason, there will
be no wear on either the track or shaft. Unless a wood track is habitually fired with a track full of sand, it will last a diver’s lifetime and probably his son’s too. Tests have proven that the plastic track won’t buy one nickel’s worth of increased range, speed or track life. The downside to plastic is its high thermal expansion rate. Temperature changes affect the plastic track to a much higher degree than wood or aluminum. I discovered this the hard way when I built my first few plastictrack guns many years ago. You can’t solidly mount the track to the wood because when the ambient temperature changes, it causes the track to expand or contract enough to cause the whole gun to warp by as much as a quarter inch. Of course, this is not a problem if you hunt in water that is the same temperature as the air in your shop when you screwed the track down. The only alternative is to let the track “float” or slide independently in the gunstock by slotting the mounting screw holes for example. This works OK if the gun is over built with a sufficient amount of wood in the stock to make up for the stiffness lost to the sliding track. I would have to say that the only advantage a plastic track has over a wood one is the durability where the thin upper surface of the track is exposed to damage from wire wishbones or accidental impact. So if you really like using wire wishbones or are in the habit of tossing your gun in a barrel with everyone else’s when you go out on a boat, then a plastic enclosed track could be a real advantage. SA



REGARDS,
Iya
 
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Iyadiver

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UR MOST WELCOME..........

In fact Jay Riffe spoke of almost the same on the matter of enclosed track in a private email to my friend.

In summary :

" Enclosed track shows no obvious accuracy improvement with thicker 3/8 ( 9.5mm ) shafts. "


If two of the world best have spoken similiar I guess they know best.


IYA
 

foxfish

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I have dug up this thread because I though it might interest some of our gun builders?
Some good points made but not much bearing on the type of guns most of us Europeans use.
 

strangelove

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Great research foxfish, I am not sure if it is a perception that I have (I do own both enclosed track and open tracks, epoxy and oil finishes), when I fire the open track, I think the shaft does not slide as easy as the fire shots with enclosed (delrin enclose). I get the feeling that the open track shot is slower then the enclosed track - this perception is accentuated with epoxy-finished gun. I wonder if any one else has that impression.
 

hteas

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A friend of mine had an Alexander open track Reef model that slowly deteriorated during a trip to Baja. By the end of the trip he had to hit the gun after pulling the trigger to make the shaft start moving. It was an oil finished teak gun, and definitely was slow. I don't know whether the track was too small or whether the wood was aging poorly and the grain stuck up, but I am sure he will never spend the extra for wood again.
Howard
 
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foxfish

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Just goes to show that you can read anything about anything on the forum & find many different opinions.
I can defiantly see the benefits of delrin enclosed tracks for small diameter spears like 6 - 7mm but as I have no experience of using such a gun I will have wait until I build one!
 

strangelove

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One more thing about the enclosed track, at least for me, it does take longer to load. Since the open track one can just slide the shaft straigth to the trigger house, the enclosed track you have to thread the shaft from the muzzle.
 

miles

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During our search for tuna gunz, we also looked at the enclosed track models from various manufacturers. One of the GREATEST dis-advantages was actually a simple thing. If your spear gets bent by a fish, you will not be able to use that spear in an enclosed track again!! With our current guns, we'd simply bend the spear back into shape and continue spearing.

Makes a big difference when you're travelling to exotic locations, as then you'd have to carry many spare spears with you!!
 

speareasy

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Jun 28, 2008
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I am not sure how old this thread is but I found it in a google search. Since I was testing this exact issue I thought it would be good to put my data out here. I recently tested an enclosed track gun for a friend. It was a 3 band x 5/8" wood gun using a 160cm 7.1mm Riffe shaft. It was the first time I had ever used an enclosed track and so I was interested in the results. Accuracy wise I did not find too much difference, but mainly because I usually test against a Riffe Euro 120X which is extremely accurate. I think by far the most impressive thing was shaft drop throughout the effective shooting range. Moving from 5 meters to 7.2 meters only had approximately a 5cm shaft drop. Now compare that with my open track Riffe ... the drop with 2 x 5/8" bands with the same shaft on a Euro 120X was approximately 25 cm !!! Of course there is one extra band there, but still! I used to pride myself at being able to calculate proper shaft drop at distance with my Riffe 120X, but with the enclosed track it was simply a piece of cake and took all guess work out. Basically you can aim at a King Mackerel from 0m to 7.2m and even if you did zero shaft drop compensation you will still get a good hit on the fish. I did a video of this test, including 3 shot group at 6.2 meters and a 3 shot group at 7.2 meters and one shot at 5 meters to check shaft drop. I will have to ask the maker of the gun if it is OK to show the video, but really the results are extremely impressive and I now am scrambling to make my own enclosed track gun.

I don't think I could add another band to my Riffe 120X to compare 3 band vs. 3 band as it would most likely hurt accuracy. But IMHO the biggest advantage of an enclosed track gun is that you are able to configure the gun to take all the guess work out of shaft drop. Shaft drop is probably the biggest cause of missed shots on fish in open water as sometimes it is very difficult to gauge how far the fish is, because there are no visual references.
 

Don Paul

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Me too.. but I would be more interested seeing the same gun specs concerning power, barrel length and shaft thickness shot at the same target distance with some gauge of penetration shown if possible.

Cheers, Don Paul
 

speareasy

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I guess it won't be a problem. The gun is from Ihab from niledivers.com and I think he posts here. The gun was shooting a little left for me and am still not sure if it was due to flinching on my side or if the gun was actually shooting left. 3 x 5/8" bands on an unballasted gun can be quite difficult to control, especially one handed. There is a lot of power behind that shaft and recoil is pretty stiff. I only took around a dozen shots with the gun (includes the shots on the video) and more than that I think my wrist would have gotten quite sore. I always test accuracy with one hand as it feels a lot like pistol shooting which I have a lot of experience in. Most likely if I ballast it, things would improve as I had to use some tension on my wrist to keep the gun level. Anyone who has tried skiing with his legs straight and stiff will know what I am talking about. If you jump without keeping your knees loose to absorb shock, you will have a painful experience.

Still I would not hesitate one second to take this gun on an open water big game hunt. The target was construction grade stiff styroboard, and the gun had much more penetrating power at 7.2 meters than a 2 band Rob Allen 140cm gun at 5 meters. Just the idea of being able to aim directly at a fish at long distance is great. To give you an idea, with a Riffe 120X with 2 5/8 bands, shaft drop is about 12cm at 6 meters and 25cm at 7.2 meters. So that extra band goes a long way in improving performance.

I think it takes a while for the video to process, but here it is

 
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Don Paul

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Very nice shooting and the gun shows very little flip at the mussel end, but you can see the barrel react to recoil in the first shot. A small amount of mass (lead wt) in the handle would really help.
Thanks for the video.

Cheers, Don Paul
 
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speareasy

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Yes exactly! It needs some ballasting to reduce the stiff recoil. But I think with 3 bands there will always be more recoil than 2 bands, but the resulting much flatter trajectory is well worth it.
 

Don Paul

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Yes exactly! It needs some ballasting to reduce the stiff recoil. But I think with 3 bands there will always be more recoil than 2 bands, but the resulting much flatter trajectory is well worth it.
Just curious what the gun without bands and shaft weigh?
Wood enclosed track ?
Thanks, Don Paul
 

Bill McIntyre

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This is only slightly off track, but today I heard a new take on enclosed track spearguns. Phil Herranen, a builder of highly regarded custom spearguns in Santa Cruz, CA, came down for a visit and I took him and his two buddies diving.

One of his buddies got his very first white sea bass, a 45 pounder, but I digress.

Phil said that people have no idea how much power they lose to enclosed tracks because water has to suck into the track behind the departing shaft, and a low pressure area is created that retards forward travel of the shaft. He said that if you use just one band, the difference becomes noticeable.
 

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Don Paul

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Phil said that people have no idea how much power they lose to enclosed tracks because water has to suck into the track behind the departing shaft, and a low pressure area is created that retards forward travel of the shaft. He said that if you use just one band, the difference becomes noticeable.Quote: Bill MacIntyre

My first enclosed track gun was built in 1984, after tests on penetration and
shaft energy I milled the pretty Teflon/graphite track to a half round and I
never looked back, I agree with Phil.

I think Enclosed tracks are great when the gun you propped against the sea wall falls over.... the shaft doesn't shear at the mechanism or stress the sear groove leading to catastrophic mechanical failure.
Cheers, Don Paul
 

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speareasy

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The gun is pretty heavy and I would have to wait to take out the bands and weigh it when I have time. I spent more time looking at the balance underwater and it seems the front wants to go up more than the back. I put on a Mori shaft that has slip tip welded on and took a few shots with 2 hands (as I usually shoot big guns). Recoil was really nothing with 2 hands compared to the clobbering you get with one hand, but for some reason the gun was now shooting right. I guess the weld, or the spectra seems to be deviating the shaft right. The groups were still very good though, and shaft drop is the same ... so no biggie, a couple of cm to the right will still knock out the spine. I was going to take the gun today on an open reef to try for King Mackerel, but the tides are strong today and we will have to go reef spearfishing hiding behind the islands depending on where the current is. For reef I usually take my small Beuchat or Riffe 100.

With regards to suction in an enclosed track. I have heard that and I must say I am really doubting the effect after testing this gun. I mean OK it has 3 bands, but the penetrating power is tremendous. I compare it to a Rob Allen 140cm with 2 bands, and even with 2 bands it had much more penetrating power than the Rob Allen 2 band gun. At 3 bands all the way back to 7.2 meters, it still had incredible penetrating power. You can see in the video with the 5 meters shot where it penetrated all the way to fins. The only example of a similar gun would be my 3 band standard wood gun which would penetrate maybe 1/2 way from the same distance. So power wise it seems to be the exact opposite and if anything, the enclosed track seems to retain more power.

Anyway I will test this in more detail when I have time. But it could be also related to how much tolerance the enclosed track has and how big the fin track cut above is. Most likely the velocities would have to be much higher before suction becomes an issue. Or maybe the suction is an issue with less speed and is not a factor with 3 bands. I will try to do more tests and do video comparisons of penetrating power.
 
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