Is the wishbone notch in the spear not a weak point, considering the fact that the line attachment point is behind the notch?
The disadvantage of having the spear line connected to the back of the spear is the wishbone notch. This can get broken when a fish struggles in a cave and manages to wedge the spear and fight against it. There are many advantages to having the line attached at the rear though such as retrieving the spear when a fish takes it deep into a cave, since in pulling from the rear you have much greater control. A spear with the line attachment ahead of the notch will jam up much easier, and both fish and spear will be lost. Another advantage of the rear attachment is when shore diving in a strong current and you shoot but miss; a standard spear will hook up in the reef at the back and in very strong currents all your equipment can be lost. This has happened on many occasions on the Natal South Coast. Having the line attached at the back means that you could lift it off the reef more easily and just shake the barb lose if it hooked up on the bottom. Still another advantage to having the line at the rear is when the spear goes right through a fish that is shot at close range. When this happens you can retrieve the spear back into the fish. Standard spears will "T off" on the other side of the fish. Also, if a shark bites the fish while the line is through it, you lose your fish and your spear. If you are able to retrieve the spear back into the fish, the fish then fights on the spear and if a shark bites it you are more likely to retrieve your spear with maybe only a bend. We have recently developed a new wishbone notch system where the spear has a 2.5mm hole drilled where the notch would be, and a mushroom shaped pin is peened into place. This is then shaped to take the wishbone. The system means that much less steel is removed and therefore the spear is thicker at this point and much less likely to break. Answer Courtesy of Rob Allen Spearguns.
Why do most divers use monofilament nylon, surely it can cut on the reef easier?
Monofilament nylon is better in many areas; it has a much greater breaking strain than the standard polyester of the same diameter. It is easier to handle in the water because it is stiffer than other lines. When firing the gun, the spear with mono nylon will be much faster through the water than that with a polyester multi-fibre line. This is because being a mono fibre, it doesn't hold water like a multi-filament which would slow the spear down when the gun is fired. With polyester, the knot in the line is also larger than that of a crimp on nylon, therefore the drag is greater. In terms of being cut on reef, the best is to do a test at home with mono line and similar diameter polyester on a very rough rock or sharp surface. We have found mono line to be much better. Answer Courtesy of Rob Allen Spearguns.
Why do railguns not have screw-on rubbers in the muzzles?
The idea of a single looped rubber makes it more economical to produce and therefore less expensive to the diver. In actual use the extra rubber that goes around the muzzle gives extra drive. In other words, the rubber can be made a little shorter than that of a screw on set up, therefore giving you a longer drive that will give more speed to the spear. These muzzles are also designed to enable the diver to exchange rubbers easily in the water without tools if he is carrying a spare rubber clipped to his float. The length of extra rubber in the head of the muzzle is 10 cm. Answer Courtesy of Rob Allen Spearguns.
Why are single fixed barbs most common on railguns?
We have found that the vast majority of spearfishermen have at one time or another used or tried a drop head (slip tip). They virtually all change back to a single barb for a variety of reasons, the main reason being accuracy. Here we have found that it is very difficult to get the drop head to sit on the tip of the spear without any play (basically sideways movement). If you can get it to fit without play, then invariably it is too tight to come off resulting in the head pulling back through the fish and the fish being lost. The very tip has to be perfectly stable and central to maintain the straight flight of the spear. Even a very small amount of play will cause the spear to be inaccurate. This is because the extreme tip is what keeps the spear traveling true. A slight movement to one side or the other will cause a varying degree of inaccuracy depending on the amount of play. To show this you just need to sharpen a spear, which has a fixed barb, slightly off center, and you will see how much the accuracy is affected. Another problem with a drop head is the hassle. Slightly too loose and it falls off when you dive down, to tight and it stays on and pulls back out of the fish. This can be most frustrating. In terms of drag the drop head is bad, since the diameter is greater than the spear. A good head shot with a slip tip can become a major problem when it jams in the head. The only way to get it out is to cut it out. This can be difficult in the water and most frustrating when your buddy is still shooting fish around you. In terms of comparing fish lost with fixed barbs to those lost with a drop head, the majority of South African divers feel the fixed barb to be the better. In South Africa several large marlin, over 200 kg, have been landed with fixed barbed spears. Large marlin that have been lost are mostly due to the float system failing, not the spear. One of 500kg + was lost because the diver couldn't handle the fish in the water and eventually the boat crew "helped" by pulling on the float which parted company with the rest of the gear at an old boingie. Another disadvantage is costs; a fixed barb spear is much less a spear with a drop head.Answer Courtesy of Rob Allen Spearguns.
Can a railgun be loaded with the line under the spear?
No. Because of the rail, anything under the spear will cause it to lift up and shoot inaccurately. When loading the gun you must make sure that the line is on top of the spear and not under it anywhere along the barrel. Answer Courtesy of Rob Allen Spearguns.
While the line on top not interfere with the rubber during loading?
No, it will not interfere because it moves off to one side when the rubber is loaded.
I have been using a standard gun for many years and now I find it difficult to aim with a railgun, is it just me or what?
Many divers have problems at first because the railgun is so different. When you are accustomed to aiming and using equipment that performs a certain way then change will feel strange and may take a while to get used to. Before getting further in this subject, let us try to visualize two geometric concepts, most important for a better understanding. 1) Horizontal plane: lean down at the head of a long table until your eyes level with the tabletop. Now everything you see on the tabletop, or along it, is in the same horizontal plane of your eyes. 2) Vertical plane: lean one ear against a long wall. Everything you see along or up and down the wall surface, like a picture, is in the same vertical plane of your eyes. That understood, be aware that the main problem area seems to be in the way some divers aim. Most look over the top of their guns while aiming, bringing the gun up onto the target. This tends to make it accurate in the horizontal plane because of the way you are looking over the gun, but not so in the vertical plane. We have found the best way to aim a railgun or any gun for that matter, is to not aim over the top, but rather along the side of the gun. What this does is it helps you to keep it very accurate in the vertical plane, which is much more important than the horizontal because most fish are much longer than they are wide. This is especially true with open water game fish that are difficult to get close to. When looking along the side of the gun, the rubbers, barrel and spear are all in the same [horizontal] plane as your eyes. All you have to do now is lift or lower the whole gun until it is on the same plane with the fish's spine. When this is in line, then the gun is moved from side to side to control the horizontal plane while keeping it in line with the spine vertically. In this way the shot will be on target with the spine but maybe a little out regarding the lateral placement. This lateral, hence horizontal, inaccuracy is not as important considering the spine is as long as the fish is.Answer Courtesy of Rob Allen Spearguns.
Is a small shock absorber on the shooting line necessary?
Some divers use them, but we feel that the mono line has sufficient stretch in it so you do not need one. The more you put onto a gun the more drag there will be when maneuvering and the more "fittings" that can fail. The only time one is necessary is when using Dynema cord. This is a very strong line, available in less than a 2mm diameter with a break strength of 260 kg. This cord has no stretch and therefore needs a line shock absorber (bungee) just to be able to stretch it onto the line release. Answer Courtesy of Rob Allen Spearguns.
