Skeg or Spade?

[Ericson38]

Cal 40

https://www.bing.com/images/search?q...1o0&ajaxhist=0

[K_V_B]

Spade rudders aren't a new thing. The Pionier, the first mass produced GRP boat in Europe, had a spade rudder. Van de Stadt was always a big proponent of spade rudders, and in an interview he describes how he managed to win over his colleagues to the spade rudder, one by one, by repeatedly beating them in ocean races.
Van de Stadt has also said, on the record, that skeg rudders actually failed more often in his experience than spade rudders...
Here's another classic beauty: The Gallant 53:

Naomi James sailed around the world in one of those...

[Ericson38]

Originally Posted by Dockhead

My boat would be faster and better with a spade. But as I've said -- I don't think it's critical for cruising boats, which aren't typically sailed upwind much. So don't think I'm actually any kind of fan-boy. I just like truth and facts.

As to boats being made with skeg keels:

Island Packet is bankrupt and not producing.
Tayana are no longer in business.
Caliber are semi-long keel boats of '70's design, produced in very small numbers.
Passport -- you are right; missed that one. How many are sold every year?
Hylas -- the new ones have spade rudders; others have semi-balanced rudders with short skegs.

If your rudder is balanced and the skeg is partial, there is not a lot of skeg to start with, about 1/3 the way down on the leading edge, but since the rudder top edge slopes up to follow the centerline rise at the stern, about 1/2 way down from an overall planform view.

49 Taswell soda blast, Gel skim-peel, barrier - 67 :: Job Photos :: Solomon Yacht Restoration, LLC

http://www.tommysolomon.com/photos/4.../51/large/#nav

I think your Dixon boat is close to this Taswell 49.....but I don't know for sure. You aren't going to gain anything measurable in pointing angle or downwind boat speed by removing the partial skeg. There is more drag from a non-folding prop by far, and as far as lift to windward, that has about 80% to do with the keel's lift to drag ratio than the rudder lift to drag, being proportional to planform area.

Sailing upwind happens more than 50% of the time it seems to me, and beam and broad reaches of any distance are less common, since apparent wind shifts forward. Out boat goes to windward well for a cutter with a roller main. No complaints at all.

How close can you sail to the wind, apparent wind angle, effectively, with and without your staysail ?

How is your main furled and does it have battens ?

[Dockhead]

Originally Posted by Ericson38

If your rudder is balanced and the skeg is partial, there is not a lot of skeg to start with, about 1/3 the way down on the leading edge, but since the rudder top edge slopes up to follow the centerline rise at the stern, about 1/2 way down from an overall planform view.

49 Taswell soda blast, Gel skim-peel, barrier - 67 :: Job Photos :: Solomon Yacht Restoration, LLC

49 Taswell soda blast, Gel skim-peel, barrier - 51 :: Job Photos :: Solomon Yacht Restoration, LLC

I think your Dixon boat is close to this Taswell 49.....but I don't know for sure. You aren't going to gain anything measurable in pointing angle or downwind boat speed by removing the partial skeg. There is more drag from a non-folding prop by far, and as far as lift to windward, that has about 80% to do with the keel's lift to drag ratio than the rudder lift to drag, being proportional to planform area.

Sailing upwind happens more than 50% of the time it seems to me, and beam and broad reaches of any distance are less common, since apparent wind shifts forward. Out boat goes to windward well for a cutter with a roller main. No complaints at all.

How close can you sail to the wind, apparent wind angle, effectively, with and without your staysail ?

How is your main furled and does it have battens ?

My boat has a different set of compromises -- the rudder is oversized, for power, and that increases wetted surface and drag. You are right that the short skeg doesn't make a big difference in the hydrodynamics, but still it is worse than a full spade. The oversized and very powerful rudder is because my boat was designed for sailing above 50N and for very hard sea conditions.

As to sailing "more than 50% upwind" -- you are absolutely right about that. Sometimes it seems to me that it's 80% of the time. And that's why you either need to make the boat capable of making miles upwind, which is hard, and expensive, or just be happy to motor quite a lot of the time (as my Father was).

To answer your other question -- my goal when I re-rigged my boat was to be able to make 5 knots VMG to windward in good conditions (20 knots apparent wind, +/-, reasonably smooth sea state). I don't think I quite made it, but I can now get upwind reasonably well in most conditions. If the sea is not too rough, I can usually manage 8 to 8.5 knots on about 30 degrees apparent, which results in a real tacking angle with no current of 95 to 100 degrees over ground, and I get a little less than the longed-for 5 knots VMG to windward, say 4.8 on a good day. But that's more than 100 miles a day, and I think that's not actually that bad.

To get to that point, I had to sell a much treasured 1970 Porsche 911S Targa, with the proceeds of which I had carbon laminate sails made, including a roller furling main with straight leech and carbon battens, and an alternative principle headsail made especially for hard going upwind in 20 to 30 knots -- a 90% blade jib, which can be sheeted inside the shrouds.

It's probably more reasonable and definitely cheaper, to just say screw it, and put the motor on, but I love to sail.

[Sandero]

Look at this "refit" / upgrade:

Adele’s Huisfit upgrade completed: and is ready for the Arctic

[double u]

But, But, Wait...... photo - Compass Marine How To photos at pbase.com

[Nineteen]

Originally Posted by double u

But, But, Wait...... photo - Compass Marine How To photos at pbase.com

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[TernEggs]

Originally Posted by double u

But, But, Wait...... photo - Compass Marine How To photos at pbase.com

that's why the only good skegs are ones that protect the whole rudder

[atrometer]

MOST skeg rudders have a full keel. Ever tried backing up in a straight line in a marina for a distance? NOT FOR ME!! The keel on mine protects the rudder quite well, although not as good as a full keel, but I will keep her anyway. Beneteau 36 CC.

[BCookCornwall]

For extensive world cruising in remote locations a full skeg is a must. Obviously there are issues with some production brands building shoddy spades but the full skeg will always be a better safety option. As far as performance goes, for such a critical item, I would choose safety over performance.

[double u]

...apparently the unbreakable skeg has been invented...
(not to speak of the affordable one...)

[jtsailjt]

I just got an email from the current owner of my old boat, a Nordic 44 I sold to him more than 10 years ago, that enroute from Bermuda to Maine “his skeg hung rudder became a spade” and he had to leave the boat in Newport for repairs. That’s all I know for right now but will update in a few weeks when I get a chance to talk to him about it. The good news is that despite obviously serious damage, he made it safely into port. From my experience with owning this boat for 11 years, I always found it to be very well made and strong. The hull is solid glass and the skeg is made from a stainless T core bolted to the hull and embedded in foam and covered with fiberglass and faired to the hull. I never had any rudder issues and he’s a very conscientious owner who’s continued to take great care of the boat so unless he hit something I can’t imagine what happened.

[lifeofreilly57]

It all depends on how well made the boat is.
I like the performance and balance of a spade rudder, two finger steering in my previous boat, but it was more prone to snagging lobster pot lines and various ocean going floatsom and jetsom, never failed though, but then again I never hit a whale or container with it.
The current boat has a full skeg hung rudder, which requires considerably more effort to control and does not have the same performance, especially in reverse. But, I find I collect far less floating debris on it, I have to guess the lines, nets, bags, etc, etc slide over the skeg and slip right by.
It's a pretty substantial skeg but I wouldn't make any claims about the superior safety aspects of one just yet.

[double u]

I think the dangers of "unbreakable appandages", be they skeg or spaderudder are higher than the danger of a reasonably dimensioned spade that might be bent 90° in a collision: to push a demolished spade out of it's trunk is no big deal, if one has an emergency system ready (casette rudder?) one could be underway in a much shorter time than if one had to find a way to get going in a straight line again with a damaged skeg or skeghung rudder.
in slight groundings or collisions of course a skeg would protect the rudder against forces that might already damage a spade.

[Dockhead]

Originally Posted by double u

I think the dangers of "unbreakable appandages", be they skeg or spaderudder are higher than the danger of a reasonably dimensioned spade that might be bent 90° in a collision: to push a demolished spade out of it's trunk is no big deal, if one has an emergency system ready (casette rudder?) one could be underway in a much shorter time than if one had to find a way to get going in a straight line again with a damaged skeg or skeghung rudder.
in slight groundings or collisions of course a skeg would protect the rudder against forces that might already damage a spade.

Indeed, but I think it's very important not to confuse a construction which is easier to make strong with a construction which is strong. Those are two different things.

Theoretically it is easier to make a skeg rudder strong because you can spread the loads out. But that doesn't mean that any given skeg rudder is stronger than every spade rudder -- that is not true. It depends on how the systems you are comparing were engineered and built.

You made an excellent point that a skeg rudder (or partial skeg rudder like mine) will turn into a mess if it breaks or bends significantly in a collision or grounding, a mess which might make it impossible to regain steering. You should be able to drop out a bent spade.

But don't assume that every skeg rudder is stronger than every spade. A spade rudder can be built as strong as you are willing to pay for. Dashew's spade rudders, I would be willing to bet, are stronger than just about any skeg rudder ever made on a comparable boat, and as some people have posted, many skeg rudders are quite weak.

Having done thousands of miles in boats with all types of rudder, I would not personally ever want to have another boat with a full unbalanced skeg rudder, especially not on a larger boat. A partial skeg, like what I have now, at least lets you have a semi balanced rudder, but introduces other disadvantages like extra wetted surface and buoyancy in the wrong place, making a slot to catch crab pot lines. Yes, it's nice to spread the bearings out from each other, and spread the loads further along the hull, but surely the same strength can be achieved by just upsizing the shaft and bearings on a spade rudder.

Another issue we haven't discussed is how the bearings are arranged inside the hull. I've just had my rudder out so I've spent some time crawling around in this system. The shipwright who did my rudder complained that modern boats have the quadrants down as low as possible in order to increase lazarette space, but that this reduces strength and makes it harder to prevent water coming in. My rudder is oversized and seems massively strong, but how much of the massiveness of the partial skeg is there just to allow the designer to move the quadrant right down to increase the lazarette space?

An excellent point! How about a spade rudder with a lot of separation between top and bottom bearing, and the top bearing right up near deck level? You would sacrifice deck storage (make the boat a bit longer to make up for it), but if you engineered it right and with a massive maybe carbon shaft, it could be strong as hell. Put a high cofferdam around it and you would reduce the risk of getting water in to nearly zero.