This folding rudder everyone is talkin about...

this is for **26' sailboat monohull**
And apologizes if there is extensive thread on this topic.
any open source design availalble and or good youtube tutorial?'

thanks yall

 

Hello aL25JR,

Welcome to the forum.
Can you give us more clues on what you are looking to find/accomplish with the rudder system?

I love this thread for ideas and animations, below is a cassette but there are others:
Kick-up rudder design options https://www.boatdesign.net/threads/kick-up-rudder-design-options.69575/#post-967070

 

Oh that is the link i stumbled on while back - thabks so much.
I got 25' post modified junkrig of mysterious origin (my guess is a catalina variation) and have the most counter intuitive clunker of rudder that im reqdy to toss into water ha
(Joking)

To be specific something that doesnt require to many tools or speciality hard to find parts that someojen intermediate level can do just a tear and few swearing. thanks again

 

What makes the current one clunky?
How is it attached to the boat?
What kind of keel/centerboard/leeboard does the boat have?
Is the boat trailered, moored, or slipped?

After a few more post you should be able to post pictures. Pictures of the boat and rudder situation will probably lead to more concise answers.

 

Aye, I will attach detailed photos of rudder measurement and configuration asap.
Im rawdawgin it. 30kg anchor.

 

So you are 'on the hook' so to speak.
Do you have to do all the work onboard or can you piece it together on land and fit to the boat in-situ?

 

sorry but here finally

 

Thanks for the picture. Do you suppose they added the 'barn door' rear flap as a knod to junk styling?

CATALINA 250 - sailboatdata https://sailboatdata.com/sailboat/catalina-250/

Rudders https://www.catalinadirect.com/shop-by-boat/catalina-250/hull-deck/stern/rudders/


I understand that your boat is not exactly a C250 (or any other known boat with the mods and junk rig) but wanted to start with something about the same size to show the approximate size of the factory and replacement units. The Catalina Direct site has the size of the blades listed, for the black-background one:

• Blade thickness: 1-3/4" (standard rudder is 1-1/2")
• Chord length: 14"
• Overall fiberglass blade length: 72"

You could do this project in phases.
Phase 1: cut most or all of the rectangular flap away, sand and paint, would get you closer to stock and a fairer fight between skipper and rudder.
Phase 2: build or buy something better.

For a more scientific approach you'd need to know areas of sail/keel/rudder and locations of their centers of effort and lateral resistance and what performance issue or gain is driving the project. I don't have the chops for that.

 

Two lines- where ill cut first second is probably where i want to go

 

I may appear harsh about the person that previously attacked that rudder but the standard of finish is such that a good part of the steering effort is likely to be generated by moving the drag component mainly to the other side of the boat.You are definitely heading in the right direction by losing the excrescence at the aft edge and I think you would make big gains in efficiency by fairing the surface of the main blade and the delta shaped tip foil.What sort of section you could strive for is a bit difficult to tell from those images and I have no idea how adept a keen but intermediate level boatbuilder might be at creating accurate templates of a successful rudder section.Somebody or other is likely to come along and quote a NACA reference,but there are lots of other families of foil sections and any close approximation of a foil with more or less the location of maximum thickness and a similar thickness to chord ratio will be an improvement.Take a look at Airfoil Tools http://airfoiltools.com/ if you need some suggestions for suitable foil sections.

 

I think the "excrescence at the aft edge" can definitely go as mentioned by @wet feet above.
I would make the first cut in the thin portion and sand back to(wards) the original rudder, getting rid of the ridges from the original attachment.

I would make sure I have time and materials lined up to deal with the trailing edge and a notion of what the rudder is made from before cutting up into the real trailing edge.

Does the main part of the rudder have a foil?

 

sorry what do you mean by foil? it has a triangular thick rubber thing at the bottom of rudder spine.
while I'm working on it going to take tiller handle off - give some tlc.. on that note what do you folks think about making it shorter? not by much 12" very most prob under

for efficiency and for convenience , what would you recommend- handsaw vs skilsaw?

thanks so much everyone

 

I befriended some old timers and commercial captains, I will def consult them and see if they can take a quick peak at crucial phases just incase some well intention-dumbassery going on.

 

so from the catalina illustration, (which Im pretty sure it is some variation of cat) after flappidyflap is gone and smoothed out, it should look alot like c250 water ballast rudder ?

 

Foil- does the rudder have a shape like an airplane wing, when viewed from above?


Or is it something more simple like examples 1, 2, or 3? Example 4 is a rough drawing of a foil.



The question is to help determine whether the rudder is simple/homemade or shaped/store-bought so to speak.

Your rudder does not need to match a C250 but a C250 would be a good starting point barring any other clues.

We would need to see the rudder in place and the tiller in the cockpit to inkle whether it seems too long or not.