Mac 26 M Rudder speed restriction

[Doupirate]

There is a 6 miles per hour (5.2 knots) speed limit on the rudders use.

It is quite easy to exceed that limit under sails, downwind, keel up, surfing on a 5 feet wave at sea.

I am wondering if that limit is applicable on the rudders in the full down position, the boat listing 20/30 degrees, or if it is designed to protect the rudders attachments in shallow waters when the rudders are largely horizontal, or when the boat is excessively listing.

The stress on the rudders attachement looks about 5 times worse when the rudders are partially raised, so that 5.2 knots limit should be about 1 knot with the rudders raised to a horizontal position.

Thank you for clarifying.

[robbarnes1965]

As far as I can see, the rudders will always flex and can take a lot of punishment sailing. Motoring above 6knts might result in rudders getting sucked into the prop I think.

[Crikey]

I would never operate with the rudders in any position, but vertical. If you took your ' partially' down rudders, ran them (disregarding the motor) straight back, that would bring your figure up into the 10 times region. Enough to snap the rudder at the pivot point, for sure, under sailing loads. At the straight down position - all the steering has to do is turn on the vertical axis only. Much lower loads are involved.
I think you are right when you say the speeds can easily surge above that without the assistance of the engine. So the six knot figure, given in the manual, represents the engineers median loading and leaves lots of room for flexing before failure. Otherwise normal periodic deviations would be resulting in a massive number of failures - not a good position to be in as a manufacturer if you're hoping to sell you're product. Besides, that ain't happening.
Another point to consider is how much the up-haul rope stretches when heavy pressure is applied to the rudder(s).

[Divecoz]

I am thinking the OP is concerned with snapping a rudder under sail?? If that's the issue.. No Problem.. I have hit and held ALMOST 8 MPH Under-sail and I believe The Mad Men of Ontario have surpassed my best # considerably.. Wheres The Highlander?? Wheres Beene? There's a few other CRAZIES in that group whose names escape me at the moment...

[Doupirate]

I am thinking the OP is concerned with snapping a rudder under sail?? ...

Yes, that is my concern.

Next spring, I do not want to see myself sending a Mayday with my Spot transmitter, 50 miles off-shores in the middle of the night in a 50 Farenheight and 6 foot sea, because I exceeded the Mac speed limitation with rudders in, riding a nice 20 knots downwind.

[Highlander]

I'd say most manufactures rate their products @ 1/3 to 1/2of their breaking point so I'd say u should be good but that's not to say it ain't gonna happen
Remember though while sailing u do have the option of easing off on the steering a little if the need arises

J

[Catigale]

50 miles offshore i would have spare rudders on board, and also master sailing on course without rudders ...not as difficult as it sounds......

[Crikey]

Raise rudders, or chop away what's left of them - then: Gentlemen, start your Macgregors!

[Doupirate]

Most fixed keel sailboats avoid riding down serious waves (and winds) for fear of surfing hence putting their rudder at risk. They take the wind and waves at an angle to slow down the descent. The Mac Gregor video in gale force wind is an extreme example of that precaution. The skipper rides completly parallel to the waves, hence avoiding the kind of speeds he would experience surfing on them.

I experienced up to 7 knots speed with my Mac, on genoa alone. This was for a few minutes, close to surfing, in 4 feet waves and on a lake. I really enjoyed it...

I am not sure I would do the same at sea though....but I sure would like to, while crossing 100 miles to the Magdalen's island in the Saint-Lawrence Gulf.

I do not know, just thinking about it....with you

[Terry]

OK, I have a 2003 26M with the original oem rudders, never broke them. I have had them down at WOT over 10-14 MPH and no damage. I have crested over some big waves slamming the bow down hard coming over and no damage. I have towed the inflatable dinghy while travelling well over 6 knots and no rudder damage. Considering how badly I have abused them over the years with no damage I'd say they are pretty sturdy, nothing to worry about.

[mastreb]

The has two rudders. It only takes one to steer the boat perfectly well under moderate heel. The outboard lower unit makes a reasonable emergency rudder as well. Worst case, I've got two dinghy oars that could be tied down to serve as a jury rigged tiller. This is not a failure I would be worried about given all the redundancy available.

[Divecoz]

Not Trying to de-rail this thread .. But I have heard of people doing this on purpose and gaining an edge... a little speed.. I "think" I have done this or very close heeling over and running the rail in the water.. ( wouldn't we all like to be part of the MadMen so our buds would film us??) So I ask Mastreb.. are you one of those who has done this? I have heard it said that running just one rudder at a time will turn her faster than with two.... when sailing "hard/fast"????

The has two rudders. It only takes one to steer the boat perfectly well under moderate heel. The outboard lower unit makes a reasonable emergency rudder as well. Worst case, I've got two dinghy oars that could be tied down to serve as a jury rigged tiller. This is not a failure I would be worried about given all the redundancy available.

[dlymn]

Took my BIL out for a sail. 7 knots downwind with wave assist. He's now buying a 42 foot catamaran. Hooked!

[robbarnes1965]

Not Trying to de-rail this thread .. But I have heard of people doing this on purpose and gaining an edge... a little speed.. I "think" I have done this or very close heeling over and running the rail in the water.. ( wouldn't we all like to be part of the MadMen so our buds would film us??) So I ask Mastreb.. are you one of those who has done this? I have heard it said that running just one rudder at a time will turn her faster than with two.... when sailing "hard/fast"????

The has two rudders. It only takes one to steer the boat perfectly well under moderate heel. The outboard lower unit makes a reasonable emergency rudder as well. Worst case, I've got two dinghy oars that could be tied down to serve as a jury rigged tiller. This is not a failure I would be worried about given all the redundancy available.

Can't be worse than healing enough for the whole dagger to be out of the water THe admiral does not scare easily but she drew the line on that one last summer !

[beene]

One rudder is all that is needed under sail.
Just make sure to use the one that is still in the water LOL

With 30 or more heel, one of them will be pretty much useless

I never sail with my motor in the water, so it does not add to the steering ability at all

One rudder, less drag, I have found about .2 to .5 kt better on average

Most of the time I just leave both down, especially when trying to give either Highlander or Rocky a chance to catch up.... LOL

Under motor at slow speeds, like under 11mph, always use both rudders, trust me, you will need all the help you can get to steer this waterbeggo in a crosswind with all that freeboard

Over 11 mph, all fins up including the keel, motor only

G