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Notched or fin shafts

Thread Status: Hello , There was no answer in this thread for more than 60 days.
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Apr 6, 2020
Hi folks , what is the pros and cons between the notch and fin shafts ?
I used to worry that the notches in my slim Omer 6.3mm shafts might weaken the stainless steel spears - the notches seem significantly deeper than the polished notches on my old 6.6mm RA spring steel spear. I also smoothed and polished the sharp edged Omer notches to work with the Dyneema wishbones that I fitted without cutting them. But for the fish I deal with, they are plenty strong enough. If you are going for 500lb Tuna or Marlin, your spears will be thicker to start with, so even then...

I bought 2 new Apnea spearguns near the end of last year, one smaller than my main Omer XXV spearguns and one longer. I haven't had a chance to try either yet and, with Corona virus not yet peaking here in the UK, unlikely to for some time. I wanted to try sharkfins and both new Apnea speargun have sharkfins, I wanted to try them. I figured they would be stronger. But the first thing that struck (esp. as I has just read a thread on spears and spear velocity on the DeeperBlue.com forum) is that a raised fin or pin will inevitably slow the spear somewhat due to increased drag and probably a significant amount. So the extra power of the double 14mm bands of the smaller speargun and the roller of the larger speargun will be somewhat offset by the raised sharkfins and heavier 6.6mm spears (the fins themselves will also add weight to the thicker spear). Some say the weight and thickness of the spearline can also affect the speed of the spear significantly, that it affects it is no surprise but significantly? No so obvious to me.

Like so many of these things, you need to balanced several factors and make the best choice for your personal circumstances.

In practice, for most fish, I think it makes little difference, provided other factors (spear diameter, power of the speargun in relation to the spear, etc.). For big game fish, perhaps fins are better being stronger but I have a feeling that a lot of world records were probably caught on Rob Allen or Rabitech railguns with notched spears. But if huge fish are your target, perhaps fins and, perhaps, a slip-tip or Rob Allen's fancy new drop barb would be the way to go? It's extra expense, mass, complication and loading effort/time if you don't really need it though.


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Thanks , will be mostly along the east coast of Scotland with the odd trip over to the west . Was mostly curious about the difference between them .
Personally i prefer shark fins when using dyneema wishbones as i like to use 3mm diameter and that size is a really tight fit in most notches !
When i first stared spearfishing, i once shot a plaice lying on the sand and my notched spear snapped in half at the notch!
However that is the only spear i have ever had fail on me in 45 years, i have never shot into the sand since and only hand spear flatfish.
i think both styles of spear are perfectly fit for purpose.
Both types of spears have pros and cons. I associate sharkfins with heavier spec. Spearguns intended for bigger big fish. But clearly they are not essential for big fish. U also associate them with dyneema or, occasionally, steel cable wishbones.

I think all my spearguns now have 1.8 or 1.9mm dyneema wishbones. They can last indefinitely if your spear notch grooves are smooth and they don't get snagged. It is quite normal to get several years use out of them. But 3mm dyneema would obviously be even more robust but as Foxfish said, probably only suitable for sharkfins or pin-fin spears.

For Scotland, either should be fine. We have at least one member in the Orkneys and they do get a few very big fish up there. I watched an old Jack Hargreaves Out of Town video last week where he visited some Orkney anglers who were also professional fishermen. They were the 100 club, membership requires catching a 100+lb fish, which they did regularly. Looked like hard work landing them!
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Thanks for the info , was curious as to the difference . Will be swapping out the metal wishbone on the gun when it arrives . I’ve got 1.5mm and 2mm dyneema, what do you recommend I use ?
I'd try the 2mm and see how it fits in he notches. If it's tight, probably best to go with the 1.5mm I would think. Rope/cord diameters are nominal, the actual diameter and hardness/softness can vary considerably. The 2mm might work fine.

I tend to use and re-use Rob Allen beads at the end if my wishbones. I think that might be the limiting factor for me. Although I think I tried 2mm and found it a bit too tight in my spear notches - can't recall if that was my 6.6mm RA spear or 6.3mn Omer spears, the notches are quite different.

Another forum member suggested using your own knotted 2mm dyneema loops instead of beads and just sheet-bend a 2mm dyneema wishbones between them. Makes changing wishbones quick and easy too. As long as it fits your spear notches. I will probably try that next time. Indeed, my new Apnea spearguns come factory equipped with something similar (possibly 1.8mm dyneema though) - but they have sharkfins rather than notches, so would likely work with almost any diameter of wishbone dyneema.
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Thanks Mr X ,
everything should arrive today . Will see what diameter fits best . Great tip about dyneema loops , will use that
The weather here is wonderful this Easter. Would have been a great weekend, week, fortnight, month even, to go spearfishing. It would have to coincide with Corona lockdown! :(. Traffic would have been awful though! :D
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Traffic is rarely a problem up my way but the sun is shining and the coast is only about ten minutes away . This lockdown is driving me crazy but on the plus side I’ve watched a lot of scuba videos which directed me to spearfishing once the postie has been I’ll be all set to sit about the house some more
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Once I was able to break a notched spear with my hands and knee, I never used them anymore... also I find loading easier (never misses the spot)...
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Yes, I could probably snap my 6.3mm spears over my knee but that's not the sort of force my spears would normally encounter. So not a concern to me.

Baz, The 2 main routes to the southwest of England, M5 and A303, would usually be choccablock over Easter but local TV showed them empty except for a few lorries this weekend. Probably makes it easy for the police to identify anyone flouting lockdown.
in my opinion i believe that a good quality sharkfin spear gives way better consistent accuracy on a roller gun. notched would be more than adequate for a short cave gun
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Ginge what brand and type of spear is that (e.g. stainless/spring steel)? The sharkfins suggests it is not an el cheapo spear but your pictures suggest otherwise. Do you know where it was made? It looks brittle. Too hard, bad steel or bad heat treatment perhaps? Perhaps the sharkfins weld hardened it? So much for notches being a weak spot! Did you shoot it into a rock at some point?

Mutley, why do you prefer sharkfins - easier loading?
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It’s from a Cressi geronimo 95. The spear in the photo is probably the forth spear it’s happened to all being Cressi spears. It’s as if the shark fin is an interference fit into the shaft and when left the corrosion needs space to expand and just cracks the spear. And no not firing it into rocks, a couple people have suggested that. Was just curious if it had happened to anyone else.

So to answer the question of the thread I’d say notched spears although I’ve got new spear with fins that are tack welded on. Will try it this week hopefully and get back to u.
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Anyone else had the spear crack where it is inserted into the shaft? Has happened several times to me when they are left over the winter.
I have had notched spears break at the notch and my dive buddy had his pin fin snap just like yours. I only use welded on sharkfins now. It is bad news if you swim a kilometre off shore and break your spear on the first shot and have to swim all the way back with no fish. One of my buddies lost the skin off the end of his finger from a dyneema wishbone slipping off the notch. You dont get that with sharkfins.
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I’ve had cressi shafts snap in the same place. I’ve also had notched cressi ones snap some years ago now. I think they must have a batch problem as they have changed the design AGAIN from notch, to pin insert, to shark fin now fused to the shaft.
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Ginge do you flush your gear after each dive, to wash the salt off?

I suspect the welding of the sharkin is screwing up the temper of the spear. BTW I notice that the rather nice spears on my new Apnea spearguns have the Rockwell hardness etched on them, which is confidence inspiring. I think it says Hrc46, which is not that hard but likely hard enough, about the same as a saw, card scraper and some axes. Carving tools are often Hrc 59-60, more for many Japanese tools and knives (which tend to be brittle so often laminated to or between softer steel). Being softer, sharpening with stones should be easy and the spear more robust but it will likely dull sooner. Fish are pretty soft though, at least the ones I encounter. :D

Cressi seem to have a reputation for quality with SCUBA divers, their reputation so might be worth contacting them to I see if they stand behind their products. Sounds like they owe you 2 spears, an apology and an explanation of how they will stop it happening in the future. The Geronimo looks like a cool Speargun, quite high up Cressi's range. If you don't get satisfaction, I would suggest switching to somebody who cares, e.g Rob Allen or Dano at Mako.
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