foiled rudder

[phil]

G'day y'all! (How about those two dialects together)
Anyone have info on where and how to upgrade my new purchase, CP19, with a foiled rudder. Word on the web it makes a big difference.

Phil (The new guy)

[Paul]

Welcome!

There's plenty of info on upgrades all over the forum.  Search function is a great asset.  But, to make things easy.  Google Idasailor.  That should get you closer to writing rave reviews on their foil rudder.

Good luck and welcome, again.

Paul

[Rick Klages]

CP-19 foil

http://www.idasailor.com/catalog/product_info.php?cPath=24&products_id=30

Ive never sailed my CP-16 without a foiled rudder.


ick

[Glenn Basore]

Whats so great about the "foil" Rudder over the stock rudder Com Pac rudders ?

Is this mostly for C-19 or is applicable to the Eclipse as well ?

[Rick Klages]

Because Bernoulli says so. Dynamic shape produces less drag and even creates  lift.  This allows the boat to "point" better.  The reason for this and why airplane wings are curved instead of flat is the foiled shape manages the flow of air/water across it producing force (lift) with less deflection or angle of the wing, keel or rudder relative the fluid flow. This equals less deflection of the tiller and less energy input. The foil section can do this by creating lift.  The Flat rudder provides force only by deflection which creates drag. So if your Sails are an airfoil and your keel should be a foil section it makes sense that your rudder is one also.

read more here about foil sections and sailing:

"The main difference between a "thin flat plate" and a NACA foil is that the foil will generate lift, i.e. power, at a higher angle versus the boat's direction. Where a plain flat rudder will stall and simply slow you down somewhere around +/- 5 to 10 degrees from center, a NACA foil will be effective over maybe twice that range. Your boat's rudder will work better. Tacking will be easier. A little bit of weather helm translates into more sideways 'push' upwind."   - Craig O'Donnell

http://www.boat-links.com/foilfaq.html

and:

http://www.sciwrite.caltech.edu/journal03/A-L2/DavidArmet.pdf

ick

[Lost Lake]

Wow Rick, sounds like a $200 answer... How much are these foils? How much do they really change the performance? They are quite a bit larger, now that is something that will chaneg the feel and effect of the rudder for sure....  Make it 20% larger and of course it will have more authority.

I don't know about the efficiency of a foiled verses flat nose thin piece of rudder at the breakneck speeds we travel at....

Anybody have a hydrodynamics program they can run this through?

Is hydrodynamics even a word??  LOL

[Craig Weis]

Can't beat this rudder with a stick. BUY it. Worth every penny. skip.

[Rick Klages]

Not larger, Foil shaped. CP-16 $220, CP-19 $250.    Believe Skip.  Don't believe me. I'm new here. 

By the way hull speed for a CP-16 is 5 Kts.  A 40 footer with a water line of 36 ft. will still only make 8Kts.

Sailing is about efficiency. 





ick

[Glenn Basore]

Rick,

My Eclipse rudder is fairly large with the leading edge being rounded, some what thicker in the center and than tappers back to thiner  trailing edge. from the top of the rudder down it starts off thick and tappers down to a thiner bottom.

So What I have appears to have the wing shape you are describing !

As a novice sailer, would I be able to notice a difference between the the two rudders ?

I could understand if I had a small flat board as you described and went to the rudder your describing for replacement I would must likely "feel the difference" in how the boat handles

I would think Com Pac would have a rudder pretty well designed for a new production boat.

Glenn

[Rick Klages]

The specifications (yes I checked) state you should have a foil rudder.  Few new boats of any quality have flat plates.

Standard equipment for an Eclipse SL  includes:

>>>>>>>> Retractable, foil shaped rudder <<<<<<<<<

Looks like you are already there!   

The Ida Sail rudders are of intrest to the owners of the 16 and 19 because OEM was a flat plate.


ick

[Glenn Basore]

Lucky me !

Glenn

[Gil Weiss]

Rick is an encyclopedia of sailing information! I am glad he bought my boat and got active in this forum!

Boatless in PA, Gil

(My CP19 is on the hard deck in NJ)

[PhotoEd]

Dang you guys!  Just had to make it sound all "nice and shiny"...didn't you!?!?!


Should have my new foil at the front door ASAP!


(and I still don't have a motor...ugh)

But I'll have a nice, new rudder!

Will report back once it's mounted.

[Gil Weiss]

My 2 cents . . .foiled rudder is more important than a motor. You can always get a few inexpensive paddles and use the armstrong method of boat propulsion.

That is the first thing I am ordering for my "new" 1983 ComPac 19.

[PhotoEd]

FYI, Idasailor had my new rudder in the mail the day after I ordered!