So here’s the head-scratcher. Being a diligent captain, you note that the capacity label of your new SurfMaster 220 tow boat reads “14 persons or 2,200 pounds.” You also know that its wake-boosting ballast system holds 250 gallons, or 2,000 pounds. So if you fill the ballast, that seems to leave enough capacity for you…and a ham sandwich. Can this be right?
Yes. And here’s why.
“Per American Boat and Yacht Council standards, the potential weight of a permanently mounted rigid tank must be included in the manufacturer’s capacity calculation for the boat,” said Ed Sherman, ABYC vice president and education director and Boating blogger and contributing editor. “If the ballast system can be disconnected and removed from the boat, then that potential ballast does not need to be included in the boatbuilder’s capacity calculus.”
The potential water weight of factory-installed ballast bags, even when placed under seats or below deck, is likely not considered when boat capacity is calculated. However, the weight of that water must be part of your calculation of boat load when you flip the switch on the ballast pumps, said Christophe Lavigne, vice president of engineering at Rec Boat Holdings, which offers Four Winns and Scarab models with a ballast system.
“The assumption is that the ballast bags may often be empty,” explained Lavigne, “in which case you’d be able to apply that capacity to more gear and people. But when you add water ballast, that weight must count toward your load.”
This standard applies to recreational boats under 26 feet in length in the United States and Canada. In Europe the potential weight of any ballast system is part of the load calculation. The logic of building the boat with ballast capacity close to the maximum load is that this allows the ballast to be allocated among several bags to achieve a certain wake shape, without using all of the capacity.
Since the advent of the Skurfer it’s been common practice for boats towing wakeboarders and surfers to be overloaded with owner-installed ballast, even in addition to the ballast capacity provided by the manufacturer. This despite the admonition in most owner’s manuals that “the weight of all persons and gear including non-factory fitted ballast bags should never exceed the maximum weight capacity listed on the capacity label.” Joe Weekender figures the pros do it so he will too, but the consequences can be an ill-handling or unstable boat and, in many states, a citation for exceeding the listed weight capacity on the decal or plate.
“It’s been my observation that tow-boat owners will add ballast until one day they chop the throttle and take water over the transom,” said Lavigne, “and then if the boat doesn’t sink they back off on the weight in the boat.” One boatbuilder that does not care to be mentioned reports that four or five of its customers manage to overload and sink an inboard tow boat each year. Which might make for a funny YouTube video but could also have tragic consequences. The smarter way to make a bigger wake is to buy a bigger boat.