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" ????
