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Measuring length.....

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So, my Apnea ST 75cm, the only 75cm measurement I can glean is 75cm from back of the stock to the dyneema on the unstretched rubbers. If I take a 75cm measurement from the end of the muzzle I get to just past the 1st sharkfin on the spear. The ST is 100cm end to end.

I've been offered a "90cm" (the guy claims it's a 90) Buchan Arka but comparing the 2 guns together the Beuchat is 80cm from back of stock to its wishbone on unstretched rubbers, the overall length of the Beuchat is 110cm end to end. And there's no relevant 90cm messurement anywhere on the gun that makes sense. .....

Are the cm lengths of guns just dreamed up by individual manufacturers??!!
 

Mr. X

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It is the length of the barrel tube ;)
 

Bill McIntyre

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Yes they are, or at least there no consistency. Long ago and far away. American guns were named for their total length in inches. Of course that could be very misleading since some had the mechanism closer to the butt than others. For instance, my 57.5" Wong has the same band stretch as a 61" Riffe Island. Euro pipe guns were easier. Generally the name indicated the length of the pipe barrel, which pretty much amounted to band stretch, and Euro guns were expressed in centimeters rather than inches.

But the waters got muddied when companies started making rear handled guns with no clear division between handle, barrel, and muzzle. Some are still diligent about labeling guns for band stretch, while others are not, and they don't all use the same rules. My Abbelans are an example. My 110 has 122 cm of band stretch. When I ordered it it was labeled a 120, but by the time it was delivered the company and downsized the labels of all its guns by 10 cm. I asked why, and the answer was something like "to make them more in line with other manufacturers." It makes no sense to me. If a gun has 122 cm of stretch, why not all it a 120? It would be a better representation of power, and more attractive to buyers. And the same with my Abellan 120. It has 132 cm of stretch, so why not all it a 130? Other manufacturers seem to label their guns as the longest they can get away with.

But it gets worse. Ulusub is a brand of American wood guns. By custom we are used to seeing American wood guns labeled by total length in inches. I own a Ulusub 155 Rear handle. Is that inches or cm, and is it total length or band stretch? Turns out its 155 cm total length, and band stretch is about 135 cm. I like the gun, but when you just look at the name, you need more information before you can compare it to other brands.

I hope this helps, but its frustrating.
 
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popgun pete

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Pneumatic guns are generally measured from the rear of the inlet valve cap to the muzzle tip, but not always as some include the back of the raked handle butt in the measurement. Also numbers have been rounded to sound better, for example the Cyrano 55 was actually a 54! A better way would be to list the spear length butt to tip, the overall gun length and the powered travel length. In pneumatic spearguns this is termed the working course of the piston, although it is a rarity to find it listed. A working course of the spear could be measured for band guns as it is the same measure of propulsion length in the gun. Don’t hold your breath waiting for this to happen.

The table below is for the "Taimen", but they include the raked handle in their gun length. Russian guns commonly have these numbers quoted. Piston stroke is the working course of the piston, this being a translation of the Russian original.

Taimen sizes R TO E.jpg

Now the "Taimen" has a new muzzle and a new handle grip with a different rake angle this table will probably be changed in the later versions of the gun's handbook.
 
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popgun pete

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Recently C4 Carbon have announced their new Gladius speargun and have offered this table of its dimensions.
C4 Gladius dimensions.jpg

C4 Gladius profile.jpg
 

Bill McIntyre

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It would be great if all the gun makers provided diagrams like that from C4.
 
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Many thanks to you all for your comprehensive replys!

It does seem odd that these two different guns, one 75 and one 90cm in barrel length, (not taking into consideration muzzle and stock length), both have the same band stretch, but only 5cm difference in their unstretched bands, one 16mm and the other 2 x 14mm.

This says to me there is a colossal range of variables when spearguns are concered! So why oh why are there no power charts from the manufacturers??
 

popgun pete

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Many thanks to you all for your comprehensive replys!

It does seem odd that these two different guns, one 75 and one 90cm in barrel length, (not taking into consideration muzzle and stock length), both have the same band stretch, but only 5cm difference in their unstretched bands, one 16mm and the other 2 x 14mm.

This says to me there is a colossal range of variables when spearguns are concered! So why oh why are there no power charts from the manufacturers??
I think they don't want to explicitly say what the powers of their guns are just in case they may be found wanting to say brand X or brand Y, plus the limitations of their trigger mechanisms and stocks are never revealed, nor rated. It is a can of worms that they leave to the market to decide. Plus there are influencers in forums who push certain brands of guns and can be relied on to say “buy brand XYZ” whenever an opportunity arises.
 

Mr. X

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Big Green, the importance of power is often overrated, esp. for the fish in UK waters in our lifetimes - 900lb great blue fin tuna no longer visit the Yorkshire coast as they once did. 9lb would be a very good fish these days. A single 16mm bulk rubber band is more than powerful enough for the vast majority of situations you are likely to encounter.

I just measured the barrel on my Apnea ST 60. The barrel is ... 60 cm. Quelle surprise.

The ST has a modern reverse trigger design. Popgun Pete recently explained that the reverse trigger, used in rear handled euro-style spearguns, made its debut relatively recently, being introduced in the popular Omer Cayman range. It typically gives about 5cm more band pull - a significant difference. My Omer XXVs immediately preceded the introduction of the Cayman but I think they are still wonderful spearguns, very well suited to UK conditions. They are much slimmer and lighter than most spearguns, making them fast tracking and easy to carry.

Band pull depends on band diameter and barrel length and personal preference among other things. For a given barrel length, thin bands are usually cut shorter than thicker bands, presumably to make loading tolerable. I've tried 18mm screw-in-bands and 20mm bulk rubber bands but I prefer a single 16mm bulk rubber band, it has a good balance of power, pull distance and ease of loading. With the ST I will get a chance to try the currently popular 2x14mm band configuration.

With the 95cm roller, I expect to experience loading challenges and pain. When the bands need replacing, I expect I'll switch from the current 18mm bulk rubber bands to 16mm, maybe even 14mm.
 

Kodama

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The best way to compare speargun size is by BANDSTRETCH. This is only one single number for each gun.
It is the longest distance a band can be stretched on that gun. From the bandhole to the shark fin closest to the mechanism.
Imperial or metric doesn’t matter since it is still comparable.
The total length as given by C4 is an adde bonus and useful.
Band stretch is what denotes the power potential anything else is arbitrary.

So here is a suggestion let’s make a list in this tread where we can all share the bandstretch length of our mass produced guns. It wouldn’t take too long before we had a good list to start comparisons from. Problem solved at least for classic non roller spearguns.
 
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The best way to compare speargun size is by BANDSTRETCH. This is only one single number for each gun.
It is the longest distance a band can be stretched on that gun. From the bandhole to the shark fin closest to the mechanism.
Imperial or metric doesn’t matter since it is still comparable.
The total length as given by C4 is an adde bonus and useful.
Band stretch is what denotes the power potential anything else is arbitrary.

So here is a suggestion let’s make a list in this tread where we can all share the bandstretch length of our mass produced guns. It wouldn’t take too long before we had a good list to start comparisons from. Problem solved at least for classic non roller spearguns.
I like your idea, are we talking centre of band hole? Edge closer or furthest from trigger? I ask because they are about 15mm across

Apnea ST 75 is 79cm from centre of hole to closest sharks fin, 47cm stretch, and 72cm for furthest 14mm band, with 55cm stretch

Beachat Arka 90cm is 87cm closest spear notch to top of screwed in 16mm bands and pulled back 57cm.

Any clever engineering folks on here that could crunch these numbers?
 

Mr. X

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I measured my "95cm" Amarok roller speargun. Hard to measure the barrel tube as the trigger mech joint is on a diagonal but it seems less than 95cm. The barrel seems about 2.5cm longer than my 90cm Omer. I guess they are trying to convey a realistic sense of length, as the roller muzzle makes the overall length of the speargun about 5cm more than a 90.
 

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Imagine my surprise when my friend bought a Riffe Marauder 120 and the darn thing is actually shorter when put next to a Dessault 110! Upon contacting Riffer they indeed confirmed that 120 is the total length. The actual bandstretch is just a little more than 100 cm.
 

Mr. X

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Imagine my surprise when my friend bought a Riffe Marauder 120 and the darn thing is actually shorter when put next to a Dessault 110! Upon contacting Riffer they indeed confirmed that 120 is the total length. The actual bandstretch is just a little more than 100 cm.
Yes wooden spearguns are measured differently to tube spearguns. For tube spearguns the length of the barrel tube is specified. Most often they were made and sold in Europe, so cm are normally used. For wooden spearguns the overall length is specified, often in inches rather than cm as many/most originate in or are sold to the USA. Having the cm/inch difference might at least discourage inappropriate size equivalency assumptions that would otherwise occur; your own being a case in point.

I would think the stretch of the bands is closer to 66cm unless the Riffe Marauder is a roller speargun.
 

Bill McIntyre

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I just encountered another illustration of the labeling problem. A couple of years ago I bought a Ulusub 155 rear handle. It’s an American wood gun so that’s total length rather than band stretch but it’s labeled in cm instead of inches. I decided I didn’t like rear handled guns that long so I sold it and bought a Ulusub 160 mid handle. Since that gun is 5 cm longer you might guess that it has more band stretch, right. Actually it has about an inch less band stretch than the 155.

Go figure.
 

Savagedragon

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Yes wooden spearguns are measured differently to tube spearguns. For tube spearguns the length of the barrel tube is specified. Most often they were made and sold in Europe, so cm are normally used. For wooden spearguns the overall length is specified, often in inches rather than cm as many/most originate in or are sold to the USA. Having the cm/inch difference might at least discourage inappropriate size equivalency assumptions that would otherwise occur; your own being a case in point.

I would think the stretch of the bands is closer to 66cm unless the Riffe Marauder is a roller speargun.

By band stretch I mean the actual length from the trigger mechanism to the end of the barrel. I guess your bandstretch means the actual real stretch from the wishbone at rest to the trigger mechanism?
This is all confusing because Abellan usually states their band stretch as the way I described : from the trigger mech to the end of their barrel. For example their Abellan 110 has a band stretch of 122cm (used to be 112cm).
 

Bill McIntyre

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By band stretch I mean the actual length from the trigger mechanism to the end of the barrel. I guess your bandstretch means the actual real stretch from the wishbone at rest to the trigger mechanism?
This is all confusing because Abellan usually states their band stretch as the way I described : from the trigger mech to the end of their barrel. For example their Abellan 110 has a band stretch of 122cm (used to be 112cm).
My Abellan 110 has a band stretch of 122 measured from the band slot on the end of the gun to the rear shark fin on the shaft. The distance to the opening in the trigger mech would be a bit longer.
 

Andrew the fish

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I kind of disagree with Bill here. Total length would be more appropriate measure, would make more sense. Would be more natural number to use. Will answer many questions, like will this gun fit to backseat of my car or my luggage. And from there, how long is a band stretch should be a matter of competition between manufacturers. Or how do you include rollers into this equation, if we disregard total length and go by band stretch alone?

That would dot all i's and clear the fog, instantly say who is who. There is also a new term coined by Jesse, the "effective length" and that should be also a matter of competition. Maybe this is not a new term, but I haven't heard it before. So that, when we compare two 100cm guns, and one of them is mid-handled, we would know how far from my hand to the very tip of the gun.

But, I am wasting my breath, such system would be too honest and put many current designs to shame.
 

Bill McIntyre

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OK, I think band stretch is the most important number, someone else thinks total length, etc. But why do we have to choose? Here is a screen shot from the Abellan web site for my Denton 120. It give you everything you need to know. It even tells you how long to cut the rubber for 370% band stretch if you don't know how to compute that yourself.
 

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popgun pete

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The overall dimensions of spearguns was necessary for their transport, but if you want to compare guns you need to look at the spears as the gun is just a launcher. One way to look at it is the working course of the spear compared to its actual length. The working course is the power stroke in, or on, the gun. On pneumatic guns this is the piston stroke, on band guns it is the wishbone stroke under tension which is pushing the spear. The energy delivered during the working course of the spear is given by the varying force applied over that distance. Once launched spears travel to the target purely by their momentum which is reduced by hydrodynamic drag on the shaft and the trailing line as they fly through the water. The spear has to arrive at the fish with sufficient momentum to crash through its body and hopefully cause fatal damage while preventing the fish from escaping.
 
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