CONTINUOUSWAVE

I am considering purchasing a 1990 Revenge 25 W-T WD rigged with 1989 Yamaha150-HP two-stroke engines. It needs repowering. From what I have read, the 25 Whaler Drive models should have 20-inchshaft outboard if running with a dual motor set up. Correct?

What would be the impact of running dual 25-inch-shaft engine besides drawing more water?

My challenge seems to be locating a pair of dual 20-inch-shaft counter-rotating motors. Anyone still produce them? Am I better trying to find a set of low hour used motors? Would prefer Yamaha or E-TEC engines and to keep the weight as low as possible.

Another question: is it possible to convert a right hand rotation outboard to a left hand counter rotating motor?

Thanks,

Tom

With 25' shafts the engines may never be able to be trimmed for optimum performance and handling nor mounted high enough on the transom to keep the anti-cavitation plate high enough for best speed and economy. Perhaps you should consider a single engine of higher horsepower. Since you are considering used engines perhaps a single four stroke such as a Mercury Verado 300 would perform well while providing enhanced reliability. Rigging costs with the "fly-by-wire" feature of the Verado could also provide some savings.

From what I have read, the 25 Whaler Drive models should have 20-inch-shaft outboard if running with a twin-engine set up. Correct?

Incorrect.

For a Whaler Drive model the transom height is for 25-inch shaft engines for twin-engine set up. This is clearly indicated in the REFERENCE section listing. See

http://continuouswave.com/whaler/refere ... hulls24-31

The reason you can't find any 20-inch-shaft counter-rotating engines: there are none. And that is why the Whaler Drive was designed as it was.

As for re-powering with twin engines, the Whaler Drive was designed for twin c.1990 two-stroke-power-cycle engines that weighed about 400-lbs. For example, the weight of popular OMC 150-HP loop-charged V6 2.6-liter 60-degree 25-inch-shaft engines was only 375-lbs. Twins would be only 750-lbs on the transom. If re-powering with modern engines, you will need to watch the transom weight.

In terms of modern 150-HP engines, the lightest four-stroke engine would be an old-style Mercury 150 FOURSTROKE (NOT VERADO), but even that engine in 25-inch-shaft is going to be about 465 to 470-lbs. And I don't think you can get counter-rotation.

The legacy E-TEC 150 with 25-inch-shaft will weigh about 430-lbs; I also don't see it available in counter rotation. If you want twin legacy E-TEC 150-HP V6 engines, you better hurry: they are about the last of the legacy E-TEC V6 models being made. See more at

Evinrude E-TEC Legacy Engines Slowing Going Away
http://continuouswave.com/forum/viewtopic.php?f=4&t=2673

As for going with a 300-HP single engine, that would certainly be less expensive than twins, and would save weight. A FOURSTROKE VERADO 300 will weigh in at about 650-lbs, plus the extra weight of its hydraulic steering boost pump that has to be located somewhere in the boat, probably another 25-lbs at least.

An E-TEC G2 big-block 300 will be 537-lbs, but that will include the hydraulic steering actuator, which will probably be about an added 20-lbs or more with other engines.

To re-power with twin 150-HP engines these days is a difficult problem because of the weight increase of modern engines. The transom weight will be rather high no matter what engines you choose. When the boat is in the water, the Whaler Drive adds a lot of buoyant force to hold up the engines and support the drive. What will worry me more: then the boat is on a trailer and all that engine weight is completely unsupported, except by the long lever arm of the Whaler Drive hanging off the transom.

Regarding conversion of standard rotation engines to be counter-rotation engines: the engines all turn the same direction, and the alternative propeller shaft rotation is accomplished in the gear case. But you cannot "convert" the gear case; you have to get a new gear case. There is one exception: the very recent and very innovative Suzuki big V6 engine can be switched electronically to have either standard or counter rotation.

Usually a counter rotation gear case weighs about 5 to 10-lbs more than a standard rotation model. The internal design is significantly different.

The 1990 BW Brochure (last page of the brochure under specifications) lists a 25" shaft of the 25' Revenge WT/WD for single engine applications, but has a very clear footnote "7" that specifies 20" shafts for dual engine applications. Was the brochure incorrect?

Just verified the outboard model, and they are in fact 25-inch shaft engines. You were right Jim. Still not sure why the 1990 brochure calls for 20-inch engines.

I looked at the 1990 catalogue. It does seem confusing. My boat's Whaler Drive does not have a V-shape; the Whaler Drive has a center flat spot. It looks like 25-inch shaft engines work as either a single or twin engine installation with the flat bottom of the Whaler Drive. I have heard--but never seen--that some early versions of the Whaler Drive carried a V-shape all the way to the transom of the Whaler Drive. Perhaps on one of those Whaler Drives you would use 20-inch-shaft twin engines.

Also noteworthy from the 1990 catalogue is the footnote warning: V8 engines cannot be used with standard Whaler Drive on 22 to 25-foot models; you need a special version 27-foot V8-Whaler Drive for those engines. I believe that is due to the increased weight of the V8 compared to the normal V6 engines. This should be considered as a warning against modern twin engines that carry that same weight increase as a c.1990 V8 outboard did, that is, you cannot expect a standard Whaler Drive to hold up twin engines with excessive weight.