Distance of tabs from the mech and each other

Quote from popgun pete

Maybe not always, check the close-up photo of the notches on speargun number one!

Prodanovich_Potts_Early_Guns

Notches were easy to cut with a hacksaw, so that is how shafts were made originally.

I meant for production line in factories...

thanks for the link

Here are a couple of mine from 1983.
Twin fin 9/32, slight notch to lower wishbone.
Single fin 1/4'' with 5/16'' ScubaPro mech tail grafted and tig welded.

Cheers, Don

The notch spacing was probably to allow bands to stack without the wishbone ferrules overlapping. A lot of European spearguns used the ferrule system and so did Australian spearguns. Georges Beuchat patented the ferrule system in 1943, then everyone copied it! Photo is of the "Sea Hornet" bands, "Undersee" bands were very similar. If you went into a store to buy bands then this is what was available for decades. In the USA the less bulky "wedding ring" band system was used, so bands could be used stacked closer together. The notch spacing on the shaft may also be to provide knuckle room when pulling successive bands back with palms up, that is how I load my bands.

Here is a 6' 5/16'' 17/4 ph shaft with wings and notches I did in 81. I engrave the year and gram wt of all my shafts. I keep this one to remind me not to shoot large grouper too close to their small cave.;) with out a brain shot.

Cheers, Don

While
you were sleeping I caught this milk fish just out in the blue off the reef in front of my house. I ocassionally venture out to see some if some fool has ventured to close to shore. However when I do I have my Wong GR 55" rigged with two bands and if I am lucky enought to come across some prey they seem to stay just out of range. Well yesterday I decided to put on a third band to reach a little further. Daryl doen't recommend 3 bands on that model but I was tired of being just short of success. So I made a 28" band out of 9/16s Rubber to go with my 2 5/8s bands. I also adjusted the length of the Dyneema Corded line so the bands would line up as close together as possible for maxium rubber to stretch but yet not interfer with each other. I pull the furtherest band away down threw the other two and placed it closest fin towards the end of the gun. I use a thick Dyneema and I have to place the other two on the back fin because due to slight flex the second fin is slightly recessed in the enclosed portion of the track and if I attempt to put a second band on the that fin it pops off.. So two bands on the last fin didn't effect this shot and the extra band gave me the much needed distance to hit the target. It was probably and 18 foot shot.

Dan: Get them made as far back as possible.

I prefer tabs as far back as possible with about an 1-1/2" spacing between them. I can see the practicality of further spacing for powering up or down provided the tabs are high enough to stack bands on the same tab. Most of the mini sharkfin style tabs or notches only allow for one band to be placed on the tab or in the notch.