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Old 16-05-2020, 17:59   #31
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Re: List of boats with skeg and sugar scoop

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My Oyster 55 has a sugar scoop and a skeg rudder. It will not turn on a dime the way my Beneteau with a big spade rudder would, but turning on a dime is not good sailing. When I was researching the boat characteristics that I required in an ocean going boat, I found that a very high percentage of boats abandoned at sea were due to rudder failure, maybe more than half. It is possible that some spade rudders are as strong as some skeg hung rudders, but does it make much sense that a big spade rudder ATTACHED TH THE HULL AT ONLY ONE ATTACHMENT POINT can be as strong as a skeg hung rudder attached at 3-5 attachment points?
No boats have the rudder attached at only one point to the hull. A proper spade rudder has attachment at both where the shaft exits the hull and at a second place ideally above the waterline.

As Dockhead stated all Dashew's designs have had spade rudders since the beginning and they average over 50k miles for the group.

As Bob Perry has stated many skegs are held on by the rudder. Walk through a yard and shake a few rudders to see this for yourself.

Bestevaer's designs by Dykstra all have spade rudders. All easy to steer. Interestingly many have tillers including the designer's own 53' boat.

A good spade rudder can and often is much stronger that a rudder on a skeg. Examples would be the Bestevaer and Outbound. Yes, you can build a weak spade rudder just as you can build a weak rudder on a skeg.

Many of the boats that do not have much ability to hold a course without a hand on the tiller or wheel were never designed to - they were racing derived and maneuverability was the design brief. A racer never leaves the wheel.
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Old 16-05-2020, 18:08   #32
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Re: List of boats with skeg and sugar scoop

Caliber 35 has both, although it's more of a half scoop
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Old 16-05-2020, 18:58   #33
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Re: List of boats with skeg and sugar scoop

Kraken Yachts.
https://www.krakenyachts.com/k50
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Old 16-05-2020, 19:14   #34
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List of boats with skeg and sugar scoop

Caliber 40LRC. The skeg is definitely not supported by the rudder.
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Old 16-05-2020, 21:01   #35
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Re: List of boats with skeg and sugar scoop

Our Taswell 43 has a half-rudder skeg, and a sugar scoop. Seems to be a bunch designed like that!
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Old 16-05-2020, 22:26   #36
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Re: List of boats with skeg and sugar scoop

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But why? Skeg rudders are terribly inefficient, and not necessarily any stronger.
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Old 16-05-2020, 23:50   #37
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Re: List of boats with skeg and sugar scoop

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Caliber 40LRC. The skeg is definitely not supported by the rudder.. .

Well, you can't say that from that photo.


How is the skeg tied into the boat structure? Let's see it from the inside.



Most of them are just superficially glassed into the outer hull skin -- not strong at all. That's what Bob Perry was talking about.


To make a skeg really strong it needs to be attached the way you would a keel, and it needs to go into a proper keelson and/or ring frame. It's harder and more expensive than making a strong spade rudder. Because as Mietiempo mentioned, spade rudders have two (or more) bearings, one located well up into the hull. All you need is a sufficiently beefy rudder shaft. See the rudder discussion in this thread: https://www.cruisersforum.com/forums...-147499-4.html



One more drawback of a skeg rudder is the propensity to jam if you hit something with it. A spade rudder will bend, given enough force, but is often still functional, where as any bend in the rudder shaft of a skeg rudder will jam it dead.
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Old 17-05-2020, 12:22   #38
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Re: List of boats with skeg and sugar scoop

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No boats have the rudder attached at only one point to the hull. A proper spade rudder has attachment at both where the shaft exits the hull and at a second place ideally above the waterline.
No boats? Can you show me on my Beneteau where the second attachment point is?

By the way, the reason she is on the hard in this photo is because I hit a rock and the rock took a shark bite out of my rudder. Fortunately, after diving under to inspect the damage, we were able to continue sailing and had no water intrusion. But the boat had to be hauled and the rudder repaired.
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Old 17-05-2020, 12:34   #39
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Re: List of boats with skeg and sugar scoop

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Originally Posted by Dr. Sea View Post
No boats? Can you show me on my Beneteau where the second attachment point is?

By the way, the reason she is on the hard in this photo is because I hit a rock and the rock took a shark bite out of my rudder. Fortunately, after diving under to inspect the damage, we were able to continue sailing and had no water intrusion. But the boat had to be hauled and the rudder repaired.
I did say "proper" spade rudder. Maybe a reason to not use a Beneteau offshore if true.

This drawing from Jefa shows a proper spade rudder installation.
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Old 17-05-2020, 12:46   #40
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Re: List of boats with skeg and sugar scoop

Skegs do tend to be rather long and of limited fore aft thickness hence of rather spindly and weak as to impact strength but they do add a second vertical strengthen compared to non-skeg mounted rudder so there is a sharing of loading across the two structures.

Recommend reading the comments of Kraken Yachts regarding skeg mounted rudders:

https://www.krakenyachts.com/skeghungrudders

"In the old days, the rudder on a typical blue water cruiser was hung on the back of a long keel. Indeed the occasional retro-design still has this feature.

Then in the ‘60s leading yacht designers such as Sparkman & Stephens moved to fin keels and hung the rudder on a skeg. This became the norm for cruiser-racers until – in pursuit of ever more speed – skegs began to disappear and most rudders became ‘stand-alone’ spades.

However the vast majority of blue water cruisers hung onto their skegs. Sailors and designers valued the extra support, strength and protection that a skeg undoubtedly provides. And as ever-more unidentified floating objects (UFOs) now litter the oceans, this protection is even more important.

​So why have almost all large modern production cruisers abandoned their skegs?

And why – even more surprisingly – is this habit spreading to serious blue water cruisers? Why are so many unsupported spade rudders now hanging under blue water cruising sterns?

​The answer – predictably - lies in the cost.

It is far cheaper to suspend a spade rudder under a flat surface than it is to incorporate a tough skeg into a hull and attach the rudder to it.

Kraken Yachts Ltd always prefers the ‘safety first’ approach. So the Kraken 50 ft sailing yacht, 58 and 66 models all have robust skegs. This process may cost more – but what price can you put on safety?

If you study the increasing number of mid-ocean rudder losses in events such as the ARC (occasionally leading to the abandoning and/or sinking of the yacht) you will find that unsupported spade rudders are leading culprits. Indeed, it was reported that one couple who lost their yacht were ‘now looking for a boat with a longer keel and a skeg-hung rudder.’ The same applies to the growing trend towards twin rudders. Unless these have strong skegs to absorb or deflect the impact of UFOs, they are just as vulnerable.

​Kraken designer Kevin Dibley and Kraken Yachts have opted for a ‘belt and braces’ approach. Dibley explains; “The bottom of the K50’s rudder is attached to the skeg by way of a bronze heel plate. Although both the robust Kraken rudderstock and the full depth skeg are self-supporting, the skeg will absorb a large part of the energy of hitting a UFO. All of this force would otherwise be on the rudder blade’s leading edge and stock.”

Kraken chairman Dick Beaumont has cruised well over 250,000 nautical miles so he understands the importance of safety at sea. Kraken Yachts’ robust skeg-hung rudder design and construction are further proof of his determination to supply safety as standard."



One might also find of interest Kraken's Zero Keel structural configuration. Zero as in NO BOLTS holding the keel with its lead ballast.

https://www.krakenyachts.com/zerokeel
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Old 17-05-2020, 12:50   #41
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Re: List of boats with skeg and sugar scoop

Here is another drawing from Catalina.

How does your emergency tiller attach?
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Old 17-05-2020, 13:04   #42
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Re: List of boats with skeg and sugar scoop

Quote:
Originally Posted by Montanan View Post
Skegs do tend to be rather long and of limited fore aft thickness hence of rather spindly and weak as to impact strength but they do add a second vertical strengthen compared to non-skeg mounted rudder so there is a sharing of loading across the two structures.

Recommend reading the comments of Kraken Yachts regarding skeg mounted rudders:

https://www.krakenyachts.com/skeghungrudders

"In the old days, the rudder on a typical blue water cruiser was hung on the back of a long keel. Indeed the occasional retro-design still has this feature.

Then in the ‘60s leading yacht designers such as Sparkman & Stephens moved to fin keels and hung the rudder on a skeg. This became the norm for cruiser-racers until – in pursuit of ever more speed – skegs began to disappear and most rudders became ‘stand-alone’ spades.

However the vast majority of blue water cruisers hung onto their skegs. Sailors and designers valued the extra support, strength and protection that a skeg undoubtedly provides. And as ever-more unidentified floating objects (UFOs) now litter the oceans, this protection is even more important.

​So why have almost all large modern production cruisers abandoned their skegs?

And why – even more surprisingly – is this habit spreading to serious blue water cruisers? Why are so many unsupported spade rudders now hanging under blue water cruising sterns?

​The answer – predictably - lies in the cost.

It is far cheaper to suspend a spade rudder under a flat surface than it is to incorporate a tough skeg into a hull and attach the rudder to it.

Kraken Yachts Ltd always prefers the ‘safety first’ approach. So the Kraken 50 ft sailing yacht, 58 and 66 models all have robust skegs. This process may cost more – but what price can you put on safety?

If you study the increasing number of mid-ocean rudder losses in events such as the ARC (occasionally leading to the abandoning and/or sinking of the yacht) you will find that unsupported spade rudders are leading culprits. Indeed, it was reported that one couple who lost their yacht were ‘now looking for a boat with a longer keel and a skeg-hung rudder.’ The same applies to the growing trend towards twin rudders. Unless these have strong skegs to absorb or deflect the impact of UFOs, they are just as vulnerable.

​Kraken designer Kevin Dibley and Kraken Yachts have opted for a ‘belt and braces’ approach. Dibley explains; “The bottom of the K50’s rudder is attached to the skeg by way of a bronze heel plate. Although both the robust Kraken rudderstock and the full depth skeg are self-supporting, the skeg will absorb a large part of the energy of hitting a UFO. All of this force would otherwise be on the rudder blade’s leading edge and stock.”

Kraken chairman Dick Beaumont has cruised well over 250,000 nautical miles so he understands the importance of safety at sea. Kraken Yachts’ robust skeg-hung rudder design and construction are further proof of his determination to supply safety as standard."



One might also find of interest Kraken's Zero Keel structural configuration. Zero as in NO BOLTS holding the keel with its lead ballast.

https://www.krakenyachts.com/zerokeel

Propaganda for a highly eccentric point of view, not shared by any of the world's great yacht designers. Comparing spade rudders with bolt-on keels is particularly telling.



Swan, Hallberg-Rassy, Contest, all Dykstra designs, all Dashew designs -- all use bolt-on keels, and all use spade rudders. Most big ships use spade rudders. It is not a question of cost.
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Old 17-05-2020, 14:04   #43
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Re: List of boats with skeg and sugar scoop

FYI: Several references.


https://www.sailmagazine.com/diy/rudder-awareness


And the King Support Rudder scheme seems novel. In this arrangement the rudder trunk is extended into the rudder blade so that the lower neck bearing is positioned as close as possible to the centre of force acting on the rudder

https://www.becker-marine-systems.co...udder-ksr.html

I also find the Twisted Leading Edge Full Spade Rudder for higher speed propeller propulsion powered vessel of clear interest.
TLKSR® Twisted Leading Edge Rudder
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Old 17-05-2020, 15:47   #44
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Re: List of boats with skeg and sugar scoop

Quote:
Originally Posted by Montanan View Post
FYI: Several references.


https://www.sailmagazine.com/diy/rudder-awareness


And the King Support Rudder scheme seems novel. In this arrangement the rudder trunk is extended into the rudder blade so that the lower neck bearing is positioned as close as possible to the centre of force acting on the rudder

https://www.becker-marine-systems.co...udder-ksr.html

I also find the Twisted Leading Edge Full Spade Rudder for higher speed propeller propulsion powered vessel of clear interest.
TLKSR® Twisted Leading Edge Rudder

Yep, spade rudders, at the bleeding edge of ship technology


They are hydrodynamically superior, while being not at all hard to make plenty strong.


The "King Support" spade rudder is interesting -- the rudder post is immobile, so the bearing is down in the rudder. Interesting whether that idea could have application for smaller vessels. Obviously the bending moments on the rudder post will not be any different -- it's still a cantilever -- but less stress on the bearing.
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Old 18-05-2020, 08:57   #45
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Re: List of boats with skeg and sugar scoop

Interesting commentary …

Moody 58's have a skeg hung rudder, performance underbody, sugar scoop transom, build-in steps and self-stowing boarding ladder.

This vessel responds well to her helm, is comfortable at sea and offers a turn of speed sufficient to average 220 nautical miles/day for 14 days during a recent Gibraltar Barbados crossing. Her skeg is a significant piece of kit.

Admittedly, she cannot turn quite as quickly as an equivalent vessel fitted with a spade rudder hung well aft, but a properly hung skeg confers more than a modicum of protection to the rudder of an offshore cruiser.
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