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BOAT SENSE: WHAT YOU SHOULD KNOW ABOUT REPOWERING

In The Fisherman's August installment of our monthly Boat Sense feature, Capt. John Raguso looks at the benefits of repowering with some of the latest technological advancements from the world of outboard engines.
By Capt. John N. Raguso

You love your boat. It has taken years to get it outfitted and made as fishing efficient as possible, but your outboards are getting long on hours and you need to know those engines will get you home from the blue water trouble free.

Repowering provides the comfort that having new engines on the transom provides, but it is also an opportunity to take advantage of the latest technology and the benefits provided by that technology. I have repowered over a dozen boats throughout the years, so I speak from firsthand experience regarding the real world challenges and costs. There were both painful and pleasurable lessons that I learned and I share them with you in this month’s Boat Sense feature.

FOUR-STROKE VS TWO
The latest boating industry stats that I reviewed at last year’s Ft. Lauderdale Boat show indicated that for new boat sales, four-stroke outboards continue to dominate the scene, with over 90 percent of new boats sold having four-strokes hitched to their transom. This trend started gaining momentum back in 2002 with the introduction of Yamaha’s first big-block V6 F225 four-stroke and was accelerated by the 2004 introduction of E-10 gasoline and has been continuing its forward march ever since.

As next-gen four-strokes have become lighter, less complex and more reliable, more coastal, river and lake boaters are becoming increasingly at ease with 100-hour oil changes (equivalent to changing their car’s oil every 3,000 to 5,000 miles) replacing the requirement to add two-stroke engine oil to their fuel or oil injection tank. But two-strokes have advantages as well, the biggest being their power to weight ratio. BRP’s Evinrude is all in with this bet, with 100 percent of its outboard manufacturing efforts dedicated to E-TEC and E-TEC G2 production. Mercury Marine continues to offer its OptiMax two-strokes and Tohatsu/Nissan still produces a number of small and midrange two-strokes that employ a similar direct injection operating system to Merc’s Orbital technology.

I ran Merc OptiMax 200 V6s for five seasons (repowering each year) on my old Phoenix 27 charter boat, and they actually achieved better range and fuel economy than the three sets of Suzuki DF225 four-strokes that followed the Mercs. They were faster overall, faster at slower RPMs and the direct injection outboards popped that boat up on plane with a full load faster than any four-stroke. Plus they were 100 pounds lighter each and kept my aft scuppers out of the water, a critical safety requirement. Looking forward, there are a lot of next-gen four-strokes that I would like to own and run, but I’m not shunning two-strokes either. I am keeping my mind and options open. When comparing one operating system to the other, you need to look at all of the facts and then make the right decision that is best for your situation.

The first generation of four-strokes all had one thing in common - they were heavy. When you add all of those extra four-stroke parts like an oil sump, valve train, etc., the engines definitely increased in both mass and weight. For example, the original Honda in-line 6 cylinder BF115 weighed in excess of 500 pounds and the Yamaha F200/F225 V6 four-strokes were over 600 pounds. Compare that to a Merc 225 OptiMax of that era that pushed the scales at about 510 pounds. Four-strokes will save you the cost of two-stroke outboard oil, but they do require additional maintenance, like oil and filter changes every 100 hours of use, and some require periodic valve adjustments, which are two expenses that don’t impact two-stroke owners.

Four-strokes that dead-head half of their cylinders with every turn of the crankshaft need more cylinder mass to compete with the peppier propshaft sea horses generated by two-stroke powerplants that are firing all of their cylinders with every rotation of the crank. This added displacement also contributes additional mass, driving the weight factor of a four-stroke even higher compared to the two-stroke option. If you are repowering a post 2002 boat, going with a four-stroke repower is a nobrainer.

When considering a new outboard for a pre-2002 vessel, there is a concern regarding which solution will work best, since these boats weren’t designed with the requisite buoyancy aft that is needed to keep cockpit and engine well scuppers above the waterline with the added weight on the transom. However, some of the latest next-gen four-strokes are solving the weight loss challenge nicely and might be a perfect fit for your pre-2002 legacy hull.


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