If there's anything I love, it's making things for spearfishing, and halibut hunting is no exception. A couple years ago a few friends of mine started going out at night looking for halibut with nothing but a spike with a flopper and handle, and were bringing in some pretty solid numbers and sizes. This was a quick inspiration for me not only to try my hand at the same, but to try making one myself.
Using a halibut hammer might be the closest you'll get to doing what people imagine you do when you say "spearfishing." Usually they think you swim around or stand above water with a Trojan spear and stab it at any wayward fish. A halibut hammer is simply a short spear with a handle in a T shape. This is amazing because it's really easy to take around while lobster diving, unlike a gun, and you can bust it out if you stumble on a halibut or other fish to bring home some extra dinner!
It's a pretty easy make, but I tried including a lot of details. To start, it is most convenient if you or a friend have a seriously bent shaft you can use. If so, skip down to the end of step one.
Most everything I already had as scraps, so building this cost me nothing in new materials. As you can see in the pictures, I made mine a double flopper, but this DIY is for a single flopper.
What you'll need:
An electric drill
3/32" cobalt drill bit for stainless
9/32 drill bit
a small amount of teak, mahogany, or other marine preferred wood, and some teak oil
2 part epoxy
3ft of spectra
spearpoint flopper for 9/32" shaft, preferably a 2" flopper
What is preferred and makes life much easier:
bench grinder or angle grinder
1. The Spike
Go to your local hardware story (or find online) and buy a 9/32 stainless steel round rod, around 1ft long, 304 will work. Cut the rod to 11 inches long.
Using a bench grinder, angle grinder, or even a hell of a lot of filing, create a point on one end that looks like a spear shaft rock point. The good news is that it doesn't need to be perfect since it won't effect the trajectory over the small distance of it's use, your hand will do most of the determining of accuracy.
An inch and a half from the point, drill a 3/32 hole as perfectly through the middle of the shaft as possible for the flopper pin hole. If you are using a drill, this is a nightmare and it will dance around like mad. To help it settle, you can use a file to mark an "X" where you want to drill, and try drilling at the center. This is still difficult but made my life easier. It's hard, but i've done it a bunch of times. If you have any sort of access to a someone with a drill press, do yourself a favor and use it.
Once that hole is drilled, place the flopper holes over the hole and push the pin through both, hammering the pin on the other side to flatten it out and keep the flopper attached.
Do a second hole 4" from the other end (non point end) of the rod, this one can be inaccurate and is for line/lanyard/safety attachment. I initially made my in the wooden handle, but realized that I'd feel more confident with it going through the steel of the spike. To smooth out the edges take your 9/32 bit and lightly drill the top of this hole on both sides.
If you already had a shaft that you could use, where the front 11" is straight, then simply cut the front 11" off and use that for the point, and consider cutting the point to within 2 inches of the flopper. This will help with penetration. You will still want to add the second hole 4" from the back for line t go through.
Take 1"x1"x6" of the wood and drill a 9/32" hole 2/3 of the way through the center of one of the lengthwise sides (3" from the long sides, .5" from the close sides). If you want, you can shape the wood into how you want it to fit in your hand i.e. round, contoured, or just square. I used a belt sander to round it out till it felt like a fit. Once everything is assembled
Taking the spike, fit the non pointed end into the hole you made in the wood. Double check that you are happy with the shape of the handle (I used a belt sander to mold my to fit to what I liked), and then use two part epoxy to glue the spike into the handle. Wiggle it around a lot because it will create a pocket of air between in the hole between the spike and the handle that you want to help get out to create a better bond.
Take your spectra and put it through the remaining hole in the spike. On one end, thread a 1.5" piece of speargun rubber onto it, and tie a double stopper knot on the line that comes out from it. On the other end of the line, tie one side of a triple fisherman's bend knot (https://www.animatedknots.com/double-fishermans-bend-knot) onto itself to act as a lanyard. This let's it you adjust the size of the loop. as you can see in the picture I tie a simple overhand knot in the middle of the line where the sliding loop is. This prevents it from sliding impossibly closed (which happened to me on a few occasions before I added this knot).
AFTER you glue, use teak oil or whatever finish you want on the wood.
The line is both a safety (the rubber stopper) on one end and a lanyard (the loop) on the other! DO NOT PUT THE LANYARD LOOP ALL THE WAY AROUND YOUR WRIST. I only put it over my fingers when using it. The knot will cinch down tight, and if a strong fish is on the other end you will be on a regrettable ride.
Congratulations! Once the glue dries, you have a fully functional halibut hammer!
4. How to's
Going at night to a popular halibut spot with a flashlight is a great way to use this, as the fish are often less camouflaged and unaware of your presence. If you're up for a challenge, there are some youtube people who get them during the day with this! Extremely fun to get a fish with, as it's even more intimate and challenging than a polespear, but brilliantly simple.
One of the best ways to hunt with a halibut hammer is to use a float line (I have 50ft of lobster trap rope I found on the beach that I use). That way you don't have to hold the spike at all when not in use, and can let it go if you need both hands for a lobster or something without worrying about dropping it. Just attach your float line to the spectra and you're good to go! This is also preferred because once you spike a fish, you can fight it with the float line at the surface, not with your hands underwater.
Since the wood and spike are connected with glue (strong glue, but still glue), your best hold on any fish is the line going through the spike.
Good luck out there!