BoatingLAB

Pumping up to get air.

There is more than one way to skin a cat, and in wakeboarding, there are two ways to fill a sack—a ballast sack to be exact. Many boats are built with integrated ballast tanks or sacks and permanently mounted reversing pumps.

Tap “fill” and they fill. Tap “empty” and they reverse the flow overboard. Then there’s the down-and-dirty way: Drop a portable pump, which is plugged to a 12-volt receptacle, overboard attached to a hose attached to a removable ballast sack, and fill away. When it’s time to pump out the ballast, hook the pump to the ballast tank and drop the end of the hose overboard.

FIXED-MOUNT REVERSING PUMPS

Reversing pumps are mounted to a bulkhead or flat surface in the bilge and above the waterline to avoid immersion and prevent backflow, should the pump impeller fail and allow water to pass. One barb on the pump is attached to a through-hull fitting below the waterline; the other is attached to the ballast tank fill port. If there are multiple tanks, as is normally the case, a diverter valve directs the water to the tank to be filled. Some diverter valves are manual, and some are activated with a switch. The pump has the ability to run two ways, pumping in or pumping out, based on the switch selection.

PORTABLE BALLAST PUMPS

These simply designed systems use a 12-volt pump powered via a 12-volt receptacle and connected to a hose. On some, a friction fitting holds the output hose to the ballast tank fill port and the waterproof pump is dropped overboard. When the tank is filled, it’s capped, and the pump hose is connected to the next bag. To drain the bags, the hose is placed on the intake side of the pump and, again, the pump is dropped over the side of the boat. To make the pump start draining, it may be necessary to hold the pump below the top level of the ballast tank to prime the pump, then quickly hold it overboard.

MAXIMUM FLOW CAPACITIES

A pump’s ability to move water is measured, usually, in gallons per hour. Wakeboarders want to know how many “pounds per minute” are added to the boat. Either way, that capacity figure is dependent on the power of the electric motor, usually measured in amps, the size of the impeller, shaft and motor, and the diameter of the water-supply inlet and overboard outlet. A higher-capacity pump will require more electricity in amps to do the job. The higher amperage the pump draws, the higher the wire gauge (thickness) needs to be to carry the current. Also, the longer the distance from the pump to the battery, the heavier the gauge needed to combat the wire’s resistance to the flow of electrons.

Here are five outstanding options, and a study of their specs and capacities.