How To Video Series - Part 7 - Ballasting Your Speargun

A How to Guide on Proper Internal Ballasting of a Custom Built Speargun

Proper ballasting is critical in the final functionality of your speargun because it affects the balance, recoil, and buoyancy of the gun. Proper ballast is one of the most under-emphasized and taken for granted aspects of spearguns today.

The most practical method of ballasting requires a body of water with the same approximate salinity you will be using the speargun in.  If you will be spearfishing in the ocean, take your mostly complete speargun to a nearby boat dock.  The only other things you will need to bring with you are some lead weights and some tape.

You want the speargun to be as similar at this test stage to how it will be in the water. You will need your spear in the gun and bands to load for this test.  Set the gun in the water to see how the gun sits in water.  Once you have an idea of how it is (un)balanced, you should start taping small amounts of lead to the gun.  Adjust the position and amount of lead on the gun until it sits level and is slightly negatively buoyant, and mark the positions and amounts so that you know where to cut your slots when you get back to your shop. 

After you know how much lead you need, you can use our calculations to determine the slot size you will need to make. DO NOT POUR MOLTEN LEAD INTO YOUR ACTUAL SPEARGUN! Use a cheap piece of wood to pour the lead. Once the lead is cooled you can put the lead into the slot you have routered on your speargun.

Once your speargun has the block of lead in it, you can mix a small batch of epoxy with pigment mixed in. Pour the epoxy to secure the lead in place.

For router table safety check out this site.

For external ballasting see the OctoSub Speargun Ballast Kit

The below video is a step by step guide to ballasting a speargun using Neptonics components.