1984 OUTRAGE V-20 Re-power

[MikeUFCfan]

My 1984 OUTRAGE V-20 is powered by an Yamaha 250-HP Ox66 engine.

The engine runs well. The boat transom is solid.

I may re-power soon.

I'll be using the boat in the San Francisco Bay area for fishing, cruising, and occasionally towing a skier. I don't think I need all the power and I'd definitely like something quieter and more efficient.

Q1: is 250-HP too much power for the [1984 OUTRAGE V-20]?

It [unspecified engine] is surely heavier than [other outboard engines of lower weight] options.

Q2: what new engine would be a good choice?

Q3: what be will the change in fuel efficiency with a new engine?

Q4: what will be the change in boat speed with a new engine?

[MarkCz]

Your 1984 boat was rated for a maximum of 180 HP so I think you could drop way down from what you have now.

[jimh]

Q1: is 250-HP too much power for the [1984 OUTRAGE V-20] boat?

Yes.

Q3: what will be the change in fuel efficiency with a new engine?

Typically the overall fuel consumption will decrease to about half the former consumption. Modern engines are very much more fuel efficient at idle or low power setting. At higher throttle setting a modern engine will be perhaps 10 to 20-percent more efficient. The overall fuel economy change will depend on the mix of high-speed and low-speed run time.

But the cost of a new modern engine will never earn back a savings in fuel cost from lower rate of consumption unless the engine runs hundreds and hundreds of hours every year for many years, as long as the cost of gasoline remains around $4-per-gallon. The higher the cost that gasoline fuel rises to, and the more volume used, then the more likely a fuel economy improvement might pay back the cost of a new engine during the service life of the engine or during the time the buyer still owns the boat.

Q4: what will be the change in boat speed with a new engine?

Boat speed is ALWAYS a function of power-to-weight ratio to the 0.5 exponent.

For example, if the total weight were 3,500-lbs and the hull factor used were appropriate for a classic OUTRAGE V-20 hull (190), with 250-HP the boat speed might be about 51-MPH. If weight stayed constant and power reduced to 150-HP, boat speed would likely decrease to about 39-MPH.

Use my Crouch-method calculator to see predicted boat speeds based on power, weight, and hull design.

https://continuouswave.com/calculators/crouchCalc.php

[jimh]

Q2: what new engine would be a good choice?

Because you will pay for the engine, not me, I recommend getting a modern four-stroke-power-cycle engine with electronic shift and throttle, the new electronic remote controls, the OEM best digital gauges, a new stainless steel propeller, and replacing all fuel line, fuel filers, and primer bulb; also re-do the primary electrical power distribution with a new set of two AGM ultra-high-purity lead marine batteries, new battery fuses, new primary battery switch, all new power distribution wiring, new fuse panel for secondary power distribution; you will need a new helm panel to fit all the new gauges; you will new engine ignition key switch panels with engine shut-off safety switch with a lanyard.

Figure the engine cost at about $1,000 per horsepower, then add $2,000 for the electronic control option, and $1,500 for the actual electronic remote controls; new digital gauges will be almost $1,000 because you will need to install a NMEA-2000 network: a new propeller will be about $500, perhaps more; two new batteries will be about $900, the new battery switch about $100, the new primary wiring and fuses about $200; the new secondary power distribution panel and wiring will be $200.

Unless you do all the work, expect several thousand dollars in labor cost. Generally with a new engine, you will not get a warranty unless an authorized dealer does the engine installation. Also the engine warranty will not cover any damage that resulted from defects in the boat’s fuel system or electrical system, and that is why those systems must be refurbished when you buy a new engine.

If you buy a 150-HP you might spend $21,000 on the engine and accessories. Add maybe $4,000 in dealer labor.

Offset the trade-in value of you current engine, although it won’t be too much; you’d be better selling the Yamaha 250 Ox66 yourself to another Ox66 owner who needed it to replace his engine or wanted it for spare parts.

Add the sales tax needed in your state, maybe $1,000.

Your total cost will about $26,000. Now you can start saving $1-per-hour in lower fuel consumption: 26,000-hours later you are back to even.

[MikeUFCfan]

Hey Jim,

Thanks for the detailed response here. It really does add up and you'll never truly make back the money on [savings in fuel purchases].

I plan to shop for a used 150, 175, or maybe 200-HP four-stroke-power-cycle engine selling for $4,000 to $6,000 locally.

My Yamaha Ox66 250-HP engine might sell for $2,000. But the buyer would have to be someone who just blew up their own ox66 250. Not a great market there.

I would be comfortable doing all the work myself, but I haven't done it before.

Thanks for all the input,
Mike