Tips for Repowering a Boat

What to know whilst thinking about repowering your boat with a brand new outboard. 

nowadays’s four-stroke outboards are more reliable than ever earlier than with fly-by-wire controls and onboard sensors that maximize overall performance and performance. however, as my Roman forebears used to say, caveat emptor: The four-stroke solution isn't always the singular magical repair best for repowering all boats. What boats are we speaking approximately? What are the challenges? What ought to you do before repowering? here’s the scoop. 2 stroke vs 4 stroke

the first technology of 4-strokes all had one factor in commonplace: They were heavy. whilst you introduced all of these more 4-stroke components, like an oil sump, valve teach, etc., the engines clearly extended both their mass and weight. as an example, the Yamaha F200 and F225 4-strokes weighed more than six hundred pounds. A two hundred horsepower -stroke engine of that technology may have weighed 425 pounds. assume nowadays’s first-rate two hundred-hp outboard automobiles to have some weight, specially four-stroke models.

After 2014, just about any maker's 200-hp outboard V6 engine expenses upward of $20,000 set up, relying in your gauge bundle, controls, set up, and many others. even though it doesn't burn high-priced -stroke outboard oil, it does require additional maintenance, like oil changes each a hundred hours of use and valve adjustments at each three hundred to four hundred hours, charges that do not effect two-stroke owners. Plus, 4-strokes that deadhead half in their cylinders with each turn of the crankshaft want extra cylinder mass to compete with the prop-shaft sea horses generated by -stroke strength flora that are firing all in their cylinders with each rotation of the crank.

in case you are repowering a newer boat, going with a 4-stroke repower might be not anything to worry approximately. however when considering a new outboard for a pre-2002 vessel, there may be a challenge regarding which solution will work first-class, in view that these boats likely were not designed with the considered necessary buoyancy aft that is had to hold cockpit scuppers above the waterline with introduced weight on the transom.

recommendations for Repowering Older Boats

1. lack of capacity to self-bail

2. feasible swamping with open transoms

3. Porpoising

four. gradual planing

five. negative visibility forward

when you have to stay with a two-stroke due to both weight or mass, Evinrude E-TEC and Mercury OptiMax -stroke direct-injection V-6s need to do the task. certain, you’ll have to buy some -stroke oil in bulk, which provides to the value-in step with-mile of boat operation, but you’ll in no way must do an oil trade, change an oil clear out or alter valves, all of which add to annual operating charges.

additionally, 4-strokes are dropping weight, which must help while repowering an older legacy boat. Yamaha has an in-line 2.eight-liter F200 that suggestions the scales at a svelte 487 kilos, which is certainly lighter than a two-stroke three.0-liter V-6 OptiMax. no longer to be outdone by way of the opposition, Merc has its personal four-stroke one hundred fifty hp — an in-line-4 with a 3.zero-liter block that has room to grow. It guidelines the scale at 465 pounds. The valves on this Merc 150 in no way want adjustment, in order to decrease running costs. An outboard motor weight evaluation is a ought to-do while thinking about engines to repower your boat. 

if you need to focus on outboards inside the 225 hp to 300 hp range, there are lots of outboard motor repower alternatives. Yamaha’s Offshore series (225, 250, 300 hp) provides the power and torque of a 4.2-liter V-6 block however lowers the general weight of these triplets to an high-quality 562 pounds. This mechanical miracle turned into carried out via taking away the six-percent of metallic-cylinder liners, which opened up the bore quantity, which changed into then plasma-infused to provide a superslick floor to reduce piston-ring friction.

hopefully a number of the classes i have shared approximately repowering older boats will assist you whilst it's time to repower yours. to peer a chart of horsepower and transom weights of outboard repowering options.

problems with adding Weight to the Boat Transom

To get some science at the challenge, I contacted reputable top-tier developers and a naval architect to get their spin at the demanding situations of repowering “legacy” boats that were constructed prior to 2002.

David Neese, vice chairman of engineering, Grady-White Boats, Greenville, North Carolina

"returned in early 2001, via fortunate planning, a redesign of our SeaV2 hulls coincided with the advent of the Yamaha F225 outboards in 2002, and the more recent Gradys had no trouble helping the load and torque of the 4-stroke electricity flowers,” he stated. “when repowering older pre-2001 Grady-White boats, lots of our bracket designs and conventional transoms will efficiently support the more recent four-strokes, but it depends on the utility.” further to the deadrise and chine width of the boat to be repowered, the burden and length of the boat have to also be taken into consideration. often the added weight on a bigger boat will not make a massive difference if the boat was nicely designed from the start. adding two hundred kilos to an 8,000-pound boat adds 2.5 percentage of the overall boat weight, while including the identical 2 hundred pounds to a 15,000-pound boat adds only 1.3 percentage.

“From a structural perspective, sound construction is sound production irrespective of the materials used,” Neese stated. “A nicely-constructed boat can be somewhat overbuilt structurally, but whilst you are talking about older boats, you attain a point where the new engines can dish out greater than the vintage hulls with some miles beneath their transoms can take.”

Joan Maxwell, President, Regulator Marine, Edenton, North Carolina

“the first factor that a purchaser must do prior to repowering a boat is to touch the manufacturer of the boat and offer the boat’s HIN [hull identification number]. There simply isn’t a short answer on whether every version in the line or even every boat built of a selected version may be correctly repowered with more recent four-stroke engines,” Maxwell defined.

“We at Regulator Marine have constructed boats that have been powered by means of each transom- and bracket-set up outboard engines. The bracket could guide the weight of the present engines, but then the game-converting 225 4-strokes got here along and we needed to absolutely redesign the bracket.

“customers have to name and ask us earlier than simply going out and slapping a brand new pair of engines on their boat,” she stated. The Yamaha F350 V-8, for instance, has a whole lot of low-give up torque. however, the engine couldn't properly be positioned on an older Regulator 23 or 24, even though the boat might also have been rated for the horsepower, because the transom clearly became now not constructed for that kind of weight and torque. “because the 4-stroke engines have gotten large and ‘torquier,’ our transom laminate structures were redesigned to guide the trade in these engines,” Maxwell said.

Lou Codega, Naval architect, engineer, fashion designer for manufacturing and custom boatbuilders

“once I layout a hull, I select a area for the middle of gravity forward of the transom early on and set up the indoors of the boat accordingly. This middle offers me the nice mixture of fuel performance at cruise pace and the highest top speed, thinking about how the boat could be used. second, dealing with problems can arise if the center strays too a ways from the sweet spot. Too some distance aft ends in porpoising; too a long way forward can purpose bow steerage, a wet journey and serious instabilities.

“None of this bodes properly for repowering with engines which can be drastically special in weight or horsepower. Weight introduced up to now aft within the boat makes a substantial change to the unique center of gravity. To make topics worse, the exchange in weight and horsepower shows a new middle of gravity to better fit the repowered boat.

“when I’ve redesigned a boat for specific strength, I’ve found that different adjustments are always wished. those can be as minor as a change to the bracket flotation, or a main redistribution of weights. obviously, this complicates the task a ways past truly swapping engines, controls and fuel fittings. it's miles a long way simpler to pick an engine package that closely suits the electricity and weight at first mounted.”

should You Repower with a single Outboard Engine rather than two Smaller Outboards?

Have big, notable powerful new outboards changed the repower sport with the aid of permitting multi engine boats to be propelled by means of simply one engine? it's a principle it really is thrown round here, our Editor-in-chief opines on the viability of that theory.

Outboards like the 557 hp Seven Marine 557 and the 350 hp Mercury Verado and Yamaha F350 can provide another repowering choice for older boats, the ones designed and built before about 2002. this is in particular true if the boat in question turned into at the beginning powered by more than one outboard engines.

as an example, in case your boat is rated for 2 outboards and four hundred hp, you would possibly keep in mind installing a unmarried 350 hp outboard. Doing so would net you relatively much less horsepower than the authentic dual set up. however with best one gear case growing drag in the water, compared to two gear cases creating drag, similar velocity and overall performance could likely be attained. moreover, the rate and complexity of the set up for one massive unmarried engine can price less than those for more than one engines, in view that fewer gauges, wiring harnesses and propellers are required, and controls and steering equipment are easier. keep in mind the price to install one outboard motor or  engines.

So why doesn’t absolutely everyone do that? There are several motives, and the first is that these monstrously powered outboards supply significant quantities of torque, in all likelihood more than your older boat’s transom can handle. moreover, unlike with more than one engine installations, all the energy and torque transmitted to the boat is concentrated at one spot on the transom as opposed to unfold across more than one places at the transom.

also, don't forget the value protection worries are some other motive why swapping out  or more decrease-powered outboards for a large single engine isn’t common. As honest as outboard motors have grow to be — they'll now rank as the most reliable propulsion type in the history of marine delivery — boaters who cruise a ways from shore nevertheless rely on the redundant safety of multiple engines: must one breakdown, the other(s) can get you home.

Then there's dockside maneuverability. even as outboards do now not respond like inboards — due in element to torque, propeller length and a pivot factor farther aft — a multi-engine boat handles close quarters better than a single-engine boat. multiple engines also allow boaters to avail themselves of the convenience of the joystick control systems now available for outboards. Swapping a couple of engines for one huge engine is a tremendous concept. but now not every boat is up to the challenge.2 stroke vs 4 stroke