MacGregorSailors.com

List,

Anyone have any experience with something link this: http://kingsmarine.co.uk/acatalog/rudde ... rudder.htm?
I'm looking for something to help off set the wandering that happens while motor cruising at 7-9 knots. Additionally, i don't know if keeping that device attached at higher speeds would be a good idea.

Thoughts?

I've got something like this on my newly-purchased 26M with a Yamaha 50 . I have only had it in the water once so far ,
But it handled well at low speed. I'll try to get a pic soon.

I’d try adjusting your trim tab first and secondly tighten up as much play in the steering as possible. I try and steer clear of gimmicky things like this IMO. We have little to no wander in the steering at any speed. Trolling for long periods I do put the rudders down but his is <4kts.

I use one rudder, all the way down, for slow speed stuff like the Erie Canal. And docking. No wander to speak of. But I don't go 8-10 kts with it down, or at least I've never tried it.

Nuh uh!
Ix

That thing looks flimsy to me, I think it would tear off just when it start to be useful, and it says right there that it is "easy to remove too when you decide that you want to take the boat out to sea at higher speeds."
Maybe so, but not so easy to do on the water.

"Low speed" being the operant wording.
In reverse this will flop the motor full over and pin it there, causing a sudden loss of control. Although it might have the "safety feature" of being chewed up by the prop before this can happen.
This invention Is lacking some simple details that would be evident to someone even minimally skilled in the art. Minimal hand pressure in any one of several directions will dislodge it from its position on the motor. The mounting brackets look to be made from flexible Spalding fibre.
This is a good example of an invention at its early rudimentary stage that requires more work in order for it to become a viable, functioning product.

Harrison wrote:List,

Anyone have any experience with something link this: http://kingsmarine.co.uk/acatalog/rudde ... rudder.htm?
I'm looking for something to help off set the wandering that happens while motor cruising at 7-9 knots. Additionally, i don't know if keeping that device attached at higher speeds would be a good idea.

Thoughts?

Don't motor at 7-9 knots (actually 8-12). The wandering is an inherent function of the boat switching between semi-displacement steering and semi-planing steering as it "wobbles" over the bow wave when the bow wave goes aft of the center of gravity. It's the least efficient speed of the boat as well, as its plowing into its own bow wake rather than either not generating a significant one or planing over it.

Either motor at displacement speeds with boards down 7 knots with all boards down, or power at 12+ knots all boards up and go through the zone of instability as quickly as possible.

My experience is drop the Mac rudders and all is well.

If you want to add additional rudders it would try this



so do no not have to hassle with mounting/demounting in high speeds.

I agree with Yukon Bob. Instead of trying to deal with the issue by adding stuff, try to fine tune things first. Trim tab is worth a try. Also, pay attention to the overall trim of the boat in the water. In my experience, I had more "wandering" problems when the boat was too heavy in the stern. If you can get the weight distributed more evenly, it should help. Also, I find that just slightly lowering the centerboard helps. Beyond that, I think it's in the nature of boats to wander off of a straight line. It's not like driving a car. I enjoy the challenge of counter steering, or anticipating when a swing to one side or another is just about to happen, and then counter steering to prevent the boat from swinging too much. A rhythm can get started, so that the boat seems to be going perfectly straight, but all the while the helmsman is making small steering corrections.

kurz wrote:If you want to add additional rudders it would try this



so do no not have to hassle with mounting/demounting in high speeds.

This is exactly what came on my M. You do a lot of slower motoring over here. Seems to work well.

If you are not stable at slow speed, try dropping the daggerboard about a foot. Makes a big difference.

Does anyone have the same or different opinions on the speeds that Mastrreb has outlined for overcoming the bow wake? (no-go 7-12 knots)

I'm no fluid dynamics engineer, so the numbers seem correct-ish to me as our boats struggle to get out of and on top of the theoretical displacement hole, but only doing 7 knots (hull speed) kind of defeats the purpose of a motor-sailor (X&M), but the standard 50-60 hp has a tough time doing 12+ knots on an extended cruise.

This is a conundrum ... and maybe we should be on Rudolf's island of misfit toys

mastreb wrote:
Don't motor at 7-9 knots (actually 8-12). The wandering is an inherent function of the boat switching between semi-displacement steering and semi-planing steering as it "wobbles" over the bow wave when the bow wave goes aft of the center of gravity. It's the least efficient speed of the boat as well, as its plowing into its own bow wake rather than either not generating a significant one or planing over it.

Either motor at displacement speeds with boards down 7 knots with all boards down, or power at 12+ knots all boards up and go through the zone of instability as quickly as possible.

[/quote]

Doesn't the load of the boat matter (heavier bow). Seems that I get on plane at around 11 knots.

Bear in mind that an and an have different hull shapes. An will plane faster.

Wind Chime wrote:Does anyone have the same or different opinions on the speeds that Mastrreb has outlined for overcoming the bow wake? (no-go 7-12 knots)

I'm no fluid dynamics engineer, so the numbers seem correct-ish to me as our boats struggle to get out of and on top of the theoretical displacement hole, but only doing 7 knots (hull speed) kind of defeats the purpose of a motor-sailor (X&M), but the standard 50-60 hp has a tough time doing 12+ knots on an extended cruise.

This is a conundrum ... and maybe we should be on Rudolf's island of misfit toys

mastreb wrote:
Don't motor at 7-9 knots (actually 8-12). The wandering is an inherent function of the boat switching between semi-displacement steering and semi-planing steering as it "wobbles" over the bow wave when the bow wave goes aft of the center of gravity. It's the least efficient speed of the boat as well, as its plowing into its own bow wake rather than either not generating a significant one or planing over it.

Either motor at displacement speeds with boards down 7 knots with all boards down, or power at 12+ knots all boards up and go through the zone of instability as quickly as possible.

[/quote]