ballesting/ballancing a gun

[Fis_Hunter]

I built a wood gun which is long enough that I could not float test in in my bath tub. When I took it to the ocean and used it I noticed that the muzzel floated up and I had to keep forcing it down to keep it on target. The gun is positivly boyent with the shaft out and slightly negitave with the shaft in.

I would like to set it up so the muzzel does not lift. What I am thinking of doing is picking the center point of the gun with the shaft in placing the gun on a bar at the center point and adding weight until it is balanced.

I sounds like this should work.

Any other suggestions would be appreciated.

[Southern Cross]

I built a test tank after seeing Grizwold's old model. Get a sheet of plywood and cut it up, glue/screw it together. I painted the inside to help it last a bit longer. I'll try to get pics.

Mine is just long enough to fit a tuna gun. fills up in a few minutes in the back yard with the hose. Project cost abour $20 and took about 1 hour.

[seahunter]

I am ballasting and balancing my 65” gun right now. I took my gun out to the bodega bay boat ramp and put it in the water. I tied fishing weights to it until I had it neutral and balanced. When I got home I took a 5/8” foster bit and drilled some ¾” deep holes in a piece of fur. Then I filled them with led that I melted with a propane torch. Because the gun I built is pretty big I had to drill 28 one inch deep holes in my gun stock to fit all the led. Then I took a plug cutter and cut 5/8” plugs out of a ¼” thick piece of teak and I glued them into the stock with west systems epoxy.

Here is what I would do different: I would use a slightly smaller diameter drill bit for the led weights that I cast because about ½ of them did not fit in the holes that I drilled. Next time I might try to use 12 or 20 ga slugs instead of casting led weights because the led weights took a while to cast and some were misshaped and did not work.

I will try to post some pictures tonight.

[thereefgeek]

doing your ballasting and balancing in saltwater would be prefered to freshwater (pool or tank) because the density of saltwater makes everything a little more buoyant. One gunbuilder told me he uses old saltwater from water changes in his 1000ish gallon shark tank in a seperate 8 foot long tank to blance and ballast his guns. Here's some basic info on the B&B subject:
ballasting: http://spearguns.netfirms.com/ballast.html
balancing: http://spearguns.netfirms.com/balance.html

[Fis_Hunter]

Sounds like I need to make a ballast tank.

Salt water is 3 percent heaver then fresh water can I just ballast it in fresh water and add 3 percent more lead?

When you drill out wood to make room for the lead does this have any affect on the boyancy of the gun. Never mind answered my own question while typing, (For those of you not in my head) No it is water displacment of the gun VS weight, as long as I keep the same surface area it will still displace the same amount of water. It will only change the boyancy by the reduction of the weight from the wood fibers removed. I guess I could pre drill all the holes for the ballast the depth of the wood plugs I will install to cover the weights. dump the shavings from this. Then dirll the holes to depth and save all the shavings weigh them and add that much more weight.

Do any of you go to this extreme?

[seahunter]

Here are some pictures. I installed about 2/3 of the weight on the first go around then I went out and tested the ballast/balance. It needed a few more ounces, but not as much as I expected (probably from all the wood that got removed). This time I used a 1/2" mold and a 5/8" hole in the stock. It worked a lot better, but I think I would use a slightly bigger bit for the mold next time because there was a lot of extra space in the 5/8" holes.

[Fis_Hunter]

Justin thanks for the picks. I like the way it adds intrest to the bottom, work of art man.

Is that a Neptonics handle?

The one I used for my gun is great with no gloves but when I put on my gloves it feels like the handle is too short. On the next one I think I will extend the grip a little more.

[phil herranen]

Originally Posted by thereefgeek

doing your ballasting and balancing in saltwater would be prefered to freshwater (pool or tank) because the density of saltwater makes everything a little more buoyant. One gunbuilder told me he uses old saltwater from water changes in his 1000ish gallon shark tank in a seperate 8 foot long tank to blance and ballast his guns. Here's some basic info on the B&B subject:
ballasting: http://spearguns.netfirms.com/ballast.html
balancing: http://spearguns.netfirms.com/balance.html

i wonder who that was
i put the gun in the saltwater tank then i hang weights until it acts the way i want it to( just + side of neutral with muzzle sinking for blue water guns , neuteral or just - for smaller guns up to about 60" , very - for ab guns or guns for bubble blowers ) then i ad the weight where the weights hung
i think it is important to be able to hold the gun by the handle in the balast tank so the balance is right when in use.
also the most important thing to avoid is a + muzzle it will throw of every shot
by lifting the tail of the shaft as it leaves the gun
phil

[kjflyfish]

If I remember correctly, you built a smaller, low-vis gun. Here's what I would do if I didn't have the aid of a tank:

The quickest solution I can think of is to get a scrap piece of timber, and carefully and slowly drill a 1/2" hole approximately 3/4" deep. Now melt some lead and pour until it almost reaches the surface. when the lead cools, knock our your "plug". Use the same bit to drill an identical hole into the stock near the muzzle and slide the lead plug into the hole. Cap with either a pigmented epoxy or a wooden plug ("tapered plug cutter" at the hardware store).

If you get out and notice the muzzle is still slightly buoyant, add another. If the muzzle is a bit heavy, you can always drill a hole into the lead plug with an under-size bit, thus removing some of the lead and re-cap the hole. It should end up just right. This combines gun building and diving at the same time.

Of course the best way is to just build a float tank. My landlady has a saltwater swimming pool

[Fis_Hunter]

I have some plywood and 6mm plastic sheeting I plan on making a box and lining it with plastic then fill it. Thanks for the advise. I have a 3/8 plug cutter but I think that is a little small. I need to pick up another.