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PostPosted: Tue Feb 07, 2006 3:32 pm 
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Joined: Fri Nov 19, 2004 6:56 am
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Location: Tallahassee, FL
Although the official name in the Hobie parts catalog for the Mirage Drive flipper or fin is “sail”, I don't care for that name since, obviously, the Mirage Drive yaks all have the capability to mount a mast and a true sail. But the point of this post is to clear up some misconceptions (including my own!) about how much water under your keel you will need to successfully operate the Mirage Drive. Obviously that will ultimately be determined by how much you and your gear weigh, and how much water the hull eventually displaces. But setting aside for the moment that important weight unknown (since it will vary for each and every pedaler), let's take a gander at just how far below the hull the Mirage Drive extends all by its lonesome. Now, I have seen widely varying guesstmates about this on nearly every kayaking forum I have ever looked at. But apparently no one has ever actually measured the Mirage Drive flipper length below the keel. So, here ya go.

1. First pic shows the normal extension of the Mirage Drive flippers (my preferred name for the “sail”) below the keel. This position occurs when both pedals are aligned exactly side by side in the cockpit. You will note that the flipper length is almost exactly 12 inches. I have seen estimates of 24 inches, 22 inches, 18 inches, etc., but I was actually surprised myself to find that it was no more than a foot.

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2. The second pic shows both flippers folded up flat against the hull. This occurs when one or the other pedal is pulled aft as far as it will go (the other pedal then is located as far forward as it will go). Hobie, in fact, has thoughtfully provided a very handy bungee cord and hook so you can latch one pedal aft with the hook when you get into really skinny water. Or you can do as I often do in the shallows, and simply unlatch the whole Mirage Drive, pull it, and place the flippers up on the bow. Takes a whole 10 seconds or so to perform this task (don't forget to always leash your Drive!).

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3. This is a beam or side view of the flippers folded up against the hull. As you can see, the boat can operate in very skinny water with one pedal pulled all the way aft and the flippers flat up against the hull.

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4. But how much draft is required for even this slight protrusion of the flipper mechanism below the hull with one pedal fully aft? Would you believe only 1 1/4 inches beneath the keel?

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Once again, how much each pedaler (and his or her gear) weighs will determine how much water will be required beneath the keel for a full pedal stroke. But everyone needs to keep in mind that regardless of individual weight variations, you can still operate the Mirage Drive in less than a foot of water simply by using partial pedal strokes. In fact, that is often the preferred way to pedal for some (myself included) in pretty shallow water. For example, after a good rain in the North Florida Big Bend, one often can't see the bottom in only 1-2 feet of water due to all the leaf tannins that turn the water almost black. This can be, and is, hazardous to the health of your Mirage Drive, since running up on a submerged oyster reef unexpectedly (as I have done on more than one occasion) will certainly chew up the tips of your flippers!

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Last edited by Apalach on Tue Feb 07, 2006 10:14 pm, edited 1 time in total.

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PostPosted: Tue Feb 07, 2006 6:52 pm 
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Joined: Mon Mar 14, 2005 3:15 pm
Posts: 122
Location: Sandy Eggo
Apalach... Thanks for taking the time to measure and post this important info. I too have seen those widely varying estimates on the subject but never got around to checking.

BTW, you have some nice tips... Not "chewed up" at all. I say display them with pride!! :shock:


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PostPosted: Tue Feb 07, 2006 7:24 pm 
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Location: Tallahassee, FL
Noal,
Shhh, don't tell my wife--her Mirage Drive that I have been using until I got mine repaired, is the one with the chewed-up tips. :oops:

My older drive is the one in the pics above. I just finished repairing my drive after both adjusting pins came out during our GAFFE trip. Matt sent me the replacement parts, but since I still had both sets of the original springs, pins, and handles, I decided to do my own repair emulating the earlier Hobie Company modification that I kind of liked. Here is a pic of my final repair--should work OK I think.

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PostPosted: Wed Feb 08, 2006 8:16 am 
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Joined: Sun Oct 09, 2005 3:08 pm
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Location: San Antonio, TX
Very Good Topic Apalach! We all have seen those wide depth estimates. It seems the less experience a person has with the Mirage drive, the deeper the water he or she thinks it needs for use! I hear, "That thing is not very good in shallow water is it." a lot. In my BigA, I have been using 15 inches as a minimum for full operation depth. As you just showed, for most persons that is a safe depth. When it gets close, the modified stroke goes into effect. BTW, I also noticed how nice, shiney and fully painted your drive looks. Hmmmmmm. Kyt


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PostPosted: Wed Feb 08, 2006 9:01 am 
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Location: Tallahassee, FL
Yep kyt,
That good appearance comes from superior maintenance and excruciating care (except when I happen to run up on an oyster reef!). :mrgreen:

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 Post subject: Duct Tape
PostPosted: Wed Feb 08, 2006 9:34 am 
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Joined: Fri Nov 19, 2004 6:56 am
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Location: Tallahassee, FL
BTW, for all you duct tape fans out there, note the dark gray strips along the keel of my (wife's) Sport on either side of the Mirage Drive well. I had removed several mm of polyethylene from the keel of the Sport on a rough concrete boat ramp a few days before, when I noticed this stuff at my local Lowe's.

It is called "Scotch Heavy Duty All-Weather Duct Tape", and according to the product info, it is "Long lasting, UV & sunlight resistant, water resistant, for indoor/outdoor use, resists drying, peeling, and cracking", and comes in a 60 yard roll for less than $9 as I recall. I don't know how well it will work as a "rub strip" on the keel over time, but after one trip in the salt, it still looks brand new, and has not started to peel or come off. Pretty inexpensive protection, it would seem. We shall see...

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PostPosted: Wed Feb 08, 2006 2:52 pm 
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Joined: Fri Dec 16, 2005 4:36 pm
Posts: 62
Location: Northfield, NH
Great info! Feel like taking it a tad further? If you have the chance, can you measure from the keel to the sponsons near the drive on the outback? Inquiring minds might be interested in that too.

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07 Ivory Dune Adventure
http://www.newenglandkayakfishing.com
http://www.aldenofsunapee.com/

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