RA Caranx
Printed From: The Fishing Website
Category: Diving
Forum Name: Spearo's Corner
Forum Description: Free-divers & spearos chat about their sport
URL: https://www.fishing.net.nz/forum/forum_posts.asp?TID=65699
Printed Date: 05 Aug 2026 at 8:37am
Topic: RA Caranx
Posted By: Gundry
Subject: RA Caranx
Date Posted: 04 May 2011 at 12:24pm
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So its time to buy my second gun and all im hearing is good things about the Rob Allen Caranx. My first gun was a 100 Rob Allen so thinking of going for the 120 Caranx as second gun. Is this a pretty logical step up or would people reccomend bigger? Im pretty much sold on the gun was just wondering What you people would reccomend as the set up? Should I put 1 x 20mm rubber on it ? im 6 foot 3 and 93 kgs so with the right technique im sure loading it wont be a problem. Or is double rubbers the way to go? Just after some feedback before I make my final decision and purchase it. ------------- Winter is Meh |
Replies:
Posted By: herby
Date Posted: 04 May 2011 at 12:26pm
| Go for it. Single 20. |
Posted By: Gundry
Date Posted: 04 May 2011 at 12:34pm
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Hey was jsut reading the thread about tropic blue water diving and was wondering if maybe a 130 was not a better option for being adequate should the opprutunity arrise to dive over there, or is this really jsut a lot of extra gun to be draggin around with you in Nz waters.
------------- Winter is Meh |
Posted By: spearbean
Date Posted: 04 May 2011 at 12:35pm
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bit of a hijack, freedivers 120 Odyssey or RA 120 Caranx? Looks like the RA had metal mech rather than plastic but have used freedivers 110 and I like it. Pros/cons.. or much of a muchness
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Posted By: herby
Date Posted: 04 May 2011 at 12:43pm
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Depends if you want a quality gun..... or a toy. |
Posted By: SharkBite
Date Posted: 04 May 2011 at 1:19pm
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Gundry you have now created yourself a 120 verses 130 dilema. It is time someone invented a telescopic gun so such dilemas can be solved. The tube is doable but f**ked if I know how to invent telescopic rubbers! ------------- "There goes another moocher" |
Posted By: Gundry
Date Posted: 04 May 2011 at 1:20pm
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Haha yeah thats where im at aye pretty keen on Gun and I thnk single 20mm rubber its just a matter of do I go for the 120 or 130 I think I should be big enough to weild a 130 I reckon alright its just a matter of is it really a bit overkill and not neccesary or what. ------------- Winter is Meh |
Posted By: Ces
Date Posted: 04 May 2011 at 1:26pm
| go for the caranx!spearbean, you can give my caranx a go next time we go for a dive |
Posted By: Gundry
Date Posted: 04 May 2011 at 1:32pm
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Hey what size Caranx do you have Ceaz and how do you find it ? ------------- Winter is Meh |
Posted By: Keeweebee
Date Posted: 04 May 2011 at 1:34pm
| Caranx. Nuff sed. |
Posted By: Ces
Date Posted: 04 May 2011 at 1:37pm
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got a 120, which really is a bit overkill in welly, but it's nice to know you have the extra range/power should you need it. i like it a lot, going from a 100 freedivers to the 120 caranx wasn't that hard, the 1st time i loaded it it took me a couple of attempts, but no issues now. i think it's got a single 20 (mjl would prob know better). can't wait to take it to theGBI!
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Posted By: SharkBite
Date Posted: 04 May 2011 at 1:41pm
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Well the RA Carbons1100, 1200 and 1400 all seem to shoot pretty straight for me so there is no reason why the 1300 would not have the same qualities. Definitely more power available the higher up the range you go. I would say my 1400 hits the fish with about twice as much force (F=ma) as my 1100, well maybe not twice as much but it is a very noticeable increase. Recoil I don't even notice it on any of the RA's ------------- "There goes another moocher" |
Posted By: Qaz
Date Posted: 04 May 2011 at 1:58pm
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Had a Freedivers 110 , didn't really like it. Got a 130RA Caranx and it's a bloody good gun , Single 20 - a lot of power. Accurate as... As herby said - it's the difference between a gun and a toy. ------------- http://www.gladiatormarine.co.nz/ A fisherman is a jerk on one end of the line waiting for a jerk on the other. |
Posted By: chains
Date Posted: 04 May 2011 at 2:09pm
| I have used a freedivers 120 a couple of times and found the handle really small and uncomfortable, have used a cranax a few times too, it was real sweet |
Posted By: Kona.
Date Posted: 04 May 2011 at 2:16pm
| I have that exact gun you're looking at getting, we can swap for a few dives if you want if it'll help you decide... not like Im shooting anything, I suck balls. Txt me and Il give you a buzz about it. |
Posted By: herby
Date Posted: 04 May 2011 at 2:18pm
| same here gundry, if im not going out and you are, you're welcome to take it for a whirl |
Posted By: Gundry
Date Posted: 04 May 2011 at 2:19pm
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Hey Qaz out of interest how tall are you? Im guessing then you dont have any problems with it as far as size goes then. Might be that the 1300 is looking more like the goes. ------------- Winter is Meh |
Posted By: Azazel
Date Posted: 04 May 2011 at 2:25pm
http://www.c4carbon.com/joker410.aspx - http://www.c4carbon.com/joker410.aspx
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SharkBite wrote:Posted By: bigbrett
Date Posted: 04 May 2011 at 4:00pm
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Freedivers are just a copy of the RA guns - not a bad gun, but the RA is def the way to go - my mate has a 120 Caranx with a 7mm sliptip and 2 16mm rubbers - it does the business on kingis!! ------------- Also known as "Dory Rider" |
Posted By: Qaz
Date Posted: 04 May 2011 at 4:25pm
About 5"11 .999999999  I've used a Alloy 130 and to be honest that was a pain to haul around when 'Trying' to snoop , but the 130 Caranx felt like the same as carrying a 120 to be honest... I was surprised. Gave Keeweebee a go with it on a dive and he can vouch for how easy to move around it was.
They did a pretty bad copy then.... ------------- http://www.gladiatormarine.co.nz/ A fisherman is a jerk on one end of the line waiting for a jerk on the other. |
Posted By: Kinabal Lector
Date Posted: 04 May 2011 at 4:35pm
| dont worry bout height cam carter uses a 140 rob allen and is not the tallest. one rubber definitley. Ive got a wettie 120 alloy and its great and simple but the ultimate plan is to make it a reel gun for shore and kayak diving and get a rob allen 130 for offshore and kingy chasing or anywhere floatlines are not going to be a pain. Its hard not to go rob allen on this forum even though ive never used one. |
Posted By: Nick.
Date Posted: 04 May 2011 at 4:36pm
| ive got a RA1.1 and a RA1.4 so a 30cm increase for a 2nd gun for your big fish to a 1.3 would be fine. |
Posted By: bigbrett
Date Posted: 04 May 2011 at 4:37pm
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[/QUOTE] They did a pretty bad copy then.... [/QUOTE] It's a case of you get what u pay for - my next gun is gonna be the RA Tuna, pity I'm getting it in October, AFTER the GBI trip! ------------- Also known as "Dory Rider" |
Posted By: Nick.
Date Posted: 04 May 2011 at 4:39pm
4 guns for the price of ummmmm well, probally 4 normal guns! |
Posted By: tab47
Date Posted: 04 May 2011 at 5:16pm
They did a pretty bad copy then.... [/QUOTE] It's a case of you get what u pay for - my next gun is gonna be the RA Tuna, pity I'm getting it in October, AFTER the GBI trip! [/QUOTE]From SA? |
Posted By: Unclejake
Date Posted: 04 May 2011 at 5:16pm
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Posted By: Azazel
Date Posted: 04 May 2011 at 5:21pm
It's better than their usual one gun for the price of four...
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Posted By: SharkBite
Date Posted: 04 May 2011 at 5:21pm
Fair enough but don't actually need a slip tip even for kings 'cause they can be a real pain to extract from the fish. No fish will bend a RA sprung shaft and anyway it gives you something to hang on to and steer the fish towards the surface ------------- "There goes another moocher" |
Posted By: spearbean
Date Posted: 04 May 2011 at 5:23pm
Have used my freedivers 1.1 yellow handle for some time, when I got new rubbers I noticed they were a bit long and weak so decided to put a shoter 18mm band on it and its really good, just wanting something a bit bigger for the GBI trip. So I guess Ceaz I will have to give your RA a whirl. Maybe go carbon |
Posted By: Unclejake
Date Posted: 04 May 2011 at 5:25pm
| ^ I will be using my 1.1 for GBI mate. It is a perfect size for snapper snooping IMHO. You hit a lot of rocks when shooting through snapper. |
Posted By: spearbean
Date Posted: 04 May 2011 at 5:30pm
| ^ I am also working on a new woodie so if I get my ass into gear that should be ready by then... hahah |
Posted By: spearfisher916
Date Posted: 04 May 2011 at 5:42pm
Advice from UJ received during Feb GBI to snapper virgin (me)
"shoot anything that moves and ID later" Fortunately it did'nt come to that.
"shoot the sucker then let go of everything" ....saved my first fish
"all my snapper I shot from the surface", which explains the rocks^^ Two outta three of mine were shot from the surface and I did hit rocks behind.
I used a 115 and it was really nice for the conditions up there, good range and reasonable targeting speed, though if I had a 100 I think I could have nailed another decent snapper which scooted past close in and too quick to track...
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Posted By: Mullins
Date Posted: 04 May 2011 at 5:59pm
I've always wondered what a 'sprung' shaft was....
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Posted By: bigbrett
Date Posted: 04 May 2011 at 6:15pm
It's a case of you get what u pay for - my next gun is gonna be the RA Tuna, pity I'm getting it in October, AFTER the GBI trip! [/QUOTE]From SA? [/QUOTE] Yeah going back for a mates wedding and seeing as its my bday 2 days before thought I would spoil myself with a RA Tuna :) ------------- Also known as "Dory Rider" |
Posted By: Besty.
Date Posted: 04 May 2011 at 6:58pm
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RA 120, great gun for nz. like a hilux, simple, does the job. I have a couple, one with a reel, one without for comps.
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Posted By: The Jackal
Date Posted: 04 May 2011 at 7:39pm
Good Call
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Posted By: fish food
Date Posted: 04 May 2011 at 10:07pm
| Id get a RA 130 still good for snapper and weedlines plus you got a gun to go tropical as well as kingys. |
Posted By: Gundry
Date Posted: 05 May 2011 at 8:07am
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Sweet well will shoot by WB tonight and check the 120 and 130 out have a bit of a gander at I guess 30cm is not really that much of a size increase so yeah might be the goes.
------------- Winter is Meh |
Posted By: TG
Date Posted: 05 May 2011 at 9:33am
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Bigbrett, Just make sure you notify them of the gun before boarding the flight. All the guys on here always note that you declare it as fishing gear, I've had issues both times with both my guns from there. The xrays the box and on an xray the speargun looks like a surface to air gun, F### me. Had my mate in a special forces van with machine guns and the box containing the gun so he could open it with guns pointed at him. What a mess mate. Flight was delayed and all. On the gun side Gundry, I'd go for the 120 and when you really want to do blue water stuff, get a bluewater woody for the job. ------------- TG http://mondoedge.com http://twitter.com/mondoedge http://facebook.com/309681785793 "Of all the things I lost, I miss my mind the most" |
Posted By: SharkBite
Date Posted: 05 May 2011 at 11:49am
I know you have just been (to the tropics) but obviously you had no sprung there. ------------- "There goes another moocher" |
Posted By: Paul M
Date Posted: 05 May 2011 at 1:55pm
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[QUOTE=SharkBite
Fair enough but don't actually need a slip tip even for kings 'cause they can be a real pain to extract from the fish. No fish will bend a RA sprung shaft and anyway it gives you something to hang on to and steer the fish towards the surface /QUOTE]
Gotta call you on this one mate, even a relatively small King can and have bent RA spear's before, especially if you shoot them wrong. Or were you talking snapper
 |
Posted By: SharkBite
Date Posted: 05 May 2011 at 2:21pm
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Interesting call. I'm talking Kings nothing else. I used to use only stainless steel shafts. They kept getting bent. Often. Annoying. So I changed to hardened-spring-steel-shafts (no slip tip). I've shot plenty of kings since and I can't say I've bent a shaft by hanging onto it. I don'tr let the fish make it down into the rocks though is that when the bend happens maybe? BTW how do you shoot a king wrong exactly? ------------- "There goes another moocher" |
Posted By: Zambezi
Date Posted: 05 May 2011 at 2:28pm
You miss it ------------- A man’s comfort in life can be measured by the quality of the toilet paper he uses to wipe his arse. |
Posted By: _Jimmy_
Date Posted: 05 May 2011 at 2:29pm
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3 pages?
just get a RA120 and be done with it.
the only people that still moan about or question their equipment are the people that bought something else.
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Posted By: TG
Date Posted: 05 May 2011 at 2:38pm
 @ Jimmy
------------- TG http://mondoedge.com http://twitter.com/mondoedge http://facebook.com/309681785793 "Of all the things I lost, I miss my mind the most" |
Posted By: SharkBite
Date Posted: 05 May 2011 at 2:57pm
9.5/10 ------------- "There goes another moocher" |
Posted By: Rusky
Date Posted: 05 May 2011 at 3:20pm
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Make it 4 pages.
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Posted By: spearbean
Date Posted: 05 May 2011 at 3:27pm
| worth spending more for it to be carbon? |
Posted By: Smoo Diver
Date Posted: 05 May 2011 at 3:58pm
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^^I'm not sure it will get to four pages. What do you guys think? |
Posted By: Unclejake
Date Posted: 05 May 2011 at 4:00pm
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Hard to say Smoo
Carbon or nah? I think this answer depends on gun length SBean
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Posted By: Qaz
Date Posted: 05 May 2011 at 4:24pm
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I had my 110 FD , they got my 130 Ra Caranx , and it feels only the slightest big longer than my 110. Thought it'd be a big difference, But I've tried an Alloy 130 and it felt Way longer. Carbon made a lot of difference I reckon. ------------- http://www.gladiatormarine.co.nz/ A fisherman is a jerk on one end of the line waiting for a jerk on the other. |
Posted By: bigbrett
Date Posted: 05 May 2011 at 4:41pm
Good call mate I am sure I with my good looks ( I ALWAYS get pulled up by airport security!!) i will have plenty of problems - but it will be worth it!! ------------- Also known as "Dory Rider" |
Posted By: spearbean
Date Posted: 05 May 2011 at 4:54pm
120.
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Posted By: Unclejake
Date Posted: 05 May 2011 at 4:59pm
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IMHO? If you can afford it and won't miss a dive trip because of the expenditure then go carbon. They are much lighter and less tiring to dive with over a long period |
Posted By: Diver Dan
Date Posted: 05 May 2011 at 5:04pm
| There are many ways to hit a kingfish wrong. You are most likely to bend a shaft on a kingy when you shoot it coming towards you. I find shooting them as they leave effective - much less tearing. I am starting to favour a solid head shot, depending on circumstances. Tail shots can be very effective too. |
Posted By: Qaz
Date Posted: 05 May 2011 at 5:22pm
Tried to stone a big kingy up at north cape this summer , spear only just went into the gill plate and ripped out after a 5min fight was only around 5-6m deep kept trying to go to the bottom bent my shaft and flopper..... was close ranged and didn't got through with 110 20mm - Was 
------------- http://www.gladiatormarine.co.nz/ A fisherman is a jerk on one end of the line waiting for a jerk on the other. |
Posted By: herby
Date Posted: 05 May 2011 at 5:27pm
| Loser!! |
Posted By: Zambezi
Date Posted: 05 May 2011 at 5:38pm
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does having a super sharp spear make a diffrence?
------------- A man’s comfort in life can be measured by the quality of the toilet paper he uses to wipe his arse. |
Posted By: herby
Date Posted: 05 May 2011 at 5:49pm
| yes |
Posted By: Diver Dan
Date Posted: 05 May 2011 at 5:58pm
| Definitely. Most kingies are lost through not keeping them out of the rocks, or shooting from long range (no penetration |
Posted By: Mullins
Date Posted: 05 May 2011 at 5:59pm
| Or bad vis |
Posted By: -Luke-
Date Posted: 05 May 2011 at 6:16pm
Heres a few pics to do the guns Len uses justice on this thread.          Tough toys.
------------- www.aquaticrehab.co.nz |
Posted By: Eric de Vries
Date Posted: 05 May 2011 at 6:21pm
I made that mistake once (gill plate shot). Now I only go for solid body shots along the lateral line or slightly above if possible. No hail mary shots unless I can secure it. They can make a hell of a mess of your gear if not kept of the rocks. ------------- http://www.southernbluefins.co.nz/ |
Posted By: Diver Dan
Date Posted: 05 May 2011 at 6:46pm
| Gill plates aren't great, but a head shot higher up is good. Great comeback Luke - I have never used a Rob Allen, and believe they are good, but I have actually managed to shoot fish with a Freedivers gun. I find they shoot straight, but are a bit heavy for my puny wrists! I have used them in 3 Nationals. Still not a Viper though |
Posted By: Qaz
Date Posted: 05 May 2011 at 6:52pm
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Luke? I hit a nerve there? ooooo!  People are allowed to state there opinions on this 'Jokle ass' thread... We are simply comparing guns - I PERSONALLY don't like my Freediver? Got a problem with that...? Never said it was a Sh*t gun. Have you ever tried a Caranx? ------------- http://www.gladiatormarine.co.nz/ A fisherman is a jerk on one end of the line waiting for a jerk on the other. |
Posted By: Unclejake
Date Posted: 05 May 2011 at 6:57pm
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You said it was a bad copy of the RA. I disagree. I will not lend you my Riffe if you are mean Qaz. So there. |
Posted By: fish food
Date Posted: 05 May 2011 at 6:58pm
| What is the fish in the fifth photo up from the bottom?. im guessing its south african? I've stoned 4 kingys in the head this summer with my trusty 100 love that gun. |
Posted By: long john
Date Posted: 05 May 2011 at 7:02pm
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It's a musselcracker, broo.!!!!! ------------- Proud member of the Glen Innes Spearfishing Club |
Posted By: Qaz
Date Posted: 05 May 2011 at 7:04pm
I'm sure you know my opinion on wooden guns.I've found one thing that they have in common between my FD and RA is how they are both near-unbreakable....  aannnyywayyyy..... ------------- http://www.gladiatormarine.co.nz/ A fisherman is a jerk on one end of the line waiting for a jerk on the other. |
Posted By: fish food
Date Posted: 05 May 2011 at 7:05pm
| looks like asilver drummer cross snapper... thats laka. |
Posted By: -Luke-
Date Posted: 05 May 2011 at 7:10pm
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I don't have a problem with you not liking your own gun. No have never used a caranax probably because I only spear once or twice max a month. Either using a free divers 120 which is a luxury to use or a polespear. Any large gun manufacturer that lasts in a country like SA with such insane spearfisherman has to be good. Both RA and FD. Mind you most of the time its not even the gun. ------------- www.aquaticrehab.co.nz |
Posted By: -Luke-
Date Posted: 05 May 2011 at 7:14pm
Yeh white musselcracker bru. I don't have any pics of his black musselcrackers... They are beasts. ------------- www.aquaticrehab.co.nz |
Posted By: bigbrett
Date Posted: 05 May 2011 at 7:39pm
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I would just like it noted I never said Freedivers were a bad gun I just said they were a copy of the RA - my mate who like me is from SA has been spearfishing for over 10years and his comments me were that Freedivers are just as good as RA - their models are just older as they are not allowed to copy the latest RA guns. Nuff said ------------- Also known as "Dory Rider" |
Posted By: Besty.
Date Posted: 05 May 2011 at 10:25pm
| whats the external diameter on the RA vs FD? VS something like picasso. might be worth thinking about how easy they are to move? |
Posted By: Qaz
Date Posted: 05 May 2011 at 10:49pm
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My Caranx 28mm ish External diameter , FD is 30mm This isn't 100% accurate just looked at the tape measure and putting a straight edge to the barrel to go off. Both different length guns , but I've used a 130 FD and my 130 Caranx is easier to move - as stated previously. Wouldn't mind trying a 130 Picaso carbon to be honest. Narrow it down to be souly the Carbon or external barrel diameter that's most effective with movement. Anyone with a picasso? your turn. ------------- http://www.gladiatormarine.co.nz/ A fisherman is a jerk on one end of the line waiting for a jerk on the other. |
Posted By: _Jimmy_
Date Posted: 06 May 2011 at 5:40am
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Luke. I like your post with the fish. It's great. I wonder what would happen if someone tried to post all the fish shot with a RA120 ? I would say the server would crash before it even got to uploading 1% |
Posted By: Keeweebee
Date Posted: 06 May 2011 at 7:56am
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Yeah, nice photos Luke, It's kind of hard to take your words seriously though when you are fiercly promoting a gun that you used to sell and when you use an example like Len de Beer of how awesome these guns are. I.e, I think it might be the diver that's awesome in this case.
There seems to be a strong followiing of people that prefer RA on here, mainly because most of them have tried both to compare so deal with it.
p.s Dont hate on Qaz because he seems like an easy target, he is young and has strong opinions on things- good on him. I think we can all vouch that we have been there.
 |
Posted By: Fishoholic
Date Posted: 06 May 2011 at 8:19am
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First gun a FD 120, after a year had shaft and rubbers upgraded this made the world of difference. No more bent spears on kings, gun was great dealt to anything. With a few more years experience I do note I was not using the best technique when landing kings back then (no angle on my shot) That gun was stolen, now I have a RA Caranx fantastic gun first three shots of the gun resulted in 3 good fish just a few weeks back. Also I like how the barrel is attached to shaft, looks a hell of a lot stronger.
But I guess it harks back to how one uses their equipment at the end of the day.
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Posted By: SharkBite
Date Posted: 06 May 2011 at 9:41am
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Regarding the gun length debate its more about the spear. eg 140 Carbon raw Gun weight difference is miniscule against a 120 Carbon (I'm saying without the spear in it!). Most of the difference is accounted for by the weight (mass) of the longer shaft (an extra 30cm of steel weighs a LOT more than an extra 30cm off carbon tube). Stating the obvious really but a second factor is to consider whether you go to a second rubber of not (eg Caranx vs Tuna) rubbers do add power (acceleration) but at the cost of bulk. Remember F=ma. Ah its all common sense, the least common of the senses ------------- "There goes another moocher" |
Posted By: Mullins
Date Posted: 06 May 2011 at 10:08am
| Erm, what does weight have to do with it? |
Posted By: SharkBite
Date Posted: 06 May 2011 at 10:13am
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Weight of Gun? Nothing. Weight of spear - iinflicts more hurt (force) to the fish. F=ma ------------- "There goes another moocher" |
Posted By: Mullins
Date Posted: 06 May 2011 at 10:26am
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Oh, with you now. Naa if you just increase the mass (m), then acceleration (a) drops correspondingly because F stays the same. If you want more force, you just need more rubber stretch. So it's mainly about barrel length and rubber thickness, not spear weight.
Of course, rubbers probably have a terminal velocity, which is where spear length/weight comes in. There's also the question of sectional density and other ballistic stuff, but that's not related to the F=ma equation.
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Posted By: Unclejake
Date Posted: 06 May 2011 at 10:29am
| *Sigh*..... if only they made a wooden Viper we could stretch this thread to five pages |
Posted By: SharkBite
Date Posted: 06 May 2011 at 10:40am
We are in heated agreement...disjointed conversations online are not a proper conversation. By increasing gun length you are effectively increasing kilogram meters per second (which is in all likelihood is a result of an increase in both m and a). So I am really thinking about a change in F between guns rather than within a single gun...at least I think that is what I am thinking about... ------------- "There goes another moocher" |
Posted By: SharkBite
Date Posted: 06 May 2011 at 10:41am
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sorry thats kilogram meters per second per scond ------------- "There goes another moocher" |
Posted By: SharkBite
Date Posted: 06 May 2011 at 10:42am
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I mean second ------------- "There goes another moocher" |
Posted By: SharkBite
Date Posted: 06 May 2011 at 10:43am
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I mean the second scond is second not scond ------------- "There goes another moocher" |
Posted By: Unclejake
Date Posted: 06 May 2011 at 10:46am
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Just to your right there is a Post Options button. You can edit your own posts if you want to.
Justsayin :-)
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Posted By: Mullins
Date Posted: 06 May 2011 at 10:53am
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Yeah, spear weight is kind of irrelevant though, no? Because F is directly related to rubber stretch and a adjusts itself accordingly whenever F is changed. Was just responding to that bit about 'it's spear length/mass that makes the difference' 'cos I reckon it's one of the less important variables. Meh. Freedivers guns... used a 120 and it shot well, nice and quiet - but the barrel flexed like a b*stard with a tight 20mm rubber on it. Had a big overhang, which I like. More m, you see.... |
Posted By: SharkBite
Date Posted: 06 May 2011 at 10:53am
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Ta. I think I'll quit while I'm still coming ------------- "There goes another moocher" |
Posted By: mjl
Date Posted: 06 May 2011 at 10:59am
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Ummmm, for fear of the inadequacies of my school c maths being shown up I'm not going to try and get into the physics of it but my understanding of how hard a spear explodes a fishs head is, I think, along the lines of what Dave's saying.
Basically more rubber stretch and speed = good, more spear weight = meh
------------- "It was the Law of the Sea, they said. Civilization ends at the waterline. Beyond that, we all enter the food chain, and not always right at the top. " Hunter S. Thompson |
Posted By: SharkBite
Date Posted: 06 May 2011 at 11:05am
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Could we use carbon fibre spears then? In other word what about momentum?Dave? ------------- "There goes another moocher" |
Posted By: mjl
Date Posted: 06 May 2011 at 11:35am
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I'm sure there is a balance there somewhere. But yes - there are/have been carbon fibre wrapped shafts before. They are much lighter than usual but super stiff so didn't whip at all - very fast and very accurate. Want to have some guesses at how much they cost?
------------- "It was the Law of the Sea, they said. Civilization ends at the waterline. Beyond that, we all enter the food chain, and not always right at the top. " Hunter S. Thompson |
Posted By: baffled
Date Posted: 06 May 2011 at 12:08pm
| Wouldnt want to shoot a rock with one... |
Posted By: Mullins
Date Posted: 06 May 2011 at 12:29pm
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Sharkbite - yeah you could use pure CF spears (in terms of the equation, acceleration would be much higher and F would stay the same) but then you run into two problems:
- rubbers probably have a terminal contractile (?) velocity that isn't all that high, so there is a practical limit placed on acceleration
- the spear would have rubbish sectional density, so friction would be very high proportional to mass. Plus the high speed would further increase friction, because friction increases exponentially with speed, not linearly.
So they'd be crap, especially at long range. The extra stiffness might help though.
For ballistic purposes (note ballistics is outside the scope of the F=ma equation) you'd ideally want a very thin, very dense and very stiff shaft. Osmium coated with tungsten?
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Posted By: chalkeye
Date Posted: 06 May 2011 at 1:57pm
Like mine. I'll do you another for $1k - mates rates. ------------- float like a crowbar, sting like a bee |
Posted By: Ergo_Rapido
Date Posted: 06 May 2011 at 4:11pm
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I suspect kinetic energy or momentum would be a rather better way to look at the hitting power of a spear - that and elastic potential energy (=1/2kx^2) for how much energy you'll get out of your bands... PS (k is spring constant, how hard it is to stretch basically, and x is the stretched distance) ------------- Chuck Norris will never have a heart attack. His heart isn't nearly foolish enough to attack him. |
Posted By: bigbrett
Date Posted: 06 May 2011 at 5:16pm
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damn this has evolved into a higher grade maths/physics debate :) ------------- Also known as "Dory Rider" |
Posted By: herby
Date Posted: 06 May 2011 at 5:21pm
| Nothing quite like a good old maths debate |
Posted By: Diver Dan
Date Posted: 06 May 2011 at 5:22pm
Hmmm, wooden viper - now there is an idea! (heading downstairs to the garage)
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