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Author Topic:   Revenge 25 Re-Power with Optimax Engines, SmartCraft Gauges
Tates posted 08-24-2004 10:30 PM ET (US)   Profile for Tates   Send Email to Tates  
The re-power of my REVENGE 25 Hard Top with Whaler Drive is complete. The boat now has twin 200-HP Mercury Optimax engines and SmartCraft gauges, and it displaces about 8,000 pounds with 140-gallons of fuel aboard. At the 18-hour mark, the results are:
1000 RPM   5.9 knots   0.6 gal/hr
2000 RPM 10.5 knots 2.6 gal/hr
3000 RPM 19.2 knots 5.5 gal/hr
4000 RPM 30.0 knots 9.5 gal/hr
5000 RPM 35.0 knots 17.0 gal/hr
5250 RPM 38.0 knots 19.5 gal/hr (WOT)

The present propellers are 21-pitch, which have been re-pitched to 19-inches. I may need to try new 19-inch or 17-inch pitch propellers to get the recommended RPM of 5600-5800.

The SmartCraft gauges seem to work well. They give me RPM, GPH, Water Pressure, Temperature, Tilt, and Speed. They also have the capability of monitoring the fuel level and oil levels . I haven't got the accessories for these yet. The SmartCraft gauges can also tie to the GPS. All considered, they rate a 7 on a 10 scale.

I did the installation of the gauges myself and removed the old motors. I assisted in the installation of the new motors, also. The rigging and engine assignment for the smart craft gauges was left to the dealer. It was a total of 6 hours paid to others and probably 12 hours of my time.

Everything works as expected. The engines start instantly and perform well. If you have any questions or comments, I will be glad to discuss them.


Peter posted 08-25-2004 08:54 AM ET (US)     Profile for Peter  Send Email to Peter     
Is it correct to assume that the fuel consumption rate figures are for each motor? Otherwise the total fuel consumption rate looks to be about 1/2 of what it should be.

You should re-prop (possibly with 17s) to get the RPM up near the max. This is particularly important for an offshore-capable rig.

jimh posted 08-25-2004 09:16 AM ET (US)     Profile for jimh  Send Email to jimh     
Considering the cost and time already invested, testing some different propellers may prove to be a very good return on investment.

Have you tried the Mercury MIRAGE PLUS propellers?

Tates posted 08-25-2004 10:10 AM ET (US)     Profile for Tates  Send Email to Tates     

Peter, The engine statistics are for one engine they are the mean reading of both.My guess is I probably could get an additional 3-4 K with 17 pitch prop.

I will have to look into the Mirage Props, I saw a new 2004 255 Conquest at the Launch with twin 250 4 stroke Mercurys,I noticed he had 3 blade Mirage props.The ones I have are also three blade stainless & look similiar.I'am not sure what differences there are between them I suspect mine are 1989 vintage . I will have to investagate. I didn't get a chance to talk with the owner.

I also had another 8 man hrs removing the engines , which I forgot to include in the orginal post.


Peter posted 08-25-2004 10:46 AM ET (US)     Profile for Peter  Send Email to Peter     
Tates, with 400 HP I assume you have the Whaler Drive. Your calculated slip is a bit on the high side assuming propellers are 19P. I would give a pair of 17P Mirage Plus props a try. That should get you up close to 5600 RPM. The Mirage propeller shape tolerates a high runnning position fairly well.

Also, check your toe-in alignment. Assuming you used the same tie bar arrangement (likely between the steering arms), the alignment of the new motor steering arms could be somewhat different than the alignment of the old motor's arms leading to a different toe-in alignment between the gear cases.

Tates posted 08-25-2004 06:31 PM ET (US)     Profile for Tates  Send Email to Tates     
The orginal post was incorrect for 2000 RPMS the speed should be 19.2 K .

jimh posted 08-25-2004 09:46 PM ET (US)     Profile for jimh  Send Email to jimh     
Email me any corrections. Your speed goes down at 3000 from 2000?
jimh posted 08-25-2004 09:48 PM ET (US)     Profile for jimh  Send Email to jimh     
Guessing you meant 19.2 at 3000, I made that change. Advise if further corrections.

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