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Canhobie

Wings on Rudders

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Want to install some wings on my Aussi Flyer A Cat.Looking for tips and advice for installing Wings so they look like this.

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If it was my money & time I wouldn't bother.

If the boat has been converted to C's there are way better winglet & rudder packages available.

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You could try a doweling jig and carbon rod, what are the design loads? Or insert a double eneded wing in a routed slot, have to imagine some local reinforcement would be needed. 14s use to figure on 80 kgs lift, also the height matters, looks like.33 from tip?

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That's a perfect molded solution, typical of your work. Retrofitting, like repairing, involves compromises. A fillet will greatly strengthen the joint but harm the flow, adding external tabbing will degrade the section, grinding out the rudder for a flush fit will weaken it and require reinforcement. It gets to be a series of compromises. Biggest question is are the wings a unit or seperated?

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Mmmmm that span that Russell is showing I think may have a lot more leverage than the small foils one is fitting to the A's. I think the Exploder foils are one piece and it wouldn't be beyond reason to simply cut the foil profile through the rudder with a dremel tool of some kind, hollow out the rudder itself, fill that hollow with a mixture of wetted out carbon strands and micro filler forcing it down and up into the rudder as far as you can get it, recut the required hole once set, then simply bond the foil through, filling the outer section with a epoxy and filler.

Do make sure you have a pretty good idea of what is O degrees though as even a mm out of kilter is going to have an effect that you don't want.

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put them at the bottom with carbon insert (think uni or woven arrow shafts) and screw into a fillet.  Don't have to break the horizontal foil in 2 pieces, and have an exit strategy if AOA is wrong or if you want to bail on the concept.

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Why install something that was superseded years ago? buy a set of exploder wings and simply screw and glue to the bottom of the rudder.

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Wayne Marlow has set out the construction method exactly. The winglets are one piece and that is how the factory does it. With that size of winglet no fillets are required and as earlier mentioned they only create turbulence anyway. Zero angle of attack is very important but not too hard to achieve if you already have the rudders set up for good balance . Simply instal the winglet parallel to the waterline  or on most boats 90 degrees to the transom.

The OP is planning on putting them on a straight board boat to use as a stabiliser and not for lift. They smooth things out a bit in chop going to windward and work hard to keep the nose up downwind in stronger breeze. Anything bigger isn’t necessary for that style of boat and would increase drag in lighter air. We did a fair bit of boat on boat testing in 2012 with those winglets against boats without in light air and there was no drag penalty. We find a penalty with bigger winglets. 

Bigger winglets are being used on C board boats to match the lift on the C boards. Some of the bigger lift winglets and particularly the asymmetric ones have been found to be too lifty and overwhelm the boards. 

Interestingly the factory supplied exactly those rudders shown with the first four AD3 Classics. They are quite good and one of them was in the top ten at the Worlds. 

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W&W is talking ok to me.  with 2 small winglets 4 in and under L&R, epoxy with filler = glued on. for a straight board boat-worked fine. Then I converted to C-boards and I left them the same.  No more pitchpoles in Breeze. Ditto for C-board boat.= Rare pitchpoles.  Craig Yandow had C boards, really tiny fins and pitchpoled right behind me 2x in breeze.  But not anymore. RIP Craig.  Then the winglets stared growing, but EXploder does not answer my mails anymore.   Why not??

 

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Back in 2013 when we put winglets on rudders like those, we made a wood jig to help stabilize as the epoxy went off.  Here is one installation with that jig that did not go well as it was a creative repurposing of a daggerboard as a rudder.  

It is important to make sure you are setting the rudder winglet at right angle of attack when you rudder is fully down.

The posters above describe the process well.  Drill and cut through the rudder and install with epoxy and filler.

The benefit of having the winglet higher is that you can be within the max beam of the boat.  Some of the older rudders would go to far out even with a small winglet otherwise.  

Some other sailors with older rudders put small winglets with a screw and bit of carbon on the bottom of the rudder.  No cutting that way and seemed to work well too.  

 

 

photo-4.JPG

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1 hour ago, Lost in Translation said:

Back in 2013 when we put winglets on rudders like those, we made a wood jig to help stabilize as the epoxy went off.  Here is one installation with that jig that did not go well as it was a creative repurposing of a daggerboard as a rudder.  

It is important to make sure you are setting the rudder winglet at right angle of attack when you rudder is fully down.

The posters above describe the process well.  Drill and cut through the rudder and install with epoxy and filler.

The benefit of having the winglet higher is that you can be within the max beam of the boat.  Some of the older rudders would go to far out even with a small winglet otherwise.  

Some other sailors with older rudders put small winglets with a screw and bit of carbon on the bottom of the rudder.  No cutting that way and seemed to work well too.  

 

 

photo-4.JPG

Some good points Lost. The max width is easy to measure before you start. With the rudders set up on the boat and secured down as you would sail just measure the outside width at the height you intend to insert the winglets. Then add 2x the amount winglet would protrude from the rudder. If less than 2300 you are good to go. If not three options. 1. Install the winglet a little inboard in the rudder blade. 2. Cut a bit off the outside tip. 3. Move the bottom gudgeon slightly inboard. An estimated job. Slot the holes the required amount, fill and redrill. The winglets on the bottom of the rudder has some benefits because they are in the water more of the time. It’s a bit more difficult to make them secure though and you still have to modify the rudder to make a flat gluing area. They are also more vulnerable to damage leaving and returning to shore. I’ve tried both spots and both work. 

Your main point is the crucial one. It’s a waste of time if you don’t get the winglet to zero AoA to the waterline. 

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On ‎1‎/‎18‎/‎2019 at 12:24 PM, WetnWild said:

Wayne Marlow has set out the construction method exactly. The winglets are one piece and that is how the factory does it. With that size of winglet no fillets are required and as earlier mentioned they only create turbulence anyway. Zero angle of attack is very important but not too hard to achieve if you already have the rudders set up for good balance . Simply instal the winglet parallel to the waterline  or on most boats 90 degrees to the transom.

The OP is planning on putting them on a straight board boat to use as a stabiliser and not for lift. They smooth things out a bit in chop going to windward and work hard to keep the nose up downwind in stronger breeze. Anything bigger isn’t necessary for that style of boat and would increase drag in lighter air. We did a fair bit of boat on boat testing in 2012 with those winglets against boats without in light air and there was no drag penalty. We find a penalty with bigger winglets. 

Bigger winglets are being used on C board boats to match the lift on the C boards. Some of the bigger lift winglets and particularly the asymmetric ones have been found to be too lifty and overwhelm the boards. 

Interestingly the factory supplied exactly those rudders shown with the first four AD3 Classics. They are quite good and one of them was in the top ten at the Worlds. 

If I was adding wings to a straight board A now, I would add the older smaller Exploder foils to the bottom of the rudders. Should be able to pick these up cheap. little drag from these

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2 hours ago, Rawhide said:

If I was adding wings to a straight board A now, I would add the older smaller Exploder foils to the bottom of the rudders. Should be able to pick these up cheap. little drag from these

Where would one find a used set laying around? I've thought of making my own just for the fun of it though. BTW I'm throwing these on my old 18sq meter. It's the same length as an A boat but weighs a lot more, like 370ish. Would the size/strength of the foil need to be modified? I'm figuring the load applied to the foils is all really based on the speed of the boat through the water right?

Figuring out what is 0 degrees AOA I'm sorta worried about too. Say I was to put some marks on the bow/hull and then go sail and remember where the water line likes to be. Wouldn't the bow wave and the way it flows down the hull make that a hard way to be accurate in being able to draw a line down the hull? Ultimately I'm imagining just using the rudder rake adjustment should be able to give me a few degrees either way that I could play with and see if there was a noticeable improvement/detriment to help me determine which angle was true 0.

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There is a real benefit to have the foil as a T foil, it does lots of nice hydrodynamic thingees that makes the rudder vertical think that its longer than it is and is easier to set up, simply mount using screws and pegs, try it and adjust with shims to suit.

But and its the big but, that T foil will then become the first thing to ground and within about 3 weeks you'll be looking at that now badly marked and scraped foil that now acts as a brake and not as a foil, and go "why didn't I move it up the rudder a bit". Don't ask me how I know this :)

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17 hours ago, TAMUmpower said:

Where would one find a used set laying around? I've thought of making my own just for the fun of it though. BTW I'm throwing these on my old 18sq meter. It's the same length as an A boat but weighs a lot more, like 370ish. Would the size/strength of the foil need to be modified? I'm figuring the load applied to the foils is all really based on the speed of the boat through the water right?

Figuring out what is 0 degrees AOA I'm sorta worried about too. Say I was to put some marks on the bow/hull and then go sail and remember where the water line likes to be. Wouldn't the bow wave and the way it flows down the hull make that a hard way to be accurate in being able to draw a line down the hull? Ultimately I'm imagining just using the rudder rake adjustment should be able to give me a few degrees either way that I could play with and see if there was a noticeable improvement/detriment to help me determine which angle was true 0.

A-cat transoms are supposed to be vertical to the waterline. 18Sq too, one would think. Ask Chris Cordes, former 18/2 Nat. Champ.     cordesusa172@gmail.com 

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1 hour ago, Waynemarlow said:

There is a real benefit to have the foil as a T foil, it does lots of nice hydrodynamic thingees that makes the rudder vertical think that its longer than it is and is easier to set up, simply mount using screws and pegs, try it and adjust with shims to suit.

But and its the big but, that T foil will then become the first thing to ground and within about 3 weeks you'll be looking at that now badly marked and scraped foil that now acts as a brake and not as a foil, and go "why didn't I move it up the rudder a bit". Don't ask me how I know this :)

Yes- vulnerable on the bottom. I was really surprised last year at the Rudder Club walking my A-cat to a mooring.  Huge explosion in the totally opaque water behind the boat, big thump....and a manatee went zooming away throwing a wake. Broke the new fin off port rudder.  DAmn!

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2 minutes ago, dacarls said:

A-cat transoms are supposed to be vertical to the waterline. 18Sq too, one would think. Ask Chris Cordes, former 18/2 Nat. Champ.     cordesusa172@gmail.com 

I sail with him on the weekends haha.

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Yes already sent him that.  I like the jig shown above.  Nice step up from the packing tape used in my process.  Main issue remains as finding the right angle.

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On 1/22/2019 at 4:26 PM, dacarls said:

A-cat transoms are supposed to be vertical to the waterline. 18Sq too, one would think.

My transoms are definitely not 90 degrees to the waterline. My rudders aren't square either. Have the old school rounded tips so screwing to the end would require building out the tip of the rudder to a square or building a new set with the intention of adding the T foils on.

thumbnail_IMG_0948.jpg

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to get a reasonably accurate idea of how you trim upwind....

1. work out what you boat weighs and find the longitudinal centre of gravity (with sail etc fitted or at least lying on tramp with luff against mast LCG can be found by moving rollers backwards and fwd till it balances.)

2. work out where you usually stand trapezing up wind.

3. with boat in water. place 50% of boat weight on each hull in line with LCG and 100% of your weight on each hull (200%) in total in line with where you stand trapezing.

4. with some form of accurate level (phones work okish) measure transom angle to horizontal

5. mark bow and stern waterlines with a marker.

6. go for a sail and watch marks to see if the appear right.

 

Having said all that, if your gudgeons are flat on those transoms don't install winglets.  they'll become breaks every time you move the tiller.

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4 minutes ago, SCARECROW said:

Having said all that, if your gudgeons are flat on those transoms don't install winglets.  they'll become breaks every time you move the tiller.

Never really thought about that but no the castings have an inverse angle such that the rudders point straight down.

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Would you not just need to mark the water line in calm water on the rudders to find 0 deg AOA?As opposed to making a line from bow to stern and then extrapolating onto rudders?

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I have done this a number of times on Australian Flyers with success. Some of you are trying to make it too complex. It is safe to use the transom as reference point and you need to get the winglets to 90 degrees to the transom vertical. Lift the boat up high enough to get the rudders down, get a big builders set square on the transom and simply draw the line on the rudders in the right place. Then you can do the rest off the boat.

There is a lot of BS written about how to set up these small winglets on non foiling boats. Here is the good news. They do not have to be really accurate to the waterline because the waterline constantly changes as you move about the boat. Think about it. Upwind you should be far more bow down than when you are going downwind. This is why simply using the transom as reference is good enough. Once you start using the big winglets like we are using on foiling boats, that is a whole different story.

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1 hour ago, SimonN said:

I have done this a number of times on Australian Flyers with success. Some of you are trying to make it too complex. It is safe to use the transom as reference point and you need to get the winglets to 90 degrees to the transom vertical. Lift the boat up high enough to get the rudders down, get a big builders set square on the transom and simply draw the line on the rudders in the right place. Then you can do the rest off the boat.

There is a lot of BS written about how to set up these small winglets on non foiling boats. Here is the good news. They do not have to be really accurate to the waterline because the waterline constantly changes as you move about the boat. Think about it. Upwind you should be far more bow down than when you are going downwind. This is why simply using the transom as reference is good enough. Once you start using the big winglets like we are using on foiling boats, that is a whole different story.

So how big is a "big" winglet and how small is a "small" one. I was going to make the foil myself but havent decided how big they actually need to be to be effective. I saw some on a nacra 17?, maybe was an F16, Not sure, but they were only on one side of the rudder and couldnt have been more than 2"x1", really small but they said you could tell the difference.

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2"x 1" is more likely to be an anti cavitation fence, most are in the 8" - 6" x 3" on both sides.

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TAMUmpower is correct, those are the size winglets they are running on the Nacra 15: Nacra15Medemblik2017_05.jpg

I think on the local 2012 DNA they are ~1" chord x 2" span each side of the rudder, maybe even smaller, really not that big.

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Interesting to see the Nacra 15 size, that's really small and one wonders if they are actually worth fitting.

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I haven't sailed the boat so won't comment. They originally had more conventional T winglets; I assume Nacra went this way for safety and maybe the area isn't needed?

nacra-15-youth-catamaran-isaf-and-og.jpg

 

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