11/32 spears

[sharkey]

I have always just used 5/16 & 3/8 spears for little & big fish, but now the gap has been filled with these 11/32 shafts. Do I close the gap between 5/16 & 3/8 & just maintain half the guns forv 11/32, or do I increase my quiver by 33% & add more guns for 11/32 which are even more specialised? To be honest at my age I'm seriously thinking about just going with only 6' (1.8m) spears in 11/32 for all the blue water stuff in future. I never thought I would ever change from 3/8, but there you go, & also just to confound things, I landed some nice fish including tuna with 5/16 spears recently. What are everyones thoughts on spear diameters?

 

[popgun pete]

Like you I used either 5/16" or 3/8", mainly because those shafts sizes were all that was stocked in sports stores and dive shops, with dive shops turning their backs on spearfishing during the eighties as we were shunned as no more than cold-blooded killers. I even made my own 3/8" shafts out of stainless steel rod and welded on the line slide stop tabs and cut the wishbone and tail notches with a hacksaw and a metal file. However it looks like 3/8" shafts are not available with shark fin tabs, only wishbone notches, whereas 11/32" shafts do come with tabs, so maybe that will be a decider.

Riffe do offer a 3/8" tabbed shaft, I just checked their website, in fact I may have one in my spear store, but it came with a bunch of assorted miscellaneous spears sold on eBay and I have never used it.

 

[sharkey]

The 11/32 are about 150g lighter than the 3/8 spears, it's not much, but when I put one in one of my guns it did make it feel very floaty. I can fix that with some ballast on the gun & that along with the lighter spear would be even better with reducing the recoil. Will the extra speed give me more range & penetration than the heavier & slower 3/8 spear? I'm using sliptips on these & even though they claim to be 5/16, 11/32 & 3/8 the diameter of the point is still the same & its only the slide on the spear which differs. So the 11/32 still has to push through the same resistance as a 3/8 spear without having the extra weight. It's important to me because its hard enough to get opportunities on fish without making the wrong choices with gear. At 7m will the extra initial speed of the 11/32 perform better than the slower 3/8? On straight shafts is not so much of an issue, but when the slip tips appear to all be made for 3/8 spears it is when using them on thinner shafts.

 

[popgun pete]

I put this up on Spearboard, but you may find it useful here: http://www.spearboard.com/showthread.php?t=191937

Comparative shaft weights can be easily calculated for shafts made of exactly the same material and which are of the same length. The answers are obtained by looking at the ratio of the cross-sectional areas of the respective shafts. Now as a ratio is being used the value of pi will cancel out top and bottom, as will 2 for halving the diameter to obtain the radius r, so the answer will be simply derived by looking at diameter d1 and d2 in the expression (d1/d2) squared or d1 squared divided by d2 squared. As an example say d1 is 3/8 and d2 is 11/32, then if we use the same base 32 we have d1 as 12/32 and d2 as 11/32. That works out at 12 squared (144) divided by 11 squared (121) which is 144/121 which equals 1.19. For d1 at 3/8 and d2 at 5/16 we have 6 squared divided by 5 squared which is 36/25 which equals 1.44. In 32nds we could have used (12/10) squared or 144/100 which also equals 1.44. So you can see that these calculations are very easy, in fact almost trivial.

In order to restore shaft acceleration when using a heavier shaft the band storage energy needs to be increased by the same amount, however shaft surface area also increases and that affects drag in which case more power will be required to achieve the same flight speeds down range. However a shopping trolley hitting you which is empty will hardly make you move, but one which is full of beer packs will knock you down flat, so more mass and thus momentum are great provided you score a direct hit.

 

[sharkey]

Something similar I did a few months ago when I first got the 11/32 shafts. I just did it by sectional density, like we use for bullets. The SD for a 3/8 spear was 12.75 & didn't change much with a Riffe slip tip. The 11/32 was better with 13.2 for a straight shaft but dropped to 10.7 with the slip tip. The 5/16 was the best, at 14 in a straight shaft, but dropped way down to 8.9 when the slip tip was fitted. I don't dispute this but this is also comparing them at the same speed. I wonder just how much speed has to do with things & will that speed in the thinner spear make up for a lower SD? I recently shot a couple of tuna with 5/16 straight spears whilst looking for emperors in relatively shallow water with guns I would generally never consider fit for tuna. I strung a 34kg model first & on another shot strung a 50 kg fish & also penetrated a 35 kg GT from the school the tuna was swimming with at the time. Both the spears are totally stuffed but penetration at relatively close range wasn't a problem.

 

[popgun pete]

Generally heavy shafts keep their speed much better at long ranges. Niko Brummer did some tests many years ago with different diameter spears towing a marked segment shooting line so that a speed detector could count the pulses generated by the line markings as they whizzed through the detector's beam. The slimmer shaft was better for speed initially, then its velocity began to fall away as the heavy shaft caught up with it and the heavy shaft had much greater impact at the target down range. I used to have a graph from his testing showing the crossover point in the spear velocities and will post it here if I can find it.

 

[sharkey]

Cheers, that's just what I expected. The 11/32 fills the caliber gap nicely, but as long as I can shoot 3/8 spears comfortably I think I'll stick with them for tuna ATM. If I could find a slip tip that was scaled down to fit 11/32 better & keep the sectional density high I may consider them again especially for fish like kingfish & wahoo. I should mention I also still will occasionally use prangers on tuna, particularly when the Sharks are bad, & that's a whole other can of worms when considering spear diameter.

 

[popgun pete]

I just evicted the spiders from the spare shaft alcove in my garage and pulled out the dusty Riffe shaft which as soon as I lifted it out I knew that it was 3/8" diameter purely from the weight. It is 62" long and has three shark fins and a rest tab. I never used it because my big band guns (home-built) are all closed muzzle guns. I do have open muzzle band guns, but this spear is too long for them. I think it came with the old "Ultimate Double" speargun which I bought many years ago on eBay, however it is really too big for that gun which weighs a ton even with two 5/16" shafts in it. The gun has hoop muzzles, so maybe the shark fins might go through without hitting anything as a top shaft. I will not be trying it anyway as a "sinker" speargun is not much use to me.

 

[sharkey]

Here is a photo of what I took on a recent trip. The shorter spear & the one in the tri coloured gun are 3/8 , 69" all the others are 72". The 3/8 spears in the longer guns are now laying on the bottom with their sliptips somewhere in the Coral Sea & the 5/16 shafts with the floppers, leading against the wall were both trashed by tuna (used in the coloured gun), to their right are a couple of 11/32 shafts which I didnt get to use because they where borrowed by others when we started to run low on gear. The weather was bad, two east coast lows, but we still managed to fish & it glassed off on the last day. We boated about 40 tuna, but the sharks were red hot & vapourised twice that. To give an idea on how hard it was on gear, one morning after only three hours, the dory I was in needed to head back to the big boat to re rig, none of the eight guns we started with that morning were functioning. The bottom at this spot was 42m but the bommbies came up to 16m, the current was raging & all the tuna were sitting just up current of these. If you got your drift just right you were pretty well guaranteed to shoot one. If they made it into those bommies, that was it, good by spear. I went to a pranger in the afternoon. It was pretty amazing at this spot, 50kg GT's swimming right up to you on the surface, plus several other species of trevallies, big Maori wrasse & a few huge Qld grouper watching all the action. Made me question why I'd taken so long to go back there

, but something I am correcting, two trips back there already booked for next October & November.

 

[sharkey]

I should add that I borroed some 3/8, 72' spears from others on the trip to keep those two large guns going. Then I ended up lending one of those guns with the borrowed spear in it back to my mate after he got his smashed up on a very large doggy. It was a seriously good fish! I was hanging off the flashers & he was off to the south & several meters below me when it came in & he hit it. I saw it all clear as day, as we measured the viso above 72m at that time. It pulled two of the new riffe floats under like they werent there before finding something on the bottom to reef up on. Not all of us are believers in breakaway rigs & this is part of that cost. I still believe I would have lost more guns over the years if I was using them than they would have saved me. This is the conditions we had at that moment. It's hard to imagime better spearfishing than this, we could see fish on the bottom in 70m. That is the average depth here & the tuna seemed to like to hang in about 40m this day. Water temp was 29C & everything was very hungry. I saw yellowfin & sailfish also on this afternoon.

 

[popgun pete]

Yes, you need extra guns on a long trip and the simpler the better as they are easy to fix in terms of replacing bands or line, with sufficient "ammo", the spears! As long as spears are interchangeable, which means the same type of guns. I don't use euroguns and stick to square cut shaft tails.

 

[sharkey]

The flight restrictions kill us too. I will always book an extra 23kg bag, & can fit personal items like clothes in the carry on. What I will change for next time is fewer bungies, these are heavy things, & I would rather take a couple of extra spears in future. On this type of diving the bungies were actually more of a pain than an asset. I think a short one at the float end, is about max, & try to slow the tuna up as soon as possible with large floats. I'm still trying to finish these demultiplied guns (might be another week now) they will be high maintenance too I reckon if they do work, but if they give an extra meter of range I might chance bringing them out there next year.

 

[sharkey]

Well I took the gamble & went on a trip with 1.8m, 11/32 spears with slip tips. They are ok for the diving I do for fish to 50kg & I managed to land a couple of respectable fish, but lost a few in the 80-90 kg range. I cant help but think the extra punch from 3/8 spears would have made the difference, particularly on one fish in the 90 kg range.

 

[behslayer]

Slob Doggie. One trick is to Neck Down the 11/32" to 5/16" for 3-4" at the tip and use a 5/16" threading. Then you can use a 5/16" Slip Tip and Slider with less to push than the 3/8".

 

[sharkey]

Slob Doggie. One trick is to Neck Down the 11/32" to 5/16" for 3-4" at the tip and use a 5/16" threading. Then you can use a 5/16" Slip Tip and Slider with less to push than the 3/8".

Top idea! I will certainly do this. I'm a bit old school & still recall the days we used to land the big dogtooth tuna with prangers, their heavy punch really seemed to visibly effect the fish. Last week I had the fish I really wanted on her side & shaking , I was even able to grab the rig line on my way up to the surface & start to put some pressure on her in the hope of getting past the Sharks intact. The spear must have been touching a nerve or something because as soon as it came back a bit & the cable was against the spine instead of the spear she came to life again, I can't help but think a 3/8 spear would have made just that little bit of difference. There is only 15% difference in weight between the 11/32 & 3/8 spears however I can't help but think the energy delivered at seven or eight meters is much greater than this.

 

[behslayer]

Yes, I remember growing up that the right way to hunt Doggies was using a Pranger, because that was your best shot at paralyzing them, and otherwise you were going to lose them and your gear.. Which proved true on many occasions for me. I've lost several complete set ups of Slipt TIp, Shaft, Nice Riffe Bungees, and Floats to those brutuses. In Indonesia, once they got the Float down and into the currents.. sometimes they just did not surface again. I like the looks of that Blue Gun. To be honest the Shaft looks a little long, but I like the Belly on that thing. I've done quite a bit of testing with different configurations of shafts, bands, on mid handles. It's amazing how dropping a diameter, ie from 11/32" to 5/16" or from 3/8" to 11/32" can effect the felt recoil. Similarly shaft length on a similar diameter can effect. Relatively small difference in mass ie 100gr. Can very much effect the felt recoil of a gun as can changes in band diameter, band %, Band #, and also changes in gun mass ie adding a Big Reel, wings, etc. You look like a Big dude, and Diver Mass, and Style, as well as a divers Recoil tolerance can all effect performance of a configuration on a platform as well. But, there is always a sweetspot.. and Recoil is the Great Robber of Range and Accuracy. I'm certainly not telling an Old Salt who's lugging around a stack of 50KG+ Doggies what to do. Just sharing some of what I've learned in general terms.

 

[sharkey]

Slob Doggie. One trick is to Neck Down the 11/32" to 5/16" for 3-4" at the tip and use a 5/16" threading. Then you can use a 5/16" Slip Tip and Slider with less to push than the 3/8".

I did this & your advice was excellent. Thank you! Its only a baby but the first shot at a fish with the new 11/32 spears & 5/16 slip tip (the ones on the left of photo) was a success.

 

[Bill McIntyre]

For what its worth, I like the necked down shafts. I have 11/32" necked down to 5/16" and 5/16" necked down to 9/32". It replaces the need for tape on the shaft to keep the slide ring from being jammed by scales or meat holding the Spectra tight and keeping the tip from deploying.