Why Barn Door Rudders?

[BillyBudd]

Were barn door rudders developed for shoal draft steering? Is rudder bottom equal to keel/skeg bottom? Won't you lose steerage in a seaway with one? Why were they developed, what are their shortcomings? (I do wonder about one on a small sailing boat where sailing over rocks or shallow waters is preferred to knocking rocks or tilt up rudders, so the question came to mind.)

[rbgarr]

I think the catboat's barn door rudder was adopted for several reasons: strength and power for weather helm, a simple tiller to rudder connection via simple metal bands through a transom, the need for shallow draft and a large area, and freedom from mainsheets catching on them. They also look right somehow on the hull shape with the plumb bows, although I think the ones on Cape Cod Knockabouts detract from the appearance of the boats.

http://i27.tinypic.com/28j8ze9.jpg

A shortcoming can arise if the heel of the tiller rides forward and out of the aft-most band along the top of the rudder. It can twist the forward band badly.

The bottom of the rudder is usually no deeper than the skeg.

http://i28.tinypic.com/oktkls.jpg

[Daniel Noyes]

efficient and effective, they have a great feel when done right.
the rudder on the boat in video draws about 5" of water.
Dan

http://www.youtube.com/watch?v=FB-qLtFz4LE&NR=1

http://www.youtube.com/watch?v=8QxzD29cQ8o&feature=related

[Ian McColgin]

To shut after the horse gets out.

[johnw]

When the boat is going fast off the wind in the conditions that lead to a big seaway, the stern wave gets high enough to increase the area that's in the water.

And while they are not the most hydrodynamically efficient for steering, they are very effective for sculling. If you put one over hard, it will push the stern around and give you a push forward, which is useful when you're going slow and trying to tack a catboat. It's not like you can just back the jib, after all. In those conditions, a high-aspect vertical rudder would be almost useless.

But mainly, it's for shallow-draft vessels.

[Thorne]

How about the obverse = "Why not barn door rudders?"

My Chamberlain Dory Skiff has a strongly raked transom, and I built the kickup rudder (roughly) to Gardner's plans for the sailing Whitehall.
http://www.luckhardt.com/sausfest09-2.jpg

But I seem to end up sailing with the rudder pulled up all the time, and can't tell the difference between down and up even in fairly heavy weather.

A barn door (or kicked up) rudder on a raked transom has got to put a lot of brakeing /stopping force into the turns, which of course you don't want, particularly when tacking in light airs.

Perhaps my boat just isn't sailed fast enough to take advantage of the high-aspect foil shape of the rudder? Anyway, I keep thinking of building a more stock rudder, not necessarily a barn door design, but one that doesn't extend below the skeg.

So the question is sorta this -- what are the disadvantages of using the kickup rudder this way?

[Peter Belenky]

There are two big disadvantages to a barn-door rudder. First, the water pressure has a long lever arm, making the helm heavy. That's why cats usually have wheels, rather than tillers. Second, water eddies under the bottom, rather than being redirected around the trailing edge. This reduces the steering efficiency, making the rudder more of a brake. For this reason, Phil Bolger used end plates on his barn-door rudders (inverted T sections) to cut eddying.

[JimConlin]

...
But I seem to end up sailing with the rudder pulled up all the time, and can't tell the difference between down and up even in fairly heavy weather.
...
So the question is sorta this -- what are the disadvantages of using the kickup rudder this way?

If the helm doesn't get heavy, then the boat is well balanced. Few catboats are so blessed.
The only disadvantages to a kickup rudder are the greater complication and cost of construction and maybe a greater risk of failure.


There are two big disadvantages to a barn-door rudder. First, the water pressure has a long lever arm, making the helm heavy. That's why cats usually have wheels, rather than tillers. Second, water eddies under the bottom, rather than being redirected around the trailing edge. This reduces the steering efficiency, making the rudder more of a brake. For this reason, Phil Bolger used end plates on his barn-door rudders (inverted T sections) to cut eddying.

All correct.
And, there was a fancy endplate on the rudder of an Arey's Pond daysailer pictured here.

[Bill Perkins]

I can see that shoal running is a prerequisite for the type . I've wondered if the barn door rudder may have also evolved in part to move the lateral resistance of the hull aft ,mitigating the weather helm the type develops at times : an operable keel ?

[slidercat]

I don't know a lot about barndoor rudders, but I'm trying them out on a little cartop catamaran I've been building for several months now. They'll be skeg mounted for strength, and the point is to have rudders that don't increase the draft of the boat-- about 8 inches, loaded. I'm going to try out a variation on Bernd Kohler's and Matt Layden's horizontal foils, rather than vertical boards. The whole idea is to have a boat that requires little fussing over-- one sheet and no boards.

I hope to overcome the heavy helm problem with good long tillers. The relative inefficiency of such rudders is something I'll have to live with, but the boat will not be speedy, so I'm more concerned with handiness than speed. They'll have a little more area than vertical rudders would have.

The other day I took the boat down to the bay, just to see how it looks on the water.

http://slidercat.com/blog/wordpress/wp-content/uploads/2009/07/slipfloat.jpg

We'll see how it turns out.

[johnw]

Certainly it would be handier for beaching.

[slidercat]

Certainly it would be handier for beaching.

True, and around here there are lots of crab traps to hang your rudders on. I've designed the skegs so that a line won't catch on them, and I plan to bridge the gap between skeg and rudder with a ss strap, so a line can't slip in between. I fish a lot from Slider, my larger open cruising cat, and on several tedious occasions, fishing lines have gotten caught between rudder blades and transom, causing great mental anguish and turning the air blue.

[Bobcat]

On my catboat, I find that a shallow rudder with an end plate is a convenient thing. I hang it on the boat while she's still on the dolly and launch her with the rudder hanging in place. I can beach the boat with the rudder shipped and steer all the way to the beach. With the end plate I have never noticed the rudder losing its bite. When the weather helm gets to be too much, it's time to reef.

[Captain Charlie]

I can only speak to the Bolger Bobcat, one of which I am lucky to have just acquired. it has a Barn Door Rudder which is fully protected by the skeg. In his book "Build the Instant Catboat", Harold 'Dynamite' Payson says this about the little foot on the bottom edge of the rudder:

"I have never seen a boat with this horiizontal foot on the bottom edge of the rudder, nor had I seen any plans calling for one. The idea is that when a boat is heeled over and the rudder's bite is reduced as it leaves the vertical plane and leans toward the horizontal, this little lateral extension does just the opposite. It becomes more nearly vertical and thus gives the rudder back its bite on the water. Phil has told me he is including it many of his current designs. I can vouch for its effectiveness on Bobacat, for her rudder holds right on when she heels over.
The Rockport, Maqine desigher Henry Scheel has adopted the same principal in the "Scheel Keel" ...."

This is on a smallish Barn Door Rudder which we have yet to get wet due to the high temps here near the Ches Bay. Will do so soon. I have pix that I can post if someone wants them.

RIP Phil Bolger.....

[slidercat]

Just a quick update: I took Slipper out for the first time Thursday. The barn door rudders were great, the helm was very light.

Details here:

http://slidercat.com/blog/wordpress/?p=222

http://slidercat.com/blog/wordpress/wp-content/gallery/otherboats/sliplnch03.jpg

[Jim Ledger]

The evolution of the catboat from the earlier underslung, counter stern rudders to the barn door rudder made several improvements to the craft, quite apart from the steering.

First, as the boats became beamier, the tiller was abandoned, in the larger boars, for wheel steering. You simply couldn't reach the tiller from a bench along the cockpit side.

The barn door setup moved the sternpost aft, sometimes two feet or more, enabling the cockpit to be extended aft, reducing the size of the somewhat useless after deck.

The barn door rudder is somewhat simpler to build. An underslung rudder needs a strongly attached rudderstock to withstand the pressure of the weather helm, a difficult thing to make compared to the intrinsically rugged setup using a tiller strapped to the top of the rudder.

The rudderstock of an underslung rudder needed an arrangement similar to a centerboard trunk. The horn timber needed to be pierced to accommodate a three or four inch stock, which required the horn timber to be perhaps ten inches wide, or have doublers that increased the width in this area. In any case, the joinery could get complicated, and it was all eliminated by the switch to the barn door.

On the steering end, the rudder added a huge amount or area to the keel aft, which would mitigate the weather helm somewhat.

Got all that?:rolleyes:

Here's a shot of a counter stern Gil Smith catboat. You can see the rudder trunk just inside the lazarette. There's some nice detailing on the tiller and rudderstock, which seems to be a typical Smith touch.
http://i104.photobucket.com/albums/m193/searover1916/DSCF7924.jpg

[Daniel Noyes]

congrats slider!
more photos to follow?

as far as Barn Doors I have used them in small boats and only have good to say, they are much more effective than high aspect foils at slow speed and are much better around sand bars and marsh grass.

breaks? eddying?, heavy helm? not on the small boats I have sailed.

helm ballance has lots more to do with relation of centerboard vs. sail area than the shape of the rudder

[slidercat]

Thanks, Daniel

I think one reason folks tend to regard low-aspect rudders as heavy on the helm is that when a rudder with a pivot point above the waterline kicks back, the leverage of that tip in the water so far aft makes the steering heavy--

But that isn't the situation with barndoor rudders-- they start just aft of the pivot point. I think the notoriously heavy helms of catboats have more to do with their hull shapes than their rudders.

[Harbormaster]

(Why) Were barn door rudders developed for shoal draft steering?

Because they were simple, relatively effective and most of all they were cheap.

[Wooden Boat Fittings]

One way of keeping tight control over a barn door rudder with it's huge surface area (and the ensuing massive torque) is to eliminate the tiller entirely. SF Bay sailing scows used gun tackles rigged to the tip of the rudder.

And further to this is that many of our Murray River paddle-wheelers are steered with chains to the top of the rudder's trailing edge, to give as much leverage to the rudder as possible.

Mike

[Canoeyawl]

The set-up on the old SF hay scows like Alma is interesting that the entire helm is movable. The wheel and A-frame can be moved up on top of a deck load to gain visibilty. It is lashed down to the deck using tackle all the way back to the rudder.
(The rig was tall enough to sail well reefed up to clear the deck load).
http://www.boatingsf.com/photos/031105/DSCN3986_edited-1.jpg

Here we go, business as usual... I think there are four loaded hay scows in this image
http://www.deepcraft.org/deep/wp-content/uploads/2009/06/scowschooner3.jpg

[boylesboats]

There are two big disadvantages to a barn-door rudder. First, the water pressure has a long lever arm, making the helm heavy. That's why cats usually have wheels, rather than tillers. Second, water eddies under the bottom, rather than being redirected around the trailing edge. This reduces the steering efficiency, making the rudder more of a brake. For this reason, Phil Bolger used end plates on his barn-door rudders (inverted T sections) to cut eddying.

Gives the rudder more bites...

It also help reduce fouling with underwater vegetations.. William Garden's TomCat..

[peter radclyffe]

http://www.ac-marine.co.uk/assets/images/Thames_Barge_01.jpglack of harbour/river draught is a worldwide problem, & has influenced millions of boat designs

[richincident]

I learned to sail on a Cape Cod Baby Knockabout and I will agree that the barndoor doesn't look as good AND has an immense helm. Little kids can't steer these boats.

On the other hand they are wonderful in shallow water--they can sail through a heavy dew! So the barndoor is welcome in places like the Great South Bay where I began sailing.

[slidercat]

I learned to sail on a Cape Cod Baby Knockabout and I will agree that the barndoor doesn't look as good AND has an immense helm. Little kids can't steer these boats.


I don't think it's the rudders that give catboats a heavy helm. When we took Slipper out for her first sail a few days ago, I amazed to discover that the helm was feather light. And these are big and long for a lightweight 14 foot boat.

http://slidercat.com/blog/wordpress/wp-content/gallery/otherboats/slipfeb03_0.jpg

[wtarzia]

The set-up on the old SF hay scows like Alma is interesting that the entire helm is movable. The wheel and A-frame can be moved up on top of a deck load to gain visibilty. It is lashed down to the deck using tackle all the way back to the rudder.
(The rig was tall enough to sail well reefed up to clear the deck load).

--- That's amazing. I'm so glad I serendipitously checked out this thread. Reminds me of how we loaded our pick-up when I was a kid bringing hay home for the nags we kept :-). Reminds me also of the photos of harvesting salt hay in the Parker River/Plum Island River region, though I think they rowed and poled. -- Wade

[Daniel Noyes]

I learned to sail on a Cape Cod Baby Knockabout and I will agree that the barndoor doesn't look as good AND has an immense helm. Little kids can't steer these boats.

On the other hand they are wonderful in shallow water--they can sail through a heavy dew! So the barndoor is welcome in places like the Great South Bay where I began sailing.

the weight on the helm means there is lots of sail area aft of the center boards area... doesnt mater what shape the rudder is there will be lots of pressure on it... it's just that with the bard door style you feel the poorly ballanced sail and resulting pressure... a little pressure is good

[Daniel Noyes]

--- That's amazing. I'm so glad I serendipitously checked out this thread. Reminds me of how we loaded our pick-up when I was a kid bringing hay home for the nags we kept :-). Reminds me also of the photos of harvesting salt hay in the Parker River/Plum Island River region, though I think they rowed and poled. -- Wade
I built a Gundalow model... with a barn door rudder!
sails impressivly well
Dan
(Parker River)