I want to build a test tank

[alden135]

For my 1990 120hp Johnson.

I was thinking I could build a plywood box 30" deep, 72" long and 36" wide with a cover.

Would this work considering I will be using a test prop?

Anything special I should add inside ie; baffles etc.?

I'm a carpenter so building one that won't come apart is no problem.

 

[Chris1956]

Re: I want to build a test tank

I saw one at a shop made of cement block, with a plywood cover.

 

[rickdb1boat]

Re: I want to build a test tank

Horse trough at a farm supply....But if you want to make your own, it should work fine if you seal it up fairly well...

 

[roscoe]

Re: I want to build a test tank

I use a galvanized cattle watering tank.

Should cost about the same as your plywood.
Has a drain, lightweight so it can be moved, and requires no maintenance and it can be stored outside in the elements.

Doubles as a mini spray booth.

 

[TOHATSU GURU]

Re: I want to build a test tank

The trough/watertank really does work. But, if you plan to run the engine above an idle you will have to fabricate a tight lid...It will still blow off, but its kind of fun to watch.

 

[alden135]

Re: I want to build a test tank

Thanks guys. I need to get this motor to turn up to 6k before I even think about blowing money registering the boat/ trailer this year.

The trough is a good idea. I'll price those out.

 

[OBJ]

Re: I want to build a test tank

Might also consider where you'll set it Alden. If you will use it much, you'll get the enevidable oil slick on top. Dumping into the better-halfs flower bed won't go over to well......:%

 

[Silvertip]

Re: I want to build a test tank

Ive seen tanks made from a 55 gallong drum with a rectangular hole cut into the side. It was mounted on wheels so it can be moved easily when full of water. When cutting the hole, the end cuts were made first. Then it was cut down the middle so the sides of the rectangle could be folded up to form sort of a splash shield. Probably not deep enough though for you 120.

 

[DJ]

Re: I want to build a test tank

A 120 HP turning at 6K is going to make a heck of a lot of turbulance, even with a test prop. I'm afraid your plywood sides/front would blow out.:^

For that size engine, BIGGER and longer is better.

 

[alden135]

Re: I want to build a test tank

A 120 HP turning at 6K is going to make a heck of a lot of turbulance, even with a test prop. I'm afraid your plywood sides/front would blow out.:^

For that size engine, BIGGER and longer is better.

Properly constructed by a professional like myself it won't fall apart.

My biggest concern is the size as you mentioned. It has to be big enough so the wheel is spinning in water rather than exhaust gas.

It's just such a royal PITA to haul the boat to the tidal ramp and hope no one else will show up to launch while I play mechanic.:|

We don't have much in the way of farming around here anymore so the trough search isn't going to well. I'd use a big trash can but I'm worried about cavitation.

 

[DJ]

Re: I want to build a test tank

Properly constructed by a professional like myself it won't fall apart.

My biggest concern is the size as you mentioned. It has to be big enough so the wheel is spinning in water rather than exhaust gas.

I idle and rev. outboards of that HP in a 55 gallon drum, all the time. Engaging the shift is another matter all together-test prop or no.

You have no idea what kind of power is in those engines, at the business end. Hydraulic power is awesome.

Go ahead. Don't say you were not warned.

 

[alden135]

Re: I want to build a test tank

Properly constructed by a professional like myself it won't fall apart.

My biggest concern is the size as you mentioned. It has to be big enough so the wheel is spinning in water rather than exhaust gas.

I idle and rev. outboards of that HP in a 55 gallon drum, all the time. Engaging the shift is another matter all together-test prop or no.

You have no idea what kind of power is in those engines, at the business end. Hydraulic power is awesome.

Go ahead. Don't say you were not warned.

Actually I do have an idea about the torque, as I spun around the mooring last summer with the test wheel enough times. As I mentioned earlier, I'm a professional carpenter, which I assume you are not. I didn't post this thread to learn how to build a strong enough tank, only looking for ideas on the size/shape.

 

[alden135]

Re: I want to build a test tank

Well I went ahead and built a tank 3' deep 3' wide and 6' long out of 5/8 ply. It worked great. I was able to turn 6k with the test prop and didn't lose any water.

Sure was a lot easier testing in the yard than dragging the boat to the water.

 

[tschamp20]

Re: I want to build a test tank

i to am a carpenter w/ a 115 .unfortunately no test prop what would happen w/ a prop attached? wanting to build one as well.if the box is fairly sealed whats the problem?too much aeration in the water?

 

[tschamp20]

Re: I want to build a test tank

oh yeah how about a picture!

 

[alden135]

Re: I want to build a test tank

I'm not sure there would be enough water in a tank the size I built to support a test with the regular prop. My boat is fairly heavy. the tires were sunk a little in the ground and chocked, but I still could feel the engine trying to push the boat with the test wheel.

I don't have a pic, and wouldn't post one if I did. The box was ugly. I built it to perform, not for looks.

I blocked the joints with 2x3's liquid nailed and screwed them together. I then banded the box 1/2 way up with 2x4's. Nice and strong. Call your local marina and see if they have a wheel you can rent/borrow or buy one on ebay.