I am looking at a Revenge 25 W-T with a Whaler Drive. I noticed in the Revenge 25 hull specifications in "Reference" that the standard notched transom hull has a 300-HP rating while the Whaler Drive version has a 450-HP rating. The only differences in specs with the Whaler Drive is 2-feet more length (8%) and 250-lbs (6%) more weight, yet the horsepower rating is 30% more!
If I buy this boat and re-power with a 300-HP four-cycle engine, will the performance match the standard notched transom hull? To get to the maximum rating for the Whaler Drive I'd have to get twin 225-HP engines, which would be way more weight, cash, and fuel costs than a single 300-HP.
So does the Whaler Drive hull REQUIRE more horsepower or does it simply ALLOW for more horsepower?
I've read many of the old threads on Revenge's with Whaler Drives. The only thing that come close to a comparison are "jimh's" observations from a 2008 thread which states
...Boston Whaler boats with a Whaler Drive are not as common as boats with a notched transom. The Whaler Drive option was expensive. Having had a REVENGE 22 Walk-Through with Whaler Drive for several years now, I can tell you that I really appreciate the Whaler Drive for:
--adding a nice closed transom to the boat
--creating closed storage space in the stern of the boat
--significantly improving the ride characteristics
--creating a nice swim platform
The downside to a Whaler Drive is that the hull seems to need more power to maintain speed. This seems to result in lower fuel economy.
However I also found an article on continuouswave (in "reference" I think) on Engine Brackets which seems to say the opposite :
It is often desirable to move the mounting point of outboard engines aft from the hull's original transom by as much as 36 inches. The two principal benefits of this are:
•The propeller runs in cleaner (i.e., less-turbulent or less aerated) water that exists behind the boat.
•The engine can be raised (sometimes several inches) which reduces the hydrodynamic drag by having less of the engine lower unit submerged in the water.
The net effect of these changes is to increase the propeller efficiency (from operating in cleaner water) and to decrease drag (from reduction of submerged lower unit). This increases the potential top speed of the boat, and improves the overall fuel economy.
If anyone can share their realworld experiences I would appreciate it. I can't go more than 300HP and I don't want to underpower the hull.
The only hard numbers I could find are in a thread from 2010. Here are "crow's" numbers from a 1985 Outrage 25 re-powered with a Suzuki 300.
Code: Select all
RPM MPG MPH
2500 2.99 12.99
2800 3.43 15.43
3000 3.72 21.23
3500 3.64 25.06
4000 3.59 33.52
4400 3.00 35.15
4500 3.00 37.75
5000 2.49 42.34
5500 2.14 47.10
5900 2.09 50.46
I would be very happy to get close to these numbers with a 25 Revenge W-T Whaler Drive hull.