Posts by Wishihadgills

Sharks and other fish like bright colors for the same reason we do, they are easy to see and catch the eye. In murky water neon yellow and white are some of the only colors that show through, especially when a diver is wearing camo. About a year ago I switched the weights on the back of my belt from black to neon yellow so that I was more visible from the surface.

I would say that bright colored fins are probably overkill. I know a lot of people that put flasher tape on their fins because it attracts fish. If you are worried about sharks, the flutter of fins or the wiggling of fingers are probably the last places to put bright colors. By comparison the bright weight on the back is relatively stationary and only visible from above.

I can't believe it has already been a year.

Like George I didn't know Nate, but think of him often as a sobering reminder of the dangers of our sport.

I would contact Popgun Pete once you get your PM ability. He has a pretty good amount of information on speargun design and could probably help you run down some more info.

I just graduated with my degree in Mech. Eng. so congrats on making it this far, it isn't easy. Unfortunately a lot of the information and experiments done in the world of spearfishing is very far from the controlled models we are used to in school. Most of it is very anecdotal and not close to an acceptable level for a thesis. Good luck and let me know if you need any help.

Hey guys, I'm looking for a little help.

I have a couple friends coming down tomorrow to do some lionfish research out of the ft lauderdale area. They are looking for some leads on spots that might have large numbers of these buggers. I know forum policy is don't ask for spots but maybe this can be an exception. If you have any information and want to help please pm me. It's for a good cause.

Xan

Beautiful gun! I would love to see the process you use to make them. Some of the cleanest carbon work I have seen.

Surgical shears work pretty well. They are cheap and have a slightly serrated edge. When they loosen up throw them away and get a new pair.

Similar to Chuck as a boat we almost never get skunked. Personally it happens sometimes but is usually because I choose not to shoot barely legal fish or only target a one or two species. I am not spearfishing to feed myself. If I don't catch anything i won't go hungry so I'm ok going home empty handed and allowing some smaller fish to grow up.

The best technique I have found for catching more fish is traveling to places with more fish and less pressure.

On a more serious note chum can be very effective and sometimes a necessity. I used to think it was cheating but I have since outgrown that naive thought. One technique we have used successfully was to drop a chum box on a nice spot, mark it with a gps and a buoy, then move down current on the reef drop another then go back up current of the first spot and start drifting. It's complicated and doesn't always work as smoothly as described but giving the chum a minute to sit undisturbed can help. Also Chum balls for like for yellowtail work well.

I personally have never found a mirror mask to be helpful like others have mentioned.

In SFL deeper seems to be better but not always.

Nick, I always enjoy seeing videos with that incredible amount of life. It's a relief to see that we haven't destroyed all the life on this planet yet. In the same regard I don't enjoy the movies that are purely shooting fish. For me, the best videos are the ones that show the adventure, the natural beauty and the camaraderie. When it feels like I am there not just a highlight reel of kills.

Basically what George said. Let the gun float behind you as you pull in the line/swim towards the fish.

Spearfishing reels are for line storage. They aren't designed like an above water reel. The handles are small the drag is simplistic. Both make them difficult to use like a reel designed for hook and line fishing but other than the inconvenience there is a serious risk to trying to "reel in" the fish. When there is little pressure on the line as you wind the reel the line gets stored relatively loosely. As the fish runs or fights back line gets put on more densely. It can even get pulled down into the looser line. It may not always cause a problem but this can result in the reel locking up on a later shot which is a serious danger.

Quote from Chuckd

Roller
2x22" bands plus 2x2" wishbones
42" top from notch to roller
30" bottom hook to roller
So 22" elongated to 70" = 318%
Force x 2 pulled over 42" length
Therefore, 84" of pull.

MGS
2x26" bands with 3" wishbones
40" and 43"
So 13" elongated to 39" and 42" = 300% and 320%
14" relaxed
Force pulled over 26"(band 1) x 2, and 29"(band 2) x 2.
Therefore, 110" of pull.

caveat: the second band on a double banded gun doesn't double the power

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Honestly not quite what I was expecting. Im still curious as to the force being produced by the bands. It would seem that as Pete stated the double banded conventional gun is producing much more force than the single banded roller. I don't think it is quite double but it may in fact be pretty close. Chuck, just from feel how would you compare loading the one roller band to loading one of the conventional bands?

Chase. It's not that penetration tests aren't useful. The problem is there are a lot of variables that influence penetration. Tip shape, sharpness, mass, roughness, variations in density of the target material, angle of penetration and others. If you could control enough of these or take enough test shots that the error is minimized you could get useful information from penetration. It's just a lot more work than simply measuring the velocity.

How much weight are you wearing?

Quote from dsculley

I have been following this thread and I see a lot of theory being suggested. There is one sure way to answer this question. Shoot comparable guns over a chronograph. If a roller gun will propel a shaft of the same mass with a faster muzzle velocity than a non-roller gun then it is more effective. If it does not, then it is not. There has been a lot of research done in archery regarding power curves in compound bows. The actual science gets pretty complicated. Still, the only way to increase the power of a bow is to propel an arrow of the same mass faster. I would have to see the chronograph numbers to believe that adding rollers and increasing the power stroke by a few inches without also increasing the pull weight of the bands would make any difference.

Whether they are more accurate/easier to be accurate with is a completely different question and mostly times comes down to personal preference.

Just my 2 cents.

Dennis

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Do you have a chronograph we can use? Not trying to be rude, I really would like to use one. That would give you a definitive answer as to velocity differences but you would still need to know the forces applied to the shaft to know which was more efficient/powerful.

It would be possible to build a scale and us a go pro with a very high frame rate to calculate the velocities more precisely than Chucks video. Not as good as a chrono but it works.

Possibly, but if George interpreted your comment as an indirect way of censoring a comment from a potential competitor then it would be a similar abuse of administrative power/influence. However, this is pure speculation and as I cannot possibly know what George is thinking I decline to speak for him.

After you have read this would you mind deleting it as it is no longer pertinent to the thread and mere conversation.

I'm not avoiding the question. Without the length measurements I need to know the force measurements. If the band lengths are very close then no. Two bands on a conventional gun should be similar, but heavier, to one roller band but, if this is the case, then I don't think the results would be what we saw in the video. I suspect there is a substantial difference in the force supplied. My calculations predicted about a 20-30% increase in power. So this could explain the video if the bands are of.

Two bands on a conventional gun should not be double the force of a roller if the band specs are the same and assuming the bands act as linear springs.

To draw a conclusion from Chucks test I would want to know the exact measurements of the bands length and diameter. As well as what force is actually being applied to the shaft. The only thing that the video shows is that the two shafts leave at pretty close to the same speed.

If I knew the forces produced by the bands I could make a comment on Seals assertion. If both shafts are leaving at similar speeds but the roller is using much less force then the roller is more efficient and given similar force output would produce a faster shaft.

Chase. It depends how you define out perform. If easier loading with less recoil and potentially more accuracy is considered out performing then certainly. If pure power is your goal then possibly. In theory it is possible but real life has a few more limits. I do agree that they are not perfect for every situation but that can be said of any gun.

As for politics. You are very familiar with how other boards promote or censor certain products and brands, preventing broader acceptance of many quality products. There are also brands that are willing to produce inferior products simply for profit and others that rip off and undercut credible manufacturers. In general I feel there is a large lack of engineering application and quite a few terrible designs that are around. Some of the best products are made at home because and intelligent and skilled individual was willing to put the time and was capable of producing something better than the current manufacturers. Honestly this could be its own thread so I don't want to discuss it much further here but working at my LDS opened my eyes to a lot of the crap that goes on.

I really wish I had the time and guns to do a much more controlled test. Maybe this summer I will get the chance.

Honestly Dan, aside from the video Chuck posted (which is missing a few details) I have seen very little "fact" from your side of the discussion. I have shown a few times how the potential exists. If you believe that I have made a mistake somewhere in my math please point it out. Until then I stand by my work and what I and others have stated. If you believe that makes me stupid then yes I would be offended. I do agree that the simple addition of a pulley does not make a gun magically more powerful but that is an oversimplification and does not tell the whole story.

As for the sale of spearfishing gear in general (a little off topic) yes I agree with George that politics and other factors have really hindered the development of quality products. I don't think you have an ulterior motive and as you stated you could certainly sell rollers if you desired.

Chase. Although I did not read through the entire article in great detail, penetration tests are terrible ways to compare multiple guns. There are way too many factors that go into it and from what I read the testers did not do an adequate job of controlling the variables to draw an accurate conclusion from their test. Despite that, other than the sizes you posted, they were overall impressed with the performance of the roller guns.

As for the pneumatics, yes they have similar advantages in power and their loading system is fairly simplistic. their complications are internal and design and reliability are often more problematic than the extra complication of loading a roller.

A lot of interesting discussion since Chuck posted the video. (Thanks, Chuck, for taking the time to do that)

From what I saw, there was not a substantial difference in the performance of the two guns. A chronograph would give more accurate results but I don't unless someone has one probably not worth getting one.

The penetration test won't show anything and more than likely will add more confusion. Small variations in the shaft can cause big differences in the penetration. But as a few people mentioned, penetration will be proportional to velocity.

As for one band two band red band blue band it doesn't really matter as Gabe mentioned. The key is how much force is being applied to the shaft and over what distance it acts. I would very much like to see what the difference in force is. If they are making equal power then the roller should be noticeably easier to load. (In terms of force)

Quality of the rollers will make a difference but it should be relatively small unless the rollers are terrible.

Looks about the same.

Any chance you have a fishing scale that will go up to 100lbs? If so can you measure the force of each band on each gun?

Dan, you are correct in saying that a single pulley does not create a mechanical advantage, and only changes the direction of the force. What it does allow for is shortening the gun by placing the relaxed band under the gun.

Seal Im not sure what you are describing in your post could you clarify?

Pete. Your diagram is correct if you assume that a single band gun and a single axle roller produce a the same force. By adding a second band you are then doubling the force being applied to the shaft. However Dan, and I both started with the assumption that the rubber on a double band speargun was equivalent to the rubber on a single axle roller. In this case they are both producing similar force at the shaft and as your diagram and my calculations show the roller would be superior. The easiest way to confirm is this is the case is to put a force gauge on a roller band when it is loaded and see if it is close to the force of both bands on a conventional gun.

From the calculations I did earlier, the best case scenario would only result in about a 20-30% improvement. for a lot of people this isn't worth the extra complications associated with a roller.