As we all know, things can occasionally break on a Mirage Drive. Although most failures are preventable or can be seen coming, that is of little consolation when you're 10 miles out and you left your paddle at home. Your emergency tool kit, if you bought one, will be of little use to you out at sea with cold wet hands and no work bench, where even the simplest repairs are almost impossible.
Fortunately, most Drive failures are not complete. With a little headwork and three tools*, most Drive failure will not leave you stranded.
*
Note: '08 and newer Drives and those upgraded to newest drums and cables do not need vice grips.Let's take a look at a variety of situations:
Broken fin mast:
Mast falls out:Either of these will give you the same result -- a one finned Drive. All you need to do is remove the Drive and disconnect the bad fin and mast at the clew outhaul. Removing the ring pin is simple, but in the water I had difficulties accomplishing this with wet fingers. If necessary, get the dikes out and cut it. You can replace it later.
The result should look something like this:
Caution: Using the Drive with one fin will rock the boat, so take it easy until you get used to the rhythm. Once you get into the swing of things though, you can move along quite well.
I was able to average 5.1 MPH cruising and reached 7.1 on a sprint (Adventure with one Turbofin)! That should be enough to get you home in time for dinner.
Clew Adjustment Screw unthreads: Remove fin if it's still there. Proceed as above.
Pedal comes loose or falls off: This is an easy one --simply push against the pedal crank. Adjust the pedal position if desired.
Pedal adjustment pin rips out of drum: Find an undamaged hole and continue at a slower pace until you get to your destination.
Cable or chain breaks: This depends on which cable breaks. It can be rather messy looking but don't let that deter you from getting back. The following picture shows front cable and idler cable disconnected, with only the rear cable operating.
In any event, the broken piece will probably not interfere with your Drive operation. But if it does, use your 7/16 open end wrench and needle nose vise grips as necessary to remove the offending part:
Idler cable failure: You should be able to continue to port with both fins fully operational. Don't do any sprints though.
Front chain/cable failure: The idler cable will probably also come loose, but don't worry about it. You should be able to proceed home on one fin as above. If you pull the Drive for inspection, the drums may want to spread. Keep them together until you remount the Drive where they will be held in place. Don't be alarmed if both pedals rock back at once -- once pedaling, this should not be an issue. As long as the rear chain stays on the sprocket you'll have power.
You can leave the front fin to freewheel if it's not in the way.
Rear chain/cable failure: This is the toughest one because both pedals will fall forward instead of pedaling. But you can continue to use the drive by re-inserting it backwards where you should have some pedaling traction. You'll have to head home in reverse since you left your paddle behind! Not to worry though -- it works. Just be very ginger with the rudder and keep your turns gentle and try not to run into anything. Here's what your "stern" wake looks like going backwards. It's kinda fun actually.
As you can see, short of an explosion, your Drive will not fail you, even if something breaks on it. The only caveat I can think of here is on worn out Drives or the old stainless steel Drives, the fat center tooth on your plastic sprocket that holds the chain in position may be worn down or absent. This can allow the chain to disengage during certain cable breaks where both pedals can move in one direction (but not the other). In that case, you may have to re-seat the chain, push the pedals in the other direction and reset the drive. I have not tried this, but I think it can be done. If not, you may have to paddle home with your hands.