Outboard Advantages

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Outboard-powered bowriders are making a comeback, and the reason is colored green. As in the shade identified with both eco-friendliness...and money.

Once nearly extinct in the entry-level bowrider market, outboards find themselves back in demand, thanks to stricter emissions laws that necessitate stern-drive engines be fitted with fuel injection and exhaust catalysts in order to make the cleanliness grade. This tightening of the emissions belt, and the subsequent price bump that comes with it, means the low-horsepower stern-drive engine is about to be a thing of the past — and that good ol’ outboard is looking more and more attractive by the minute.

Ever wonder what the differences are between a boat equipped with an engine that resides below the sun pad and one equipped with power that hangs on the transom? we did, so we decided to hit the water with a pair of nearly identical Ebbtide 188s — one sporting an outboard, the other a stern-drive.

Here’s how they compared.

Performance Breakdown
For the purposes of Boating’s test, one of the 188s sported a 115 hp Evinrude E-TEC outboard, the other a 190 hp MerCruiser 4.3-liter stern-drive. Obviously, that’s not an apples-to-apples comparison, but it’s the reality of today’s market.

The aforementioned emissions laws have pretty much done away with the availability of the once-popular 135 hp 3.0-liter stern-drive. While the days of the carbureted 4.3 may also be numbered, there are simply more of them in inventory, ensuring their availability in the near future.

Despite what seemed like an obvious disadvantage on paper, the outboard proved a worthy competitor, part of which can be attributed to its significantly better power-to-weight ratio. Coupled with an Alpha drive, the MerCruiser 4.3 tips the scales at 865 pounds; by comparison, the Evinrude 115 weighs only 390.

Coming onto plane, the outboard came up and over the hump in 3.6 seconds, the stern-drive in 4.8. While the stern-drive’s greater torque likely helped it post the better time to 30 mph (seven seconds), the outboard still kept things close, hitting the mark less than one second later. The stern-drive’s added horsepower truly resulted in a clear advantage only at top speed. The 115 hp outboard peaked at 43 mph, while the 190 hp stern-drive continued on to finish just a fraction shy of 48 mph (47.9).

Torque is worth considering when you compare the two forms of power. It’s directly proportional to engine displacement, meaning the 4.3-liter stern-drive has a decided advantage. Torque has practical benefits, like allowing the boat to stay on plane at lower speeds or muscling a skier out of the water in a deepwater start.

Outboards are presumed to be more fuel-efficient at low speeds and stern-drives more efficient on the top end. Our test proved half that statement. Looking at the fuel-flow data of our two test boats (as well as results of several additional tests with similar engines), the outboard burned 30 percent less fuel at 5 mph. A big percentage, but a small difference in actual fuel burned. If you idle often, it results in savings. At 31 mph, the outboard consumed 7 gph, while the stern-drive burned 7.6 gph at 32 mph — nearly a dead heat. At its peak 43 mph, the outboard burned 11.1 gph for 3.79 mpg compared with the 48 mph, 2.77 mpg stern-drive’s 17 gph.