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This is a consolidation of several posts made to "C&C 27 General Questions" - questions by Frank Marsden and responses from me. Perhaps the creation of a new rudder-specific topic will bring in comments more learned on the subject than mine, which are limited by my lack of experience with the 'scimitar' rudder of the earlier boats. Does anyone have an _informed_ opinion about the amount of helm induced by the two rudders? More to the point, does anyone know of a boat that has had its early-style rudder swapped for the later spade?
As to Frank's last question - "is the rudder available?" - the answer is yes. Making one here would be simple, but it probably wouldn't make sense financially as the shipping costs would be vile and there are lots of people capable of this work in England. If an informal copy of the rudder were required, any one of us could provide an outline and foil shape. If more formal advice were required, there are a number of C&C alumni (George "Big C" Cuthbertson, Rob Mazza, Steve Killing) who could be asked to advise.
>I have a Trapper 500, which has the MK I rudder design with tiller. Under sail the steering loads are light, but under power, quite heavy, and if you let go the rudder immediatly goes hard to port.
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>Does the later rudder behave similarly?
I wouldn't describe the load as heavy, but it's definitely there.
If you leave the tiller, the boat immediately begins making a tight circle. I prefer to think of this as a 'feature' rather than as a 'bug', because given enough room for a circle, the boat tends to stay on the same patch of water more reliably than when stopped. When single-handing the boat, I have several times found myself having to make changes to the fender or line setup before approaching the wharf. Allowing the boat to describe slow circles while I do this is a better option than trying to stay put while stopped.
>I have just made an adjustable strut, which is the remains of a dead (Navico) tiller pilot, to see if that will help, will try it out this weekend. I am often single handed.
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>The outer harbour I use most frequently (Weymouth, Dorset, England) is fairly narrow, busy with yachts, dinghies, fishing boats and rowing boats ferrying holiday makers across. The concept of a sudden hard turn to port is simply not acceptable.
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>My last boat (Hustler 25.5) didn't do this, but gave enough time to put out a fender, etc. The fundamental difference between the boats, which are quite similar in hull shape, both with balanced rudders, is that the balancing area on the C&C design is high, and in the prop wash, whereas the Hustler (Holman & Pye) has a higher aspect ratio rudder, which the balancing area at the tip.
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>Both boats are remarkably similar under sail. Impeccable. Hence my query abut the later, higher aspect ratio rudder.
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>If I were to make a change to the rudder, I would rather fit a recognised design than cobble up one myself. Is the later rudder available?
David Weatherston
"Towser", Toronto
C&C 27 Mk IV
David Weatherston
Towser, Toronto
C&C 27 Mk IV
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David,
I have a 1972 Mark I and have long been disappointed in the rudder.
I would very much appreciate direct contact informing me where I can get the design for a spade rudder, especially a high-aspect design.
While the original tracks nicely in smooth water and with sails properly adjusted - the "no balance" scimitar design is a major pain in a number of situations - especially backing, heavy seas, and in puffs. I have sailed many boats in my 30+ years of sailing - everything from Sunfish to 65' sloops - and this comes closest to the least desirable performing rudder I have encountered. Otherwise - I love the boat, great sailing and fast for her size.
I would appreciated the newer rudder design.
Warren Smith: <A href="mailto:wbstx@aol.com">wbstx@aol.com</A>
David,
The only concern I would have in making a rudder is the specification of the rudder design, i.e. details of the tangs welded to the stainless tube, and the specification of the lay up.
I assume that the rudder section would be NACA 0012, for which I have full details
This week I found that the boat would remain stable with the tiller free at about 60 degree to port (rudder to port, tiller to starboard) at about 2000 rpm engine. (1000 prop) resulting in turning in circles of something in the region of two boat lengths diameter. No sails set, no wind to speak of, slack water.
In this condition, the rudder angle remained stable.
This is a desirable feature.
I also had a discussion with a Simrad salesman wrt a tiller pilot, and he thought that the rudder loads, and rate of change of load with angle may well be unacceptable, and thought load measurement was necessary.
Frank
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Could not any reputable marine welding shop help with specification of the internal webbing? If sailors in Britain are anything like sailors in Canada, they must frequently be called on to mend or replace rudders and be familiar with the general spec. Same with the layup.
No idea what the NACA number is, but if you like 0012, run with it. As I said, I can give you a rough outline and foil sketch after haulout and you can compare them.
Your "stable rudder" condition sounds like mine. As I said, I use it to "orbit" in one spot when putting on lines and fenders.
The load to get to that stable condition remains a concern. We powered out into the lake to watch the air show on Monday (boring - they've moved the quarantine line a lot farther out into the lake than it used to be, so it's much better to be on land). I took particular note of the effort required to maintain a straight course, and it really only is a light pressure on the tiller. Even in waves, my Autohelm handles it easily.
I can't believe that I wouldn't have heard if the earlier boats couldn't be handled with an autopilot, but that's just guessing. What we need here is someone with a Mk I or Mk II to jump in here with real experiences with autopilots.
David Weatherston
"Towser", Toronto
C&C 27 Mk IV
David Weatherston
Towser, Toronto
C&C 27 Mk IV
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David,
Lots of places to get the s/s bits tig welded, my concern is the sizes to achieve the strength of the original. I will try to get a sail on a Trapper 501. These have a rudder similar (but may not be the same as) to the later 27's
Frank
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>Lots of places to get the s/s bits tig welded, my concern is the sizes to achieve the strength of the original.
That's why I suggested an experienced rudder shop or marine welder. They would have experience with similar jobs and could give you a strong rudder at a racing weight.
"Amateurs always overbuild." - George Cassian
>These have a rudder similar (but may not be the same as) to the later 27's.
The image on the Trapper 500/501 page in this site's Links section is labelled as a 501 and it has a Mk I/II rudder. For the differences in rudders used on Canadian boats, see the side views in the Description (Mk I/II) and Profile (Mk III/IV) sections of this site.
I have been corresponding with a friend who has a deep knowledge of C&C development and he believes that the scimitar-style rudders used on early C&C's came about through some misleading data that came out of a Stevens Institute tank testing program. This data seems to have been widely accepted -- I distinctly remember seeing some Ericson boats (and perhaps also Cal) with a similar rudder.
David Weatherston
"Towser", Toronto
C&C 27 Mk IV
David Weatherston
Towser, Toronto
C&C 27 Mk IV
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David
Looked at those, but I feel that the views lack accuracy.
Frank
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I wouldn't use them to build a rudder, but they give an accurate _impression_ of the different styles.
The important thing is that the newer rudder is deeper and of a constant chord that is aligned with the rudder stock. A very small part of the area provides balance. I confess I have never measured this, but it _appears_ that there is less aft rake to the stock.
David Weatherston
"Towser", Toronto
C&C 27 Mk IV
David Weatherston
Towser, Toronto
C&C 27 Mk IV
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David,
Today, I found in Ian Nicolson's "boat data book" 4th edition page 194 " a balanced rudder normally has 1/6th of the area ahead of the centreline of the stock. More than that can be dangerous"
From the views of the 27 it seems to me that the total balance area is about 1/12th . however, the area in the prop wash is about 1/5th
This would tie in with good sailing handling, but less than good undaer power.
Further winter project. new rudder. (adding to all the others)
Frank
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C&C 27 (+ Trapper 2<img src="emoticons/icon_cool.gif"> - both 1973 : East Coast UK
The old scimitar rudders were replaced on both a long long time ago with spade rudders of one-off design. Keels are original.
While the concept of the scimitar rudder was formed from the elipse being the theorhetically most efficient shape, the designers messed up becuase it looses control.
The spade design we have solves all issues. esp on the trapper, tight kite reaches in windy conditions are comfortable (the C&C 27 has taller rig so cannot carry upto same wind but reaches beautifully in perfect control upto abt 16kts - after which we have a smaller kite !) .
However, not sure i have the details - if can get, would you be interested ?
Rgds
<A href="mailto:j.millar@virgin.net">j.millar@virgin.net</A>
Yes, please.
My preference would be to fit/make a 501 rudder, if that solves the issue.
However, if it does not, and there is a further improvement to make, then a non-standard design is ok.
I infer that there are some C&C 27's (Canadian built) in the UK. Must predate the RCD
Frank
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