Need a foiled rudder ; can I pay someone out there who can do it ?

[hockeyfool]

Hello all, a Good Friday & Happy Easter weekend to yous guys....
I have almost all updated on my ol' 1981' cp23 , and am really feeling she is not seeing her potential without a proper rudder, didn't somebody here at CYOA say they built there own foil ? Can somebody tell
me if you know who I can talk about hiring out for this ?
I have a modest boat budget this season, as lasy year I took my head sails to SailCare for a revamp, after $700,
wife said next year we need to scale down, mind you I have about $10k into my boat so far( at least ) so...
If I can get a modest foil that will be less costly than from Rudder craft or Hutchins' chandelry, maybe we can swing it.
I live in SE Michigan, so can drive a reasonable distance ( under 300 miles? ) to meet, or otherwize can ship/mail/ext.. ??

[Bob23]

Hey Hock:
  I did indeed build my own wood covered foiled rudder blade but I if I had to charge even a meager amount for my labor, it'd be much more expensive than just buying one! It was quite labor intensive which means it took forever to build however it has lasted well (going on 9 years or so) and has greatly improved the speed and pointing ability of the boat. By the way, I sail a 1985 23/2.
  I used Sailcare in the past and although they do what they say, at best it's just a bandaid for the sails. I pryed my wallet open about 6 years ago and sprang for a new suit custom made for my particular boat and it was worth every dime! In my most humble opinion, put your money to better use and buy new sails. I could not believe the difference the new suit of sails made! Really transformed the speed and handling of the boat!
  Bob23 in NJ

[jdklaser]

Try Jibetech.  Pimental knows his stuff.   http://www.jibetech.com/ 

[DanM]

Just an opinion: I have an Ida rudder on my Suncat. Although I don't know a lot about the rudder business, I am involved in custom craft work in another field and so I'd say that intuitively I agree with Bob. It's a common misconception that you can beat the price of an off-the-shelf product by having it custom-made. Anyone who'd offer to custom-build something for less than the stock product is an amateur. Besides, they will have to figure out all the problems that Ida rudder has already dialed in, and the Ida folks will be around if you need help. Personally, I wouldn't waste my time looking for a craftsman to beat the Ida on price.

[Bob23]

So true Dan. If I had to pay myself to build my wooden rudder blade, it'd probably cost $1500.00 or more. Good thing I have the skills...it really wasn't difficult but it did take some brain cells...and lots of time!

[Andre]

Hey, I was just wonderin'  .....   Always looking for a cheap way out, ha, ha

Has anyone ever tried just radiusing the rudder and/or centerboard leading edge?  The sharp leading edge must aggravate flow separation and a radius should help that somewhat.  I would think it wouldn't be too hard with aluminum rudder, stainless centerboard another story!

Andre

2008 PC
2014 HC

[Bob23]

It's the proper foil shape that makes the difference, Andre.

[Andre]

No doubt, but I bet that for small angles of attack a rounded leading edge would get you 25% or so of the way there.

Pure (somewhat educated)  guesstimation on my part here - more research is definitely in order!

Andre

[ruffwind]

Many of you might disagree with me on this, but I don't think a foiled rudder will actually add that much sailing performance to a ComPac 23.  I have owned my 1992 boat for 10 years sailing it on Lake Michigan only.  When I 1st bought it it had the original sails on it and I found that the 150% Genoa and bagged out main created a lot of heal and weather helm.  I bought a loose footed main with 2 full battens and a 110% jib.  I also raked the mast back about 2" at the top.  All of these things pretty much got rid of the weather helm and balanced the boat allowing it to slip forward easily on all points of sail. 

The top full battens allow the main to twist off and let the gusts out of the sail.  Keep the draft down low and about 1/3 back and the ComPac is fast.  Yes a foiled rudder might even give some lift, but the balance of the rig and the sails is most important.

[Bob23]

  True, balancing the rig is quite important and the conventional wisdom is to rake the mast forward a bit. What year is your 23, Ruff? When I had new sails made for my boat, I could not believe the difference it made! So much lost wind energy which was evident in excessive heeling was not transferred into forward motion.
  But the foiled rudder blade made so much difference in the handling of my 1985 23/2 as to be irrefutable. But I also remachined the top of the blade to allow it to tilt forward of plumb which together with the blade, eliminated all weather helm.
  Of course all these factors work together on our 23 as well as on every sailboat.

[ruffwind]

Bob, my boat is a 1992.  I have been very involved with windsurfing and this is where I learned about sail twist and how important mast position is to rig balance and control.  To keep a windsurf board moving, planing the sail rig, the mast must be raked correctly.  To far forward and the board drags more slowing down.  Too far back and the board rails up and starts to fin walk. 

On the ComPac, I don't know if my mast is forward of straight, I'll have to measure when I put the mast back up.  I just know after I got my new sails that I moved the mast back at the tip about 2 inches to reduce weather helm and balance the boat.

Your results with the foiled rudder make we wonder now about how much faster my boat would be with that change.

[Potcake boy]

Ruff, I'll support Bob's comments, especially about mast rake. Raking the mast moves the center of effort aft placing the effort farther behind the lateral resistance (keel) and pushes the stern around, which results in weather helm. Generally a little weather helm is considered good, but if the rudder angle is greater than about 15 degrees from center then your rig and/or sails are not properly balanced. Moving the mast aft INCREASES weather helm as does moving it forward REDUCES weather helm.

Bob's moving the rudder angle forward provided more "balance" area on the rudder, the surface area forward of the pivot point of the rudder. That balance helps to make a lighter tiller by offsetting the force of the water against the aft portion of the rudder blade when when sideways motion is applied, E.g. steering.

I have owned 5 different ComPac models with and without a foiled rudder. The NACA description of a foil ( https://en.wikipedia.org/wiki/NACA_airfoil ) has been used by many manufactures to describe the shape of their keel, though I am dubious of claims of "lift" as the shape is symmetrical unlike aircraft wings which are asymmetrical and provide lift in only one direction. Your sails reverse their foil shape each time you tack, but so far I haven't heard of such a keel. The lift gained in a asymmetrical keel shape would probably be out weighed by the loss of forward speed.  The foil shape however does provide less resistance thereby making the boat a little faster with the same thrust. It also provides a more stable laminar flow and helps prevent stalling at higher angles. The same applies to a rudder blade. The most notable performance gain I experienced with the foil rudder vs. flat blade was the ability for the rudder to avoid stalling when forced hard by excessive weather helm. Of course if you are encountering excessive weather helm that is an indicator of an out of balance rig ie. sail trim.

Another common cause of speed robbing weather helm is excessive heeling. When heeled, the center of effort in your sails (approximately one third of the height of your sails) is located off center line to leeward and therefor pushes that side of the boat harder causing it to steer to weather. Like pushing a pencil sideways from a point not in the center. As a rule of thumb, you should keep within a 20 degree range of heel. More heeling introduces weather helm, and especially on our shoal draft boats, reduces the presentation of the keel area and allows more leeway. Excessive heeling also makes more wetted surface because the sails are providing more downward lift and less forward lift, pushing your hull deeper into the water.

Increasing sail twist reduces the lift generated by the sail and also lowers the center of effort. It is commonly the first measure used by sailors to avoid excessive heel as the wind picks up.

I've not sailed windsurfers as they arrived later in my life and seemed a bit pedestrian to someone with more moderate levels of testosterone, but I have much experience with trimarans which satisfied my need for speed. I suppose there are parallels between trimarans and wind surfers like planing and not heeling, but they share as many differences with monohulls. It's hard for me to get excited about the improvement in speed of a quarter knot when the maximum speed potential of my boat is less than 6 knots. Since I use my boat for cruising and not racing, the significance of speed with my boat is a factor for navigation. What I love about ComPacs is that they are very good with the fundamentals and sail well to their design criteria. Properly set up they are fun and easy to sail and provide a stress free relationship with the sea and nature.

If you enjoy sailing your boat then all these things don't matter, but if you're not happy with the handling then it may be old sails and/or rudder issues. Keep in mind however that a thorough knowledge of how your boat works is the best accessory to have on any boat.

Just curious, what method did you use to rake your mast?

[slode]

A flat plate and symmetrical foil will both produce lift if the angle of attack is anything positive of 0.   A foil will generate the same lift at a lower angle of attack than an equivalent flat plate, and stall at a much higher angle than the flat plate.   A proper foil will also generate less drag at all angles of attack.   

Ever see a plane fly upside down?  Stunt planes and fighter jets have symmetrical or near symmetrical foil wings.  Wonder why they aren't flat plates?  Because then they would fly like a poorly made paper airplane.

Keels generate lift because they flow through the water at a slight angle (boat is getting pushed leeward).  The lift is in the opposite direction of the sails helping to reduce heeling.  A foil keel will do this better than a flat one. 

Not saying a foil rudder will reduce drag enough to see any noticeable gain in speed, but it will turn significantly better.

[ruffwind]

Ron, a lot of good stuff in your post.  I agree with almost all of it.  I raked the mast back by tightening the back stay and aft shrouds and loosening the forstay and forward lowers.  Again, I am not saying I raked the mast aft of centered just aft of where it was when I bought the boat.

What I really learned from windsurfing.  A windsurfer doesn't have a rudder, you steer with mast rake and you are constantly changing the mast rake in conjunction with boom position to keep your direction and hopefully keep on a plane.  With a windsurf sail you can only trim the sail with the boom while underway.  With a sailboat you have a rudder,  out haul, down haul, Cunningham halyard tension, jibsheet and main sheet to control the sails.  The mast position is fixed when under sail. 

this learning has enlightened my boat sailing.  If you balance the rig and get the sails pulling the boat where you want to go, there is very little helm and the boat moves faster thru the water.

[jdklaser]

for the do-it-yourselfer  http://epoxyworks.com/index.php/how-to-build-rudders-centerboards/

Windsurfing is a great way to understand balance, trim, center of effort, center of lateral resistance.  My windsurfing days go all the way back to teak booms.  (hand cramps)  With dinghys one of the best learning experiences is to go rudderless and learn balance and trim that way. 
The bottom line is with a compac you are sailing a cruising sailboat.  Simple foil additions are easily found.  If you want a lesson in blade dynamics talk to a 505 sailor.  They have to get it right.....OR LOSE.    You can get into chord length, max thickness, working the trailing edge, working the bottom, but keep it simple.  That .1kt that you may get will not be noticeable to you or anyone else.  A foiled rudder will help you drive and tack better.  One missed 5 degree shift will do more to get you there later than all the foils and finishing in the world.  Sail the boat.  Up the front and down the back.  Simple, simple, simple.