MD180 ST Fin vs MD180 ST Turbo Fin
New from Hobie for 2017 is the Mirage Drive 180 - a pedal drive system that has reverse! This comes supplied as standard in their 2017 Mirage Kayak range, Pro Angler range and Mirage Island range. The Mirage Drive 180 that comes with the Mirage Kayak range - including the Outback, Revo 11, Revo 13, Revo 16 and more - comes equipped with MD180 ST (Square Tip) fins as standard.
These fins are perfectly adequate to propel the Hobie Mirage Kayak range through the water.... however Hobie do produce a longer, more powerful fin - the ST Turbo Fin!
The ST Turbo fin is longer than the standard ST fin. This provides more surface area, and therefore more resistance against the water whilst pedalling, resulting in more thrust! Its not all about going fast though... you can get a greater top end speed and a slower cadence (less pedals for a given distance) for cruising.
The ST fins are approximately 260mm long and 90mm wide at the tip, whereas the ST Turbo fins are 50mm longer at approximately 310mm long and 90mm wide at the tip. The ST Turbo Fin is therefore around 4500mm²²² squared (45cm squared) greater in surface area than the ST fin. Over the two fins thats 9000mm squared (90cm squared) more fin pushing against the water, providing more propulsion and power!
The is a small disadvantage though - the ST Turbo Fins are a little harder to pedal - but in return provide increased performance.
This is one of the most popular upgrades Hobie users carry out to their Mirage Drive kayaks, so it was inevitable that as i could get my hands on a set of the MD180 ST Turbo Fin kits i would be upgrading!
Hobie MD180 ST Turbo Fin Kits
The kit come supplied with:
Minimal tools are required for installation, you'll need:
These kits are readily available from Hobie dealers - i purchased mine from Cornwall Canoes where they can be purchased in-store or on their website with delivery - see here for more information.
Fitting MD180 ST Turbo Fins to a Mirage Drive 180
This is a fairly straightforward install - allow 20 minutes or so to carry it out.
Step 1 - Removing the MD180 ST Fins
In order to remove the fins from the 180 drive, you'll need to gain access to the top of the rotating boom which holds the fin masts. To do this, pull the reverse toggle slowly until the fins rotate 90° - this will reveal the top of the boom.
Take a closer look at the top of the boom and you'll see the top of the fin tensioning bolt thread, which has a hex head. This sits within a plastic housing which slides side-to-side within a carrier channel during use, allowing the fin to flex.
The bolt runs down through a thumb wheel and then into a nyloc nut located on the fin. This holds the fin in place on the mast and keeps it attached to the boom. This bolt must be undone from the fin nut to allow fin removal. To do this, use the 1/8" Allen Key on the bolt head and hold the fin nut using a set of pliers. Now simply unscrew....
Once undone, the fin should slide straight off the mast. Put the fin nut somewhere safe as you'll be needing that later.
Now repeat with the other fin to reveal both masts.
Step 2 - Removing the MD180 ST Masts
Time to remove the masts. The mast ends are threaded and screw into the boom within a brass threaded insert. These are dipped in Loctite thread locker when installed in the factory to prevent them loosening during use, and are then screwed quiet tightly into the mast housing. This can make them a complete pain to undo and will require a lot of forceful persuasion to release them! Pliers are required for this job.
Look closely towards the end of the mast and you'll find a flattened area.
Use a pair of pliers to grip this area tightly and then twist to break the loctite bond within the mast housing - this can take a lot of force and may feel like you'll break the drive but persist with it. I find rocking the pliers can help to crack the loctite and release the mast. If it really is not wanting to undo, then grip the mast within a metal vice and twist the whole drive itself to provide more leverage.
Once the bond is broken, the mast will simply unscrew.... hurrah!
Step 3 - Instaling the Turbo Fin Masts
Now that the ST masts are removed we can replace these with the longer ST Turbo masts. The masts have a threaded end which screws into the mast housing...
A 0.5ml tube of Loctite 243 Thread Locker is supplied with the kit - put a drop of this on the threads before screwing into place to ensure a strong hold so that the masts won't loosen during use.
Screw each mast into the housing on the boom and screw up to a snug fit using pliers on the masts.
Step 4 - Fitting the MD180 ST Turbo Fins
Now that the Turbo Masts are installed, we can fit the ST Turbo fins. Firstly, slide the fin onto the mast...
The fin can then be re-attached to the boom using the fin tensioning bolt. Use the 1/8" Allen Key to tighten the bolt down into the fin nut, using pliers to hold this in place. Tighten until the bolt end is flush with the end of the nut.
Repeat with the other fin.... Installation is now complete!
The fins can then be re-tensioned to the desired amount. Using the thumb wheel, adjust the bolt downwards (counter-clockwise) so that the nut sits at the bottom of the fin notch and this sets the fins in their tightest setting. They flex less in the water, providing more resistance - this results in greater top end speed but is harder work on the legs! Adjust the bolt upwards (clockwise) until the nut sits at the top of the notch of the fin sets their slackest setting. This provides greater low end torque with easier pedalling at cruising speeds. Mine are a little loose and can move during use, but a small dab of loctite has sorted that out. I find having the nut sitting about a a 3rd of the way down from the top about right - not completely slack but not tight enough to be hard work on the legs.
Hobie warn not to over tighten the fin tensioners - the fin must be able to move from side to side in the traveler slot located in the boom. If the fins are too tight, it will lock up and not move in the traveler slot, potentially causing damage to the fin or the adjustment hardware.
Hobie Mirage Drive 180 with ST Turbo Fins
My Mirage Drive 180 is now equipped with the MD180 ST Turbo Fins and is ready for use with the Revolution 16, providing greater performance with higher top end speeds and a lower cadence whilst at cruising speeds. Happy days!
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