Mirage Drive Flippers: How Different for SUP?

I come away from other threads with the impression that the SUP Mirage-Drive fins are bolt-over compatible with the AI Mirage Drive.

They look to me like they have a wider-chord profile that might enable one to apply more power at lower RPM - which would make sense in the context of people standing on them: standing steps-per-minute vs the higher recumbant strokes-per-minute.

I recall FusionEng commenting that the effort was too high when he tried a set in his TI's Mirage Drive, but I find the effort on my AI's stock Mirage Drive frustratingly low - sort of like trying to pedal a bike on the flat in a super-low gear.

So I am thinking that maybe a set of SUP flippers would give a more satisfying effort level on my 2015 AI.

Does anybody see a flaw in this line of thinking?

First thing that occurs to me is an issue with the thicker foils and 8-10 mph speeds under sail on the AI vs 4-5 mph on the SUP with, of course, no sail.

_________________
2015 AI in "Dune" - "The Grey Pig"
2017 Trailex 450 Trailer
Pre-September 2015 cradles
(anybody want to buy a slightly-used AI SpinKit?)
eMail: [email protected]

I've been using the flow 90 (eclipse) fins for a while now. They definately take more peddling effort to operate, and I'm not sure how well the cables would hold up if you started peddling like a madman (extra strain on the mirage drive mechanisms). My normal cruise speed is around 8mph and I alway pedal 100% of the time. The regular turbo fins kinda give up at about that speed, (can't provide any additional useful thrust), plus they tend to flutter and vibrate at speeds over 10mph.
At first I was only using the flow 90 fins when sailing fast and was switching over to my turbo fins when regular kayaking. Well I got tired of switching out the drives all the time, and am only using the flow 90 fins now for everything. When wife is along she uses the turbo fins (I doubt she would like the eclipse fins).
You have to realize though my boat is not setup like any other, what works for me may not work for others. With my motors at idle (lowest possible throttle setting) I can't go any slower than about 6mph. When the motors are cold at startup the motors idle low enough for the clutches not to engage, however for some reason once the motors warm up the idle goes up and the cluches partially engage at idle. So my minimum possible speed is 5-6mph unfortunately.
I typically start the motors when we pull out and shut them off as we come in. The wife and I went exploring the shoreline at lake hartwell last week in late afternoon in almost no wind, (3-4mph max wind). We only brought one motor along on vacation so we ran that at just above idle (almost minimum throttle, (very quiet)) with the wing and main out. We cruised in and out of all the coves looking at property and exploring along the shoreline just putting along at around 6mph. We were out there a couple hrs and I pedaled 100% of the time and didn't get tired. The wife had the turbo fins but I strongly suspect she didn't pedal at all.
I plan on keeping the eclipse fins and using them exclusively for everything (they kinda grow on you and you get the same thrust peddling much slower). Keep in mind though I have really strong legs from peddling my peddleboat 10-15 miles a week year round for the last ten yrs.
Not for everyone I'm sure .
FE

this could be interesting also for me. though i am using a very standard AI without any special improvement (no haka, no motor, no gennaker)
i have very strong leg and maybe i could manage more powerful finns. moreover the cost of this change seems to be quite low. do I need to change also the masts or just the finns?

FE what do you think about what daft said that the 2 systems are not completely compatible?

Sounds like we have 3 kinds of Mirage Drive fins:

• The old, smaller, pre-Turbo fins
• The Turbo fins that come stock on my 2015 AI
• The more rigid, thicker-chord Flow 90 (aka "Eclipse") fins that come on the Hobie SUPs.

Have I got it right so far?

If so, can you elaborate on Daft's incompatibility observation?.... and how you worked around it?

_________________
2015 AI in "Dune" - "The Grey Pig"
2017 Trailex 450 Trailer
Pre-September 2015 cradles
(anybody want to buy a slightly-used AI SpinKit?)
eMail: [email protected]

I have no clue what I did to adapt the flow 90 fins (don't remember), I don't think I did anything at all, I think I just slipped them on and went, (90 seconds (lol)). There is some sort of tensioning system on the bottom, I just ignored all that I think.
Unfortunately I can't go look at it right now my TI is in a storage shed in atlanta for the next 3 months while we are out west visiting all the national parks, we are at the grand canyon right now as I'm typing this.
We will pick it up on the way back to florida.
FE

The product description from Hobie (http://www.austinkayak.com/products/236 ... e-180.html) says they only fit the Mirage Drive 180 (almost nine-hundred bucks..!!!) and give "as much as a 10% increase in speed ...".

I wouldn't admit to chomping at the bit, but they do look interesting and, for $130, I would probably give them a try if somebody reported they could be retrofited to the plain-vanilla Mirage Drive on my A2.

FWIW, I checked with AustinKayak, and the chains for the Eclipse Mirage Drive have different part numbers from the chains on my AI2's Mirage Drive.... dunno if that reflects more robust construction or what... but it calls into question any assumption that the two drives are equal in strength where it counts.

_________________
2015 AI in "Dune" - "The Grey Pig"
2017 Trailex 450 Trailer
Pre-September 2015 cradles
(anybody want to buy a slightly-used AI SpinKit?)
eMail: [email protected]