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Old 18 May 2009, 10:35   #1
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Got my RIB! Could do with some help on engine alignment

Hi everyone,

We finally settled on a Zodiac Zoom two years after posted here for advice in "Very Small RIBS". I've gone for a 6HP motor on the advice of the boatyard who use the same combination as a safety boat for their sailing school.

I was wondering what the best procedure is to set the height and angle of the motor. Zodiac suggest that the motor might need to be shimmed with a spacer above the transom to lift it up a little. I've started off with the motor fully down, and the tilt pin in the furtherest forward position as well.

Running in a new engine, I can't do too much charging around just yet, but once its had a few hours how should I go about determining the best height and angle?

Thanks in advance, Tony S
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Old 18 May 2009, 18:01   #2
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Hi Tony, congrats on your purchase, I hope you get many hours of fun from her.

Haven't a clue about your question, but can't bear to see a thread with no replies

Hope someone with an ounce of nouse comes along with a sensible answer soon.

Have fun,
Ian
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Old 19 May 2009, 13:25   #3
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Hi there, this is the article I think you are looking for http://www.tropicalboating.com/power...-and-trim.html . Basically you need to set the trim angle so that the prop runs approximately level, if the engine angle is too high the bow will lift too much, too low (towards the transom) and you may find yourself ploughing through the water. If you get the boat to run flat on the water you will get up on the plane a lot easier. I hope that helps.
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Old 19 May 2009, 14:44   #4
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if you mount the obm with the cavitation plate level with the bottom of the boat if an aluminium prop fitted, if a stainless steel prop fitted you can go an inch or two higher
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Old 19 May 2009, 14:55   #5
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Quote:
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I've gone for a 6HP motor ...
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if a stainless steel prop fitted you can go an inch or two higher
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Old 19 May 2009, 15:09   #6
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I have a small narwhal rib with a 4 hp on it, with a 1" jack it planes easily with just me in it, merc xr10 going on it soon. , and thanks Mr Dai for yet another worthwhile contribution.
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Old 19 May 2009, 15:24   #7
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.. thanks Mr Dai for yet another worthwhile contribution.
You're very welcome, yet again.

I could question the value and relevance of your comment re: the XR10, but that would be petty.
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Old 19 May 2009, 15:41   #8
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A perfectly relevant part of the conversation as it related to the boat I was talking about. Perhaps you would like to elaborate on your comment and furnish us with your infinite wisdom on this subject, or actually maybe not.
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Old 19 May 2009, 16:17   #9
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Certainly:

Uncle al kindly offered advice on set up with either an aluminium or stainless prop. As the OP asked for advice on setting up a 6hp outboard, this caused me to chuckle, as I consider it highly unlikely that this motor would have a stainless prop fitted. Does that help?

I remain curious as to how your intention to fit an XR10 to a Narwhal contributes anything worthwhile to this thread, when the OP is seeking advice on a 6hp on a Zodiac Zoom.



I anticipate a detour to the bilges here.....
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Old 20 May 2009, 03:31   #10
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Thanks for the comments guys. Yes its only 6HP and the prop's plastic. Out of interest, why would the running depth be different for different propeller materials? Is it just that a stainless prop's more durable, less likely to be damaged by cavitation? How would the depth for a plastic prop compare with alloy or SS?

Currently the cavitation plate is maybe an inch or even two inches lower than the bottom of the transom, and I have the tilt fully down with the pin in the hole nearest the transom.

Set like that I can get smartly onto the plane with just me aboard, on nowhere near full throttle. With two on board the stern swats down and the motor labours. I don't want to do too much messing around at full throttle until the engine's had a few hours.

Based on the comments here, I'll try the motor up a little by sticking one or two strips of wood on top of the transom.

Tony S
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