Optimal distance

[Gabriel86]

Hello. What are the minimum distances for the best possible propulsion and efficient rudder?
Is it true that the rudder axis should be slightly to the right for the right-hand propeller?
Currently the rudder is aligned with the propeller shaft, and when I turn right at high speed it doesn't work properly, it goes headfirst into the water.I received a drawing and I want to know if the values are correct.

 

[montero]

Welcome to the forum Gabriel .
Single prop is alway asymetrical .
A lot of people here have knowledge about this .
This isn't my blues

 

[philSweet]

The usual reason for the offset shaft is so you can pull it out past the rudder. The question then becomes which side do you want it on.

 

[HelmutSheina]

To me your issues have a safety component, not just efficiency, because the boat is broaching (sometimes called bow steering); and that can cause it to sink in certain conditions, as well as creating palpitations in all aboard.

This could be a hull issue rather than a steering or propulsion issue, or could be a combination of factors. I suggest you give full details of what you have, with pictures if possible, for more comprehensive assistance.

 

[gonzo]

The dimension depend on the rest of the design. They are not universal. What you describe is a serious problem. Can you post photos of the boat? Also, at what speed is this happening?

 

[Gabriel86]

It is a fishing boat. 80x32 cm

 

[gonzo]

It's an RC boat. Do you have a photo of how it sits on the water. It may be bow heavy.

 

[Gabriel86]

It's an RC boat. Do you have a photo of how it sits on the water. It may be bow heavy.

 

[gonzo]

That boat is bow heavy. Can the batteries be shifted back?

 

[HelmutSheina]

The upside down photo possibly shows a hook (or hollow) in the hull near the transom to me. If that is the case it will definitely ride bow down as it acts like lowered trim tabs.

A straight edge longitudinally on the hull between the strakes should tell. A planing hull should be straight for most of its length aft of the bow, and particularly closer to the transom.

Propshaft angle is another factor affecting trim that is indeterminable from a photo, and why many propulsion systems are able to vary the thrust angle in the vertical plane. (Eg power trim)

Is there a forum situation involving these boats? Because if this is a design issue you ain't the only one suffering, and others may have a simple fix.

 

[Gabriel86]

The angle of the propeller shaft is not a problem. It runs well on the water. The only problem is that at high speed if I turn suddenly it goes into the water with its head. Someone told me it is because the propeller spins to the right. The rudder is fixed on the center of the propeller shaft.

 

[Gabriel86]

That boat is bow heavy. Can the batteries be shifted back?

If I put the battery further back, it jumps on the water.

 

[Night Sky Yachts]

Maybe your rudder doesn't work symmetrically and when you turn right, the rudder generates too much force. You can try to reduce the maximum rudder angle on the starboard.