Question Question about weather helm and rudder shape, Aerosouth rudder etc.

Cascadian505

Active Member
I’ve been sailing my boat and enjoying it. I went out in some breezy weather and had a lot of fun. Got the boat planing which was great. The gusts were around 14 kts. Going upwind was a bit of a bear with the weather helm though. I was rigged at 17” on the gooseneck and the 10th clip from the bottom for the halyard.

Has anyone used one of the Aerosouth rudders that are more plumb? If so, how you you like them in terms of the helm feel?

I might build my own version this winter if I hear good reports.

Thanks!
 

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I have read many positive comments about the Aerosouth rudder. Of course, it not class-legal but this matters only to the (more serious) racers.
On the other hand, one can prevent weather helm by hiking hard(er) and using a Jens-type rig.
 
I have read many positive comments about the Aerosouth rudder. Of course, it not class-legal but this matters only to the (more serious) racers.
On the other hand, one can prevent weather helm by hiking hard(er) and using a Jens-type rig.
Admittedly I was a little lazy on hiking! Our bay is ccccold and I was the only one out so was being conservative. Also, that little lip around the cockpit well kind of hurts. Might have to pad it. If I put the bow down more and hike more that might help.
 
How old is your boat? Does it have a hiking strap? I would get a foil board over a rudder blade. If you are heeling you are sidesliping and the foil board helps that.
 
How old is your boat? Does it have a hiking strap? I would get a foil board over a rudder blade. If you are heeling you are sidesliping and the foil board helps that.
It’s a 73. I installed a hiking strap. It was still kind of painful on the backs on my legs.

I could build a new daggerboard too. I don’t want to buy any big ticket items for the boat but am up for making stuff. I have access to wood and a woodshop and expertise.
 
I agree with all of the above comments. Gooseneck back some more, hike, and get - or make - a foil shaped daggerboard. That newer board makes a huge difference. Hiking is always somewhat painful, and a new rudder won't help that!! The newer rolled edge boats are more comfortable to hike, but a padded pair of shorts will help - esp regarding the metal edge. I don't know anyone who has sailed with an Aerosouth rudder, but given absolutely no other boat class in the world has a rudder shaped like that, I doubt it is an optimal shape. If you wanted a vertical rudder, the first step would be making one similar to a Sunfish rudder blade more vertical. That would most likely get the job done.
 
Leave the rudder as is. Tuning the halyard and gooseneck plus a 39" Barrington or 44 inch daggerboard will get you where you need to go.


Daggerboard - Race Style (1).jpg


Sunfish Daggerboard Specs 1980 1993.png


Where are you sitting and what were the winds? Light winds = loose outhaul, heavy - haul the foot and luff out.
 
Leave the rudder as is. Tuning the halyard and gooseneck plus a 39" Barrington or 44 inch daggerboard will get you where you need to go.


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Where are you sitting and what were the winds? Light winds = loose outhaul, heavy - haul the foot and luff out.
Sitting fwd part of cockpit except for brunt of waves where I’d slide back a few inches.

Winds were 7-12 gusting 14 kts. From flatter water to 1.5’ waves. It’s a big bay with miles of fetch

I left outhaul and cunny slack. The adjustments I have done seem to work well. I tried to snug them when it breezed up but it didn’t seem to work so well.

I’m not building anything or buying anything now. It’s time to sail. But might build both DB and rudder over the winter. I don’t get the raked rudder. I like a neutral helm.
 
Sitting fwd part of cockpit except for brunt of waves where I’d slide back a few inches.

Winds were 7-12 gusting 14 kts. From flatter water to 1.5’ waves. It’s a big bay with miles of fetch

I left outhaul and cunny slack. The adjustments I have done seem to work well. I tried to snug them when it breezed up but it didn’t seem to work so well.

I’m not building anything or buying anything now. It’s time to sail. But might build both DB and rudder over the winter. I don’t get the raked rudder. I like a neutral helm.
Leave the rudder as is. Tuning the halyard and gooseneck plus a 39" Barrington or 44 inch daggerboard will get you where you need to go.


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Where are you sitting and what were the winds? Light winds = loose outhaul, heavy - haul the foot and luff out.
I think my daggerboard is the one on the left.
 
... but it didn't seem to work so well for... what... reducing your weather helm (by moving your center of effort forward)?

- Andy
The Cunningham didn’t seem to snug the luff very much. And the outhaul didn’t reduce draft. I was trying to pull them on to try depowering when the breeze pulsed up a bit.
 
You really don't want a neutral helm, both for safety and performance. You want the boat to round up by itself for safety. In terms of performance, you want enough weather helm to allow the rudder to contribute to working the boat to windward. If you have neutral helm your rudder is at that point nothing but drag. If you have lee helm it's not only drag it's pulling you in the wrong direction.

Most modern boats have a rudder about 70% of the area of the centerboard, and the rudder is designed to work with the centerboard to bring the boat to windward.

The Sunfish board is really too small for the boat and the additional lift from the rudder can only help (so long as your not stalling it)

The Aerosouth rudder doesn't effect weather helm so much as it effects effort to counteract the weather helm. The center of effort of the rudder on a sunfish rudder is ten or twelve inches behind the axis of the rudder pin. The Aerosouth rudder moves this center of effort to more inline with the rudder axis. If you want a rudder with even less effort you'd add area to the rudder ahead of the rudder axis to create a more "balanced" rudder.
 
(L-R) are the 39 inch Spoon Tip used 1960-1972 on the fiberglass Sunfish, then the Shadow Board with less surface area, a "Shadow" of its former self. Sometime in the early 80s the Barrington Frostbiters pushed for their Barrington board with more surface area. When the plastic boards showed up they grew to 44 inches and gained a different airfoil shape, someone in here probably knows the "NACA 4 digit airfoil number" (National Advisory Committee for Aeronautics).

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NACA Airfoil.jpeg


Now let's dig up the debate on which edge is the leading edge... We put the shorter edge forward, so that if we find the bottom or a rock the daggerboard has a chance to ride up over it vs jamming into it.

1 Spars and rigging.jpg


1971 Sunfish swept daggerboard.png
 
The Cunningham didn’t seem to snug the luff very much. And the outhaul didn’t reduce draft. I was trying to pull them on to try depowering when the breeze pulsed up a bit.

From looking at the pictures of your sail, cunningham and outhaul I think there's two possibilities. First, from what I can see, you've got a 2 to 1 mechanical advantage on your cunningham. Can't quite tell with your outhaul but looks like 2 to 1 also? As I remember, I've got 3 to 1 on my cunningham and at least 4 to one on my outhaul.

So, I'm able to pull quite a lot of tension through my luff and the lower 3rd of the sail. In fact, while showing off my new cunningham a while back to my sailing buddies (in the parking lot at the boat ramp) that I had rigged on an older race sail that had a dacron, fully reinforced cunningham grommet area, I badly tore the sail in that area! Just ripped the luff area near the grommet in half. :eek:

I replaced the older race sail with an Intensity practice race sail and I am able to feel quite a dramatic difference in decreased power and that flat, nice manners, locked in feeling when I've applied the right amount of cunningham and outhaul as the wind comes up.

So, 1) you may need some more mechanical advantage or 2) your Intensity sail has lost enough of its stiffness and low stretch so that you aren't getting the same level of de-powering control that I am.

Another thing you can try in addition to your outhaul and cunningham is, when the wind comes up, sheet out, luff up into the wind to unload your sail and then crank your vang down quite a bit. This will hold your flatter sail shape more when you have to sheet out slightly is stronger cycles.

Cheers,

- Andy
 
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The Aerosouth rudder doesn't effect weather helm so much as it effects effort to counteract the weather helm. The center of effort of the rudder on a sunfish rudder is ten or twelve inches behind the axis of the rudder pin. The Aerosouth rudder moves this center of effort to more inline with the rudder axis. If you want a rudder with even less effort you'd add area to the rudder ahead of the rudder axis to create a more "balanced" rudder.
Exactly! Well said. :)

- Andy
 
As Andy said you need more purchase.

Also, the Cunningham with the thimble off to the side is not giving you true downward pull.

This is from Eugene Schmit,t who is a very fast sunfish racer.

Sunfish are amazing boats when you think when they were designed and today with minor updates are racing is winds over 20 mph
 
I have a knockoff of the aero south rudder that I bought on eBay. Makes for a lighter helm, and has better bite when the boat heels over on big gusts. It has accidentally kicked up on me a time or two, not sure if it hit a seaweed tangle.
Also I get a hum at speed. The daggerboard already does that, I think this rudder does it too.
I'm probably going to go back to the standard rudder just to compare the feel.
 

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What I am looking for is a rudder that doesn’t load up too much as soon as you heel a few degrees.

I’m used to sailing 505s which have very refined rudders. You get feedback, and can flatten the boat by either hiking harder, easing sail, or depowering in other ways. When you are tuned in the ballpark, the rudder is your sensor of needing more fine-tuning. Granted it’s a more tunable boat. I’m used to sailing with a lighter helm than the Sunny. Bear in mind I haven’t sailed the Sunfish that much yet, nor have hiked hard enough to keep it flat in conditions that deem it necessary. Also I have a big box of spare blocks, line and cleats to make the depowering systems work better (outhaul and cunny for me; probably won’t do the vang set up d/t extra rigging time). I also have a new sail which should help. It will be more reactive to adjustments.
 
(L-R) are the 39 inch Spoon Tip used 1960-1972 on the fiberglass Sunfish, then the Shadow Board with less surface area, a "Shadow" of its former self. Sometime in the early 80s the Barrington Frostbiters pushed for their Barrington board with more surface area. When the plastic boards showed up they grew to 44 inches and gained a different airfoil shape, someone in here probably knows the "NACA 4 digit airfoil number" (National Advisory Committee for Aeronautics).

View attachment 57472


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Now let's dig up the debate on which edge is the leading edge... We put the shorter edge forward, so that if we find the bottom or a rock the daggerboard has a chance to ride up over it vs jamming into it.

View attachment 57474

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I have one of the two boards on the right. Too tired to go look (I work nights).
 
You really don't want a neutral helm, both for safety and performance. You want the boat to round up by itself for safety. In terms of performance, you want enough weather helm to allow the rudder to contribute to working the boat to windward. If you have neutral helm your rudder is at that point nothing but drag. If you have lee helm it's not only drag it's pulling you in the wrong direction.

Most modern boats have a rudder about 70% of the area of the centerboard, and the rudder is designed to work with the centerboard to bring the boat to windward.

The Sunfish board is really too small for the boat and the additional lift from the rudder can only help (so long as your not stalling it)

The Aerosouth rudder doesn't effect weather helm so much as it effects effort to counteract the weather helm. The center of effort of the rudder on a sunfish rudder is ten or twelve inches behind the axis of the rudder pin. The Aerosouth rudder moves this center of effort to more inline with the rudder axis. If you want a rudder with even less effort you'd add area to the rudder ahead of the rudder axis to create a more "balanced" rudder.
Re: the safety issue, I’m talking “virtually” neutral helm. I still want to boat to round up. I’ve rarely sailed a boat that rounds down when you drop the tiller (ie falling out of the boat).

Re: the lift off the boards, I think Hobies are sailed like that where the lift from the deflection supersedes the drag. My instinct says that is not true for Sunfish but you know better than I do. My “instinct” prefers virtually no helm when the boat is flat and most powered up and holding the tiller extension between two fingers letting it tell me which way to use body weight to steer. But it’s hard to keep the boat perfectly flat above 8-9 kts of wind.
 
I have a knockoff of the aero south rudder that I bought on eBay. Makes for a lighter helm, and has better bite when the boat heels over on big gusts. It has accidentally kicked up on me a time or two, not sure if it hit a seaweed tangle.
Also I get a hum at speed. The daggerboard already does that, I think this rudder does it too.
I'm probably going to go back to the standard rudder just to compare the feel.
Please report back when you compare them both, preferably on the same day in similar conditions. That is kind of the meat of this discussion but it won’t shed light on which is faster.
 
That's a great instinct and I think it will serve you well on any boat. I would only warn that the sunfish will have a bit more helm pressure than many other boats of similar size due to rudder geometry. So you may have to recalibrate your helm force expectations.

Often as good an indicator as any can be rudder head deflection. I am looking for under 5 degrees of deflection. Notice I'm saying rudder head, any loosness in the rudder head tiller connection coupled with the inherently bendy tiller (assuming you're not using an aluminum one) will show the end tiller often a ways of centerline.
My “instinct” prefers virtually no helm when the boat is flat and most powered up and holding the tiller extension between two fingers letting it tell me which way to use body weight to steer.
 
Cascadian, a couple more things. One, the vang can be rigged in maybe 30 seconds tops using only the tail of the halyard. For heavy air it should really pull the boom down so that the boom is significantly curved without any sheet applied. Two, neither the cunningham nor the outhaul are very easy to use when you use sail rings instead of sail ties. The ties slide along the boom, whereas the clips bind up, making it hard to tighten things - or loosen them. Lastly, as mentioned, the cunningham line needs to parallel the boom. The cunningham line should be tied to the eyebolts, go up thru the c-ham grommet on the sail, back down and through the tack grommet, then go back to the cleat. It'll work much better that way.

With proper adjustments you can get the helm down to a very manageable level, although you do have to hike. And the new foil shaped board is a must if you want any type of performance out of a Sunfish.
 
Everyone here is going to hate me for saying this but....I don't really have a big problem with your Cunningham. The force vector the sail will see respective of the upper yard is half the angle of line to the thimble and the boom (assuming the other end of the line is tied to the tack which it seems to be). To my eyes the Cunningham line on that side is about 10 degrees so the resultant vector is 5 degrees off the boom. This will only effect the sail shape below the first sail tie as the first sail tie realigns the force to run parallel to the yard from this point up. The end effect of this slight pull to the rear will be a slight bag in an area that bags up anyways when you are using the Cunningham, and always has unattached flow due to the yard anyways. The only other downside I could see is slightly more drag on the system at that first sail tie from that resultant force pulling the ring away from the yard. If we assume a 20 pound Cunningham pull at the grommet, comes out to 1.74 pounds sideways force (sin of 5 degree* 20lbf).

Would I run it like that, no I wouldn't. But I think you could competitively race with that setup. (I tie my Cunningham at the tack grommet, up thru the Cunningham grommet, and then back thru the tack grommet using it as a turning block. From there use whatever purchase and cleat you desire.)
 
Cascadian, a couple more things. One, the vang can be rigged in maybe 30 seconds tops using only the tail of the halyard. For heavy air it should really pull the boom down so that the boom is significantly curved without any sheet applied. Two, neither the cunningham nor the outhaul are very easy to use when you use sail rings instead of sail ties. The ties slide along the boom, whereas the clips bind up, making it hard to tighten things - or loosen them. Lastly, as mentioned, the cunningham line needs to parallel the boom. The cunningham line should be tied to the eyebolts, go up thru the c-ham grommet on the sail, back down and through the tack grommet, then go back to the cleat. It'll work much better that way.

With proper adjustments you can get the helm down to a very manageable level, although you do have to hike. And the new foil shaped board is a must if you want any type of performance out of a Sunfish.
Roger that. Thank you!
 
... someone in here probably knows the "NACA 4 digit airfoil number" (National Advisory Committee for Aeronautics).

I do not know for sure, seems like it's somewhere between a NACA0008 and 0009 with some monkey business to fit the max dims and/or round of the trailing edge.
tops_naca_dagger1.jpg
 
You really don't want a neutral helm, both for safety and performance. You want the boat to round up by itself for safety. In terms of performance, you want enough weather helm to allow the rudder to contribute to working the boat to windward. If you have neutral helm your rudder is at that point nothing but drag. If you have lee helm it's not only drag it's pulling you in the wrong direction.

Most modern boats have a rudder about 70% of the area of the centerboard, and the rudder is designed to work with the centerboard to bring the boat to windward.

The Sunfish board is really too small for the boat and the additional lift from the rudder can only help (so long as your not stalling it)

The Aerosouth rudder doesn't effect weather helm so much as it effects effort to counteract the weather helm. The center of effort of the rudder on a sunfish rudder is ten or twelve inches behind the axis of the rudder pin. The Aerosouth rudder moves this center of effort to more inline with the rudder axis. If you want a rudder with even less effort you'd add area to the rudder ahead of the rudder axis to create a more "balanced" rudder.
Thanks for the explanation!
 
Hi All
I just tried out my new Aerosouth keelboard and rudder on my 92 fish with a recreational sail. I sailed it, class legal on Wednesday with similar winds (10-15 mph).
The difference is like going from a dump truck to a sports car. The boat feels less draggy, the rudder is very light, and small movements make the boat move. It's very responsive and turns are awesome; you have to be on the ball. The boat heels less (wants to sail flatter), but it's faster, no doubt.
My wife noticed the difference in heel from shore.
Absolutely no weather helm, and if the boat is moving at all, it turns on a dime and gives you back change.
It's almost like having another boat it's that different.

Worth every penny! (I bought retail)
 
You're deluding yourself if you think the board and rudder made the boat heal less. The sail carrying power of a dinghy/skiff is controlled by the vertical location of the center of effort of your sail, the size of your sail and the lateral location of your righting force and the amount of right force (how much you weight) . I'll acknowledge that sail carrying power can be effected by the vertical location of the center of board if it pulled up to the point where its allowed to slide sideways due to high loading as is often done in high powered skiffs but for this discussion we're talking about windward progress where we leave the mostly board down. Nothing the Aerosouth board and rudder did effected the sail carrying power of your boat. It wouldn't surprise me if it did sail faster, we've learned a lot over the years about what makes a boat fast, although I don't see anything obviously wrong with the sunfish racing board. The sunfish rudder is a bit club like in all aspects but it works OKish. No weather helm is not really a good thing, you want the rudder to provide complimentary lift to windward (this is true in across the board with keel boats as well). If your sailing to windward only on your board you're missing the performance advantage of a smaller board with less drag (see Julian Bethwaite's development of the 89er on Sailing Anarchy for an example of this, he keeps shrinking the keel to almost comical dimensions in search of every last drop of speed).
 

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