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PostPosted: Thu Aug 13, 2009 8:34 pm 
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Location: Toledo, OH
My impression is yes, absolutely, peddling increases sailing speed.

The obvious reason is that peddling imparts a forward force, which is added to that from the sail, providing more forward thrust and thus speed. Obvious as heck.

But I think there is more to it than that.

I find that I get a significant kick even with very slow peddling while under sail. Especially when in a close reach. It feels like far more than what I would get from peddling alone.

I suspect two things are going on here.

1) The mirage fins produce significant drag when left stationary, even very slow peddling negates that drag and gives you the equivalent of a smoother hull.

2) An active mirage drive, even in slow motion, acts as an "active keel" - allowing you to run with a much closer haul than you could with just the daggerboard, or - it is like it becomes a much larger 'virtual keel'. More of the vector forces from the sail are able to be turned into forward motion and more of the side force is resisted - perhaps because the motion of the mirage drive actually redirects some of the side vector force rearward. Think of them as two rudders that turn side force into forward motion instead of turning forward motion into a side force like when you turn the rudder at the rear. Damn ... I took a dynamics course in college, but that was too long ago and this is complicated stuff.


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PostPosted: Thu Aug 13, 2009 8:59 pm 
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Location: Terrigal NSW, Australia
BlueMark wrote:
An active mirage drive, even in slow motion, acts as an "active keel" - allowing you to run with a much closer haul than you could with just the daggerboard, or - it is like it becomes a much larger 'virtual keel'. More of the vector forces from the sail are able to be turned into forward motion and more of the side force is resisted - perhaps because the motion of the mirage drive actually redirects some of the side vector force rearward. Think of them as two rudders that turn side force into forward motion instead of turning forward motion into a side force like when you turn the rudder at the rear. Damn ... I took a dynamics course in college, but that was too long ago and this is complicated stuff.

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Bluemark, the Mirage drive can't direct the side force forward, because it is acting at 90º, but it does direct the resultant force forward and as the vector triangle shows, the greater the force (BA) from the drive, the more the resultant force (CA) approaches straight ahead.

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PostPosted: Thu Aug 13, 2009 9:59 pm 
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IMO, it depends somewhat on the fins. Standard fins seem to "mush out" about 7 MPH. Turbofins will pull well past 9 MPH and I think quite a bit faster. Personally, when I get going faster than that, I'm not usually pedaling, but concentrating more on enjoying the sailing. For pinching and tacking though, they're sure handy to have on the ready! 8)


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PostPosted: Fri Aug 14, 2009 5:39 pm 
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I have found that the Mirage Drive fins when fully extended exert some drag, but not really a huge amount. They have less drag when one pedal is forward and they are up against the hull. I still find that hard to believe, but it keeps happening, so...

When you're sailing at about 5 knots or more, you have to really pedal pretty fast to make any difference. I don't bother. I pedal when I'm going too slow, or when "motorsailing" trying to get upwind.


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PostPosted: Sat Aug 15, 2009 2:22 am 
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Location: Coram N.Y.
Pirate wrote:
Aledal wrote:
Thanks man-she could probably kill me.
and I`d probably surrender myself to her.

but as we Americans say...
If they dont have an A.I.
They ain`t crap.

Quote:
:shock: :? .......mmmmmmmm. Back on the beetle nuts again I'd say...Pirate :wink:

I thought it was "betel" nuts.. Yeah slipped up with the betel nuts(again)and made a totally toasted fool out of myself. 12 beers will do that to a guy! At least its only once a week :wink:!

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PostPosted: Sat Aug 15, 2009 2:30 am 
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Location: Coram N.Y.
Ditch Crawler wrote:
reconlon wrote:
Ditch doesn't have one yet! :o


For myself, a revo mirage drive would be very acceptable indeed, but what I need most is a boat which I can throw in the back of the car along with my grandkids, and take them to a place where we can all be getting wet within minutes!

A soft boat with no moving parts, but which would be treated with respect by other boaters.

I have bought an inflatable sitontop kayak which uses the same dropstitch construction as the Hobie inflatables. Like the Hobie, it is not widely available in the UK, but I found a dealer who had imported some remaindered stock, so the price was less than a third of the Hobie inflatable price. So far I have had it on the water once, and it is awesome - next week I have three days at the coast....

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Mostly, I would like to be able to instal a mirage drive into a plywood dinghy of my own construction

Thanks Ditch. And sorry for being such a wild man!I drive a transit bus in New York City long unpredictable hours and get really stressed out- so I make up for it if Im lucky enough to get 2 days off in a row.Anyway you sound like you really know your stuff-its a shame about the availability and price etc of the Island in England.A tandem would be great for you-especially having grandkids. Making your own boat out of plywood would be time consuming and a pain and the boat would be heavy. Why not go to France or Ireland and get one there?

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Last edited by Aledal on Sat Aug 15, 2009 3:32 am, edited 2 times in total.

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PostPosted: Sat Aug 15, 2009 3:05 am 
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Tom Ray wrote:
I have found that the Mirage Drive fins when fully extended exert some drag, but not really a huge amount. They have less drag when one pedal is forward and they are up against the hull. I still find that hard to believe, but it keeps happening, so...

When you're sailing at about 5 knots or more, you have to really pedal pretty fast to make any difference. I don't bother. I pedal when I'm going too slow, or when "motorsailing" trying to get upwind.


Okay Mr Ray-thats more my speed! I was thinking the boat CANT be moving faster but if Im not mistaken Im a minority!(once again). You guys out there in cyberspace sure know your engineering/physics& dynamics and all that stuff I`ll give yuh that. Thats why I love this site.I think I really should go back and revise the initial post though because it is too vague.Thanks for the input.(You too Pirate! :D :shock: )

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PostPosted: Sat Aug 15, 2009 5:25 am 
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Location: Bairnsdale, Victoria Australia
Aledal wrote:
Tom Ray wrote:
I have found that the Mirage Drive fins when fully extended exert some drag, but not really a huge amount. They have less drag when one pedal is forward and they are up against the hull. I still find that hard to believe, but it keeps happening, so...

When you're sailing at about 5 knots or more, you have to really pedal pretty fast to make any difference. I don't bother. I pedal when I'm going too slow, or when "motorsailing" trying to get upwind.


Okay Mr Ray-thats more my speed! I was thinking the boat CANT be moving faster but if Im not mistaken Im a minority!(once again). You guys out there in cyberspace sure know your engineering/physics& dynamics and all that stuff I`ll give yuh that. Thats why I love this site.I think I really should go back and revise the initial post though because it is too vague.Thanks for the input.(You too Pirate! :D :shock: )


I too love this site Aledal and where we can all learn something and get a smile at the same time. Pirate :D

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PostPosted: Sat Aug 15, 2009 5:46 am 
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Went for a sail today in about 5 knots of breeze. I didn't have my dagger-board with me unfortunately but experimented with the mirage drive using it as a centerboard and the AI seemed to be working quite well to windward with the fins vertical. Using the horizon as a guide I could see my heading fall off the wind quite dramatically every time I flattened the fins out to horizontal but returned to heading when I returned them to vertical. Alongside a much larger vessel (and with a bit of pedalling) I was making better distance to windward. Not very scientific I agree but the fins do very much act as a centerboard which is an added bonus to their original function. I am hoping for some wind and wave to try out my custom tramps and will take out my daggerboard if I go out again tomorrow....Pirate :wink:

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PostPosted: Sat Aug 15, 2009 10:04 am 
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Pirate,

I think you will find using the daggerboard instead of the vertical fins while sailing windward, the same difference again (pointing that much higher). I know I also see a small additional "help" in pointing higher by also using the fins "down", as well as a little bit more downwind speed by keeping the fins "up".

Here's yesterday's sailing adventure: http://www.trailguru.com/wiki/index.php/Track:8IE1

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PostPosted: Sat Aug 15, 2009 12:12 pm 
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Location: UK
Aledal wrote:
I drive a transit bus in New York City

I too drive buses - around the market towns and rural villages of Middle England. Do you know any media people - we could have a LifeSwap, and make megabucks - you can borrow my grandkids (and my lodgers), whilst I get to use your Manhattan Penthouse and your Adventure Island...

Deal?


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PostPosted: Sat Aug 15, 2009 2:06 pm 
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Location: Bairnsdale, Victoria Australia
reconlon wrote:
Pirate,

I think you will find using the daggerboard instead of the vertical fins while sailing windward, the same difference again (pointing that much higher). I know I also see a small additional "help" in pointing higher by also using the fins "down", as well as a little bit more downwind speed by keeping the fins "up".

Here's yesterday's sailing adventure: http://www.trailguru.com/wiki/index.php/Track:8IE1


I am confident Bob you are spot on there and I will test them today. Looks though like I am getting my wish of plenty of wind and wave so it may not be ideal conditions in which to test it but will be great to test the tramps.

The reason why I have not been carrying the daggerboard is primarily finding somewhere convenient to put the board when not in use. I however recently spotted another of your inovative AI improvements with the sleeve to hold the board so I am thinking that difficulty will soon be overcome.

Does your experience show if the boat is assisted or hampered to windward if both the daggerboard and the mirage drive are in place at the same time Bob?...Pirate

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PostPosted: Sat Aug 15, 2009 4:03 pm 
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Location: HISC Chichester Harbour UK
I managed to get out today and was experimenting with the Mirage drive. I believe pedalling it make a substantial difference. It was quite gusty today with choppy water. I have invested in a Velocitek speed puck http://www.velocitek.com/products/speedpuck which has proven to be very useful. I was averaging around 6 knots today with a recorded max of 8 Knots. It was too rough to get any real speed up and kept burying the bow and Amas into waves that constantly knocked a lot of speed off. I found I could point probably 10 degrees higher if I peddled.
I experimented with the dagger board up and the Mirage blades down. I found it didn't point as well as the dagger board and also lost speed, presumably due to drag. As I see it, unless you have them both exactly in alignment, the front blade will cause turbulence that is then stirred up further by the rear blade. Also the blades do not sit flat so they will twist wherever they feel like going. They do offer lateral resistance but at the expense of speed. I found it faster with the blades separated and flat against the hull, although I am interested in trying them hanging down at 45 degrees or so and see if that makes any difference. I also tried the dagger board and the Mirage fins down whilst trying to point in quite strong winds, I believe it helped a bit with lateral slippage, but I still couldn't point anywhere near as high as a standard monohull. The rudder was constantly being overpowered in strong gusts whilst going upwind.
I believe we will see a few more down here next season, it is attracting a lot of attention.
My next move will be some tramps. I can't use the full width setup as I often need to quickly fend it off mudbanks with the paddle when the wind blows it sideways onto the mud when I am trying to take pictures of the seals I am helping to monitor. The channel isn't wide enough to anchor easily. I think Pirates design looks the best bet for what I need and the spray skirt at the front will also be very useful. Are you going to have any for sale Pirate?

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PostPosted: Sat Aug 15, 2009 4:50 pm 
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Quote:
Does your experience show if the boat is assisted or hampered to windward if both the daggerboard and the mirage drive are in place at the same time Bob?...Pirate

Assisted

When going upwind in all but light wind, it will point better with both the daggerboard and the fins down.

Downwind, except for in heavy wind or larger waves, both out or up is best for speed.

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PostPosted: Sat Aug 15, 2009 6:06 pm 
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Joined: Sat Nov 29, 2008 7:33 pm
Posts: 305
Location: Coram N.Y.
Ditch Crawler wrote:
Aledal wrote:
I drive a transit bus in New York City

I too drive buses - around the market towns and rural villages of Middle England. Do you know any media people - we could have a LifeSwap, and make megabucks - you can borrow my grandkids (and my lodgers), whilst I get to use your Manhattan Penthouse and your Adventure Island...

Deal?


Keep the beautiful kids -my penthouse is yours anytime.
Nobody touches my Adventure Island-sorry :cry:
Dont know any celebs-never met any-wouldnt want to-
Except the Genesis clan of course. Supernatural.

Hey,is it true English busses have 4 front wheels just like in Magical Mystery Tour? :wink:

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New to PCs and this forum stuff. Had an original Outback and Classic. sold them both for the A.I.. Love the boat and especially this site... (if I can figure out how to use it)


Last edited by Aledal on Sun Aug 16, 2009 1:35 pm, edited 1 time in total.

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