Re-powering 1989 Outrage 18

[afinelli]

I purchased [a 1989 Boston Whaler OUTRAGE 18] hull over a decade ago with [1989] Yamaha 150. We use it primarily for relaxed cruising in tidal rivers and interconnected waterways of mid-coastal Maine--nothing far off-shore. The engine rarely gets above 4,000-RPM, but like the speed when we need it.

[The 1989 Yamaha 150] engine has been properly stored and serviced over winters by our boatyard. I have gotten tired of the poor fuel economy and intermittent starting problems. Re-powering ideas in my non-expert head include 135 to 140-HP newish vintage Evinrude or Suzuki but boatyard service chief thinks I can get away with a 2013 Yamaha F115XA four stroke. Here's his pitch:

"It is a 2013 engine but it was commissioned in 2016, has only 100 hours on it, and is under warranty until July of 2019. Judging form other 18 Outrage boats we have here at the yard your boat probably goes 42 to 43-MPH with the 150; we expect with the F115 you would probably top out at 35 to 36-MPH. This includes all new binnacle, gauges, cables, wire harness. and a used hydraulic steering system that came off the same boat as the motor so only a 100 hrs on it as well.

Proposed all-in cost is about $12,000.

With very little to go on, I'm thinking this is too little power and too much price. Experienced feedback appreciated.

[Shadburke]

Yamaha F115 will be fine as long as the [1989 OUTRAGE 18] does not have a T-top. [Expect] mid-30 to high-30 MPH at wide-open-throttle. If you have a T-top, then [puchase an] F150, hydraulic steering, and a set of LENCO trim tabs.

I configure a lot of the local boy scout Whaler GUARDIAN 18 boats with F115 and F150 engines. They seems to lean toward the F115 as the F150 makes for a rocketship that in the hands of an unskilled operator can become a problem.

[jimh]

I agree with your assessment that a cost of $12,000 for a used Yamaha F115 engine seems a bit high, although it does include all the rigging and hydraulic steering, which can be substantial costs if your present rigging and steering must be replaced or refurbished with the re-power. Also consider cost of instrumentation that may be needed with a new engine.

Assuming weight stays the same, if a boat with a 150-HP engine is re-powered with a 115-HP engine, we can expect the top speed to decrease by the square-root of the horsepower/weight ratio as follows:

(115/150)0.5 = 0.875

If the boat formerly hit 42-MPH, you could expect it to then reach 0.875 × 42-MPH = 36.8-MPH

If total weight increases, speed will be reduced.

You should also consider the cost of a new propeller. With reduced horsepower available you may have to change the propeller to a lower pitch to reduce the propeller load on the engine so the new engine can accelerate into its optimum power band. For engines with four-stroke-power-cycle, the peak horsepower generally occurs at the very top end of the rated engine speed maximum range.

[Phil T]

The summer boating season in Maine is very short. Most boaters are Memorial Day to Labor Day. Many do not run more than 50 hours due to weather and water conditions. This is very hard on an outboard. The less they are run, the more tempramental they can be.

The F115 is an excellent motor and a good fit for a classic Outrage 18, as shown by our past member Elaelap, see http://continuouswave.com/ubb/Forum4/HTML/002632.html

The dealer offer for the engine and rigging is VERY overpriced. Especially given the short season. I would expect a BRAND NEW F115 installed to be $12k given the trade in value of your current motor and a lot of shop time.

A new 115hp motor by itself in the crate is ~ $9,000 before any rebates.

Please note that engine height and prop selection are VERY important. Check back with us after the engine choice has been made but before it is installed.

Personally I would buy a new battery, new battery cables and have all the carburetors rebuilt.

[RichS]

Two years ago (2016) I had a new Suzuki DF140A installed on my 1988 Outrage 18. The boat will hit about 41 to 42-MPH with three people and a half-full fuel tank. The propeller is a Suzuki three-blade 14 x 20 stainless steel. The engine is mounted one-hole-up, but I will be raising it another one or two holes and hope to gain 1 to 2-MPH. Engine and installation cost about $12,500 and included a wiring harness, remote controls, cables, hydraulic steering system, a simple two-gauge package, and moving the battery to the console. I couldn't be happier with this combo. It's really quiet, economical, and so far no problems. As others have said, the location of a dealer with reliable service is a big deciding factor.

[afinelli]

Shadburke, Jim, Phil, Rich:
Thank you all for your extremely helpful comments.
Phil: (1) what do you think would be a reasonable price for the used Yamaha 115 installed with all the listed equipment?
and (2) what do you think re-building the carburetors on the 150 might cost?
Anton

[Phil T]

I have not had carbs done in so long my pricing information is worthless.

As for used F115 rigged, ~ 5k? Depends on shop, location etc.