Skeg hung rudders

[Jeff_H]

I figured you knew what they were but was not familiar with the terms. One of the oddities about American rudder terminology is that in my life it has changed pretty dramatically. Back in the 1960's, both skeg hung and post hung rudders were called spade rudders. Today it seems that a lot of folks consider only post-hung rudders to be spade rudders.

Jeff

[chucklesR]

sorry, I of course disagree - mine is best:
http://www.geminicatamarans.com/Perf...ni_Rudders.htm

[Stillraining]

I cant compeate with that!...

[Giulietta]

my old rudder was wide...the new one is narrower and longer

[JohnRPollard]

Originally Posted by Giulietta

By the way...ours are the best !eheheheehe

"Best" at what?? Breaking? Snagging? Oh, you mean "fastest"? Okay, I'll grant you that.

Mine is "best" at going slow. And for driving over pot warps and "dead-heads" (erps knows what I mean).

Chuck Paine does a nice semi-balanced skeg hung rudder on some of his designs. Here's a photo where you can almost see the angle of the rudder post as it passes through the rudder, with a portion of the rudder area (about 30%) forward of the rudder post and the remainder trailing behind it:


Morris 32


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[tdw]

Originally Posted by Giulietta

Just a small request..what is a skeg and a post rudder and a protective flap??

Someone show me the different things and the names,,,very confused now.

Alex i'm a little confused by that as well , it doesn't appear very clear from Jeff's photo. Pardon me if I'm not answering your question and am telling you something you already know but a skeg hung rudder is.....



while a post hung rudder is as per ........ (same as yours).....



Post hung is generally referred to as a spade rudder down here.

Now, I've long been an advocate of skeg hung for reasons of safety and strength but I confess I'm starting to wonder. The well reported failure of spade rudders has been largely confined to lightish weight modern production boats and/or out and out racers. While the number of failures does seem to have increased over the years its well to remember that the huge increase in the number of cruisers out there could well account for this. Raven is getting on for 20 years old and has had zero problems with her rudder, while the boat we are looking at to buy is slightly older and again has had no problems. I think the jury is still out on this one but while I'm equivocating over the issue I still think that if I was building a cruiser I'd go skeg but the lack thereof is not going to automatically disqualify a contender that is second hand.

Regarding the tracking abilitities of such boats I'm of the opinion that this is more to do with the keel and hull than it is to do with the rudder. Again, Raven is spade rudder fin keel and steers herself quite happily unattended for hours at a time. Bit of sail adjustment and a constant wind required but it does work. I'm thinking its the amount of meat you have underwater that counts.

All of this is my opinion only, I certainly don't have the scientific knowledge to back any of this up, but a good mate of mine who does design work on major racing boats reckons that provided the design is right and the construction top quality the argument twixt spade and skeg hung is moot.

Val, my PB was a 1960's full keeler. For her time considered moderate in weight but these days would be considered a heavyweight (for a 28'er) yet where she was unlined you could see light through the hull.

[jrd22]

Erps- so right you are. I, unfortunately, can attest to the fact that logs can and do hit keels and rudders. While this is probably much more prevalent here in the PNW, I'm sure it occurs with any wooden debris that becomes waterlogged. In my case I was sailing very slowly in practically calm seas (near Friday Hbr) when I hit a submerged log about 30' long and 16" diameter floating more or less horizontally, which is contrary to the normal vertical deadhead. It thumped the front of the keel, then the bottom of it, and then slightly bumped the rudder as we went over it. It came to the surface briefly about 30-40' behind the boat then went under again, occaisionally breaking the surface at one end or the other. No damage but I hate to think what might have happened if I had been going 6K instead of 2 (or 20 in the crab boat). We only have a partial skeg on that boat and I remember worrying about it getting hit by whatever we hit (didn't know what it was until it surfaced behind us). I'm sure that a lot of other floating or partially submerged debris, if hit dead on, will behave the same way that log did. By following the forward edge of the keel down and under then trying to surface at the first opportunity, which is right in front of the rudder. The exception of course, is a full keel with the wheel in an aperture. On our new boat that has a fin keel and full skeg I am in the process of deciding whether to have a heavy (3/4" X 4") SS bar glassed from the bottom of the aft end of the keel to the bottom of the skeg, so this discussion is timely. I have seen this done on some other boats. Anyone have experience doing something like this?

I think that it is fairly safe to say (even here) that a skeg offers some protection to the rudder which is absent with a spade. The ways that you can hit something, or it hit you, are limitless, and personally I like knowing the skeg is there to help protect and support an important part of the boat. Especially here in the land of ten thousand deadheads.
For cruising I can't think of any viable reason to choose a spade over skeg all things being equal; for racing the reverse makes sense of course.

John

[Jeff_H]

This is a close up of the skeg where it meets the rudder that shows the flaps.

http://www.sailnet.com/photogallery/....php?file=3288

http://www.sailnet.com/photogallery/....php?file=3288

[sailingdog]

One thing nice about the rudder on the Gemini and Telstars is that they're designed to steer in the kicked up position as well as in the down position, and anywhere in-between.

[JohnRPollard]

JeffH made an interesting point about the historical use of the term "spade" rudder. So I will leave it to JeffH to comment whether I'm using the terminology "balanced rudder" correctly either. I have always used that term generally to describe a rudder with some of its surface area forward of the rudder post and some trailing behind.

I also use that term to refer to some rudders lacking an embedded rudder post that nevertheless have a certain amount of surface area forward of the rudder's axis of rotation and some aft of it. An example of this latter type would be the Melges 24, which has what I would call a balanced transom hung rudder (it looks a lot like Giulietta's rudder, but smaller and hung from the transom with pintles and gudgeons, so no embedded rudder post).

More comments below....

Originally Posted by tdw

Alex i'm a little confused by that as well , it doesn't appear very clear from Jeff's photo. Pardon me if I'm not answering your question and am telling you something you already know but a skeg hung rudder is.....



while a post hung rudder is as per ........ (same as yours).....



Post hung is generally referred to as a spade rudder down here.

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Regarding the tracking abilitities of such boats I'm of the opinion that this is more to do with the keel and hull than it is to do with the rudder. Again, Raven is spade rudder fin keel and steers herself quite happily unattended for hours at a time. Bit of sail adjustment and a constant wind required but it does work. I'm thinking its the amount of meat you have underwater that counts. ...

TDW,

I can't tell from your photos, but it looks like Raven may not have what I call a "balanced" spade rudder? Could it be that the rudder post on Raven runs down through the leading edge of the rudder (like in the photo of the Crealock 31 that I posted at the beginning of this thread)? Such that all or most of the rudder's surface are trails behind the rudder post? In which case, I would still call it a spade rudder, just not a balanced spade. If so, that might partially account for how well your boat tracks. Any more close up photos you could show us?