Power & Motor Yacht

Power & Technology

Super clean and efficient, common-rail diesels look to shake things up in a demanding, white-hot outboard market.

- By Jeff Moser

Two outfits from across the pond enter the white-hot outboard market with efficient, torquey diesels.

Demand for high-horsepower outboards has never been greater. And the latest-gen motors have answered the bell: They’re more powerful, reliable, environmen­tally friendly and won’t work as hard to keep a faster cruise speed.

They’ll get you there quicker, but that increase in horsepower means you’ll burn more fuel. Could a diesel outboard be an efficient power option? A few companies from across the pond are betting on it.

Recently, I got on board a 21-foot Highfield 660 RIB with a 150-hp OXE diesel outboard on its transom, the first oil-burning outboard to meet EPA Tier 3 emissions standards in the U.S. OXE’s parent company, the Sweden-based Cimco Marine claims it’s 55 percent more fuel efficient than a 150-hp gas outboard—an eye-opening statement.

The first thing I noticed was the size. The cowling is wider than a comparably powered outboard because the diesel is mounted horizontal­ly, not vertically. Also unlike gas outboards, it utilizes a belt-drive system reportedly more durable than bevel gears and allows for the diesel’s increased torque to be transferre­d more efficientl­y to the prop.

I ran some numbers and came away impressed. The 2.0L turbo is definitely torquey. I had Chris Ponnwitz, marketing specialist for OXE distributo­r Mack Boring firewall the throttles and the RIB was on plane in less than five seconds on its way to 32 knots in 15. It’s also stingy on fuel: At an optimum cruise of 3250 rpm, the boat ran at 24 knots and burned a minuscule 5.9 gph, good for a 294-mile range.

Don’t expect a clamorous powerplant, either. I measured 73 decibels at the helm and 78 at the transom at idle. (The wind and water obviated a true reading at higher speeds, as the RIB is an open boat.)

OXE has big plans for its outboards. The 150- and 200-hp models are here and there are plans to fill out its offerings with models from 125- to 300-hp.

Like OXE, England’s Cox Powertrain began the developmen­t of its diesel outboard with the NATO Single-Fuel Directive in mind: The idea is to have one source of fuel for all types of water- and land-based craft. While the concept is aimed primarily at the military sector, it’s a potential gain for superyacht tenders and other accompanyi­ng vessels to match the fuel of the mother ship.

Cox premiered its pre-production (full EPA certificat­ion is imminent, and production is slated for mid-2019) twin-turbo, 300-hp model at last year’s Ft. Lauderdale Internatio­nal Boat Show with a twin setup on a 34-foot Intrepid. Like OXE, the claims are impressive: 25 percent better range and 100 percent higher torque versus its 300-hp gas counterpar­t.

There are a few caveats: weight and price. The OXE outboard tips the scales at 770 pounds and will sell for about $46,000; that’s an average of 300 pounds heavier and about three times the cost of a gas outboard. The average weight for a 300-hp gas outboard is 551 pounds and Cox’s V8 is 826 pounds; at $50,000, it’s roughly double the price.

A diesel outboard could potentiall­y recoup these costs over the engine’s lifespan: Both claim their engines have a longer run life than their gas competitor­s based on the superior durability of diesels. And service intervals are further apart. One thing is certain—you’ll burn less fuel.

Time will tell if a diesel outboard can take market share from the traditiona­l outboard sector. I suspect the engines can have a big impact with outfits like the Coast Guard, in commercial applicatio­ns or for recreation­al boaters who run the heck out of their boats. Weekend warriors will never make up the cost.

We plan on running the diesel outboards head-to-head with their gasoline counterpar­ts to get some real comparison­s on fuel burn, cruise, top speed and other stats. Look for the results in an upcoming issue or in our sister publicatio­n Outboard magazine ( outboardma­g.com).

 ??  ?? Both the OXE (shown) and Cox diesel outboards can be matched to single-lever and joystick control.
Both the OXE (shown) and Cox diesel outboards can be matched to single-lever and joystick control.
 ??  ??

Newspapers in English

Newspapers from United States