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Got my first pneumatic: looking for mods!

Thread Status: Hello , There was no answer in this thread for more than 60 days.
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spearbobs

Member
Sep 6, 2020
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Hello everyone,

I have been spearfishing for about 20 years and always used bandguns. After trying my friend's pneumatic however, I wanted to own one in order to play with it a bit!

I just got a SEAC asso 90, choosen it for it's polyvalence, as I do a mix of open water and cave hunting. So far so good!

At the moment it's really stock, and it seems I get about 2.50 to 3 meters of thread usable range from my tests. (+ gun length + arm length + shaft lenght, that gives something like 5m - 5m50 "eyes to fish" distance )

1) Haven't pumped it (it's supposed to be 20 bars upon delivery, but I can't check). It's however quite easy to load.
Stupid question probably, but is it possible to "pump it too much" with the manual pump?
How many pumps would you suggest to put it to 25 bars, if it was actually 20? The manual is unfortunately just 1 page and doesn't talk numbers
I have browsed the forum a bit, and it seems you suggest to put some oil before pumping it the first time. Is some wd40 ok for example?

2) It's delivered with a thick 3mm cord, I believe to increase the range, I should rather switch to something thinner, like 1.5mm Nylon. Does anyone have the numbers to see how thread thickness really affects speed?

3) mods: I have stumbled on quite many threads about them (Tomba, mamba, Tovarich kit etc..). From what I understand they allow to shoot "dry barrel" and avoid the friction of water in the barrel, so the shaft comes out faster and travels further.

However a few things are still not super clear:

A. What are the differences between these mods?
B. What are the drawbacks of using these mods?
C. Can I still shoot rather point blank for cave hunting?
D. Any idea of the shaft speed/extra range you can get in %?
E . Last but not least: It seems they need to be made custom for the gun, an idea of where I can get them made for my SEAC Asso 90? In another thread I have read, I saw @tromic was maybe making some.

That was a long first post, thanks for reading and looking forward to discussing with you!
 
There used to be sticky topics that answered common questions, but they have rolled out of sight as the forum seems to have dispensed with stickies. Here is one of them.

Pumping up pneumatic spearguns

I note that there have been comments about the difficulty in pressuring pneumatic spearguns. While it might appear obvious to some it is worthwhile reviewing why the hand pump supplied with each speargun works. The pump only transfers air into the gun when the pressure developed inside the...
forums.deeperblue.com

The gun should work OK as is. I suggest you use it before contemplating changes.
 

Attachments

  • Asso operating manual.pdf
    112 KB · Views: 468
Another ex-sticky.

"Vacuum Barrels" aka "Dry Barrels"

I have been asked to write this as a primer for those who know little about spearguns, and even less about "dry barrel" systems. This speargun arrangement should really be known as a "pneumo-vacuum" system as strictly speaking a "dry barrel" system is something else, the latter use an...
forums.deeperblue.com
 
Hi Pete,

Thanks a lot for the manual, it's a lot more detailed than the 1 page I have !

Thanks also for the long post you posted back in the day, it's all very interesting and well explained. It's sad these aren't stickies anymore, as I couldn't find it while searching (was probably too old and I didn't went back in time far enough).

I have already used the gun about a dozen of times before posting, that's how I feel like it can do better in terms of performance.

The thread about pumping is very interesting too, thanks! However, as the manual recommends 20 bars and it was supposed to be delivered with that pressure, I wonder if I should pump it more (and if I can manually "pump it too much", or if as long as I can reload it, I am fine, which seems to be what you say in the pumping thread?).

I know some Mares guns can hold up to 40 bars, but as this one is supposed to be 20 bars (well, 25 bars max from my manual), I don't want to screw things up.

Thanks again!
 
The pressure limitation is most likely due to the use of plastic pistons and the shock absorber that they slam into. In the sixties pneumatic guns had metal parts in these items and they were not likely to break, but making them from plastic was much cheaper and faster even though they can be cracked. Pistons used to wear their seals out, now they break! At one time a pneumatic speargun was about double the price of a band gun, so the manufacturers began to find ways of making them cheaper and today they can sell for about the same price, but in the process they cut back on the materials used in them. That trend has reversed in recent times as new guns appeared after decades of making the same ones with minor facelifts such as new stickers and colour schemes. However there has been no return to metal pistons and stronger muzzles. Larger muzzle relief ports in the muzzle are common now because the impacts from the pistons are lower, whereas before the ports were smaller to strengthen the muzzle nose end.
 
Thanks again for your answer! I stumbled a few days ago on one of your posts (on this board or another one, I can't remember), showing some of these metal parts present in ancient pump guns, it was interesting!
 
Regarding the line thickens you may look at this:

Different setups performance

Different set-ups performance
forums.deeperblue.com
Also at this, but pictures missing..:

Comparison of Sliders for Spears

Order of the testing may also have a bearing on the results as the rubber being stretched may not completely recover after each shot as the test series progresses. So shots made at the start may be different from those made at the end due to this rubber elongation effect. To determine if that...
forums.deeperblue.com
Also:

Calculation of speed of the shaft on some distance

There is an excel file attachment based on my real measurements in water in years 2011. and 2012. I suppose it might be useful to calculate the real speed of the shaft on some distance in water for several cases: for 7/1003 mm 301 g shaft and for 8/1280 mm - 483,5 g shaft. Both shaft using two...
forums.deeperblue.com
 
Thanks a lot for the links!

A sticky post with all Pete's and your links should be made, as they are very educative for everyone starting with a pneumatic speargun. So much valuable info, and almost impossible to find with the search or google.

About the line thickness, the performance differences is insane! I thought I would gain 5-10% usable range, but it seems to be a lot more!

At the moment, the gun uses an 8mm shaft, so 1mm might be a bit weak? The thing is, I don't hunt huge fish, as they are none here, I am more in the 1-5kg range, so I am not sure if a think line will be a problem.

If I am not mistaken, you are making the Tomba system, do you make it for the SEAC asso 90?

If yes, for usable range/speed/penetrating power, would you recommend:

Tomba + 7mm shaft + 1mm mono (if possible to use a 7mm shaft, not sure!)
Tomba + 8mm shaft + 1mm mono (if it's not too weak, keeping in mind I hunt relatively average fishes)
Tomba + 8mm shaft + 1.2mm mono

Thanks in advance!
 

Yes, please write to Marko: marko.romich@gmail.com ASAP. He is still on vacation this week. Maybe he would have time...?
7 mm shaft with 1 - 1.2 mm line is widely used for 1- 5 kg fish.
8 mm has more range and penetration but maybe 1.5 mm line would suite better. Also it is more difficult to load than 7 mm.
 
Thanks a lot, I have just sent an email to Marko!

So you think 8mm gets a longer range despite the larger line? interesting! I will thus maybe keep the 8mm.

About the loading, it's not a problem, I find it quite easy with the 8mm. A lot easier than then bandgun I had previously, which was a nightmare to load at the most powerful setting!
 
Longer range with the same line as for 7 mm..., but 8 mm shaft is for bigger stronger fish and than 1.5 mm line is more appropriate than 1 mm line.
Look at the link:

Calculation of speed of the shaft on some distance

There is an excel file attachment based on my real measurements in water in years 2011. and 2012. I suppose it might be useful to calculate the real speed of the shaft on some distance in water for several cases: for 7/1003 mm 301 g shaft and for 8/1280 mm - 483,5 g shaft. Both shaft using two...
forums.deeperblue.com
There you have an excel file in Speed7_8mm.zip. From that excel file you can see (calculate) that on some distance, for example 5 m you would have higher speed with 8 mm shaft and 1.5 mm mono than with 7 mm shaft and 1 mm mono... That excel formulas I made based on my real measurement in water using 7 mm/301 g shaft, and 8 mm/843 g shaft , both with 1 mm mono and 1,5 mm mono line.

About loading 8 mm shaft... You would have to increase the pressure in speargun to near 30 bar. That would not be so easy to load...
 
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Thanks for pointing the excel file!

I however don't understand when you say: " You would have to increase the pressure in speargun to near 30 bar "

Is the pressure when shooting the 7mm and 8mm different during your tests?

At the moment for example, I have a 8mm shaft (seems fine so far for my kind of fishing ^^) and the gun is supposedly around 20 bars.


Another small thing I didn't understood, in you "different setups performance" post, you said that the best setup is 4, with the 1mm mono.

However on the picture https://imageshack.com/i/2gm1719j, for "4" It seems that rope is used and not nylon mono. Or maybe only a small part is rope and the rest is mono? (Excuse me for being a total newbie for this!)
 
Yes, pressure for 7 mm and 8 mm should be different if you want to have the same initial speed of the shaft. 20 bar would be OK for 7 mm shaft in most cases but not for 8 mm. Initial speed usually should be more than 30 m/s, maybe 33 - 35 m/s.
Here is another excel in Speed-Energy.zip on link:

Calculation of initial speed and energy of the spear

Here is an excel file to calculate the initial speed and energy of the spear in pneumatic speargun.I find this calculation helpful to estimate the expected initial speed of the shaft that influences the performance of an pneumatic speargun. The initial speed is only the basic condition for...
forums.deeperblue.com
so you can calculate the initial speed of the shaft for your speargun depending on pressure and other parameters of your gun like piston diameter, working course of the piston, weight of the shaft..

As for image 4, you were right. Only small piece is not 1 mm mono.
 
Ok, good to know, thanks!
So I should ideally order a 7mm shaft like this one seac 90 7mm shaft (no idea of the weight however) and tell Marko I am taking the 7mm kit?
 
spearbobs said:
Ok, good to know, thanks!
So I should ideally order a 7mm shaft like this one seac 90 7mm shaft (no idea of the weight however) and tell Marko I am taking the 7mm kit?
Click to expand...
Yes, just be sure if the shaft is 7.00 mm or maybe 7.15 mm. Some shaft are like 9/32 " what is about 7.15 mm.
 
Perfect thanks, I have ordered the shaft + seeing with Marko to purchase the kit!
 

To give you some numbers..
From the excel file (based on my measurements in water) speed of two shafts on distance 5 m from tip of the speargun.
Both shafts had initial speed 33 m/s.

1. shaft: 7mm/1003mm/301g with 1 mm mono line
2. shaft: 8mm/1280mm/483g with 1.5 mm mono line

At distance 5 m speed of the 1. shaft was 10.3 m/s and of the 2. shaft 14.6 m/s (would be 16.3 m/s with 1 mm mono)
 
Last edited:

Yes, thanks, that's what I saw in the doc! I ordered both kits, for 7mm shaft + for 8mm shaft. So I will be able to try both.

I will also have a backup in case I break my 7mm shaft.

It's really interesting to see all the mesurements you did, I am looking forward to see what it gives in action
 
That is the right way! Give us some feedback after testing it in hunt. The packet is on the way to you. Do not forget to empty the water from the muzzle before pushing in the slider.
 
tromic said:
That is the right way! Give us some feedback after testing it in hunt. The packet is on the way to you. Do not forget to empty the water from the muzzle before pushing in the slider.
Click to expand...
Yes sure, I will let you know!

When you say "Do not forget to empty the water from the muzzle before pushing in the slider.", you mean just "put the slider in when the gun is dry", I don't have anything specific to do if i haven't used it for the past day for example?
 
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