Rudder Modifications

[Northern Spy]

kapnd posted a picture of the US Navy utility boat backing rudder earlier in this thread.

 

[123]

I Post this picture to keep it in the forum archive;

 

[HeadedToTexas]

I appreciate that I am too new to operating a 37' single screw boat, but improved rudder response would sure provide more confidence when backing into my slip in wind. Assuming a stern thruster has the same impact as a bow rudder, that seems like a smart move. Assumptions being what they are, adding inches to the leading edge of the rudder seems like a smart move too.

To me, it looks like there is a lot more clearance between the leading edge of my rudder and the prop than I see in other pictures in this thread. What am I missing?

 

[Xsbank]

I added an angle to my trailing edge and there are no adverse effects at cruise but at slow, maneuvering speeds, huge difference.

Also, notice where the anode is welded? Much better than where it previously was, in the middle of the "blade." Much less vibration from wash.

 

[trawlercap]

After 68 years and a bunch of $ (I suspect) this rudder works really well on a 61 ton dis. vessel. It's been plated (foiled sorta) A leading edge added to front for balance, and an articulating tail. As the redder deflects, the tail accelerated the force. The hull shape and loading makes all the difference in how a boat handles. This rudder corrects in 1º increments to stay on track.

 

[ofer]

wood Rudder

What if anything should I do with my wood rudder. nothing wrong with it. would like better steering around the dock.

 

[Xsbank]

I would get 2 2x4s, the length of the vertical dimension of the rudder and through-bolt them on the trailing edge like a clamp then try it out. Don't penetrate the wood of the rudder, then if you don't like the results, a diver could knock them off so you don't have to get hauled again. I can't really see the size, 2x6 might be necessary.

I'd also lose that 5-bladed monstrosity and get a 3 blade. (Cue the link to the lottery sales site.)

Ps, that's a gorgeous boat. Beautiful boats always get a second look when you leave them and walk away but mine rarely does except to make sure it's shipshape. The advantage of an ugly boat is that you don't need to keep them beautiful...

 

[Nomad Willy]

My rudder is actually big enough.

I gained a huge increase in maneuverability, however by increasing the deflection from 32 to 45 degrees.

Rudder and rudder controlling mechanisms need to be strong enough for the increased rudder loads. And probably only fully safe on FD boats.

 

[DDW]

I appreciate that I am too new to operating a 37' single screw boat, but improved rudder response would sure provide more confidence when backing into my slip in wind. Assuming a stern thruster has the same impact as a bow rudder, that seems like a smart move. Assumptions being what they are, adding inches to the leading edge of the rudder seems like a smart move too.

To me, it looks like there is a lot more clearance between the leading edge of my rudder and the prop than I see in other pictures in this thread. What am I missing?

You could add to the leading edge, but be careful of going too far. 25% of the total area ahead of the pivot point will make the balance neutral, usually NAs don't go much more than about 20% to keep the helm from going unstable.

I added an angle to my trailing edge and there are no adverse effects at cruise but at slow, maneuvering speeds, huge difference.

Also, notice where the anode is welded? Much better than where it previously was, in the middle of the "blade." Much less vibration from wash.

But when you did that it turned your boat sideways. Not a good tradeoff....

 

[Xsbank]

That's Apple Disease. I don't even apologize any more.

 

[Choices]

I also have a single screw and have considered rudder modifications.

My approach of going very slow only compounds the problem of loss of steerage.

Goosing the throttle does help, but I consider numerous shifting to be almost destructive to my Borg Warner.

My background was yachts then offshore supply boats, each end of the spectrum. I use wind to my advantage along with crew speed and tactics.

Give it a little time. I watched a guy dock a single screw he had just bought into an incredibly tight spot. It was his first boat, and he had taken ownership that morning.

 

[Lepke]

Assumptions being what they are, adding inches to the leading edge of the rudder seems like a smart move too.

You can't just add more rudder in front of the shaft. You have a balanced rudder. More in front would make the wheel want to go hard over from the prop wash. Having that piece in front makes turning the wheel easier. Adding too much will make the rudder want to go hard over on it's own.

 

[kapnd]

No common single screw boat will steer by the rudder in reverse until the boat begins moving backwards, as the rudder is not in the propellers thrust path.
Single screw boats initially move with the prop walk until some rearward momentum is obtained.
It’s reflexive to twist the wheel To the stops in the direction you want the boat to back, but my rudder actually bites better in reverse at about 25 - 30*, and improves when you get some momentum and can slip it back into neutral, then coast against the rudder.
Keel size factors in here too, longer, deeper keels help reduce prop walk.
Propeller configuration also has effect on prop walk, but I’m not qualified to discuss that!
The main thing is to learn how to utilize the peculiarities of your boat and use them to your advantage.

 

[waltini]

Becker Rudder

The ferry I work on has an articulated rudder, the hinged flap angle increases the more the rudder is applied. We call it a Becker Rudder.

https://en.wikipedia.org/wiki/Flap_rudder

 

[kapnd]

Goosing the throttle does help, but I consider numerous shifting to be almost destructive to my Borg Warner.
.

Your transmission should be good for many thousands of shifts, as long as they are properly executed, and your installation and maintenance is meticulous.
The most common transmission abuse I see in docking operations is shifting with too many revs on.
A single lever shift/throttle arrangement can eliminate that problem from ever occurring

 

[Sailor of Fortune]

I also have a single screw and have considered rudder modifications.

My approach of going very slow only compounds the problem of loss of steerage.

Goosing the throttle does help, but I consider numerous shifting to be almost destructive to my Borg Warner.

My background was yachts then offshore supply boats, each end of the spectrum. I use wind to my advantage along with crew speed and tactics.

Give it a little time. I watched a guy dock a single screw he had just bought into an incredibly tight spot. It was his first boat, and he had taken ownership that morning.

Numerous shifting of the Borg Warner gear isn't destructive... The gear is made for that. Just make sure your throttle isn't advanced while shifting

 

[FF]

IF anyone is converting a Navy boat with a backing rudder , remember it moves as the steering rudder does , so its a great spot to install the autopilot rudder position device.

 

[Steve1.0]

It’s reflexive to twist the wheel To the stops in the direction you want the boat to back, but my rudder actually bites better in reverse at about 25 - 30*, and improves when you get some momentum and can slip it back into neutral, then coast against the rudder.
The main thing is to learn how to utilize the peculiarities of your boat and use them to your advantage.

My Morgan 45' ketch was like that. With a skeg hung barn door for a rudder, when going astern with the rudder hard over, the rudder stalled (turbulence on the back side) just like a wing with too high an angle of attack.

I would keep the helm centered until the boat started moving astern, then turn the rudder.
Once I figured that out, backing up was less of an adventure, but still thrilling!
P.S. no bow thruster either