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I have decided to use a rudder blade attached to the lower unit of the engine as a spare steering arrangement. The Lower unit can almost steer the boat under sail. The prop ads drag but only about half a knot. With the additional rudder blade it should steer the boat fine in event of rudder bracket breakage.
Anyone have a suggestion on how to mount the blade before I get into this project?
I deem the motor and mount far and away strong enough. Instincts tell me loads will be less then engine experiences while running full throttle.

My first idea is to make a plywood wedge to fit on the lower unit for the rudder to rest against and perhaps lash the blade to the engine. I could also get creative and make a whole sheath the rudder could slide up and down in, and have a way to attach it to the motor.
For long distance sailing I would remove the prop, then anchor to replace it before entering harbor. We Can do that here in the land of shallow waters!
I could carry spare brackets. It would be a chore to replace them while cruising though.

Ixneigh

The lower unit is most certainly strong enough to handle a mounted rudder--the lateral forces it deals with during a high speed turn are far greater than what the rudders could routinely withstand, and furthermore it's made of stronger material than the rudder, so any force that would break it would have already taken off the rudder. So no worries there.

For injury rigging, I would just use a SS large hose clamp to bind the rudder both above the prop shaft housing and below it (the lower skeg) with enough force that the rudder bends a little around the shaft housing. That'll guarantee that it can't slip vertically and should be more than tight enough to keep it from moving vertically.

I have host clamps, wire clamps, lots of bolts and nylocks, U-bolts and plates, and numerous various shackles in my injury rigging kit. What's in yours?

Spare steering of sorts?? I made a bracket with a rod sticking out facing forward from the motor,a pipe goes over the rod to enable me to steer the outboard at least and if attached to the rudders allows for reasonable control...also have my dinghy motor rigged to reach the water and useable...not fast 3.3hp but at least some propulsion

Im not worried about the linkage really. Just the rudder brackets. I could probably work around a linkage failure. It's pretty simple anyway except for the wheel. My boat has no weather helm so the strain on the system is minimal. That's why my dinky little steering wheel lock works so well.
I keep a fair assortment of fixit stuff onboard. Plus the trash pile on each island offers many possibilities. Built a new aluminum tiller for the 22 one day from things I salvaged. Still on the boat 12 years later.

Ixneigh

Could just mount an oarlock on the transom and use one of the dinghy's oars as a rudder.

A spare steering arrangement as described assumes failure of both rudders, presumably while deployed... which then assumes loss of daggerboard at the same time, thus rendering rudder steering relatively ineffective... just sayin'...

I often sail with half the board, or no board at all. Im not worried about hitting the rudders since they will kick up. I know how to sail the boat in these conditions to ease pressure on the rudders. My boat also has skegs specifically for sailing like this. They help a lot. I spent three days in Florida bay where I couldn't see the bottom. Only had the board down a foot most of the time.
What I worry about is the brackets. They should be double the thickness.

The brackets are the weak part, agreed. Mine aren't even drilled in the right place on the hull, but they have been that way for 10 years.... so I have let them be....there is a picture somewhere in the fora

I'll buy a set of them properly made for four hundred bucks. Any welders out there? Double thickness tubing for the rudder stocks please!

Why go thro all the fuss when you can install a quick release cam for both rudders?
Mine works great and any debree thats hits the rudders auto kicks up rudders.
If you are talking about total failure you only need a small wood arm attached to pivit point with two Y arms at rudder location.(acts like a tiller)
Dave

Ixneigh wrote:I have decided to use a rudder blade attached to the lower unit of the engine as a spare steering arrangement. The Lower unit can almost steer the boat under sail. The prop ads drag but only about half a knot. With the additional rudder blade it should steer the boat fine in event of rudder bracket breakage.
Anyone have a suggestion on how to mount the blade before I get into this project?
I deem the motor and mount far and away strong enough. Instincts tell me loads will be less then engine experiences while running full throttle.

My first idea is to make a plywood wedge to fit on the lower unit for the rudder to rest against and perhaps lash the blade to the engine. I could also get creative and make a whole sheath the rudder could slide up and down in, and have a way to attach it to the motor.
For long distance sailing I would remove the prop, then anchor to replace it before entering harbor. We Can do that here in the land of shallow waters!
I could carry spare brackets. It would be a chore to replace them while cruising though.

Ixneigh

I am not quite sold on the need for alternate steering as described when the only single point of failure for three different directional controls (2 rudders and a motor) is the linkage between the wheel and the inside steering mechanism. If something happens that results in damage to both rudders and the outboard resulting in all three being non-functional (other than the internal components), I would think you may have bigger problems than just steering. I have seen alot of discussion about rudder brackets here - but this part of the system is already redundant - if one breaks, you have another.

If I were wanting to be prepared for a single point failure (cable and inside mechanism), I might be more likely to figure how to move the motor manually (as one member recently had to do).

If a jury rigged rudder is important, find a place to store a boat oar and use it like a sculling oar - could just tie to a rear cleat.

My thoughts exactly RobertB, right down to the oar. I don’t think it’s uncommon to have some sort of backup steering contingency plan on a sailboat; sometimes a separate lever to bypass the steering mechanism and link directly to the rudder is standard equipment.

And while it is always a good idea to have a backup plan on hand, there are already redundancies built into the Mac configuration, making a total failure less likely than other sailboat designs.

Like you, and Roger, I am a member of the Society of Redundancy Society.

- Brian.

(presently awaiting delivery of the quick-release clam cleats DaveB has installed).

I've tillered my using an oar lashed to motor. It works great.

My tiller pilot also does not use the steering gear ...that mod was my application example for membership into the SRS

I was more referring to a solution that could bring you home from some distance, like days away. Not just a quickly to get back to the mooring or launch ramp. A long enough oar to effectively steer this boat in real world conditions will be hard to store. I'd spend a few days on an island making an oar out of a rudder blade and found materials before I would do that. I know one rudder will sort of steer the boat until you tack and it's on the up side.
The idea is to be able to carry on with few losses in performance. With a blade attatched to the engine, your major loss would be the prop in the water, and for long sailing days that could be removed.

Ixneigh

Ixneigh wrote:I was more referring to a solution that could bring you home from some distance, like days away. Not just a quickly to get back to the mooring or launch ramp.

Wow, sounds like you are a real long distance type explorer. There was a day when sailboats carried spare sails and masts. Maybe if you reconsidered the oar, you could also use it as a short mast if you lost your mast

Personnaly, as some of the Muckers found out, I prefer to carry a set of tools and hardware to enable me to make repairs to the boat away from home.