Appolo 13 look a like shaft for MT0 and modified shaft for Mares Cyrano 850 | DeeperBlue.com Forums
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Appolo 13 look a like shaft for MT0 and modified shaft for Mares Cyrano 850

Thread Status: Hello , There was no answer in this thread for more than 60 days.
It can take a long time to get an up-to-date response or contact with relevant users.

Iyadiver

Mr. Long Post
Apr 22, 2002
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I just got the 3/8" (9.5mm) shaft of the MT0 to be converted as pictured below, the right side, an Apollo 13 look alike. The machine shop never installed a flopper before and I think they squeezed my flopper. I am getting bad "action" from the flopper opening. Spent 1 hours filing it down nicely but it can not be as smooth as Riffe original flopper movement. The flopper will not drop some 40 degrees as easy as Riffe original. The last 60-70 degrees opening is almost as good as a Riffe original. New skill to learn...... my my. The machine shop was also not careful, my flopper position is not as 6 o'clock like how a Hawaiian should be but at about 6:30 to 7:00 o'clock. This is one drunken Hawaiaan.... he he he he.


The left shaft is a Riffe regular 6mm theread shaft modified to be a Hawaiian flopper for my Cyrano 850. In fact in a pneumatic where the shaft can spin it can be a Hawaiian, a Tahitian and probably Westerian and Easterian shaft as well...:D :D. Notice the hole for the Hawaiian flopper is not as rearward as Riffe original, I don't expect much power out of my 850, so I do not want the flopper to be so far behind like Riffe set up. I used a 48" 9/32 (7mm) Hawaiian shaft for this conversion. Now I have an extra short shaft with 2 loading tabs as left over about 8" long. Maybe I need to make a spear pistol......:p :p

I will let the curious know how my Apollo 13 Riffe shaft works and how the modified Riffe shaft for the 850 behave. I am still waiting for the flopper. No one in the entire country has one....damn. I bought the last flopper from the dealer for my Apollo 13.
 

Iyadiver

Mr. Long Post
Apr 22, 2002
998
72
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CYRANO 850 modified shaft

Photo below on right side is the end butt of the modified Riffe shaft to fit the 850 Cyrano. The left shaft is the original shaft....Inox steel they say.....yet it bent cause I load fast....and the dealer is asking US$40 for a stupid rusting non high performance steel..........:yack. The lousy Mares original spearhead which looks like aluminum and built like a toy goes for US$20...:yack. My modified shaft cost me US$45 for the 48" 6mm thread x 9/32 diameter and US$7 something for the Hawaiian flopper and labor only US$10 ( labor is cheap here man ) for the entire conversion of my Apollo 13 shaft, install flopper, drill 2 flopper rivets holes, make me a custom shaft to pneumatic piston adaptor (stainless steel ) as seen bottom right. For US$ 62, I get Riffe quality Hawaiian shaft for my 850 Cyrano...what a deal. I still get a left over 8" Riffe shaft for experiment......

Best part is that Mares probably never even have or will ever offer 17-4 hardened spring stainless steel of the Riffe shaft material..........cheapo.

I am very happy. The Scubapro pneu I used to have comes with 17-4 hardened Spring SS, Scubapro needed to maintain that high-end image.

I am going back to my shipwreck tomorrow ( in 6 hours ) to test my Apollo 13 and from there to a friend's private island to get drown by Uncle Jack Daniel at night and shoot some plywood for my Cyrano new shaft..... He Ho...He Ho. :eek: :eek:
 

unirdna

tropical wuss
Sep 16, 2002
1,016
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Hey Iya,

Good lookin experiment. Momentum of a large shaft without punching big holes - is that the goal? ... Keep us informed. I've decided to go with the 9/32" Hawaiian instead of the 5/16" threaded. It's just a better shaft for our "little" freshwater fishes. I'd like to get your opinion on yet something else...the Riffe enclosed track for the metal tech guns. Did you pick this up? I know that your favorite shaft is the 3/8", so the track doesn't apply, but if you used this I'd like to hear your thoughts (even if you haven't used it for that matter). You mentioned that you fired the 9/32 " hawaiian shaft with four bands. Was this too much snap for this shaft to remain accurate? If so, do you think the enclosed track could help? I know that Riffe has said that there is no evidence that the enclosed track improves accuracy, but I bet that these tests were done with the standard 2 bands. If 4 bands were used, it may create a very different firing dynamic.
 
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Iyadiver

Mr. Long Post
Apr 22, 2002
998
72
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Hi guys,

The last saturday trip was bad. The sea was flat but the visibility was poor 15 feet in the morning and going down to 10-12 feet later in the day. The current was at 2.5 knots after 12PM, even stronger than last 2 weeks. It was full moon, so the tide was messing up.

My first dive, I had a video camera with me and I saw only 6 of 5kg Giant Trevaly, so can not do anything. Later on the 2nd and 3rd dive I only manage to see a few snappers and shot only one. I was on the no current side and under the superstructure of the wreck.....I hate it, the viz was bad an very dark. My eyes could not see the fish properly and focusing alone gave me headache.

Funny, I did not see any trevalies at all on the up current side of the hull. I swam up and down the entire wreck and nothing !!!! The snapper was not a challenge to test the shaft cause I could get very close to it, so penetration naturaly come easy. Must shoot a 5kg+ trevaly from 4.5 meters to realy know the result. I had a lousy dive but my other friends saw nothing at all. It must be because there were about a total of 20 divers on the wreck from 3 other boats, so their bubble noise made all the fish ran away.

My friend the island owner also cancelled his trip, so I ended up having a day trip and can not do testing in protected lagoon for my Apollo 13 and Mares shaft .............:waterwork



UNI,
I do not yet have an enclosed track. Next year I will get a set for my MT0 for experiment sake. Riffe told me that it is good for longer guns like MT3 and longer.

If I recalled correctly I think I did get shaft whip at 4 or 5 bands from the 9/32 shaft cause the shaft penetrated the plywood in a very unique angle. If I ever had the chance, I will do 9/32" test for you on my MTO. I need a shallow peaceful lagoon to do it. No pool I can borrow...sorry.

I think 34" x 9/32 Hawaiian shaft for MT0 is very light, too light if you want 12 feet range. 9 feet probably is beautiful. I have not done the accuracy test but my calculation is as such :

A 5/16" shaft or 9/32" has the same shooting line thickness and length if you want the 12 feet range ( 3 wraps ). This means both shaft has to drag along a similiar shooting line. In my opinion, a 9/32" shaft will do more work and get more effected by that shooting line if compared to 5/16" shaft which has more mass and thus more momentum. If the drag result not only in speed loss of the fired shaft, the next possibility will be accuracy loss at longer range, more so if the shooting line is very thick. Any shooting line in one way or the other must effect accuracy because it causes drag on the tail of the shaft, the drag can become a steering-like effect, similiar to a boat rudder but in a very small effect quantity.

Take a small sedan towing a jet ski on a trailer, it will be more unstable than say a big 4WD towing the same. The weight ratio of the puller against what is being pulled surely matters. In underwater, we have hydrodyamic drag as additional factor.
My client's boat is about 55,000 lbs and 53 feet long and it has 2 rudders with a size of only 2.5 feet by 1 feet each. At 27 knots, a two degree turn on the rudder swing the boat very effectively.
The faster you run the less rudder to turn to get result. A shaft supposedly travel at +-50 knots underwater according to Alexander, imagine the steering effect caused by thick and long shooting line.

I am just afraid if 12 feet range is ur expectation on a 9/32" shaft ( must be 3 bands ) , it will not be easy to produce consistent accuracy because Riffe basic unit on two bands stated 7.5 feet or we can calculate range as 2.9 times shaft length. At 12 feet the shaft will need to travel 4.6 shaft length, this is a lot to ask even from any gun.

I been playing with calculation on range and I think it is quite realistic to use "X" multiplied by shaft length as a measure for possible range of a gun to estimate its maximum accuracy and punch potential.

Take a Riffe Blue Water as the extreme unit. It uses 72" shaft length and with the Ice Pick on it, add another 6" = 78". It shoot according to Riffe as 29 feet. Thus we are looking at 4.5 times shaft length of travel. Since the shaft is 3/8", the left over energy at maximum factory specified shaft travel must be still a nice WHACK. All you need to do is estimate shaft drop at longer range. All shafts travelling only has one way to go, which is down, the effect of gravity, we can't hide that.

Take the Mid Handle Bottom as the smallest unit. It uses 42" shaft and with large spearhead, add 2". It shoots 14' , thus 3.8 times shaft length.

On the other hand my MT0 with 3/8 x 36" shaft shoots effective for 5-7 kg trevaly up to 14 feet with 5 bands and it does 4.4 times shaft length of travel.

If we calculate a gun shooting range potential based on how many times of shaft travel, we can then map out its accuracy potential because we have a value to use as reference. I might be wrong but at least this get me busy typing.....he he he he.
Guns accuracy comes from two sources/categories. First is the gun itself as the firing platform. This one too long to discuss, now lets move to the shaft in flight as the second category.

The perfect shaft to fire will be a shaft and a spearhead that has the least hydrodynamic resistance. Put mass and length aside. It also has to maintain perfect shaft when fired, no shaft whip and so on. Now lets put the amount of work a shaft has to do equals to the range it has to travel, more accurately how many times shaft length it has to travel. If a shaft has 1% inaccuracy per shaft length of travel, we expect 4% inaccuracy if that shaft has to travel 4 times its length. It is then unfair to expect that we insist an MT0 ( fully rigged ) to be as accurate at 14 feet range as a MT3 just because we can launch the shaft out that far on the mini MT0. MT0 with 3/8 x 36" shaft will need 4.4 times spear length of travel while an MT3 will need only 2.9 times of spear length travel.

So now he have a theoretical figure to use as a measure.
Make sense or juts an Iya " Theorem" ????:eek:
 

Iyadiver

Mr. Long Post
Apr 22, 2002
998
72
0
If you guys want to know the kind of lousy visibility, here is a video capture of the propeller shaft of the wreck. That big inverted 'V" is the bracket. The propellers been salvaged. Taken at 80 feet of water. I think video capture degrade the sharpness of the picture by 20% or so. Taken from 10-12 feet away. I think that propeller shaft is like a 12" diameter or something.
 
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Iyadiver

Mr. Long Post
Apr 22, 2002
998
72
0
This is 2.4 knots of current as seen pushing water bubbles on the 20 liter plastic jerry can which I anchored as marker float to the wreck.
 
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unirdna

tropical wuss
Sep 16, 2002
1,016
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Thanks for the reply Iya.

Many good points. I think that your system of accessing accuracy ratings is very good. It keeps accuracy relative to the gun itself, rather than just saying one is better than the other. Now....how to create a standardized accuracy test? I think the other thread is still mulling over this one :D.

Here's what I've been thinking about...

As you know, I want good range without creating big holes in the fish. The hawaiian shaft has a small, sharp point, but this shaft has nearly 20% less mass that the 5/16 shaft and over 40% less than the 3/8 shaft (assuming equal lengths of course).

So, I'm thinking of assembling a compromise between the two. It is not as elaborate as your prototype Apollo 13 spearhead, and I'm quite sure I'm not the first to think of it, but I don't think it has been mentioned yet. No wait, Sven might have said something about it a while ago :confused:.....anyway, here it is. Nothing any more complicated than playing with legos; just using Riffe's own parts (smaller speartips and 6mm adapter).

I predict that this is how the small/medium spearpoints might fit on a larger shaft. I know it is not to scale, but you get the idea. Is this accurate? Would a smaller speartip be flush with the shaft - same diameter? If someone could confirm or deny this, I would appreciate it.

oh yeah, one last question: Are Riffe spearpoints tricut or rockpoint? I can't tell by the photos on the website.
 
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