Green laser on speargun

[sancarlos]

I've read some inconclusive reports on mounting lasers to spear guns to facilitate hunting. I started my own little project on that since previous reports (at least ones I found) was lacking any real-world results.
Recently I purchase green 5 mv laser (red ones shouldn't be working too well under water, albeit it is also the function of emitting power of the laser), which is claimed to be water-proof to 100 m. I want to drop the percentage of the wounded fish, which was able to escape due to the shoot in the soft areas. I'm only do spear fishing 3-4 times a year so I cannot maintain good aiming skills, unlike you lucky ones in CA, Florida, Texas and Hawaii. It is hard to practice in the middle of the desert, you know (I'm living in Arizona). Public pools also do not encourage spear fishing training for some reason .
Hence my project - to help me and other guys with occasional spear fishing to land bigger percentage of the fish I shoot. I'm pretty successful in getting whatever fish me and my family eat (we eat only what I spearfish on vacation, just a family tradition), but I'm disappointed that about 20% of the fish I shoot is able to escape due to the hit in the belly or other soft parts.
Anyone want to share the previous experience with laser scopes for spear gun? I'm planning to mount my laser to the pneumatic, JBL 48" and Wong 55" (impatiently waiting on this one to be delivered!) to be able to compare the benefits and drawbacks.
I will report the results, and I will appreciate any comments\suggestions\previous experience.
Another question: anybody know what is the drop of the spear of the spear gun - an inch, 2-3 inches for distances, say 10' for JBL with 2\3 rubbers?
Thanks!

[Pastor]

Only getting the chance to spearfish 3 or 4 times a year, I feel for you and for once I'm a little more sympathetic on this issue. BUT, if you spent 10 or 15 minutes at the beginning of each dive with a little target practice you would be amazed how fast your skills would return. Trust me on this, it's the only effective way to hit the target

[sancarlos]

Thank you Pastor. That what I normally do with my son on the first day of vacation - shoot the plastic bottles anchored at 5-10 feet. It helps, but didn't make me Wilhelm Tales. Besides I use to work in laser R&D years ago hence it is natural for me to try to improve my wicknesses with technology I knew. The problem with that application is not that I'm not sure that it will help (it will), but what will be the difference. If the gain is only, say 5%, then there is no reason to bother. Preliminare tests showed that I can see the dot about 30 feet away in the pool with salty water, but the thing I don't know is - what is the drop of the spear in the reasonable targeting distance (5 to 20 feet), hence I don't know what kind of adjusments I have to have to compensate the drop.
Off course I can do a lot of experimenting and figure it out, but I don't have a pool to shoot in and don't have time to go to nearest lake (30 miles) to try it there.
Preliminary calculations (just plain highschool stuff) produce calculated drop of about 2 inches in 15 feet or so. Sounds reasonable, but I would like to have any experienced spearo opinion on that.
Thanks again!

[TB2Scuba]

The problem that I see with it is the laser will not stay true due to band age. The bands will age making them less and less powerfull making your point of impact lower and lower. You would have to constantly adjust the laser as the bands age.

[sciencemike]

Spear drop will be dependant upon your setup. I practice shooting in my pool 3 times per week at least when i cant make the coast.


My Omer 110 HF Clusters 6 shots within about 2 inch diameter @12-15 feet it shoots 5-6 inches low at that distance. Im using one 5/8 inch band and one 9/16th band. If i put a muzzle lift under the spear, it shoots dead on at 12 feet, but 6 foot is up a few inches, and vertical shots are way off.

PS dont use Bottles for shooting, That makes it tough to see where you missed. Instead use the Foam flooring material for gyms. Its a 2ft x 2ft square and floats, so simply make a target mark on it with tape or marker and attach 2 small lead weights to the sides so it stays perpendicular to you. This way if you miss by 11 inches in either direction you can always see where you missed. Also the small crosshairs allows you to aim better. Otherwise you will just be aiming a a large bottle, not a small X. Lastly because it doesnt rotate in the water like a bottle will you can see your cluster better. It also sucks when your tip toggles on the inside of the bottle.

[sancarlos]

T2Scuba: I appreciate your input. I never thought about that variable - age of bands. I guess that is why I'm willing to try the laser setup in real-world conditions - too many unknown variables to decide whether it will work or not upfront. I use to be in experimental physics so I know that sometime there is no replacement for an experiment!
Thanks.

[sancarlos]

Sciencemike:
Thanks for the great idea with foam squares - bottles are pain in the neck to shoot!
Regarding the drop of the shaft: is it pure gravitational drop or the upkick of the front of the speargun due to recoil is also a factor? I my land experiments when shooting from support the drop even with one band when target was about 10' away was never more the 2 ". I was using only one band in the air to try to compensate for the fact that water is denser then air (I shoot 3 bands in the water).
I guess that if the accuracy of entire system will be within 2" for all reasonable distances (3 to 15 feet) and for all reasonable angles (-45 to +45 degrees) than given the size of the fish we interested in (2+ lbs) it can be considered accurate enough. The goal is to maintain consistent head shoots for an occasional shooter. I would love to have opportunity to target practice in the pool, but I don' have one. Any comments on accuracy requirements etc. ?

[DSRTEGL]

I would be concerned about the effect of recoil on the laser unit itself.........Most are not really made to handle jarring impacts like that.

[sancarlos]

DSRTEGL: Thanks for the input. The lasers in laser pointers are semicontactor type hence they don't really have any outside 'optics' (mirrors) - unlike gas or solid-state lasers. So SC lasers are very shock-resistant (remember all those laser sights for land guns? - the shook from the rifle is much more violent...) so the only consern I have is the mount of the laser - how sturdy it is. I finally assemble the unit and try it in the pool. Just like Sciencemike said the spear have about 2" deviation (group of 4 shoots @ 15 feet) and the drop of the spear at that distance is about 4" for my gun (Wong 55). I shoot with 2 bands out of 3 because I didn't want to damage pool plaster... In about a week I will go to the San Carlos, Mexico for a week and rest assure I will test my design to the death. I will also post the results...
Thanks everybody for the great discussion and inputs!

[sancarlos]

Hi, Here is the results on my spearfishing trip to San Carlos, Mexico with green laser mounted on the two spearguns interchangebly (JBL Special 48'' and Daryl Wong 60'' Hibrid).
1. The dot from green laser with about 5 mW output is only visible at about 6 feet in good visibility (40+ feet) sunny conditions. To use the green laser as a sighting device on any decent gun the outpus should be at least 30 mW, which pose some kind of problem since there is legal limit of 5 mW output in USA for class III lasers :-(.
Security and safety reasons.
2. The pointer should be really good sighted to match as close as possible the trajectory of the spear. In my case I don't want to spend a lot of time on preliminary test, hence the laser was mounted beneath the Wong gun, hence the distance between the spear and beam was about 4 inches hence I should remember to make that mental correction all the time and miss one fish when I forgot to do that.
3. Upper mount is a lot better since it almost automatically (just by adjusting the inclication of the laser) compensate for the drop of the spear (around 3 inches for Wong and about 6 for JBL). But again before whole thing start working lots of hours needs to be spend in the pool adjusting the sights.
4. On the distances around 6 feet it works great, take the guess work out of shoot. I hit the eye of the fish numbers of time, just to make sure that setup is working.
5. Cheaper guns (like JBL) bends a lot (I mean - a lot, good half an inch!) so setting up the pointer with those ones even more problematic on the longer ranges (15' and up).
6. Bottom line. Good gun give you almost the same capabilities. I miss 1 fish because of the laser and 3 (out of 3 dozen I shoot in a week) because the fish tear away. Total miss ratio: 1 because of laser, 1 of every 4-5 shoots without laser. Laser only make sence on the good guns, which are not bending a lot. It give you additional confidence to take the shoot though, since with laser I shoot almost every time I get the fish in sights (exept when it was in front of the rock), without laser I normally shoot only 2 out of 3 times because I'm not confident enough to take a shoot.
Lasers do make sence, but expect spend about 250-300 USD on the overall setup and some time on the designing and manufacturing mount system for laser. Again, it is a lot easier if your gun have a place for the top mount.
Don't forget to compensate for an additional weight of the laser....
Daryl Wong guns rules - it is the sweetest thing I handled under the water so far :-)
Have fun!

[jtkwest]

i would give up on this idea, at least as far as db is concerned. this is a very unpopular idea around here. i myself tried to gather info on this, and got into a battle with some very opinionated anti technology activists. VERY strongly opinionated. its kindof a cool idea, but isnt really practical, as it seems you have discovered. i wanted to explore the idea as an experiment,and was met with less than friendly comments. the rule on db is: you may only use technology that already is in use, or you are cheating and should be shunned. carbon fiber and pneumatics with dozens of moving parts are oksince they have been around a while . and dont give an unfair advantage. lasers are unfair and uncool. search out my threads on this. you will find like 9 pages of heated debate, and worse. quit now while you are a head. darryl wong guns are awesome. darryl also chimes in on the subject on my thread, check it out.

[sancarlos]

jtkwest, thanks for the reply.
I didn't experience of opinionated replies you described. I guess times are changing...
I did whole experiment out of curiosity and in loving memories of my earlier years in laser physics. I post my results just to provide some info for another poor soul who has burning desire to try new things. Next guy (or may be me next year) will move forward another step and eventually everybody who wants will have more or less cheap design to follow if they want to pursue the 'guided spearshaft' path. Same thing happens with land guns - laser sights are minority, only special forces uses them en masse, but they have their nishe...
Personally, I don't see why I couldn't spend another $200 on the device for the $1000 gun to sharpen the shaft less often :-).
Thanks for the support

[slingshaft]

Hey San Carlos, you can count me in on your exploration in the world of laser physics. I think that perhaps a pneumatic gun might be the perfect candidate for experimentation. PM me.

[chrismar]

jtkwest: It's not what you say, it's how you say it. Actually, it is what you say. If you show respect, be open-minded and add something positive, people will treat you by the same set of standards. I suggest popping off the high horse for a bit and rereading your post history.

As for the laser idea, the practicality is the limiting factor for me. In the green water with plenty of suspended particulate that we dive in here, the beam would be lost at the kind of ranges where it's needed. Until stronger/smaller/cheaper lasers come along, I'll leave this alone.

[Marwan]

JT..I think your last statement was a bit too general..in any idea you might find resistance or disagreement with someone, like what happened on the laser thread but that doesnt mean that DB as a community is against it or against technology by any means ... there is no one set of standards here, its an international forum, the only rules that exist are the rules that are posted and announced, and granted you, me anybody is bound to disagree with others on one or several issues and that ill be the case in any forum on any topic..as long as everyone is constructive and respectful there shouldnt be an issue
cheers