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AeroSouth Sunfish Components

kmisegades

Swamp Goose
A few of you have asked me to give more details on the components we've been working on. These are shown now at aerosouth.net, the section on Sailboats.

None are in full production but the three small things (sheet clip, tiller extension and mast hole plug) are essentially ready now.

The daggerboard and rudder are now being tested. So far, they appear pretty good. We sail any day there is wind and have a timed triangular course to measure against.

Short of leasing a tow tank (ain't gonna happen), we trust our predicted numbers as these CFD programs have been well validated and we know how to use them.

Currently everything we do is aimed at recreational sailing. We are not against working with ISCA and ILCA, but know that this would have to be initiated by them.

We'll probably offer things directly from our web site starting January.

Comments will surely be made, and we welcome them.
 

Sailflow

Active Member
Interesting. I will be interested to see if the general sailing market will use the parts. Racers can't use the centerboard or rudder as they are not class approved.
 

kmisegades

Swamp Goose
Thanks. I understand that the Sunfish parts suppliers sell about 2/3rds of their parts to recreational boaters. The Vestas Sailrocket shows that some people like going fast all by themselves.
 

tag

my2fish
reading on your website about the Sabre daggerboard - are you saying the curved edge goes towards the front of the boat?
The smooth, curved leading edge sheds weeds and results in softer 'stall' at higher angles of attack, reducing deceleration during maneuvers.
I won't question the fluid dynamics aspect, but do know that it likely won't help with some of the inland lakes weeds I run into here in Michigan. the daggerboard would likely have to be swept backwards at an angle for the weeds to actually shed.
 

kmisegades

Swamp Goose
Yes sir, the Sabre leading edge is curved from the very top, increasing towards the tip. The trailing edge is vertical. This shape was primarily designed for flow efficiency reasons. You are probably correct that a swept daggerboard would shed better, but the shape of the trunk does not allow this. The Sabre rudder has stronger curvature than the daggerboard so it might shed better. I’m guessing though that the weeds collect more on the daggerboard than on the rudder? I go to Oshkosh every July for the big airshow and tried once swimming in Lake Winnebago. One could almost walk across the lake on the weeds. Sounds like you have the same problem, my sympathies.
 
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tag

my2fish
kent lake weeds.JPG
yeah, here's a snapshot from a video I took - the video actually showed more weeds than I could see while under sail.
I've never sailed on that lake since...
 

kmisegades

Swamp Goose
Oh gosh, that is such a pity. We are spoiled living on a spring-fed lake with a sandy bottom and no weeds. What you need is a 'Lake Cow', a contraption they use on Lake Constance, Germany, where I used to live. Known as the 'See Kuh' as it feeds off the lake weeds, it does a pretty good job of keeping the shore clear of weeds. Not sure what they do with the weeds - probably make beer from them.
Seekuh.jpg
 

beldar boathead

Well-Known Member
I transferred this over from the other thread - in response to your testing via sailing a triangle:

Are two boats sailing together - one with and one without the new parts?

Do you expect to see speed gains offwind or just upwind, and which do you expect to be more significant?
 

LaLi

Well-Known Member
https://aerosouth.net/sailboats

Sheet guide clip: this looks pretty cool. I like the articulation, might figure out something roughly similar for the Lightning.
Tiller "extension": whoever thinks this works, doesn't know much about tiller/extension geometry, or steering a dinghy in general. (Will elaborate if wanted.)
Mast hole plug: smart little thing, simple enough to homebuild, though.
The Sabre daggerboard: looks like it just swings the existing planform around, front to back. Not very interesting.
The Sabre rudder: this probably is an "improvement", but so what? Is there a market for these foils?
Not sure what they do with the weeds - probably make beer from them.
That would be against the purity law, wouldn't it :D

_
 

kmisegades

Swamp Goose
https://aerosouth.net/sailboats

Sheet guide clip: this looks pretty cool. I like the articulation, might figure out something roughly similar for the Lightning.
Tiller "extension": whoever thinks this works, doesn't know much about tiller/extension geometry, or steering a dinghy in general. (Will elaborate if wanted.)
Mast hole plug: smart little thing, simple enough to homebuild, though.
The Sabre daggerboard: looks like it just swings the existing planform around, front to back. Not very interesting.
The Sabre rudder: this probably is an "improvement", but so what? Is there a market for these foils?
That would be against the purity law, wouldn't it :D

_
Thank you for the good comments.

Sheet Clip - Feel free to send me the diameter of the Lightning's boom and I will send you some clips if you agree to test for me. Contact me through my web site. We made a few dozen different clips before we found the right shape, flexibility, etc. Making them for other boats is now relatively easy. We have one for the Laser now and will make others upon interest.

Tiller Extension - I have been using the extension as well as a standard Harken extension since June. Both have there pros and cons, for me, on my lake.

Mast Hole Plug - I'd rather sail than spend lots of time making simple things like this. I was surprised that no one offered it, so I made one. Might as well offer it to others. Lots of people sail, but few make things, I have found. In general people these days spent far less time in home workshops than in years past.

The rudder and daggerboard are both clean-sheet designs, constrained to fit existing hardware / dimensions and keep the same length as the current fiberglass units. In both instances, the baseline for comparisons was the official parts for competition Sunfish. The CL/CD plots on the web site show that the performance is quite different compared to the originals. Fluid flows are like that - a small difference can have a big impact. The shape of the new daggerboard is in fact quite a bit different than the original - things like area, sweep angle, taper ratio, aspect ratio and how one handles the important flow at the tip. A winglet would have been nice down there, but you'd never get this through the narrow trunk!

People like choices and the free market is generally a great indicator of what people want.
 

tag

my2fish
There is a mast plug out there already, not sure how many people buy them.
BFA9BE3B-8EC1-405F-8191-EBB950A53D25.jpeg

A tennis ball fits fairly well and works as a cheaper alternative.
 

beldar boathead

Well-Known Member
The sheet hanger clips look nice. It looks like the sheet may be rubbing on the hanger as it looks like the opening in the hanger is closer to the boom than the exit of the boom block, which will result in friction. Intensity makes some nice ones Intensity Mainsheet Hanger for Sunfish and one of their pluses is they are soft so you won't get a divot in your head if you don't duck enough.

Intensity, which is a go-to place for parts, also sells that mast plug. Your best bet might be to get Intensity to market your plug at a lower cost.
1576076483779.png

As far as your new foils, do you have a means of testing VMG upwind vs. a boat that is identically equipped except using a normal racing board and normal rudder? If not, you should do paired testing between those same two boats. While your foils may have less drag relative to lift, they are attached to a boat that has a lot of drag itself, so the reduced drag may not have a noticeable effect on VMG.

As you can see in Tag's photo, weeds typically are right near the surface, so the curved lower part of the board will be below most of the weeds and not be able to help shed weeds.
 
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andyatos

Well-Known Member
Yes sir, the Sabre leading edge is curved from the very top, increasing towards the tip. The trailing edge is vertical. This shape was primarily designed for flow efficiency reasons.
Excellent. But where have I seen that leading edge shape before. Oh ya, now I remember. It's similar to the outer leading edge of my Atos VQ Race competition hang glider. Also designed with software... and wind tunnel tested.

- Andy

vq-race-tip-cropped.jpg
 

Charles Howard

Active Member
The sunfish is not a fast boat.

Did the Portsmith number even change when the sail changed from flat to a much better shaped race sail or with the foil centerboard?
 

kmisegades

Swamp Goose
There is a mast plug out there already, not sure how many people buy them.
View attachment 35576

A tennis ball fits fairly well and works as a cheaper alternative.
Thanks, I did see the other unit, which has been 'out of stock for months'. This is why I designed and made my own. Our price will be about half of this one.
 
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kmisegades

Swamp Goose
Excellent. But where have I seen that leading edge shape before. Oh ya, now I remember. It's similar to the outer leading edge of my Atos VQ Race competition hang glider. Also designed with software... and wind tunnel tested.

- Andy

View attachment 35579
Wow very neat! Things sure have come along way since the Rogallo glider I flew on Jockey's Ridge in the 70s.

Leading edges all look about the same, but 'the devil is in the detail'.

Our shapes were designed for water, not air. Much different Reynold's numbers than for the Atos.
 

andyatos

Well-Known Member
Much appreciate your efforts and initiative on the Sunfish foils. I would be particularly interested in one of your rudders.
Our shapes were designed for water, not air. Much different Reynold's numbers than for the Atos.
Indeed. And for clarity, I was referring to the "leading edge shape" of your daggerboard foil in the context of root to tip, not the cross section.

Cheers,

- Andy
 

kmisegades

Swamp Goose
Much appreciate your efforts and initiative on the Sunfish foils. I would be particularly interested in one of your rudders.

Indeed. And for clarity, I was referring to the "leading edge shape" of your daggerboard foil in the context of root to tip, not the cross section.

Cheers,

- Andy
Oh, now I understand. The Atos has a nice-looking curved wing tip, much like the latest competition sailplanes. I looked at these, but was concerned that the sharp tip would be the first thing to break if the board hits the ground. Most such tips on planes are also curved upwards, ie dihedral, or are winglets. This of course is impractical for a daggerboard. A pivoting centerboard might allow a symmetric winglet, but it too would be susceptible to damage. The ATOS has what we call a 'TNT' planform, with several straight sections tapering to the tip. This was the main feature of the TNT wings developed at Germany's Dornier when I worked there in the 1980s. Most sailplanes use them. Modern CNC machinery allows us more flexibility though, the reason the leading edge on our daggerboard and rudder are curved from root to tip.
 

kmisegades

Swamp Goose
FYI Laser booms come with a plastic sheet hanger already installed and I believe they work fine.
You are - as always, accurate and correct! Consumers love choices. A friend of mine has raced Lasers for many years and asked me to make him some clips for his boat. It was an easy change in our CAD model. He is testing them now on his lake in Florida.
 

kmisegades

Swamp Goose
The sheet hanger clips look nice. It looks like the sheet may be rubbing on the hanger as it looks like the opening in the hanger is closer to the boom than the exit of the boom block, which will result in friction. Intensity makes some nice ones Intensity Mainsheet Hanger for Sunfish and one of their pluses is they are soft so you won't get a divot in your head if you don't duck enough.

Intensity, which is a go-to place for parts, also sells that mast plug. Your best bet might be to get Intensity to market your plug at a lower cost.
View attachment 35578

As far as your new foils, do you have a means of testing VMG upwind vs. a boat that is identically equipped except using a normal racing board and normal rudder? If not, you should do paired testing between those same two boats. While your foils may have less drag relative to lift, they are attached to a boat that has a lot of drag itself, so the reduced drag may not have a noticeable effect on VMG.

As you can see in Tag's photo, weeds typically are right near the surface, so the curved lower part of the board will be below most of the weeds and not be able to help shed weeds.
Lets' see...

Sheet Clip - The bore for the sheet is parallel to the boom and at a height roughly the same as a line drawn between the two blocks, to minimize friction. It has large radius openings on either end for this same reason. It rotates easily around the boom including when it hits my head, speaking from experience.

Testing - I believe in real testing, which means get some boards and rudders out to people who sail a lot and see how they work. In theory one should see an improvement. If the predictions had only been a few percent better, I would not have bothered. But 40%-60% potential improvement in drag reduction or CL/CD increase on the only underwater lifting surfaces must be worth considering. Especially the existing rudder, which is not much better than a piece of plywood with the edges rounded off. The only other underwater source of drag is the hull surface, and short of polishing I do not know what could be done to reduce it. A fairing where the daggerboard protrudes from the trunk might help, but would entail modifying the hull, not very practical and probably of questionable benefit. The new parts are superior at all speeds and angles compared to the existing parts, so there should be no disadvantage to using them. As they were designed with an eye towards minimizing lift-induced drag, which increases with the square of speed, the difference should be seen the faster one sails.

Weeds - The shape of the board and fin was chosen purely for hydrodynamic efficiency reasons. For both we looked at everything from straight leading edges (as on the current board) to the two shapes we finally chose. There was a clear advantage to going with them. The curvature begins immediately at the point where the board protrudes from the trunk opening, and gradually increases towards the tip. While not being designed explicitly to shed weeds, it is surely more likely to do this than for boards with a vertical leading edge. Only actual trials in lakes with weeds will tell us. Given the existing trunk shape, there are only so many options. I'm guessing that the shorter rudder is less likely to snag weeds than the daggerboard.
 

kmisegades

Swamp Goose
The sunfish is not a fast boat.

Did the Portsmith number even change when the sail changed from flat to a much better shaped race sail or with the foil centerboard?
I can not comment on the sail change but have seen a number of postings claiming the current daggerboard being superior to earlier ones, which I believe. The current daggerboard is a nice design and the quality of the fiberglass is excellent. But we found some room for improvement on the shape and cross sections. We are fortunate to have a local partner with advanced German CNC machinery that can precision mill just about any shape based on our CAD model, much easier than making composite parts.
 

andyatos

Well-Known Member
Considering your background, perhaps you could use the following photo as inspiration for a logo to attach to your daggerboard and rudder products. :cool:

I have closely followed the Thrust SSC and Bloodhound stories with great interest.

- Andy

bloodhound-2-cropped.png
 

kmisegades

Swamp Goose
Considering your background, perhaps you could use the following photo as inspiration for a logo to attach to your daggerboard and rudder products. :cool:

I have closely followed the Thrust SSC and Bloodhound stories with great interest.

- Andy

View attachment 35581
Very cool. The ThrustSSC was an exciting project to be associated with, even in the small way my group was at the time. They had a strong team of engineers who paid attention to detail. Richard Noble is a visionary person who has a knack of motivating people. Maybe someone can convince him to take on the amazing Sailrocket? A drag race along the Namibian coast would be amazing. Hello Red Bull?
 

LaLi

Well-Known Member
Laser booms come with a plastic sheet hanger already installed and I believe they work fine.
I believe all new Laser booms actually come with a loop of webbing around the spar for this purpose. You can alternatively use the original stainless eyestrap (I do, and it does work fine) or another type of "soft" (at least somewhat flexible) lead, as long as it's fastened by rivets at the original location. A lead like the ones we're discussing here is illegal.

_
 

LaLi

Well-Known Member
Feel free to send me the diameter of the Lightning's boom and I will send you some clips if you agree to test for me.
Thanks for the offer, but as the Lightning boom section isn't completely round, the "clip" fastening won't work - they'd snap off at the first gybe :D But at least this got me thinking of possible alternatives to what is commonly used (I've had sleeves made of sailcloth, or an internal mainsheet).

Tiller Extension - I have been using the extension as well as a standard Harken extension since June. Both have there pros and cons, for me, on my lake.
The fundamental problem is that a longer tiller makes steering harder, because the range of motion increases for a given rudder angle. That's why in classes where the lengths aren't controlled, evolution has led to shorter tillers and longer (articulating) extensions. I absolutely can't imagine what pros an extra long tiller without a real extension might have unless you're only sailing in light air and in a straight line :confused:

People like choices
The more choices there are, the harder it is to choose :rolleyes:

_
 

kmisegades

Swamp Goose
I believe all new Laser booms actually come with a loop of webbing around the spar for this purpose. You can alternatively use the original stainless eyestrap (I do, and it does work fine) or another type of "soft" (at least somewhat flexible) lead, as long as it's fastened by rivets at the original location. A lead like the ones we're discussing here is illegal.

_
Please note that our components are intended for recreational boaters, who have more freedom than One Design competitors.
 

kmisegades

Swamp Goose
From the Z banding on the sheet hanger and deck plug, it looks like they're 3D printed, right?
Yes sir. Production parts would be injection molded. But pre-production parts will be 3D printed and offered. The part is not heavily loaded and the plastic we use (PLA or PETG) has held up very well this summer and will likely last quite a few years as long as the parts are not in the sun too long.
 

kmisegades

Swamp Goose
Do you have any idea on the price of the Sabre Daggerboard?
Thank you for asking. Our goal from the outset has been to keep pricing around the average price for the current competition composite daggerboard. At this time we believe that this is realistic, but we're not quite ready to set pricing. Should be ready by the end of the year though.
 

kmisegades

Swamp Goose
How strong is the centerboard material as they are stood on to right the boat when it flips.
Important question! One of my early boards made from plywood broke under my 160 lb weight while righting it one gusty day. We're going with a laminate of a very dense, strong wood (Sapele), which will only make it stronger. Think of a butcher block. The grain and glue joints are aligned in the spanwise direction, just as with the aircraft wing of the Hatz biplane I am building. I do plan on doing static load tests on a production board, to failure, to see how much weight it can hold out towards the tip. I am guessing that the load will be on the outer 3rd of the board and be 100-200 lbs - one needs to account for the buoyancy of the person pulling down on it. As an aside, we're working on a mast float / direction indicator to prevent the mast from going beyond 90 degrees when it flips. These are common on the Hobies on my lake; I do not understand why they are not available for the Sunfish. Maybe they are and I have not come across them on the web?
 
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