Mirage Drive Fin Creep

I have a 2013 Oasis. I use it for fishing saltwater year around, once or twice every week, mostly solo but an occasional friend will join me sometimes. Never had any problem with the mirage drives other than the following minor issue. I love this kayak.

I have used the mirage drive with the fins adjusted both looseland tight. Loose is definitely better for me. However, when I recently noticed a slight drop in performance I checked the fins and discovered that the fins had slid up the fin shaft and thereby taking away much of the loose adjustment advantage. I have pulled the fins back down to, what I believe to be, the intended position on the shaft and noticed what I thought was a definite improvement. But, they seem to keep creeping back up the shaft again in short order.

Just wondering if anyone out there has experienced a similar problem and what they did to correct it? I've thought about taking the fins off the shaft and putting short piece of rod down the fin's shaft hole thereby extending the shaft length, or, perhaps just a few wraps of Gorilla Tape around the top of the shaft might hold the fin in the lower position.

Thanks for any advice or help you can give.

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All is well, life is good.

One thing I have noticed about my turbo fins is they tend to stretch out over time and use , especially heavy use, (I pedal a lot). They definately wear out over time and need to be replaced every season or two if you want optimum performance. I can tell when mine are worn out when the trailing edge gets all wavy and the fins begin to flutter and vibrate when sailing (we have a TI).
I didn't realize that they eventually went bad until went out with one of the other forum guys and he brought along his new glide drives for us to use. The difference was like night and day so I converted my mirage drives to the glide tech (needle bearings), I put new fins on as well, the difference was dramatic. My second drive I didn't convert to glide tech but I did put on new fins, now the both work great, the glide fins are just a little better, but boy what a difference new fins made.
Just suggesting if your fins are all wavy they might be stretched out, that might be somethin to try. I just throw my old fins into the hull for backup if I ever lose one.
FE

That creep might be because the masts are slightly bent. A side effect of a bent mast is it exposes base of shaft and further loosens fin tension as it compresses on the tension screw.

Measure the distance between mast bases and compare to dimension from tip to tip. They should be the same when masts are straight.

Fins do become slack with age

They will be able to slide up the mast when not loaded (if you just pull on they out of the water). As soon as you pedal, they pull back tight against the sprockets.

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Matt Miller
Former - Director of Parts and Accessory Sales
Warranty and Technical Support
Hobie Cat USA
(Retired 11/7/2022)

Loosening the clew outhaul enables the fins to slide up and down the mast (fin shaft) and operating more efficiently. When they twist they ride up the mast, giving them a better warp or pitch angle. You can demonstrate this by pulling on a fin and twisting it -- you will see it ride up the mast. If it rests up near the top of the mast that is OK as long as the fins are able to twist easily.

If you were to use a plug or tape to restrict the fins' movement, this would effectively be the same as tightening the fins so you don't want to do that. The fins need both free space below the mast and room to slide up (using up that free space in the process).

When you pull your fins off, check the masts for straightness and alignment as WAVERIDER suggests, and clean off any rust or sand with fine steel wool. Flush the fin pockets. I like to shoot a bit of silicone spray (NOT WD-40) in the fin pockets and run them up and down the masts a few times. -- besides reducing friction, this cleans any remaining debris out of the fin pockets. Then they should slide and twist much easier.

When finished, check the operation of the Drive -- salt water is hard on equipment. The Drive should operate by hand with very little friction. If not, it's time for a general lube and tune. If running well, the Drive will be much easier to pedal!

Really appreciate all the help. There were several comments that I didn't know about, or, hadn't thought of. This forum and it's members are a valuable resource. Thanks again.

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All is well, life is good.

Just thought I would post a reply on the results of all the help you guys have gave me on this problem.

I checked the mirage drives and thought they flip-flopped back and forth pretty good although I could feel a little resistance. I decided to take the fins off to see what I could see. I removed the fins and found that after four years and several hundred fishing trips in salt water, the shafts were pretty clean and the fins still were quire pliable. I measured the distance between the shafts (top and bottom) and found the measurements to be the same (shafts not bent). I went ahead and dusted the shafts off lightly with some steel wool, cleaned and rinsed the fin shaft pockets as best I could, then sprayed some silicone on the shafts and the down the shaft pockets, then reinstalled the fins. I was amazed at the improvement in what I would call the "flip-flop factor". I've had the Oasis on the water twice since the cleaning and silicone treatment and the fins seem to be as they were when they were new. Remarkable improvement. I'm one happy kayaker.

Thanks again for all the help. You were spot on.

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All is well, life is good.

I have an early version of the Mirage drive (V1 I was told). The "locking" pin or the center pin that is used to lock the drive in my Revo is starting to move to the right so that it is uneven in the drive. While pedaling this causes the drive to be off center making me crooked in the boat. I can tap the pin to center it but it migrates out with use.
Is this a known problem? Is there an "easy" fix?
Appreciate any solutions!

I would try giving the pin and the spline hole (the part the pin fits into) a good cleaning with something like Acetone so that it is clean dry and no residue then applying a good bead of 'Loctite' to the pin and refitting it and let it cure for a day or two. The loctite must/should be waterproof as Hobie use it on the fin masts. It might be worthwhile trying to 'pucker up' the splines centre section of the pin with a centre punch to make it a tighter fit into the spline. Other than that you might need a new spline, I'm not sure about V1 availability though.

You have the older style drumshaft, which has no splines in the center part where it passes through the spine. (upper shaft in pic).



Zarbs' solution might work, at least for awhile. If not, you can purchase a new drumshaft and those splines will keep it from sliding around. It will fit your Drive just fine.

Just the info I needed for now! Thanx
I'll be ordering a new drumshaft.