The Outboard Expert: Yamaha Gets Tough with Its F15C and F20 Outboards
Stout 15- and 20-hp Yamaha four-stroke outboards are built to take punishment.
January 30, 2007
The new Yamaha models replace the 323cc F15 and the 498cc F25, which have been discontinued.
Yamaha introduces some new features and fills an odd slot in its portable outboard line with an all-new 362cc twin-cylinder four-stroke motor offered as a 15-hp F15C and a 20-hp F20.
Most builders use the same powerhead for both a 9.9-hp and a 15-hp model, and then skip up to a larger powerhead for a 25 or 30 hp rating. Honda is the only other builder to offer a 20-hp model, a rating that's larger than most freshwater anglers will typically use for a trolling kicker, but perhaps smaller than most would use as primary power on a compact fishing boat. Yamaha (www.yamaha-motor.com) figures the F20 will see duty mostly on tenders, inflatables and sailboats, but I think the news here is that Yamaha now offers a very robust 15-hp four-stroke.
Bigger and Better
The new Yamaha models replace the 323cc F15 and the 498cc F25, which have been discontinued. From the F20, Yamaha skips all the way up to its 40-hp F40 model. The old 323cc engine stays in production as the F9.9. This gives Yamaha a bit of a performance advantage over other 15-hp models on the market, which typically use the same powerhead for a 9.9 and a 15. The Mercury 15 Four Stroke displaces 323cc, while the Suzuki 15 displaces just 303cc. The Yamaha powerhead is even larger than the 350cc Honda BF20. More displacement generally produces better bottom-end power and stronger acceleration. If you are looking for a stout motor for a small pontoon boat, for example, or a work skiff that's often heavily loaded, the new Yamaha might be just the ticket.
At its lightest dry weight spec of 113 pounds (15-inch shaft and manual start) the F15C/F20 is a little heavier than other motors in this class. The Honda BF20 is the lightest at 101 pounds. Like all the other motors available at 20 hp or less, the Yamaha is also carbureted, and I'm guessing that the 25-hp price point is the minimum we can expect to see fuel injection on a portable motor. Mercury put EFI on its new 25/30 Four Stroke, but there may not be enough margin in a smaller motor to make EFI an affordable alternative to a carb.
Yamaha has done its best to make the new motor an easy-starter, with an automatic decompression feature and a light-load manual starter with minimal end-play that makes the most of every pull. A new, larger handle is also easy to grip. Yamaha also fits these motors with its Prime Start feature (also used in the past on some Mercury motors built as a joint venture with Yamaha), an automatic enrichment circuit that replaces a choke. Prime Start delivers a richer mixture on cold starts and then gradually leans itself out as the motor warms up.
To protect the engine from our suspect navigational skills, Yamaha has designed a new feature called the "waist driveshaft." The new Yamaha shaft is machined down to a smaller diameter in its middle section (the "waist") so it can temporarily twist — but not break — if the propeller makes a hard impact with the bottom. This isolates the expensive crankshaft and gears from this shock, and acts as a second layer of protection beyond the rubber hub of the propeller.
These new motors have two "function over form" features that make them user-friendly. The first is a large, external latch on the back of the cowl that's simply less fussy to use than an internal latch, especially if you are on the water and need to reach over the transom to remove the cowl. I also like the flush fitting, which is attached to a hose on the starboard side of the motor, so you can reach it easily from any direction, in any situation.
If you use this motor to charge an accessory or starting battery, you'll appreciate a new alternator that makes 6.5 amps at just 1000 rpm, and its peak 10 amps at 3000 rpm even with manual starting. Other manual-start motors in this class make about 6 amps. With electric starting, the Honda BF20 peaks at 12 amps, while the Mercury 15 Four Stroke peaks at 10 amps. A new Yamaha tiller handle incorporates the stop switch and kill-switch lanyard, and places a gear-shift paddle on the front of the motor, easy to reach but not as convenient as the shifting twist-grip feature used on Mercury motors in this class.
Both the Yamaha F15C and the F20 are offered with 15- or 20-inch shafts, in manual or electric start, with remote or tiller steering, and manual tilt or power trim. Pricing for the F15C starts at $3,030, and the F20 starts at $3,410, with a standard three-year warranty.
Editor's Note: Charlie Plueddeman is the editor at large for Boating, the nation's largest boating magazine.
