Outboard handling

[grandbanks]

I've noticed that many cruisers with outboard motors add additional rudder area to the drive leg, aft of the prop. The area added to a 10 -15HP motor is around 1 square foot or so. Does this make a difference to handling?

I've always thought that an outboard steers very effectively simply by directing the flow from the propellor and am surprised that this added rudder area makes a difference.

My boat has an outboard motor on one side of the transom and a tiller operated rudder in the centre. That's because it started life as a sailboat. I'm planning to remove the rudder and move the outboard to the centre line and use it to steer. The rudder was necessary when the boat sailed, obviously, but I was hoping to steer just with the motor now it's a power boat.

Any thoughts?

[PhilR]

I've noticed that many cruisers with outboard motors add additional rudder area to the drive leg, aft of the prop. The area added to a 10 -15HP motor is around 1 square foot or so. Does this make a difference to handling?

I've always thought that an outboard steers very effectively simply by directing the flow from the propellor and am surprised that this added rudder area makes a difference.

My boat has an outboard motor on one side of the transom and a tiller operated rudder in the centre. That's because it started life as a sailboat. I'm planning to remove the rudder and move the outboard to the centre line and use it to steer. The rudder was necessary when the boat sailed, obviously, but I was hoping to steer just with the motor now it's a power boat.

Any thoughts?

 

A rudder fixed to the leg of an outboard/outdrive makes a massive difference and it makes it possible to retain a bit of steerage when going forward in neutral.

[WotEver]

A rudder fixed to the leg of an outboard/outdrive makes a massive difference and it makes it possible to retain a bit of steerage when going forward in neutral.

 

... and when travelling at canal speeds.

[grandbanks]

So, it's slow speed handling and tracking that's enhanced by the additional rudder area. I can understand that.

I suppose the typical canal cruiser has quite a flat bottom in the interests of minimal draught and, therefore, little to aid directional stability. The added rudder area would help this.

My boat, although only 2' draught, has a short keel running for at least half the boat's length which provides good tracking; I may get away with not having to enhance the steering ability of the outboard - it remains to be seen.

This transformation of a traditionally styled sailboat to a powerboat, and one suitable for canal cruising, is proving to be an interesting project!