Need engineering assistance for kayak weight and balance question

[john from md]

For my side mounted motor, I am using the Island Hopper motor mount. This mount has a weight opposite the motor to balance out the kayak. Their weight only weights seven pounds and my MK 40 weighs 17 pounds. I had to add an additional eight pounds to the weight to get the kayak on an even keel while hanging from the ceiling on straps.

Should I make up a weight to equal the motor or does the motor being in the water change the physics of the whole thing?

Thanks for your help,

John

[Memory Maker]

For my side mounted motor, I am using the Island Hopper motor mount. This mount has a weight opposite the motor to balance out the kayak. Their weight only weights seven pounds and my MK 40 weighs 17 pounds. I had to add an additional eight pounds to the weight to get the kayak on an even keel while hanging from the ceiling on straps.

Should I make up a weight to equal the motor or does the motor being in the water change the physics of the whole thing?

Thanks for your help,

John

........ Being in the water changes everything ......... The whole yak is supported with the water and you can use your weight and the weight of your battery and equipment to balance the engine. Also ....... I hope you don't store the yak without taking the mount and engine off it could stress or warp it

[dsiekman]

There is also the question of distance from the centerline of the boat. All things being equal and not considering buoyancy, multiply the force(weight) x the distance to the centerline and adjust how far out the weight hangs as required. For instance, a 10# weight 1' from the centerline would be balanced by a 5# weight 2' in the opposite direction from the center. Id guess the man'f probably took this into consideration when they provided the 7# counterweight.

[john from md]

There is also the question of distance from the centerline of the boat. All things being equal and not considering buoyancy, multiply the force(weight) x the distance to the centerline and adjust how far out the weight hangs as required. For instance, a 10# weight 1' from the centerline would be balanced by a 5# weight 2' in the opposite direction from the center. Id guess the man'f probably took this into consideration when they provided the 7# counterweight.

Well, do to the design of the mount, and the resulting proximity of the motor head to the mount, I had to center the tube on the kayak. This leaves about six inches on either side, one side having the wood block for the motor and the other for the weight. This gives me the clearance needed for turning the head.

If I wanted to re-engineer the whole mount, I could make a longer tube and have the weight shift outboard but I don't feel like doing that.
What I think I will do is pour lead ( I make my own weights and bullets) into several different containers to make different weights. I will drill and tap the original supplied steel weight and try each of my lead weights until I hit the right combination.

No, I don't leave my motor and weight attached to the yak. Everything comes off before I hoist it up to the ceiling. (mostly to save my back )

[Memory Maker]

Well, do to the design of the mount, and the resulting proximity of the motor head to the mount, I had to center the tube on the kayak. This leaves about six inches on either side, one side having the wood block for the motor and the other for the weight. This gives me the clearance needed for turning the head.

If I wanted to re-engineer the whole mount, I could make a longer tube and have the weight shift outboard but I don't feel like doing that.
What I think I will do is pour lead ( I make my own weights and bullets) into several different containers to make different weights. I will drill and tap the original supplied steel weight and try each of my lead weights until I hit the right combination.

No, I don't leave my motor and weight attached to the yak. Everything comes off before I hoist it up to the ceiling. (mostly to save my back )

What I think you should do is to just try it before you go overboard ........ I have 1 and my engine is a 45lb thrust which is more than 17 lbs and it works fine .......... There are a lot of things in a yak that will unbalance a yak ....... In fact ...... I don't think there is a balanced loaded yak ......... Before you pour and tap, you might want to take another piece of pipe the same diameter and put the weight on it and make a simple sleeve to put over both pieces ....... But I really don't think you need it. Oh and the weight that it comes with is iron ..... At least mine is

[john from md]

It's hard not to go overboard when I have to wait till March before I can throw it in the water. But, you are right, I should wait and probably will since it is too cold to work in the garage now anyway.

[Memory Maker]

We'll ..... You can fish in the winter if there isn't too much ice but if this weather continues that might be a problem ...... Or do some more rigging ....... Good luck