Outrage 18 Top Speed

Optimizing the performance of Boston Whaler boats
Blackduck
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Outrage 18 Top Speed

Postby Blackduck » Fri Jun 18, 2021 10:43 am

There always seems to be interest in the top speed of a Boston Whaler classic OUTRAGE 18 powered with a 150-HP two-stroke-power-cycle engine. I have been around a few OUTRAGE 18 boats , and I owned one that I regret selling to this day. Without a doubt the [the OUTRAGE 18] boat will make 49 MPH when trimmed properly and the engine in top shape. No tricks or add ons are needed.

For me, when shopping for this model, I always use this performance level as being critical to the boat's overall condition.

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Phil T
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Re: Outrage 18 Top Speed

Postby Phil T » Fri Jun 18, 2021 12:43 pm

Walter -

Your boat is the very rare exception to the rule. I think I can only count on two hands the number of Outrage 18's that can reach that speed.
1992 Outrage 17
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jimh
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Re: Outrage 18 Top Speed

Postby jimh » Fri Jun 18, 2021 1:23 pm

For a classic Outrage-hull with a Crouch' Speed Prediction Method hull factor constant of 190, in order to hit 49-MPH with 150-HP the boat weight {with crew aboard] would have to be 2,250-lbs or less.

An owner of an OUTRAGE 18 with an OMC 150-HP engine weighed his {empty] boat on a certified scale and found it weighed 2,540-lbs.

Using 2,540-lbs as the weight, the Crouch' Speed Prediction Method indicates top speed would be 46.5-MPH.

Using a more conservative hull factor of 180, with 2,540-lbs and 150-HP the predicted speed is down to 43.7-MPH.

The concept that every Outrage 18 with 150-HP will hit 49-MPH seems rather optimistic.

Environmental factors will also have significant effect on performance:
  • water salinity
  • water temperature
  • air temperature
  • humidity
  • altitude above sea level
  • sea state
  • favorable or adverse current
  • favorable or adverse winds

So testing in very cold, very salty seawater, on a cold day, with low humity and high pressure, with some favorable current and winds will tend to boost performance compared to testing in warm freshwater on a hot and humid day with less than ideal sea state, wind, and current.

Blackduck
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Re: Outrage 18 Top Speed

Postby Blackduck » Fri Jun 18, 2021 1:35 pm

If I said I believe that 50-MPH without bottom paint was possible, you would really think I was nuts.

My boat did weigh [1,975-lbs] without fuel or operator, so the [Crouch Speed Prediction Method] says that is possible.

Blackduck
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Re: Outrage 18 Top Speed

Postby Blackduck » Fri Jun 18, 2021 1:38 pm

These old two stroke 150's did produce more than their rated HP-

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Re: Outrage 18 Top Speed

Postby jimh » Fri Jun 18, 2021 2:50 pm

Thanks for reminding me about crew weight. I will add 400-lbs to the 2,540-lbs scale weight, giving 2,940-lbs. With 180 hull coefficient and 150-HP the speed predicted is now 40.7-MPH.

At that weight to hit 50-MPH will need an engine with propeller shaft power of 227-HP.

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Phil T
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Re: Outrage 18 Top Speed

Postby Phil T » Fri Jun 18, 2021 3:02 pm

There has been a contest for any classic Outrage 18' owner with a stock 150hp engine to reach 50 mph running for many years.

No winners yet.
1992 Outrage 17
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Blackduck
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Re: Outrage 18 Top Speed

Postby Blackduck » Fri Jun 18, 2021 3:35 pm

Phil, what is the prize?

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Re: Outrage 18 Top Speed

Postby Blackduck » Fri Jun 18, 2021 3:45 pm

Hull design, total boat weight, engine RPM , and propeller pitch and diameter predict the real top end boat speed, not the engine's power.

Whatever makes the designated propeller turn at the required speed will work.

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Re: Outrage 18 Top Speed

Postby jimh » Fri Jun 18, 2021 4:14 pm

Blackduck wrote:Hull design, total boat weight, engine RPM , and propeller pitch and diameter predict the real top end boat speed, not the engine's power...Whatever makes the designated propeller turn at the required speed will work.


The Crouch Speed Prediction Method incorporates the hull design (moderate speed planing hulls) and the total boat weight. The other factor is engine power output. The method assumes that a suitable propeller has been selected with a reasonable efficiency in the range of 50 to 60-percent. The method has been demonstrated to provide very useful speed predictions for Boston Whaler boats using hull factors in the range of 180 to 190.

Propeller pitch and diameter do not predict boat speed. If they did you could just put on any propeller you like and obtain any boat speed you wanted.

I really do not understand your argument. You seem to be saying that engine horsepower has no influence on boat speed. That is a crazy assertion.

In order to turn the propeller shaft at a certain speed the engine must be able to accelerate to that speed. Propeller load increases exponentially as the propeller rotation speed increases. Engine power output does not continue to increase with engine speed, and often actually begins to decrease with engine speed once beyond the peak power output. The engine only accelerates until its power output matches the propeller load. To accelerate to a higher speed requires more power from the engine. Thus engine power determines how fast the propeller will be turned. Once the propeller is turning, the amount of thrust produced depends on the design of the propeller blades and their overall efficiency.

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Re: Outrage 18 Top Speed

Postby ConB » Fri Jun 18, 2021 6:53 pm

Phil, what is the prize?

I will throw my hat into the ring if I ever get my Outrage 18 back with a second hand Yamaha F150 on it. Scuttlebutt has it 49-MPH.

--Con
!987 Outrage 18 / 2011 Yamaha F150
1969 13 / 30hp Johnson tiller

Don SSDD
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Re: Outrage 18 Top Speed

Postby Don SSDD » Sat Jun 19, 2021 7:24 am

With the lightest 150-HP engine, lightest fuel load, no hull bottom paint, best top end speed propeller, all extra gear removed including anchors, maybe no rails, no antennas, and no windshield, 135-lbs operator, all conditions perfect, then perhaps [an OUTRAGE 18] could exceed 50-MPH.

With my HONDA BF130 and me, I won’t be in this race.
1986 Outrage 18 with 2001 Honda 130 HP
Former Owner 1991 Guardian 19 with 1994 Evinrude V4 140HP
Former owner 1987 Montauk with 1998 Mercury 90HP
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Re: Outrage 18 Top Speed

Postby jimh » Sat Jun 19, 2021 10:37 am

Regarding measurement of boat speed, most data is taken from GNSS receivers that are measuring speed over ground. Most GNSS receivers used on small recreational boats do not actually measure speed directly, but calculate speed based on time to travel a distance between two position fixes. Since there is some uncertainty in the position fix accuracy, there is thus uncertainty in the calculated speed based on the distance between the position fixes. The accuracy of the position fix varies with the horizontal dilution of position (HDOP), which in turn varies with the particular geometric alignment of the satellites positions relative to the GNSS receiver. The position error also varies with the due to many influences. Some augmentation of position accuracy can be achieved with use of the FAA's Wide Area Augmentation System (WAAS) for GPS satellites. In summary, GPS speed measurement is susceptible to many influences that reduce the accuracy of the calculated value. And, of course, any effects from wind or current produce an offset between actual boat speed through the water and boat speed over ground.

To see some flutter or variation in calculated speed from a GNSS receiver is normal. For a boat driver to pick the highest displayed speed value as the true speed is also normal.

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Re: Outrage 18 Top Speed

Postby Blackduck » Sat Jun 19, 2021 1:53 pm

My point is the [OUTRAGE 18] boat [with 150-HP engine] is close to a 50-MPH boat, not a 40-MPH boat: just like a Montauk with a 90-HP engine is close to a 45-MPH boat, not a 37-MPH boat. As far as how accurate is GPS, most commercial GPS receivers are stated to be capable of an accuracy of 0.1-MPH or better under ideal conditions.

Don SSDD
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Re: Outrage 18 Top Speed

Postby Don SSDD » Sun Jun 20, 2021 5:38 am

Automobiles with digital speedometers also have a slippage in instantaneous accuracy in order to make [the speed] readable. Similar to GPS measurements, they average a few seconds of speed data to show you a readable number, one that is not changing a few times each second. The original digital dashboard from back in the 1970’s changed numbers too fast and were difficult to use.
1986 Outrage 18 with 2001 Honda 130 HP
Former Owner 1991 Guardian 19 with 1994 Evinrude V4 140HP
Former owner 1987 Montauk with 1998 Mercury 90HP
Nova Scotia

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Re: Outrage 18 Top Speed

Postby jimh » Sun Jun 20, 2021 9:23 am

Blackduck wrote:...most commercial GPS receivers are stated to be capable of an accuracy of 0.1-MPH or better under ideal conditions.

Please give a pointer and URL to a GPS receiver which specifies its speed accuracy is 0.1-MPH and specifies the conditions under which that accuracy is obtained.

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Re: Outrage 18 Top Speed

Postby jimh » Sun Jun 20, 2021 9:28 am

Blackduck wrote:...my point is that the boat is close to a 50 MPH boat, not a 40 MPH boat,


I don't think there is an argument that an OUTRAGE 18 with a 150-HP engine may exceed 40-MPH, but your initial argument was that if an OUTRAGE 18 with 150-HP could not reach 49-MPH there was a defect in that boat. I disagree with that criterion.

Boat speed depends on the power-to-weight ratio, the hull form, and many environmental factors. To establish a paradigm that all OUTRAGE 18 boats with 150-HP should reach 49-MPH is not reasonable, as my many comments above explain.

You are welcome to hold your own belief regarding the use of a reaching 49-MPH for an OUTRAGE 18 with 150-HP as an important criterion for assessing the boat, but I do not hold that belief.

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Re: Outrage 18 Top Speed

Postby prj » Thu Jul 15, 2021 11:17 am

Phil, the Outrage 18 is not included in the challenge, assuming we're talking about Jeff's.

Posted elsewhere back at the end of 2015, here is my performance report:

    In spring of 2014, I repowered my 1990 18' Outrage with a new 2014 Mercury 150 HP Fourstroke engine.

    I now have 2 seasons of experience with it, and 72 hours of engine operation under my belt, mostly on Lakes Superior and Michigan, including substantial time in Green Bay from both the western shore and Door County, along with few hours on larger inland lakes in the Northwoods of Wisconsin.

    The following is a performance report on the engine, undertaken in the following conditions:

    Date: 10.22.15
    Location: Milwaukee Harbor, Lake Michigan
    Air Temp: 60 degrees F
    Water Temp: 57 degrees F
    Wind: Light and variable, 5-8 MPH from NE and SE
    Waves: < 6" in the harbor
    Load: One person, light gear, no canvas, half plus fuel (30 gallons plus a few I suspect)
    Prop: Stiletto Advantage P/N E600319 three blade and I believe 14 1/4" x 19 (please verify or clarify if you know)

    Speeds were taken in both directions available, with minimal difference and varied results whether with or against wind in each test. Speeds were read from a Lowrance HD-7 Chart Plotter / GPS and are presented in MPH.

    RPM SPEED SPEED
    1000 4.5
    2000 9
    3000 26 25
    4000 36 35
    5000 45 45
    5600(WOT) 51.1 51.2

    Minimum planing speed was 2200 RPM and 16+ MPH

While receptive to evidence to the contrary, I posit that this is the fastest legal HP outboard ever presented on a stock 18 Outrage. Of the many reports I've read over the years on all the various 150 HP outboards installed on 18 Outrages, consistently tops speeds of 45-47 MPH have been reported. Occasionally, a 49 MPH report shows up, but those are quite rare and seldom shown in a performance report, most often simply referenced in passing.

This rig can hit 50 MPH as a matter of course, even with a fuel tank more full than ideal for maximizing speed.

Updated after 6 years or more, the boat performs the same; readily hitting 49 mph even with several guys and medium load, not optimized for top speed.
Not certain why, but this particular hull seemed to perform faster with the previous engine (Yamaha 130 HP 1.7L 4 cylinder) and with this new(er) motor. Maybe it was a light layup!

Patrick
Milwaukee, WI

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Re: Outrage 18 Top Speed

Postby jimh » Fri Jul 16, 2021 10:25 am

Patrick--many thanks for the detailed performance report on the OUTRAGE 18 boat with 150-HP engine hitting 50-MPH.

I note that the test was performed in rather cool air (60-degrees) and rather cold water (57-degrees). Those are environmental factors that favor or enhance engine and propeller performance.

Some additional observations:

I believe the gear ratio of a Mercury 150 FOURSTROKE is 1.92:1. I will use that factor for the RATIO in a propeller calculator. Entering:

    RPM=5600
    RATIO=1.92
    PITCH 19
    MPH=56.2
and solving for SLIP results in a value of 2.4, an extremely low value. Since there seems to be a bit of doubt about the propeller pitch, I recalculated with a 20-pitch propeller.

    RPM=5600
    RATIO=1.92
    PITCH 20
    MPH=56.2
and the resulting calculated value for SLIP is a more reasonable 7.3.

The big jump in speed that occurs with the last 600-RPM of engine speed is impressive. The boat speed jumps to 51.2-MPH from 45-MPH, an increase of 6.2-MPH. We have to look at the calculated SLIP at the 45-MPH speed to see why this is happening>

    RPM=5000
    RATIO=1.92
    PITCH 20
    MPH=45
SLIP calculates to 8.8, which, again, is a reasonable value.

The propeller SLIP decreases as the boat speed increases. That's how the last 600-RPM of engine speed can add 6.2-MPH of boat speed.

There may be another factor in the achievement of 50-MPH boat speed with just 150-HP: the Mercury engine. As readers of this forum have been told for more than two decades, Mercury engines always produce more horsepower than the value on the cowling decal.

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Re: Outrage 18 Top Speed

Postby prj » Mon Jul 19, 2021 11:06 am

Anecdotal follow up from July 19, 2021 before noon:
  • 72-degree-F water temperature
  • 75-degree-F air temperature
  • 6-inch-high wavelets
  • negligible wind of 1 to 3 knots in direction of travel
  • location was Strawberry Channel off Fish Creek, Door County on Green Bay.
  • measured in only one direction--I was traveling not testing)
  • fuel tank level 3/4-FULL or 45-gallons
  • Mills Suntop up
  • 50.2-MPH maximum boat speed with a steady 49.n MPH showing.

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Re: Outrage 18 Top Speed

Postby jimh » Mon Jul 19, 2021 1:09 pm

Patrick--I believe your OUTRAGE 18 boat with 150-HP engine is now eligible to be purchased by BLACKDUCK--should you ever decide to sell it. And Phil T will now need a third hand to count the number of OUTRAGE 18 boats to achieve this distinction.

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Re: Outrage 18 Top Speed

Postby jimh » Wed Jul 21, 2021 4:33 pm

Blackduck wrote:My point is the [OUTRAGE 18] boat [with 150-HP engine] is close to a 50-MPH boat, not a 40-MPH boat: just like a Montauk with a 90-HP engine is close to a 45-MPH boat, not a 37-MPH boat.


Please explain your analogy between a moderate V-hull OUTRAGE 18 and a rounded bottom MONTAUK 17. I am unable to draw any logical inference.

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Re: Outrage 18 Top Speed

Postby prj » Fri Jul 23, 2021 10:22 am

To wrap up my thoughts on this topic, I tend to agree with Jim and Phil despite the speed results with my boat. Waiting to find an 18' Outrage powered by a 150 HP that consistently hits 49 MPH is likely to result in a frustrating purchase process, and lots of WOT test drives.

Blackduck
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Re: Outrage 18 Top Speed

Postby Blackduck » Fri Jul 23, 2021 10:55 am

The Outrage 18 is quite capable of making 49-MPH. I do not say that every 18 will do this, or that a boat making 47-MPH should be rejected for purchase. If an Outrage makes only 43-MPH it is underperforming by 10-percent.

To say a Boston Whaler Outrage 18 should make a lot more speed than 43 MPH is not silly. [That an OUTRAGE 18 with 150-HP can go a lot faster than 43-MPH] is common knowledge for those of us who have been around these boats their entire lives.

[This will be the final word in this thread. I thought the discussion was extremely civil and very interesting.—Moderator ]