Moderated Discussion Areas
  ContinuousWave: Whaler Performance
  prop recommendation

Post New Topic  Post Reply
search | FAQ | profile | register | author help

Author Topic:   prop recommendation
cdnturbo posted 10-29-2002 03:13 PM ET (US)   Profile for cdnturbo   Send Email to cdnturbo  
What is the recommended prop for a Mercury 200 hp on a 1989 20' Outrage?
jimh posted 10-29-2002 11:06 PM ET (US)     Profile for jimh  Send Email to jimh     
If the total weight of the boat is known, you can estimate the maximum speed potential with 200-HP.

Knowing the maximum speed potential, you can then calculate the propeller pitch necessary, making allowances for the lower unit gear ratio and maximum rated crankcase speed.

This is all explained in the series of articles in the REFERENCE section on propellers.

If you will post the additional data, I would be glad to work through these calculations for you.


Total weight of boat
Lower unit gear ratio
Maximum crankcase speed

cdnturbo posted 10-29-2002 11:35 PM ET (US)     Profile for cdnturbo  Send Email to cdnturbo     
the weight would be a standard 1989 20" outrage
max rpm 5800
gaer ratio 1.86:1
jimh posted 10-30-2002 01:15 PM ET (US)     Profile for jimh  Send Email to jimh     
Re: the weight.

You need to include the following in your weight calculation:

--Hull weight (1850# for 20-Outrage. I looked this up in the REFERENCE Section article on SPECIFICATIONS.)
--Engine weight ( ?? )
--Fuel weight (500# approx. full tank)
--Gear on board ( ?? )
--People on board (A "fiftieth percentile" adult male weights on average 165-lbs, but for some reason Whaler owners seem to be a bit heavier..)

Once you collect your weights and total them, use the formula shown in the Reference section to determine potential speed based on horsepower (200). See

Bigshot posted 10-30-2002 02:45 PM ET (US)     Profile for Bigshot  Send Email to Bigshot     
Easier yet....what are you running now? Merc props should have a little 19P or 21P on the side or top under nut. What Rpm are you running WOT?
jimh posted 10-30-2002 02:48 PM ET (US)     Profile for jimh  Send Email to jimh     
I know that there is a very high probability that the answer we'll get will be in the range of 19 to 21 inches of pitch, but by explaining the process it allows others to learn how to make these calculations.

You can always visit the Mercury website and use their propeller calculator/predictors, too.

jimh posted 10-30-2002 07:12 PM ET (US)     Profile for jimh  Send Email to jimh     
To keep this moving forward, I'll just take a guess at some of these numbers for the example at hand.

Hull = 1850
Engine = 400
Fuel = 500
Crew = 600
Gear = 300
Total weight 3650#

Total Horsepower = 200

Using the formula with a hull factor of about 200, this gives a speed potential of about 46 MPH.

Now we take this info to the Propeller Calculator, entering:

MAX RPM = 5800
Ratio = 1.86
Speed = 46 MPH
Slip = 10-percent (reasonable)

The answer is 17.3 inch pitch.

Note that this is for a rather heavy load case.

Bigshot posted 10-31-2002 10:19 AM ET (US)     Profile for Bigshot  Send Email to Bigshot     
I never had much luck with the calculators....just trial & error.
Sal DiMercurio posted 10-31-2002 09:52 PM ET (US)     Profile for Sal DiMercurio  Send Email to Sal DiMercurio     
Jimh explained that very well, but the engine needs a 14.25x19 to reach 5,800 rpms trimmed out, with a medium load, providing the engine is mounted up on the 2nd or 3rd set of holes.
If you going to be carrying heavy loads, you will need a 17 or 18 pitch prop.
jimh posted 11-01-2002 08:56 AM ET (US)     Profile for jimh  Send Email to jimh     
I should also mention the fine table of information created by Whaler enthusiast Peter Elke. Pete has precalculated the speed potential for most Whaler hulls when powered at their maximum recommended horsepower.

See Pete's fine work at:

I noticed that Pete used a value of 180 for the hull factor. That is probably more appropriate for the Outrage-20 hull. The hull is more of a constant-deadrise moderate vee hull than a "classic" Whaler style hull.

Sal DiMercurio posted 11-02-2002 12:55 AM ET (US)     Profile for Sal DiMercurio  Send Email to Sal DiMercurio     
Looks like he also used 4 stroke weights, as a 4 stroke 200 hp weighs 636 lbs, a 2 stroke is 500.
His speeds are a little slow, unless he's figuring the newer outrage hulls.
Mine is a 1980 V-20 & my 200 FICHT [ putting out 222 hp at the prop, per dyno at OMC test center ]is pushing her at 60.3 mph, shot on police radar on 3 seperate runs.
Of coarse my engine is up 3 holes with a Stiletto 14.25 x 21 s/s at 6,000 rpms, ultra light load.
This engine has been torn down at least 4 times, & gone through & re-done by OMC instructors, every nut & bolt has been torqued & re-torqued to perfection, so it might not be fair to compare to an assembly line engine.
Don't forget, the 80s outrage bottoms are much flatter then the newer boats, thus far more speed, but much harder riding.
jimh posted 11-02-2002 10:28 AM ET (US)     Profile for jimh  Send Email to jimh     
In the Reference article the author states "Engine weights are based on weights in recent Mercury and Bombardier catalogues for typical engines of the maximum rated horsepower for each model." I don't think there are many 200-HP 4-stroke engines in there because at the time he compiled the list there weren't any available.

The V-20 Outrage hull is different from the 20-Outrage, the 22-Outrage, and the 25-Outrage, all of which have greater deadrise (deeper vee) in their hulls.

The 20 and 22 foot hulls have the same deadrise. I think the 25-foot hull may have greater deadrise.

Some of the newer models with an AccuTrack hull may have greater deadrise than the Outrage hulls from the 1980's.

Sal's boat, the V-20 has the least deadrise of any of the Whaler Outrages. The boat being discussed, cdnturbo's 1989 20-Outrage, has a different hull than the 1980 V-20 Outrage, and it has more deadrise than Sal's boat.

Sal, those are very interesting numbers on the Ficht engine horsepower. Of course, I am curious to know how you got such a custom-built Ficht engine. Can you reveal the story behind that?

Sal DiMercurio posted 11-02-2002 09:15 PM ET (US)     Profile for Sal DiMercurio  Send Email to Sal DiMercurio     
Jim, i really can't say how I was able to buy the engine.
It was legal, but I was told not to say how I got it, as it's not for everyone, just in the right place, at the right time & knowing the right person.
All I can say is, it was a test engine for OMC, had 13 hours on it, putting out 222 hp at the prop, [ not uncommon ].
Omc was notorious for putting 100 hp stickers on 120s, & 150 decals on 165 hp engines.
All the engine manufacturers are allowed 10% hp over what it says on the engine, but some exceed that.
The merc 250 is actually putting out 280, instead of the 275--------250 + 10% = 25 hp = 275 hp.
My 2000---200hp FICHT cost me $7,500 in June of 2000, with full warranty, absolutly "NO" problems in just under 500 hours.
One "VERY, VERY ", powerful engine on my boat, like putting a 25 hp on a canoe rated for a 10 hp max.....she flies.
Sal DiMercurio posted 11-02-2002 09:19 PM ET (US)     Profile for Sal DiMercurio  Send Email to Sal DiMercurio     
The freshwater 225 FICHT weighs 498 lbs, the offshore series weighs 504 lbs.
The 4 stroke 225 Yamaha weighs exactly 636 lbs, [ thats the weight he used ].
I don't know of any 2 stroke 225 that exceeds 504 lbs.
Bigshot posted 11-04-2002 11:15 AM ET (US)     Profile for Bigshot  Send Email to Bigshot     
From evinrude's website V6's(200-250hp) with FichtŪ Ram Injection Weight lbs:

200hp 25" 514 & 30" 518lbs

Mercury AND yamha 225 four strokes weigh 583lbs.

Yamaha 250HPDi weighs 543lbs.

Mercury 225 Opticrap is 531 25" and 547lbs 30"

Now you know the facts! 4 strokes are not that much heavier than DFI units. Mercury is now actively comparing DFI to 4 strokes in advertisement campaigns and shows the benefits of both designs.

Swellmonster posted 11-06-2002 11:58 AM ET (US)     Profile for Swellmonster  Send Email to Swellmonster     
1998 20 O/R, 225 EFI. 19 prop could only get 5200. 17 prop rocks! Major diff in holeshot, get my proper rpms trimed out.

Post New Topic  Post Reply
Hop to:

Contact Us | RETURN to ContinuousWave Top Page

Powered by: Ultimate Bulletin Board, Freeware Version 2000
Purchase our Licensed Version- which adds many more features!
© Infopop Corporation (formerly Madrona Park, Inc.), 1998 - 2000.