Setting motor height.

[Mark42]

I have read conflicting info on setting the cavitation plate height and am confused.<br /><br />My hull is Lapstrake design. So the rear center 18 inches of the bottom of the hull is flat with the keel running down the center. The keel is about 2" wide and 2" high. The cavatation plate is level with the bottm of the lapstrake flat area, not the lowest point of the keel.<br /><br />Is this right?<br /><br />Was under the impression that raising the motor (it is currently as low as it can be mounted on this transom) may improve performance and speed. Is that correct?<br /><br />Thanks,<br /><br />Mark

 

[Dhadley]

Re: Setting motor height.

Any time you reduce drag the efficiency improves. Raising the motor will reduce gearcase drag. How high depends on prop design & condition and how well that particular prop interacts with your given hull design.<br /><br />The ultimate set up is to "hide" the bullet of the gearcase behind the boat so theres no gearcase drag at all.

 

[CATransplant]

Re: Setting motor height.

How's the boat performing now? You might get a little more out of it by messing with the height, but...if your boat is planing nicely, the engine's running at the proper WOT RPMs, and you're not ventilating the prop or porpoising, then you're probably set up very nicely.

 

[Mark42]

Re: Setting motor height.

I like the way it runs now. I just want to make sure that the setup is not really bad. I had lost some top speed when adding the gas tank to the bow, but last week on a calm inlet with me, wife and two little kids boat was doing 29 mph in both directions like it used to. So I guess my speed loss in earlier post gas tank trials was from weight, or weight distribution or even wind or a combination of them. I have the boat fully trimmed in and it performs best that way. <br /><br />I get a real kick out of running WOT on still, calm water so it is important that the boat is set up as well as I can get it. If the wind comes up and the water gets choppy, it has to run between 7 and 13 mph or the ride is gets too uncomfortable in this little boat.<br /><br />Edit:<br /><br />There are some really poorly performing boats out there. My Dads friend has a 21ft cuddy that I drove on the same waters as my boat and it handles terrible. The boat wanders even at high speeds. And porpoising is very pronounced over 28 or so mph. I think there are lots of people who just don't know that their boats will run better with some owner applied fine tuning. Thanks to everyone.