Revisiting Repower: Putting New Life In Your Ride

There are myriad reasons for repowering this season.

Depending on the age of your existing outboard power, it may be dead, dying, or just past its prime. Maybe you are having occasional hiccups where it doesn’t want to start or the engine tilt/trim is cranky and unreliable. If you like your boat and want to keep it, swapping out engines might be the simplest and most economical way to rekindle the relationship. If your current engine is still working and serviceable, it will have some value either in the aftermarket or as a dealer trade-in for the new powerplant.

Perhaps you’re still running an older two-stroke outboard that needs a separate tank of expensive two-stroke oil for daily operations. With none of the major outboard manufacturers offering two-strokes in their 2025 lineups and new outboard sales being 99% four-stroke gasoline powered (with the remaining being propane and diesel), it might be time to make the move. This is especially true as marina mechanics start to focus more on four-stroke repairs and the knowledge base for fixing two-strokes gets lost in the historical fog. Spare parts for two-strokes will become harder to find and more expensive when you do, so the reason to switch now becomes even more compelling.

There’s also a pretty significant paradigm shift. When I initially repowered my 2006 EdgeWater/Yamaha F225 V6 four-stroke combo in 2020, I went from a mechanical throttle and shift control to a full fly-by-wire Mercury 250 V8 four-stroke DTS (digital throttle and shift) model. This meant I needed to add a NEMA2000 backbone to interconnect all of my engine info, new digital instrumentation and existing suite of multi-function display (MFD) based electronics. The controls needed to be upgraded to the new fly-by-wire type, along with other junction boxes and electronic panels to allow everything to be plugged into a central hub. This added a significant parts cost and dealer installation time to the bottom line of this adventure, so be sure to factor this into your calculations when going down this road. But the results were worth it with super-smooth operation and performance.

In addition to overall performance, modern, fuel-injected four-strokes get better fuel economy than their historical counterpart two-stroke outboards. Even if you took an example where a certain boat achieved similar fuel economy between these two technologies, the ace in the hole for four-stroke fans is that they don’t need to add expensive two-stroke oil to the gas and produce a cloud of smoke when idling at dockside. One thing that is requisite for four-stroke operation is a periodic oil and filter change every for every 100 hours of operation or at the end of each season.

Noise, Warranties & Economics

Test after test with dB meters when comparing two-strokes to four-strokes show that the four-bangers are noticeably quieter when idling and operating at typical cruising speeds. There are times when you can actually have normal conversations when underway and have to check your tach to ascertain if your engine is still on at idle speeds.

Consider as well that most four-stroke outboard manufacturers offer a minimum 3- to 5-year warranty on their products. At certain times of the year, they might entice new sales with a “free” extended warranty that can range from 5 to 7 years in length. This past year, I had an option to extend my new Mercury 250 ProXS warranty out to 8 years of factory backed service. This protection is certainly a compelling reason to upgrade to new power and to enjoy hassle-free boating for future seasons. Factory engineers and mechanics who I’ve talked with over the years have also projected a 1,000- to 1,500-hour typical lifespan for two-stroke outboards, versus a longer 2,500-plus hours for a well-maintained four-stroke.

I have adhered to the core belief that most cost-effective way to owning a boat is acquiring the best 5- to 10-year old used boat you can find for the money and then repowering it. This gives the operator a relatively new boat that has been set up and broken in. Equipping it with a new powerplant should provide stress-free boating for the foreseeable future at a fraction of the cost of purchasing a new ride. I haven’t bought a new boat since the mid-90s and have been enjoying “relatively affordable” fishing inshore and offshore for the past 30 years with the many used boats I’ve purchased since then, upgrading each with new powerplants.

I reached out to a trio of repower experts local to me on Long Island to gather some professional tips that will help you think through the process; the following is their sage advice on the subject.

I have had the pleasure to do a total of four repowers with the folks from Albertson Marine located in Southold on Long Island and owner Bill Witzke and his son Dave offered the following tips:

• Make sure to look at the capacity plate on your boat to make sure it can handle the horsepower that you want to put on it.
• The new four-stroke outboards are heavier than the older two-strokes, so be sure that your scuppers will be above the waterline with the new power.
• Make sure the transom is the correct height for the model you are buying; 20 inches requires long shaft, 25 inches means an extra-long shaft, and 30 inches means XXL.
• Verify the transom is in good shape with no rot or cracks. You might have to add a reinforcing plate or transom cap.
• Use the correct sealant on mounting hardware and don’t skimp on the amount.
• The boat’s steering system may need to upgrade. If there is a mechanical system on board may want to consider upgrading to a hydraulic system, it is more money but well worth it.
• Check fuel tank condition for any signs of corrosion. All fuel lines should be replaced. Is the fuel filter housing is it in good shape? Replace if necessary.
• Replace the control cables so there are no concerns with hooking up to the new engine. They might need replacement if the existing parts don’t match the new engine.
• And as for controls, some models offer DTS Digital Throttle and Shift, “Fly by Wire”, which means no more mechanical cables. DTS offers very smooth operation.
• Batteries, some engines require an AGM glass mat battery. Be sure to get a 1000MCA battery. Don’t cheap out on a battery, you’re the one who can have a weekend ruined by not having a quality battery or batteries in your boat.
• Make sure to have the correct gauge wire and battery cables that the manufacturer recommends. Improper size battery cables can damage a starter motor, plus the computers on engines are very voltage sensitive.
• It’s absolutely crucial to the engine/boat performance is that it has the correct propeller to ensure the engine is achieving max recommended rpm.

I purchased my first Grady-White, a 24 Offshore powered by a 200-Merc V6 back in 1984, so I have known and worked with Jim Luttieri at Suffolk Marine for over 40 years. They’ve been selling Regulators for the past 25 years and I spoke to Jim and his head mechanic Arty Troll recently on their best tips for repowering, who offered the following advice:

• Check both the capacity plate for both horsepower and engine weight before moving forward with the process.
• Choose a dealer that you can trust with your repowering project. Reputable, on-the-water dealers can assist you with trying out different sets of props until you find one that works up to expectations and achieves recommended outboard rpms.
• Check the transom for cracks, flex and moisture before swapping out your engines. Some repairs or bracing might be required, especially if going from two-strokes to four-stroke power. Anything major might require an expensive transom replacement.
• Repowering is more than just changing the engines. Depending on brands or generations within the same brand, you may have to add the cost of new gauges, MFDs, wiring, control boxes, cables, dash panels, etc. to the overall project cost.
• On older boats, check the tank for any leaks in addition to the condition of all fuel line hoses, fills and vents.
• Some old boats have their outboards connected to the transom with the requite engine bolts in addition to a “permanent” 5200-type of sealant. This is a labor-intensive pain and frequently causes the underlying fiberglass gelcoat to crack or peel. Life Caulk is the preferred sealant for all repowers.
• Some of the new Yamaha engines like the 150 to 200 2.8L series mechanical engines feature built-in hydraulic cylinders, which mean you won’t need to replace your older external steering cylinder for the repower.
• The newer Yamaha engines with built-in onboard electric steering will require a new helm and harness, adding to the project cost.

I ran into Artie Chiodo of Seaborn Marine in Bay Shore, Long Island at the New York Boat Show this past January and he had a few tips he wanted to share about repowering:

• The most important thing is find a local dealer and build a relationship. Don’t buy an engine out of state to save a few bucks. Shopping price is not always the best option. Find a brand you like and a dealer you can work with locally.
• Always take advantage of getting the longest warranty possible. It’s often better to negotiate additional extended warranty terms then getting a discount on the engine itself. The longer warranty will pay for itself down the road, with better resale value when trading-in or selling.
• Always check the condition of the boat itself prior to repowering. Often times the transom may need to be repaired or replaced, adding a significant unexpected cost to the job.
• If you love your boat don’t keep the engine forever. Trade it every few years before the warranty expires since that’s when it still holds most of its value.
• Educate yourself on the product before you start shopping and always compare apples to apples. Understand the warranty terms and ask questions. Often things aren’t what they seem. Buyers forget how involved some of these repowers can be and how long they can actually take; ask yourself, “do you want it right or do you want it right now?”

More Can Be Less

One of the most intriguing questions when repowering is what size engines to purchase when making the move, staying within the maximum horsepower and weight limit ratings of your boat’s capacity plate. I have spent some quality time chatting up this topic with the folks from Yamaha with the introduction of their new F350 V6 and some of the answers that I have received are certainly thought-provoking. I met up with Senior Regional Sales Manager Mike Browne both at the recent Fort Lauderdale and New York Boat Shows to get his thoughts.

One thing I’ve noticed is the recent trend for OEM Yamaha partners to quickly switch over their twin V6 F300-powered boats to the newer V6 F350s. The weight differences are not significant (562 pounds for the F300 vs 629 pounds for the F350, 61 pounds ‘times two’ equaling 122 pounds net added weight on the transom). Pricing is about $8k-$9k more as of this writing, but the F350s might be worth the added cost to some and offer serious upgrades that we’ve discussed in the past. The most intriguing aspect of this move is not only are the twin F350 powered boats anywhere from 3 to 5 mph faster than their F300 counterparts, they can also get better fuel economy.

“What? How is that possible?”

It’s simple prop math; factory tests for a Grady-White Freedom 307 powered by twin F300s and spinning 15.5 x 17 3-blade stainless wheels generate a top speed at wide open throttle (6,000 rpm) of 50 mph, with a best cruise at 3,500 rpm burning 17.6 gallons per hour at 27.8 mph for a net of 1.58 mpg. In contrast, the F350-powered Grady Freedom 307 can turn a larger 15.5 x 19 prop, with a top speed of 54.4 mph at wide open throttle (6,100 rpm). Optimum fuel economy also occurs at 3,500 rpm, where the F350s deliver 29.3 mph at 17.5 gph for a net of 1.67 mpg, which is a 6% improvement.

There are more examples of how sometimes more can be less, or how larger engines can produce improved fuel economy. Searching through the various Yamaha Performance Bulletins, Mercury Boathouse Bulletins and other similar data offered by Suzuki and Honda can back up this claim.

On my older twin outboard powered Phoenix 27 Combi that I ran from 1997-through-2005, I swapped power on this boat every season (original Yamaha 200 V6 two-strokes, Mercury 200 V6 two-strokes, four sets of Mercury OptiMax 200 V6 two-strokes and three sets of Suzuki DF225 V6 four-strokes) and it was a lesson in naval architecture and center-of-gravity shift with every change. Upgrading to newer engines improved reliability, performance, speed and fuel economy as predicted.

But the added weight of different types of fresh power also caused some center of gravity and waterline shifts that adversely affected my boat’s self-bailing abilities until I was able to identify the problem areas and make the necessary weight change adjustments (like moving batteries forward) to fix it. The Phoenix’s open layout and removable cockpit sole hatches allowed me to mix and match onboard component’s to address the weight and waterline issues, but your ride may not allow this type of flexibility, so be advised.

Final Considerations

Recent upgrades on my two current family sport fishing boats, a 1999 EdgeWater 185CC and a 2006 EdgeWater 228CC, have given me additional revelations on the art and science of repowering. Since purchasing the gently used ‘99 EW185CC back in 2017 for my two sons and four grandchildren, I repowered the original Yamaha 130S V4 two-stroke back in 2018 and then again in 2023. Both times I opted for Mercury’s 115 ProXS, which was consistent with this center console’s horsepower limitations (150hp) and transom weight for the engine guidelines (less than 390 pounds). Whereas the maximum horsepower is typically listed on each boat’s capacity plate, the other critical number (max engine weight) is not and you might have to check either with the boat’s operating manual or make a call to the factory to gather that critical intel. First time around the block, the initial 115 ProXS required a swap out of the engine gauges, control box and control cables to make things work, but I also decided to upgraded the OEM Teleflex steering to their next-gen XTREME mechanical steering setup, with a new tilt helm, smaller wheel with speed knob and some upgraded marine electronics.

When I replaced this engine last season to get a similar 115 ProXS with a new 5-year warranty after four seasons of totally reliable use, it was a simple removal, replacement and cable and wire swap that my dealer was able to execute in a few hours. All the existing gauges and controls plugged right into place seamlessly.

It was a similar story with my EdgeWater 228CC with the first repower, a 550-pound Mercury 250 horsepower V8 four-stroke with digital throttle and shift. Back in 2020, all of the Yamaha gauges and controls from my 600-pound F225 V6 required removal. In their place, my dealer installed a new NMEA2000 electrical system trunk with fresh harnesses, MFD engine monitoring system, plugs, junction boxes and wires that were compatible with the paradigm shift. The engine weights were important, since I wanted to make sure that I stayed within the max engine capacity limit (250 hp) and engine weight (600 pounds) of the original, to ensure that my waterline and scupper position (2-1/2-inches above the water line) would not be compromised by the switch.

When I upgraded this motor to a new Merc 250 ProXS last season (actually 13 pounds less weight due to a different cowling material), I opted for the 7-year factory warranty and the rest of the process was a relatively simple exercise of unplugging the connections from the old engine and reattaching them to the new powerplant. This new outboard is a high-performance juggernaut that is faster in the midrange where it counts compared to my original 250 V8, is a few mph slower on the top end where I rarely travel, but generates a high-speed “passing gear” that the original lacked for emergency situations. It gets similar 2.2 nautical miles per gallon fuel efficiency from 3,500 to 4,500 rpms. But since I’m running a smaller 15 x 15 Enertia prop compared to the original 16 x 16.5 XP Mercury Racing Prop, I need to run it a few hundred rpms higher to get similar speeds to the original 250 V8, at roughly the same fuel economy.

The 15 x 15 Enertia three-bladed stainless steel wheel gives me a top rpm of 6,200 revs – versus 5,700 rpm for the older 250 – required for most ProXS outboards to “unleash the beast” that lurks inside. This translates to “instant” hole shots that are akin to a steam catapult launch of an F/A 18 from a carrier flight deck and exhilarating performance with a deep-throated growl.

Bottom line, it pays to do your research when considering an upgrade to new outboard power, and once you realize that there are multiple considerations you will be in the best position to make the right move.