Long shaft engine on 15" transom?

[IanBBA]

Long shaft engine on 15\" transom?

I have a XM 3m RIB capable of taking (the manufacture states) a 15HP outboard.

My Beneteau First 24 has a Yamaha F15 L/S aux. Is there any reason why I should not use this long-shaft outboard on a short 15" transom other than the prop pitch may be a bit fine?

The F15 is also missing its tiller; obviously removed by the previous keeper to enable it to fit within the engine well. Any idea where I might find such a thing without paying Yamaha's exorbitant spare part charges?

Many thanks, Ian.


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[Moose]

Re: Long shaft engine on 15\" transom?

The prop will be too deep in the water and will push the bow up to the extent that it may/will flip over, believe me I know!!

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El Alce

 

[ccscott49]

Re: Long shaft engine on 15\" transom?

Been there, done that, got the wet tee shirt!!

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[Moose]

Re: Long shaft engine on 15\" transom?

It will flip with a standard shaft if you sit at the back, I have a Avon 3.1RIB and 9.9 outboard, and No1 Moose can get 24kt's in it So I would love to here what speed you get with a 15!! For me 20+kt's is fast enough but not for No1 who is pestering me to have the engine up rated by changing the carbouretta (why can't I spell that??)

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El Alce

 

[IanBBA]

Re: Long shaft engine on 15\" transom?

Thanks for all comments.

I had not considered the extra prop depth would substantially increase the moment that lifts the bow; obvious really! Now that I'm aware of that, I'll probably give it a go anyway. It's very unlikely the engine will be able to deliver the full 15HP anyway as the prop is pitched to push a 2t yacht along and I'll be very conscious of the possibility of over-revving it to destruction! Not the right engine really but is perfect for its primary role as the yacht aux and I'm loath to change it especially as it's just three years old, has hardly any hours and has the luxury of electric start.

If anybody comes across an upside-down RIB on Windermere next weekend with an outboard leg rising up clearly further than would be normal, please throw me a tow-line!!!

Thanks to all. Sill interested in any further comments.

Ian.


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[Moose]

Re: Long shaft engine on 15\" transom?

How are you going to steer?/forums/images/icons/smile.gif

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El Alce

 

[IanBBA]

Re: Long shaft engine on 15\" transom?

I'm going to lock the engine in straight ahead. To turn left I will dip the left hand oar in the water and to turn right, dip the right.




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[Sybarite]

Re: Long shaft engine on 15\" transom?

Didn't they just introduce speed restrictions on Windermere? Or am I mixing up lakes?

John

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[IanBBA]

Re: Long shaft engine on 15\" transom?

They are and thank goodness; there are lot of lunatics zapping around without a consideration for anybody. I'm a hardened yachtie; the RIB is just a bit of fun.

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[Moose]

Re: Long shaft engine on 15\" transom?

You will kill yourself, You do not understand how fast 25kt's 6inches from the water is and how unstable a RIB is at this speed (it will be stable upside down/forums/images/icons/laugh.gif)
Have Fun and tell us how you get on/forums/images/icons/smile.gif

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El Alce