Hobie Cat Forums

Trying to get a little more up wind performance out of my AI, I already fitted it with an extremely sophisticated wind indicator fabricated using a coat hanger and video tape, but I have another idea.

Adding extra dagger boards to the ama bars. .. I could create them easy enough out of plastic cutting boards from the grocery store and use circular mounts that would clamp onto the bars, the tension will be adjustable, if something hits the fins they will simply fold up. I have a pretty good idea how I can do it.

Originally i was thinking of just adding fins to the read of the amas, but adding them to the bars sounds better, no drilling holes in things.

I think I could work something out with a few hours of work on a budget of no more than $50.



Thoughts?

Upwind performance is largely limited by the rig we have not leeway made. (at least on the TI) We use a cat rig which is less effective than the far more common and complicated bermuda rig. The cat rig is very simple and very competative on all points of sail except very close hauled, while a bermuda rig excells upwind but is not quite as good on other points of sail. The bermuda rig is artificially popular due to the way sail rigs are handicapped for racing.

J

_________________
2011 Golden Papaya TI with a 250 square foot spinnaker!
also a more manageable 100 square foot spinny...
&
the TI3 rear ama mod

I just notice, especially when trying to close haul, how much side slip the AI has, so I figure more "grip" in the water would help up wind sailing.

been tinkering with the jib idea too.

Wingnutt, you probably realise this already, but:

- Pedalling helps you point higher than anything else.

- If you feel pedalling is "impure", you can leave the drive in with the fins down (pedals together). That makes for a very effective extra daggerboard.

_________________

Of course, well basically I sold my wave, I miss "pure" sailing a little.

just want to get more out of the AI is all.

I have an elastic strap that I use to assure that my Turbo Fins are in the 'up' on the hull position if I am moving over shallow water. I can also use the strap to hold the Fins in the mid-position. This effectively creates a second 'centerboard' which can help the Hobie from slide-slipping somewhat.

now Im getting the itch to create a centerboard that fits in the fin slot, something with a lot more surface area than the standard dagger board. I have a pretty good idea how to do it too.. the gears are turning..

I don't see why we couldn't adapt a Hobie plastic dagger or rudder with a 1/2" rod and drop it into the drive well. At least on a TI. Wasn't this a Roadrunner project?

The thing is, this will create extra drag on most points of sail, when you don't want it. (Daggers should not be left down 100% of the time).

We also have 2 hulls in the water at any time, which helps us keep pointed. I don't think we experience slip like a monohull.

Agreed with Chris. Light pedaling going upwind is the best pointing feature this boat could have... it's our secret weapon.

Someone posted a mod that pins the Mirage pedals together, in the perfect upright position. That's probably the best compromise.

_________________
"You can avoid reality, but you cannot avoid the consequences of avoiding reality."
- Ayn Rand

Hang on a sec guys! Call me stupid, but surely (don't call me Shirley ) the Miragedrive fins will be pretty well ineffective?

Why? Because due to their flexibility, they will not offer any resistance to side slip, as they will simply flex til they are pointed directly into the water flow which includes the side slip.

Yea, I've never experienced much of an improvement while holding them in the straight down position and sailing close hauled in strong wind.

However, they are a huge improvement if you actually use them. Slow, periodic stroking is all that's required. It's like activating "traction control".

_________________
"You can avoid reality, but you cannot avoid the consequences of avoiding reality."
- Ayn Rand

Yea, I believe the fins being down is probably more of a detriment to performance, the added drag they cause is probably not offset by the slip resistance they provide due to their flexibility.

Building a larger centerboard is actually quite easy, the tricky part is making it "friendly" when it hits something.

I find personally, that keeping the Mirage drive fins strait down help me point slightly higher than others not keeping the fins down. I don't usually put my AI daggerboard in until the wind gets above 6mph, using the Mirage Drive fins instead.

_________________

http://KayakingBob.com - - - - - - - - - - - - - - - - - - - - - - - - - - - 2007, 2009 & 2010 Hobie AIs and a 2010 TI

rough cut, still have some sanding and such to do, but you get the idea.

Tony,
I'd never call you stupid ....but.........the mirage fins do indeed stop sideways slip -despite their flexibility. Remember that they flex to a degree but with the fins clue and mast restricting total fin rotation there is still resistance to slip. It's why Hobie can offer the sail kit on all Miragedrive kayaks. Our first Hobie was an Oasis and sailing into the wind without pedaling could only be achieved with fins in the down position. I made up a simple lock using an eyebolt to stop the tendency of the fins to fold up under the hull when underway:
viewtopic.php?f=32&t=10831&p=57071


Wingnutt,
I eventually made a daggerboard holder out of the drivewell plug, much like what you are doing, except I used the AI DB. See end Page 2 here:
viewtopic.php?f=32&t=3176&start=15

You will probably want to beef up the drivewell plug locating pins. I've used an old SS drumshaft and also the gray plastic rod that comes with every Hobie (the Miragedrives are cable tied to it for transport.) If you haven't got one your dealer should have some lying around.