Three prongs
I started spearing using a pranger head. First I used six barbs, then five, then six again (due to the vagaries of supply here in Wollongong).
THEN I started making my own prangers by replacing the barbs myself. To do this, make a shroud around your oven stovetop out of aluminium foil to keep the radiant heat in. Then put your pranger on the stove element, and wait for 10 minutes for it to heat up. After the solder melts, you can pull the old barbs out.
Put some solder in the holes, and push the new barbs in. Works great!
After some experimentation I found that three barbs worked best for me (shooting luderick up to 1.5kg). Three barbs gave me about half a metre extra range, which at the time was just what I needed. Six barbs slowed the shaft down too much, so I only had one metre effective range. An extra 50 cm was an extra 50% range!
I found that three barbs would penetrate the fish so well that it was impossible for the fish to pull off, as opposed to six barbs where the combined force smacking the fish meant that the barbs wouldn't penetrate all that much.
The downside to only three barbs is the top shot, shooting down on a fish, where the barbs can just slide off the skull of the fish, leaving it with a couple of white skid marks and leaving me a bit annoyed
I suppose that with 6 barbs the spear wouldn't have made it that far anyway.
One trumpeter that I shot from above was interesting -- only one prong hit the fish, and it only just went into the gillplate. The fish didn't seem to notice that it was shot -- it kept slowly swimming around the cave that it was in. I kept tension on the line, slowly brought the fish nearer till I could grab the spear, then heaved the whole fish out of the water onto a nearby rock shelf!
I use tahitian shafts now, I know that when I hit a fish the fish stays hit.
