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Get Behind Your Boat
by Pat Piper

A new Guinness Book world record was set earlier this year for the most waterskiers pulled behind a boat. In Australia, a 120-foot catamaran towed 114 people more than one nautical mile, soundly defeating the earlier record of only 100 people over the same distance. From the Department Of Don't Even Think About It, your boat on the trailer in your driveway isn't going to be a contender.
That said, chances are good you'll be asked, if you haven't been already, about pulling someone, though not with 113 others, behind the boat. After all, if you've got enough horsepower, a towrope, and a waterski or a wakeboard or even a tube, there's always someone ready to "give it a try."
"We've always had boats for pulling waterskiers," says Robin Brendle, vice president of Sport Boat and Sport Cruiser Sales at Sea Ray. "Today we offer 17 different models from 17.5 feet to 30 feet in length. There's a lot of variation in what people want from their boat today and though we've been building boats for 50 years, there's a desire by many for boats they can use to waterski or wakeboard behind."

In The Beginning

Sea Ray and other boat manufacturers saw the potential right away for pulling people behind their products. The first attempt at waterskiing took place in 1922 on Lake Pepin, Minnesota, when the idea occurred to avid snow skier Ralph Samuelson, who thought it ought to be possible to do the same thing on water. We all know how that turned out because more than 11 million people are waterskiing in the United States this year. Wakeboarding began in the 1980s on San Diego Bay. As the story is told, someone had a small surfboard and was somewhat successful being towed behind a boat. Others watched and were soon trying it themselves. Word got around and waterski maven Herb O'Brien started offering a "ski board." Others watched the ski board in use and soon the sport was featured in the 1996 Summer X-Games on ESPN. Mastercraft boats designed what came to be called the "X-Star" that was the official boat of the games. Today it continues to be one of the most popular designs for wakeboard fanatics and Mastercraft offers 13 different models.

A wakeboard-friendly boat has a tower to which a towrope A is attached. The "X-Star" designed for the 1996 games didn't have a tower, but the towrope was still attached at a higher point on an extended pylon in the boat than from the traditional transom (Mastercraft introduced a tower in the 2000 model year). The tower is preferred because the higher elevation pulls a wakeboarder out of the water faster and provides a better angle from which to jump the wake and find more "air" above the water. Wakeboard boats also have board racks for storage, an inboard engine that adds more weight (and a bigger wake) and a water bladder that is filled with the press of a button once the boat is in the water. The bladder provides even more weight and, yes, an even bigger wake. But wait, there's more: Serious wakeboarders have "wake plates" on their inboard boats. Tigé, one of the go-to wakeboard boat designers, came up with the idea in 1995 and features them on all their models. The wake plate looks like a large adjustable trim tab positioned above the propeller. It's hydraulic and raised or lowered depending on the preference of the person at the end of the tow rope. A wake plate never interferes with loading or unloading on a trailer.

"On a runabout the last trailing edge or part of the boat touching the water is the prop that is creating wash," notes Tigé Marketing Director Daniel Gutierrez. "This creates turbulence that typically will cause the wake to wash out or crumble. It is almost impossible to clean the wake with the prop washing the water out. In a Tigé, the final trailing edge is a clean running surface allowing the water to trail off in a crisp and clean peak designed to make a perfect ramp or wake. This allows for wakeboarders to hit a wake that is designed to 'pop' them in the air and progress more rapidly. Tigé uses a convex V-hull with an adjustable wake plate we call TAPS2, that allows even more detail in the wake generation by allowing the adjustment of the running attitude and detailed wake shape. TAPS2 also allows the driver or wakeboarder to adjust the wake size from 1 to 8 depending on the skill of the rider from beginner to advanced." Some wakeboard fans drop the use of a tow rope altogether and simply surf the wake behind these kinds of boats.

"The advantage to a wakeboard boat," Mastercraft Marketing Director Jason Boertje says, "is that these are designed for wake-boarding, meaning the hull is designed to give the beginner-toadvanced rider a superior slope and lip to the wake for a better wakeboarding experience. Obviously all boats (even jet skis) put off a wake. The question is, can the rider really do anything with that wake?" The answer is yes, but …

"Pulling a skier or a wakeboard is where you focus on the horsepower of the engine," says Sea Ray's Brendle. "If you are going to have a boatload of people and/or participate in watersports, that's where you'll want to look at a higher available horsepower for the boat. Sea Ray makes as many as three different horsepower engines for a specific boat for this very reason. In most cases it's in 50-hp increments. The higher the horsepower, the less strain and the better response from the boat."

Still, Tigé's Gutierrez says serious wakeboard folks ask their drivers (and boats) to pull at a specific speed. "The speed that you ride at is typically a result of the rope line length and 22 mph seems to be about the average speed for a wakeboarder riding on a standard 75-foot line. However, many pro wakeboarders prefer a longer line than 75, which means they will ride at speeds more around 24 mph to keep a consistency in the wake width. If you would rather ride around 20 mph, then the rope should get shortened to 60 or 65: otherwise the wake will widen too far to clear at the distance of a long line."

The Towing Basics

Larry Koschak, accessories product manager for Bombardier Recreational Products (manufacturer of Evinrude outboard engines and Sea-Doo jet skis), says there's no way to determine what size engine is going to produce the best ride because every boater is different. "I have not seen a formula to determine hp required for a boat 'X' feet long for a skier weighing 'X' pounds," he says. "In my opinion, any such formula is prone to error as children grow. That means the boater needs more hp every year as the children get bigger and that's just not a practical solution. As an ex-waterskier and currently a driver, I prefer maximum hp for the boat rating. On a new boat and motor purchase, don't go too small. You don't want a purchase of a 16-foot boat with a 115-hp engine to be unable to pull teenagers or young adults after only two years of ownership. Always remember the driver has a device called a throttle and the driver can always throttle down to control speed."

There's a critical moment when you'll know, as will the person in the water behind you, if the boat and engine are on the same page. When the person in the water yells "hit it," the throttle is pushed forward, creating "the hole shot," so named because the stern of the boat is pushed into the water (a hole) by the skier's weight and the rapid acceleration of the boat pulling the skier out of the water (the shot).

Koschak says this is where you'll know right away if the boat is properly aligned for a skier or wakeboarder: "The hole shot and the boat's pulling power are the desired traits of a propeller used for waterskiing and other watersports," he says. "Get the skier on top of the water as easy as possible because a lack of pulling power tires the skier out and makes the activity more of a chore." So if it takes a while to get the person out of the water, it could be a lack of adequate horsepower, but the first thing to look at isn't a new engine, it's the propeller.

The Proper Prop

Propellers are identified by a pair of specifications: the diameter (the distance from the end of one blade to the end of the blade directly opposite) and the pitch (a measurement of how many inches the boat moves forward with one turn of the propeller). "Look at the pitch specification," advises Bombardier's Koschak. "Many waterski drivers, including myself, change props to the next lower pitch size to improve pulling power. If the normal cruising prop has a 19-inch pitch, you would install a prop with a 17-inch pitch specification. A two-inch-lower pitch change is typical. But remember that getting a good hole shot means you're also going to have a decrease in top speed."

Ben Duke, director of Mercury Propellers, spends a lot of time looking at and testing ways to provide a good hole shot for boaters. "Pitch is the most important consideration for skiing/acceleration," he notes. "It's important to use a prop with a pitch on the boat that puts the engine near its maximum-rated rpm at wide-open throttle. Pitching to the high end of the rpm range lets the engine make more power at slower boat speeds. The Mercury Marine High-Five and Quicksilver QST propellers are good examples of props designed to accelerate well, so look for props that have four and five blades because they'll give a better hole shot than a threeblade. These propellers have smaller diameters to allow the engine to spool up into a decent power-producing RPM while maintaining enough blade area to hold the water."
Koschak says before buying a new blade, make some inquiries first. "Talk to your dealer and inquire if they have a demo prop program because this allows the boater to borrow a loaner prop of different styles and pitch to 'try-before-I buy.' This eliminates an expensive experimentation process." Korschak adds that most boat manufacturers have already established what props work most efficiently with specific engines, horsepower, and hull designs. One moreconsideration, and this is about endurance rather than performance: Stainless steel propellers are preferred over aluminum propellers. Aluminum is lighter and as such is more likely to chip or bend if it comes in contact with a hard bottom than the heavier stainless steel.
For both safety and performance reasons, a driver must also be aware of the bow rise upon acceleration. "The bow is always going to go up when the throttle is pushed forward," observes Sea Ray's Robin Brendle. "This can be dangerous because the operator isn't going to be able to see over the bow for a few seconds. If this is occurring, first consider the location of your passengers because, if everyone is in back, that's pushing the stern even farther into the water, which in turn pushes the bow higher. But also check the position of the outdrive (if applicable). Make sure it's all the way down. I think the outdrive setting is most often forgotten when bow rise becomes a concern."
One more point to consider for the well-tuned towboat: Look at the running strakes under the hull when the boat is on the trailer. "The strakes on our boats run the full length under the hull, from bow to stern," says Brendle. "Typically a 20-foot boat has three on each side; they have a horizontal component that helps the boat get up on plane quickly, but they also have a vertical component which helps the boat carve into the turns."
By the way, it took eight tries in Australia to beat the record. The boat performed beautifully but the skiers kept falling. On the eighth "hit it," they got it right. Sounds familiar, doesn't it?