Digital, Fuel-Efficient Outboards for Your Boat - Power & Motoryacht
If your old outboards are sputtering, it may just be time to upgrade.
Evinrude Outboard engines

A new pair of outboards can help improve your boat’s performance and style.

Time for a New Outboard?

Is your Bush-era eggbeater sounding a bit wheezy? Maybe it’s time to upgrade to a new digital, fuel-efficient model. Your boat will thank you.

I’ve always been an outboard guy. My earliest memory is being tossed aft in my dad’s Penn Yan runabout when he hit the throttle, ending up face-planted against the sun-warmed red gas tank. My mom hauled me back onto the midships seat, while dad never eased back on the steam by a single rpm. (Not that he knew the rpm. Outboards in those days didn’t have tachs; you adjusted the gas by ear and by feel.) I must have been about 2 years old, but my affection for motors hanging off the transom was already growing.

And what’s better than the smell of exhaust erupting from an old two-stroke on a brisk autumn morning? Makes me think of going with my grandfather to tend his fish traps, an adventure that always started right about sunrise. If somebody bottled the aroma, I’d wear it as cologne. Boating kids today probably don’t know that smell, since new outboards, both two-stroke and four, run cleaner, leave no oily sheen on the water, burn less fuel, hardly ever break down, respond to zero-effort digital controls, can steer independently of each other if fitted with a joystick, and generally make excellent shipmates. While old outboards carry the scent of romance, new ones are a heck of a lot better; if your motors are showing their age, maybe it’s time to pry open the treasure chest and replace them.

Two-stroke guys like me are not the only ones proselytizing for outboards these days. Dyed-in-the-wool sterndrive builders like Formula and Regal have introduced outboard-powered express cruisers and crossovers. Formula’s 430 Super Sport Crossover carries four—count ’em, four—joysticked Mercury Verado four-stroke outboards, from 300- to 400-horsepower apiece. (The 400s add $62,630 to the 430 SSC’s $1.1 million base price with 300s. I’m not suggesting big outboards come cheap.) Sea Ray is building several models in both a sterndrive and an outboard configuration, and just added a triple-outboard version of its SLX 400 crossover. MJM, a builder of efficient express cruisers powers its 35z with twin 300-horsepower Mercury Verados. Even Azimut has an outboard dayboat, the Verve 40 with three 350-horsepower motors. Flip through the ads in this magazine and others and you’ll find more examples. It’s truly the Age of the Outboard.

The Azimut 40 Verve’s use of outboards has contributed to its popularity.

The Azimut 40 Verve’s use of outboards has contributed to its popularity.

The End of the Stern Drive?

In 2018, Mercury—and Evinrude, Yamaha, Honda, Suzuki, etc.—outboards are cutting deeply into the popularity of stern drives, and even inboards. Here’s why: Outboards have major advantages: They are lighter, so outboard boats are faster, horsepower-to-horsepower, than inboards and sterndrives. They demand little maintenance, especially two-strokes—no oil to change, no valves to adjust. They are more accessible than inboards and therefore easier to service. They are trimmable, making fine-tuning of running angle, both positive and negative, possible. They are often quieter than inboards. Mounting the engines outside the boat makes for more room inside for stowage or accommodations. And some manufacturers provide custom colors to match the boat’s graphics; check out Evinrude’s options.

Full disclosure: There are downsides to outboards. Watersports enthusiasts prefer the wake patterns thrown by inboard-powered ski and wakeboarding boats, and having the propeller hidden under the hull is a big plus from the safety aspect. Swimmers, divers, water skiers, and their ilk prefer an unobstructed swim platform, not one blocked by two or three outboards. Some outboard-powered express cruisers and crossovers get around this with drop-down “swim patios” on the sides of the hull; check the Sea Ray SLX 400 to see one.

Most outboards are raw-water cooled, which means they require conscientious flushing of the motor after every use to combat corrosion. Not an onerous task, but if it puts you off, consider ponying up for a Seven Marine outboard with closed-loop cooling, just like a freshwater-cooled inboard. Only thing is, the smallest Seven Marine model is a 557-horsepower behemoth, and costs around $80,000. I’ll stick to flushing my raw-water-cooled OBs.

And some folks just don’t like gasoline. There are a couple of diesel outboards: Oxe, a Swedish company, builds a 200-horsepower diesel, but it weighs 770 pounds, almost 300 pounds more than Yamaha’s inline-4-cylinder 200-horsepower four-stroke. One advantage to outboards is light weight, and the Oxe negates that. Yanmar distributes a 50-horsepower diesel outboard, the Dtorque 111. It’s built by Neander Motors, and is targeted at small workboats and tenders for larger yachts, doing away with the need to carry gasoline onboard, a plus for the megayacht crowd. Yanmar compares the real-world performance of the Dtorque 111 to a 70-horsepower gasoline outboard, but burning about half as much fuel at wide-open. The Dtorque 111 weighs 385 pounds, not much more than a 75-horsepower Yamaha F75 four-stroke (353 pounds.). Yanmar predicts a service life of 10,000 hours for the Dtorque; most of us will want a new boat long before that. But then again, diesel is an option.

Repowering: Nuts and Bolts

Repowering with outboards is easier than replacing inboards, but still has its issues. First, and most important to many people, it’s expensive: Replacing a pair of 250- or 300-horsepower motors can set you back 50 grand or more, especially if you need new digital controls and steering. A joystick will add another $20,000 or so. Crunch the numbers and you might find that buying a new, joystick-equipped boat with new motors and new everything else is the smarter course.

If you decide to repower, stick with the same number of motors and simply add horsepower to each one if you want more power, up to the boat’s maximum rated horsepower. New 300s will provide a world of improvement vs. tired 250s; actually, new 250s will, too. And while triple 300s would look cooler than the twins you have now, you’ll get almost the same performance with twin 350s: What they give up in horsepower, they get back in less weight and lower drag. If you need max power from twins, invest in a pair of Mercury Verado 400s.

When replacing the motor(s), replace the fuel lines, controls, cables (your new controls probably will be digital now, so you’ll have wires instead of push/pull cables), wiring, batteries and so forth. Inspect your fuel tanks, too. Basically, make everything new.

When the old motors are removed, check the transom for water in the core. Older boats with wooden cores will almost certainly be wet and need repair. Foam-cored transoms can have water in the sandwich, too, and if stored in freezing winters, might have some delamination. Now is the time to bring the transom back to better-than-new condition. (Don’t hang new motors on a soggy transom.)

The Fallacy of Fat Four-Strokes

Check motor weight carefully when repowering, and compare it to the weight of your boat’s original outboards. When four-stroke outboards first became popular, around the turn of the century, the new motors were heavier than the two-strokes they replaced, enough so that some boatbuilders altered the aft sections of their boats to support the heavier motors. Too much weight aft can screw up handling, cockpit draining, running trim, and reserve buoyancy.

But today, four-strokes aren’t always heavier on a horsepower-to-horsepower basis. For example, a 200-horsepower Evinrude V-6 two-stroke outboard from 1995 weighed between 450 and 470 pounds, depending on shaft length. A 200-horsepower Evinrude E-TEC, a modern, fuel-efficient two-stroke from 2017, weighs between 528 and 541 pounds, 70 or 80 pounds more than the older motor. But a 2017 Yamaha F200 four-cylinder four-stroke, a very popular engine with fishing-boat builders, weighs 487 pounds, which is only a bit more than the old ’Rudes. Mercury’s 200-horsepower Verado V-6 200 four-stroke weighs 635 pounds, the two-stroke V-6 Optimax, also 200 horsepower, 505 pounds, and the inline 4 Verado 200, 510 pounds. (Fewer cylinders means fewer pounds.)

Confused? So am I. Different outboards are engineered for different service, so rather than buy solely based on weight, or number of cylinders, or stroke cycle, consult with someone who knows—the head mechanic at your yard, a technician at the shop where you’re buying the motors, or someone at the engine builder. The carpenter adage, “measure twice, cut once” applies here. Balance all the factors to make sure you buy the correct motor.

Outboards have never been as powerful, reliable and fuel-efficient, nor as versatile or as aesthetically interesting, as they are in 2018. I’m sorry I don’t own a boat with a tired outboard motor. If I did, I’d invest in a fuel-smart, digitally managed, joystick-ready outboard, exponentially better than the bangers I grew up with—the ones that, nevertheless, made me an outboard guy. Invest in one, or two, or three (or more) modern outboards, and you might become an outboard guy, too.

Boatyard-Rule

Swap Outboards for Inboards?

What about repowering a stern drive- or inboard-powered boat with OBs? Many folks into rehabbing old boats are doing just that. And if you’re into this kind of project, it’s a good idea: You’ll have the boat stripped out anyway, and re-engineering it for OBs won’t add too much to the overall project. The result should be a faster boat with better fuel economy. The now-empty engine compartment can hold an extra fuel tank for added range.

The transom will need reinforcement to take the thrust of the new OBs, which typically means more fiberglass and a beefed-up, high-density foam core. This requires expert engineering to make it strong enough without going overboard, and skilled fabrication so the whole thing bonds correctly.

A bracket makes it easier to mount the outboards, and will usually improve performance, too. The bracket must be positioned to facilitate mounting the engines at the optimal height, which depends on how far the engine is set back from the transom: The farther back, the higher the engine should be. The correct elevation is determined by the location of the cavitation plate vs. the hull bottom, and should be calculated by someone who knows his/her business. Armstrong is a well-known bracket builder with a long track record, and an Internet search will bring up many others: D & D Marine is one; its website has lots of information on measuring and positioning a bracket, dealing with deadrise, and so forth. It’s worth studying no matter where you buy the bracket.

What results can you expect? In 1980, Bertram built some 28- and 33-foot sportfishermen with Sea Drives instead of the standard twin inboards. Sea Drives were essentially outboards with proprietary brackets—a little more complex than that, but not much. They were designed for offshore use, with a remote air intake mounted inside the boat so it wouldn’t pick up water when backing down in rough water. (Outboards of the day had their air intakes under the cowl, on the forward side of the powerhead.) The Sea Drive Bertrams outperformed inboard models with similar horsepower, adding more than 30 percent to the top speed of the 28, increasing it to 39.4 knots, and with better fuel economy.

Bertram built about a dozen boats with Sea Drives, but the motors weren’t the most reliable products on the water, and despite their advantages they never took hold as power options. Some Sea Drive Bertrams were later converted with outboards on brackets; a 28 usually gets twin 200s or 225s, and the boat typically performs fine with that power.

If you’re thinking of rehabilitating an older boat, or rejuvenating one, moving the engines outside could be worth a look.

Boatyard-Rule

Evinrude Didn’t Invent the Outboard

Ole Evinrude is the man most associated with the earliest outboard motors. But Evinrude didn’t invent the outboard—he just made it famous. Before the turn of the 20th century, both electric- and gasoline-powered outboards had been built in small numbers. Gustave Trouvé, a French electrical engineer, built an electric outboard in 1881, carrying out “sea trials” on the Seine; apparently, he built only one motor before moving on to other inventions, including the battery-powered headlamp and an electric horn, which he also mounted on a boat. American Motors Company sold a handful of gas outboard motors in the late 1890s, and in 1905, Cameron Waterman filed a patent application for a Boat-Propelling Device, marketed as the Porto-Motor.

But it was Evinrude who clamped outboards onto the transoms of thousands, and by now millions, of boats. He built his first one in 1907, a 3-horse, one-cylinder model that was patented in 1911. By 1912, Evinrude had 300 workers building outboards, including Arthur Davidson, who, with his friend William S. Harley, also built motorcycles. You might have heard of them. (Wisconsin lore says that Ole Evinrude helped Harley and Davidson develop the 405 cc engine that powered the first Harley-Davidson.) In 1919, Evinrude built a lighter, more efficient two-cylinder motor, made partly of aluminum, the Evinrude Light Twin Outboard. By then, one of his competitors was the Johnson Brothers Motor Company. In 1935, after a series of mergers and acquisitions, Outboard Marine Corporation owned both Evinrude and Johnson, along with Briggs & Stratton. (Stephen Briggs started OMC in 1929 as the Outboard Motor Company.) When I was a kid, the only outboards worth consideration in the Smith household were Evinrude and Johnson.

But how about Mercury outboards? When Evinrude built his first outboard, Carl Kiekhaefer was about 1 year old. In 1927, Kiekhaefer worked for Evinrude as a draftsman for a short time; he got fired and kicked around for a while, earning some of the more than 200 patents he held during his life. Then, in 1939, he bought a struggling outboard-motor builder in Cedarburg, Wisconsin. There were 300 defective motors in stock; Kiekhaefer got them working, sold them to Montgomery Ward and Mercury Marine was born. The following year Mercury took orders for 16,000 motors at the New York Boat Show. The company has been a leading innovator in marine propulsion ever since—it built the first V-6 outboard, the 60-horsepower Mark 75, in 1957, and the first 100-horsepower outboard in 1962 (it was painted Phantom Black). I thought it was about the coolest thing I’d ever seen—100 horsepower! But I couldn’t convince Dad; he had Evinrude in his blood, so I had to admire that big Merc from afar.

This article originally appeared in the January 2018 issue of Power & Motoryacht magazine.

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