Once a staple of sailing charter vacations, cats today are popping up everywhere – in hot and cold climates and as power or sailboats. Cats offer numerous benefits not the least of which is being easier to handle under power in close quarters - once you learn to drive one, that is.
The Basics
Cats have the distinct advantage of having twin propellers set far apart so the boats will spin in their own length. When learning, it’s easiest to leave the rudders centered not only because messing with the wheel adds complexity, but also because at slow speeds, catamarans don’t need flow over the rudders to turn – the engines do the trick. If you have a rudder angle indicator, check to see that the rudders are centered. If you don’t, spin the wheel from lock to lock and then cut the number of turns in half to figure out where center is.
Once the rudders are centered, lock the wheel and work the throttles with your hands. Imagine holding a bar with both hands in front of you. Moving your right hand forward will move your left hand aft. Notice how your shoulders turn and in which direction you end up facing. Now apply this to the throttles. Powering forward with the starboard engine and aft with the port, will turn the cat to port and vice versa.
It’s often better to use one engine at a time for fine tuning a cat maneuver because both props racing can overpower a simple turn. Also, since cat propellers are so far aft, the boats are usually quicker to respond in a given direction while in reverse.
Docking and Departure
Leaving a portside tie up with boats both fore and aft like at a fuel dock, put a fender on your port quarter. Then put the starboard engine in reverse until the bows pivot out, clearing the boat ahead, and drive forward with first the port and then both engines. If there is limited space forward, back out but first put a fender on your port bow to cushion any contact. Then put the starboard engine gently in forward and the port in reverse until the transoms clear the boat behind and back out by using reverse on both engines.
Coming to a portside tie up, put a fender on your port quarter, come along and slightly ahead of the space where you want to end up on a busy quay. Pivot so that your stern angles about 45 degrees to the dock with the port engine in forward and the starboard in reverse. Power aft slowly with both engines and a few feet before the fender makes contact, put the starboard into forward, keeping the port in reverse to pivot into the dock.
Catamarans don’t coast well primarily because they don’t have a deep keel to track. Relying on coasting to a dock at a shallow angle and then going to reverse and using prop walk to cozy up the stern won’t work as well as it does on a monohull. It is better to come in at a sharper angle and then pivot the boat into position with the engines especially if there is little room fore and aft.
Backing into a Slip
Backing into a slip is easier on a catamaran than a monohull because there are twin counter-rotating propellers that negate propwalk which is the pull to once side when a single screw boat is in reverse. To back into a slip (which will make it more convenient for crew to step on and off) pull up until perpendicular with the slip, pivot the boat with the engines and then use both in reverse, adjusting as you back up if there is wind or current.
Picking up a Mooring
To minimize swinging on a mooring, and to keep it quieter for anyone sleeping in the forward cabins, use two lines to hook a cat up to a mooring. Attach one line to each of the forward cleats and bring the loose ends to the center. Pick up the mooring with a boathook and find the eye – often well below the float. String one line through the eye and bring it back to the same cleat. Repeat on the other side, keeping the lines the same length so the cat is centered. It’s best if you have at least two people to do this quickly but one can manage while you keep station with the engines. Communication with your crew will be key since you’ll lose sight of the mooring before reaching it so make sure you you’re lined up and don’t’ overrun it. Instead of centering the mooring on the bow, it can be easier to maneuver so that the mooring is by one hull where the driver can see it and where the crew are standing on a solid deck rather than in the soft trampoline when managing the lines.
Tracking and Walking
Most cats have mini-keels to help them track. Others have daggerboards that may be retracted into the hull. Coming into a shallow anchorage, it may be intuitive to raise the boards all the way up to avoid grounding. However, the round hull bottoms provide little grip and picking up a mooring or anchoring in windy conditions will make the cat slip around like on a bar of soap. Leaving a foot or so of the daggerboards down will provide enough traction to spin and maneuver as you need.
To walk a cat sideways, as in toward a dock on the port side, spin the wheel to about 80% away from the dock (to starboard), put the starboard engine into idle forward and the port engine into low rpm reverse. Keep it slow and controlled. Each cat will react differently and there are also the issues of wind and current to contend with so this maneuver may need to be adjusted in its percentages and rpm based on conditions.
There is no substitute for practice, not only to learn the basics, but also to get the nuances of a particular boat. Spend an hour docking in various situations and you’ll soon be a pro.