Ballast

[Snufkin]

Hello - if ballast is put at the front of the boat in order to make the boat more level in the water, is the effect on the stern to push the stern further into the water, (but to lesser extent than the effect on the bow), or does it have a see-saw effect on the boat, so that as the bow goes down the stern will come up? Thank you

[Robbo]

Seesaw effect. If you want to find out where the middle is then untie all the ropes on a calm day and them push the boat out from the bank. Where it pushes out and the boat leaves the bank equally both stern and bow is where your centre is. It's also where your turning point is when not moving.

Edited September 21, 2016 by Robbo

[David Mack]

Depends where you put it. If your boat was a rectangular pontoon, then putting ballast in the front third of the length will lift the stern up, putting it in the miďle third will take both ends down, and putting it exactly at the 1/3 point will result in no change at the other end.

 

More complex for a boat with pointy ends, but the same principle applies.

[alan_fincher]

If you have a boat with its water tank in the bows, looking at what happens at the back end as you refill it should answer your question.

[MtB]

Seesaw effect. If you want to find out where the middle is then untie all the ropes on a calm day and them push the boat out from the bank. Where it pushes out and the boat leaves the bank equally both stern and bow is where your centre is. It's also where your turning point is when not moving.

 

 

I'm not sure I buy that. The effect of water resistance will intervene and affect the result, in my opinion.

[Snufkin]

Thank you for your replies.

[Tiggs]

 

 

I'm not sure I buy that. The effect of water resistance will intervene and affect the result, in my opinion.

You are right Mike.

 

It's sort of like a seesaw but not quite.

 

If we use the children's play park analogy I think it's more like one of these horses in the picture attached.

Edited September 21, 2016 by Tiggs

[ditchcrawler]

 

 

I'm not sure I buy that. The effect of water resistance will intervene and affect the result, in my opinion.

Just look at a sailing dingy or yacht, its turning movement is somewhere near it dagger board or keel and nothing to do with the buoyancy