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| Cavitating https://www.smwebhead.com/phpBB3/viewtopic.php?f=3&t=921 |
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| Author: | GregNVirginia [ Sun May 27, 2007 9:45 pm ] |
| Post subject: | Cavitating |
Hi all, Got a question for you... When I'm pulling a skier and they drop, fall, wipe out, etc.... I like to turn the boat as fast as I can to get back to them (especially now that there's a lot of boats out). However, I've noticed that I really cavitate big time in a sharp turn. So, I try a little less sharp turn, same thing. A little less, etc, etc, etc, same thing. Yes, if I turn a normal sweeping turn, it's ok, but that's not what I want to do, I want to turn kinda sharp to get back to them as soon as I can. Could this be the prop? I do have the tilt/trim full down when I turn. My prop is the standard 3 prop aluminum, and no, I don't know the size/pitch (I'm going to check that tomorrow, sorry I didn't have that info tonite). Tell you what though, I'm loving this boat big time!!!!! |
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| Author: | 230 Mike [ Sun May 27, 2007 11:33 pm ] |
| Post subject: | |
Can you describe the cavitation a little more, and how far up are you trimmed? |
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| Author: | Txjole [ Mon May 28, 2007 8:32 am ] |
| Post subject: | |
Nothing you can do about it if you are trimmed past 90. Its caused by the lower unit getting in the wash from boat turnining. In the powerboat market you can get a spacer to extend your lower unit. It goes between the lower and upper unit. Not really made to help pulling a tube, more for stablity at speeds of over 100. |
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| Author: | GregNVirginia [ Mon May 28, 2007 8:46 am ] |
| Post subject: | |
Ok, I have the standard Michigan Wheel prop, 14.5" x 19" pitch. When I pull a skier, I always have the tilt/trim all the way down and that's the position it's in when I make the sharp turn. Maybe cavitation is the wrong term, however, when I make the sharp turn, it's like there's no "bite" whatsoever from the prop (I can hear the motor winding up in RPM's and always have to back it down). The turn is made at approximately 25mph and while the boat does turn sharply, that's also when you can tell it's lost "it's bite" in the water... Oh, I should mention that yes, I have a few dings in the prop and will be getting another one (actually two so that I'll have a spare). |
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| Author: | 230 Mike [ Mon May 28, 2007 2:27 pm ] |
| Post subject: | |
Are you sure that's the right prop for your boat? You certainly should be able to make a 25mph turn without it slipping to the point where you have to reduce power. |
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| Author: | GregNVirginia [ Mon May 28, 2007 6:11 pm ] |
| Post subject: | |
yeah, think I'm gonna have to post in the other section for this. I "think" that the prop that's on it is the recommended prop, though not positive. I'm going to go look for some composite (4 blade) props since i'm not woried about top speed at WOT. We just wanna ski and tube.. THanks all for your responses, they are most appreciated as always.. |
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| Author: | 230 Mike [ Mon May 28, 2007 11:57 pm ] |
| Post subject: | |
You might give FW a call and ask them (if you don't already know) what the original prop was. They usually nail the prop spec pretty well for general, all-around use. At least then you'd have a known reference to start from. |
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| Author: | Architectdave [ Tue May 29, 2007 6:43 am ] |
| Post subject: | |
One thing the dealer told us on our shakedown run was that tight fast turns and skiing should be done with the trim all the way down. I have found that a full wheel over turn at 3k rpm will fall off speed a touch at the end of the turn unless I throttle up a touch and she literally jump up and back out of the water...so my guess is its either your trim or your prop...is you prop balanced a damage free? Even a small bur on the edge of your blade can cause cavitation.... |
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