Moderated Discussion Areas
ContinuousWave: Whaler Performance
13-foot hull: Engine cavitation in turns
|Author||Topic: 13-foot hull: Engine cavitation in turns|
posted 05-06-2003 10:13 AM ET (US)
I had my first outing in my 1971 13-foot Whaler with Evinrude 40-HP and stick steering [Note: the author does not mean steering with an engine mounted tiller, but instead refers to an unusual forward console arrangment with a side mounted steering arm mechanism. See a photo of his boat in the hyperlink below--Moderator.] The boat cavitates on less than gentle turns at speed. Is this common with these hulls?
posted 05-06-2003 07:43 PM ET (US)
Boats with hard chines tend to raise one side when in a turn, lifting the prop. Can you lower the motor further? I had a Proline that did the same thing, only way around it was to keep the bow down from its normal position. With power trim it was an OK workaround as the dealer/factory had no other solution.
posted 05-07-2003 10:38 PM ET (US)
Thanks for the reply GeneNJ. The motor is in the lowest trim stop and the bow rides a little higher than the stern on plane. It's a short shaft Evinrude. I haven't checked the prop pitch and dia but I suspect it's the 'OEM'. It's in good shape no dings dents or gouges. It seems the boat side slips and the prop doesn't bite. I hear an audible rpm change not a over-rev decoupling... if this makes ant sense. I'll try a different motor trim position.
posted 05-07-2003 10:40 PM ET (US)
Here's a rear view.
posted 05-07-2003 10:54 PM ET (US)
[Changed TOPIC; was "13...cavitates in turns"--jimh. Also, added comments about steering position.]
posted 05-08-2003 03:45 PM ET (US)
Just to be technically correct, this subject is ventilation (air being drawn into prop) rather than cavitation, which results from damaged props.
posted 05-08-2003 11:35 PM ET (US)
Yes maybe sucking air. This configuration may lend itself to this condition...? It is very responsive. May be the nature of the beast. Hence my query.
posted 05-09-2003 12:17 AM ET (US)
I sued to run my whaler with the fuel in the front. I would try doing the opposite and try and get as much weight in the stern as possible. This way it will be lower and wont come up in the turns,
posted 05-09-2003 12:18 AM ET (US)
I used to run....... not sued
posted 05-09-2003 12:28 PM ET (US)
Are sitting in the front seat? Maybe you have too much weight forward like Captbone says.
How does the steering handle with that stick?
Is it kind of awkward to get to the throttle?
posted 05-09-2003 12:48 PM ET (US)
Steers just like an Air Boat! I'd take the prop off and carry it to a prop shop and have them cup it. I had to do this to my 9.5hp Evinrude on my Zodiac years ago. With cupping on the prop, it was nearly impossible to get it to ventilate/cavitate. It's amazing what a little lip edge on the trailing end of the prop blade can do to help these problems.
posted 05-09-2003 04:28 PM ET (US)
With the Trophy you sit on the front twart so stern is way light. those old engines cavitate REAl easy so try cupping the prop like where2 said. My 1982 did the same thing even with weight aft, especially in following seas.
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