posted 04-08-2011 11:54 AM ET (US)        

I sometimes run in the Atlantic outside Casco bay and I am concerned that any gains in efficiency would be offset by blowout in the swells. Any sage advice from the Whaler masters?

posted 04-08-2011 08:51 PM ET (US)            

I am afraid that you cannot be certain you have raised the engine as high as possible until you raise it too high. If too high you will see the cooling system water pressure start to fall off and the propeller start to blow out. When that happens you know you went one hole too far, and you can lower the engine one hole.

posted 04-25-2011 08:29 AM ET (US)            

http://continuouswave.com/whaler/reference/propellerWDSingle.html

At the time that image was taken, the engine was mounted in the lowest position. From the dimensions shown, it appears that the anti-ventilation plate of the engine is 0.25-inch above the Whaler Drive flat spot.

NewportMe (Bruce) describes his engine mounting when in the "highest position" (which we will assume means three-holes up) as putting the anti-ventilation plate 2.0-inches above the Whaler Drive flat spot. We assume that the three-hole increase has produced 3 x 0.75-inch or 2.25-inch increase in the height of the engine. Working from my baseline dimensions, this would mean the anti-ventilation plate ought to be 2.5-inches above the flat spot of the Whaler Drive. We have about 0.5-inch of difference, which we will have to assume can be attributed to variations between engine manufacturers in the actual length of the outboard. And, of course, I am assuming that both the engines are designated at 25-inch shaft engines.

When I fitted a new engine on my Boston Whaler, the dealer was quite strong in his suggestion that we try mounting the engine one-hole up. Again, working from my dimension in the reference article and assuming that the two engines have the same length, this implies that my current engine is mounted with the anti-ventilation plate 0.75-inch higher than shown in my illustration, or about 1-inch above the Whaler Drive flat spot. The engine has two more holes of lift available, and if moved to the highest position its anti-ventilation plate would then be about 2.5-inches above the flat spot of the Whaler Drive.

posted 04-25-2011 03:21 PM ET (US)            

I will make an effort to clarify my statements. There are 4 holes in the upper mounts to my motor. My motor is now mounted in the lowest hole (all the way up). Before Saturday the motor was mounted in the second to the bottom hole (2 holes up?). The a/v plate is now 2.125" higher than the "flat spot" on the whaler drive. I was rounding my measurements, and did not take any measurements from the keel.
Hopefully I will be able to check the performance and the handling this weekend...we will see what the weather brings.

posted 04-25-2011 08:39 PM ET (US)            

--location of holes drilled in transom

--measurement error in extending plane of the Whaler Drive flat spot to the plane of the anti-ventilation plate

--variation in the shaft length of our engines, even though both are specified as "25-inch" shaft length.

posted 05-01-2011 01:07 PM ET (US)            

There is no misconception about the effect of raising the engine on the cooling system: the higher you raise the engine the more cooling problems may occur. Modern outboard engine gear case design has evolved, however, and on my current engine, for example, there is a water inlet for cooling that is located on the leading edge of the nosecone of the gear case. This inlet is going to be in the water all the time, unless you have your engine running in mid-air.

My engine manufacturer (Evinrude) also provides several different types of inlet covers for the main water inlet, with several types intended to increase cooling water pressure and flow in compensation for raising the engine mounting height. I think there are even some designs which begin to look like scoops, again intended to improve cooling water flow when the engine mounting height is increased or there are other problems with cooling water flow. Some boat hull bottoms have some strakes or other appendages which can affect the flow of cooling water into your engine.

posted 05-02-2011 07:21 AM ET (US)            

The prop is an advantage II 15 pitch. At WOT during my highest speed run downwind I was running around 5850 rpm. Motor is E225CXCCE, I believe this indicates that the motor is counter rotating but prior to my ownership the lower unit must have been swapped because the rotation is right hand.

posted 05-02-2011 03:56 PM ET (US)            

Thanks for the encouraging words, this site has been an invaluable resource to me and many others. Hopefully I can leave a small scrap of information that will be a help to someone, or help them try to improve their boat somehow. The amount, and quality of information here is awesome.

posted 05-02-2011 07:28 PM ET (US)            

So, do I understand correctly that your motor is now "two holes up" on your Whaler drive?

What about raising it another hole?

posted 05-03-2011 07:43 AM ET (US)            

My boat is an Outrage so it should be lighter than a Revenge, I don't know if that would change your opinion on the prop. My motor is currently all the way up (3 holes?)

posted 05-03-2011 10:46 AM ET (US)            

I suspect the frontal area of the Revenge 22 Walk-Through will have a greater effect on top speed that the trivial added weight, but even that should not be that profound.

posted 05-03-2011 04:04 PM ET (US)            

Wow only 100 lbs. I would think the tables benches cushions etc. would tally over 100 lbs. but who knows. I am quite pleased thus far with the prop but what would be your suggestion for one. I may damage mine.... or hit the lotto, any information I can salt away is appreciated.