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Old 30 September 2011, 13:26   #1
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Poor Engine Trim - Help.

I took my RIB out today, well the Mrs drove, and once we got onto the plane there is a lot of water shooting directly up, I've tried to capture it in the photo but not very well, it's kinda like a curtain, I've tried with and without wings but there seems do be no difference, I'm sure someone will know straight away but I'm very new to small boats and have no idea, but wondered if it was something to do with the angle of the engine.

The RIB is a 4.5m Valiant with a Selva 50hp 4 stroke.

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Old 30 September 2011, 13:32   #2
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I think it will be engine height and/or trim angle. What height is the anti ventilation plate relative to the bottom of the keel? A photo taken from the transom looking towards the prop would be good (be careful sitting there and if there is any risk you might fall/slip consider adding a second kill cord).
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Old 30 September 2011, 13:41   #3
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Is there an obstruction at the bottom of the hull, maybe a sounder transducer? My transducer flings up like this a bit though perhaps not quite as bad.
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Old 30 September 2011, 13:43   #4
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I had thought that the leg might not be long enough but trusted that it was done properly, does this look a little short?

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Old 30 September 2011, 13:52   #5
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That engine is the correct length. I would raise it an inch or so and see if it improves things. Is it Power Trim or Manual?
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Old 30 September 2011, 14:01   #6
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it's power, on the throttle lever - how would I raise it?
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Old 30 September 2011, 14:20   #7
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Quote:
Originally Posted by thomas View Post
it's power, on the throttle lever - how would I raise it?
Hi like Neil I think your plate is to low and it needs to come up a little. Hope you find the answer.

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Old 30 September 2011, 14:23   #8
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It depends if your engine is bolted or clamped (or both!) on.

Exactly how you do it will depend on how much muscle you have available as well. Very simply:

- balance / support the engine. ** Beware that lump probably weighs more than me and is an awkward shape**
- unbolt / loosen the engine
- either lift the engine or lift the front of the trailer to drop the transom
- refasten the boat to boat (if it is bolted you can probably do this without drilling any holes)

NORMALLY the starting point is to have the bottom of the keel level with the antiventilation plate - as highlighted in yellow here.

BUT if you are new to all this then perhaps play with the trim angle first to see if you can eliminate it without the spanners. The preferred trim depends on lots of things (speed, load, waves etc) and should be tweaked as you go.
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Old 30 September 2011, 16:47   #9
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Having a second look at it and I maybe wrong as I sometimes is! Is the angle of the OB rather severe as against the transom as it does seem a little at an angle would have thought the plate and the keel should be more towards the parallel.
Just a thought.

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Old 01 October 2011, 02:12   #10
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I can move it up quite easily as it's bolted on and there are lots of holes in the mounting plate to adjust, but I guess you lot knew that.

It's hard for me to play with the trim as I can't get the Mrs, who said "what on earth do we want one of those for" out of the healm seat.
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