The Outboard Expert: Mercury Introduces Big Tiller

Tiller-steering offered for up to 250-hp outboards.

14th November 2007.
By Charles Plueddeman

 Rated for up to 250 hp, the new Mercury Big Tiller has a die-cast aluminum arm designed to withstand a 400-pound load. The shifter has been moved forward, while the trim control is now located under the operator's thumb in the end of the throttle grip. The up-and-down Troll Control toggle switch forward of the shifter controls a speed control feature.

Rated for up to 250 hp, the new Mercury Big Tiller has a die-cast aluminum arm designed to withstand a 400-pound load. The shifter has been moved forward, while the trim control is now located under the operator’s thumb in the end of the throttle grip. The up-and-down Troll Control toggle switch forward of the shifter controls a speed control feature.

Mercury Marine will offer outboarders a new handle on big-horsepower motors with the introduction of its new Big Tiller, an accessory tiller-steering kit for outboard motors up to 250 hp. Three versions of the Big Tiller will be offered, including two with full hydraulic power steering. Big Tiller was introduced with a static display at a marine trade show in October, but last week I completed an exclusive test drive of a validation prototype version of Big Tiller on the Fox River in Oshkosh, Wisconsin. It worked like a dream, if your dream has always been to tiller-steer a V-6 motor.

When I worked at OMC 25 years ago, we would occasionally get a photo showing a V-6 Johnson motor bolted to the transom of a long canoe or some other indigenous craft, being piloted up the Congo River or down the Amazon through a crude tiller, often a length of gas pipe welded to the motor, with a wire connected to the throttle. So the desire to tiller-steering a big outboard has been around for a long time. In recent years, all outboard builders have offered a tiller kit for motors in the mid-size range, from 90 to 115 hp, mostly for walleye anglers who prefer a tiller motor for backtrolling. Right now, Mercury offers a tiller kit for its 1.5-liter Optimax two-strokes (up to 115 hp) and for its 75-115-hp Four Stroke models.

“But there are people who still want more,” explained Mike Reilley, the product manager for control and rigging products at Mercury who met me at the river with the Big Tiller prototype. “In the Pacific Northwest, there are salmon anglers running 27- to 29-foot aluminum V-bottom boats with 225-hp outboards that they are controlling with a modified OEM tiller, usually put together by a dealer and the boat owner. That was the first market we wanted to address with the Big Tiller, but there are also commercial applications and other sportsmen, such as duck hunters or charter fishing guides, who would like to run a tiller on a big boat just to eliminate a steering console and have as much open deck space as possible in the boat.”

Reilley explained that Mercury (www.mercurymarine.com) and the other outboard manufacturers have limited tiller installation to 115 hp for safety reasons.

“I just don’t think you can safely control a motor larger than 115 horsepower through a tiller without power assist,” he said. “And Mercury will strongly recommend the use of the Big Tiller with power assist on motors from 75 to 115 horsepower, although we will offer a version without power for those motors.”

An aftermarket power-assist tiller system has been on the market since 2004, when Merten Marine Ltd. Of Oshkosh, Wisconsin, received a patent for its EngineSteer product, which it also began selling that year. In development since 2000, EngineSteer utilized a stock Mercury, Suzuki and Yamaha tiller handle with parts that made it compatible with a hydraulic power steering system. The EngineSteer patent was so broad, according to Reilley of Mercury, that the most practical way for Mercury to proceed with a power-tiller project was to get the rights to the EngineSteer patent. In July, Mercury announced that it had reach a licensing agreement for exclusive rights to the patent that Reilley believes will make it impossible for anyone else to offer a power tiller.

While the Mercury Big Tiller utilizes many of the basic ideas from EngineSteer, it has been engineered to use many existing power steering components from the Mercury Verado outboards, including the compact Verado hydraulic pump and hoses. The pump is located under the aft splashwell deck, and should be rigged to a deep-cycle battery separate from the starting battery. The pump feeds a hydraulic valve manifold that is built right into the die-cast aluminum tiller handle. Four hydraulic lines connect the manifold to a steering ram mounted on the engine bracket. Mercury says the steering ram was subjected to extraordinary durability tests – 300,000 steering cycles at a load of 575 pounds.

The Mercury Big Tiller with power assist locates a hydraulic valve manifold with the tiller handle. Two hydraulic lines carry fluid to and from an electric pump mounted under the aft deck, while two other lines feed the hydraulic steering ram on the motor bracket. An amber light on the underside of the tiller illuminates the area around the motor at night.

The Mercury Big Tiller with power assist locates a hydraulic valve manifold with the tiller handle. Two hydraulic lines carry fluid to and from an electric pump mounted under the aft deck, while two other lines feed the hydraulic steering ram on the motor bracket. An amber light on the underside of the tiller illuminates the area around the motor at night.

The valves in the manifold are actuated through the throttle grip on the end of the tiller handle, which is designed to pivot about 6.5 degrees to port or starboard which the boat operator pushes or pulls on the handle to steer the motor. When you run the motor, this movement in the grip is so slight it’s almost unnoticed. Hand pressure on the tiller opens the hydraulic valving and applies the power assist to the motor and eliminates all steering feedback to the tiller. When there is no hand pressure on the tiller, the hydraulics hold the motor in place, so the operator can set a course and then relax his “steering muscles.” A by-pass system allows the motor to be steered manually if the power steering system should fail.

I was a little disappointed when Reilley pulled up at the dock in a Lund 2010 with a 115-hp OptiMax on the transom – I was hoping to experience Big Tiller with a really big motor, like a 225 – but I got a good demonstration with this rig. The power assist is essentially invisible, which is just how it should be. Trimmed out at full throttle, I could steer the motor with fingertip pressure on the tiller. Around the dock, it was easy to swing this compact triple from lock-to-lock. One clever detail is a collar between the throttle grip and the tiller arm that can be turned to adjust the pressure required to activate the power-assist valves. On a rough day, for example, you’d want to dial up more pressure avoid inadvertent steering input as the boat is banging through rollers. For trolling, you might set the collar for minimal pressure.

There’s a lot more to the Big Tiller than power steering. It’s been about 25 years since Mercury redesigned it’s tiller handle for larger motors, and it took this opportunity to incorporate a number of updates that frankly help it keep pace with the tillers offered by Yamaha and Suzuki. A spring-loaded pin at the base of the tiller can be used to lock it in place in one of three positions’ fully up for storage or in two angled positions for operation while the driver is standing. The trim switch is located on the end of the throttle grip, right under the operator’s thumb. A Troll Control toggle on the tiller arm allows the operator to fine-tune trolling speed in 10-rpm increments from idle to 1000 rpm. The shift handle has been moved close to the forward end of the tiller, has a new ergonomic grip, and operates through premium cables rather a rigid linkage.

Mercury Marine project manager Mike Reilley (red jacket) with the author and a validation prototype version of the Big Tiller before a test-drive in Wisconsin. This tiller was rigged to an Optimax 115 wearing a Mariner cowl that just happened to be handy at the test center shop. The Mariner brand is not coming back to the United States market.

Mercury Marine project manager Mike Reilley (red jacket) with the author and a validation prototype version of the Big Tiller before a test-drive in Wisconsin. This tiller was rigged to an Optimax 115 wearing a Mariner cowl that just happened to be handy at the test center shop. The Mariner brand is not coming back to the United States market.

The Big Tiller will also be offered in a DTS (Digital Throttle and Shift) version for Mercury motors with that feature, which replaces the shift and throttle cables with drive-by-wire. Finally, the full rotation of the throttle grip has been reduced from 180 degrees to 105 degrees, so most operators will be able to twist to full throttle in one movement, but still have good control at low speeds. An optional amber courtesy light located on the bottom of the tiller illuminates the area around the motor.

When it reaches Mercury dealers in February or March, three versions of the Big Tiller will be available. One has all the tiller features except power steering, and will fit 75-to-115-hp Four Stroke models. A Big Tiller with power steering and optional DTS will fit Optimax models from 75 hp to 250 hp (1.5-liter, 2.5-liter and 3.0-liter), while another with DTS will fit the four-cylinder Verado four-stroke models from 135 to 200 hp. Mercury will officially recommend installation on current motor models only, but the Big Tiller will certainly back-fit to previous model series. Final pricing has not been determined, but Reilley estimates that the Big Tiller with power steering will cost between $2,500 and $3,000, while the manual-steer Big Tiller will cost about $850. Not cheap, but Big Tiller will put V-6 power safely in the tiller hand of boaters who have been in do-it-yourself mode for too many years.


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Charles Plueddeman

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Charles Plueddeman is Boats.com's outboard, trailer, and PWC expert. He is a former editor at Boating Magazine and contributor to many national publications since 1986.

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