Outboard mounting

The dreaded Iron Top Sail we sometimes have to rely on.....

Outboard mounting

Postby Chris Wicks » Sat Apr 04, 2009 7:28 am

Hi,
I use a 5hp Honda. A problem I've experienced is even when locked in the vertical trim the O/B leg can hit the leading edge of the rudder. To overcome this I've machined off some of the cavitation plate from the engine but it can still occur. In the first season this caused the rudder to split, it is now reinforced over the joins of the two moulded sections. But still it makes occasional contact. I'm not sure when, but probably when undersail in a biggish sea I think as opposed to when under power. The reverse gear locking devise works correctly.

If I were to put the wooden mounting pad forward of the stainless steel mounting plates, this would set the OB to the fwd end of the OB hole in the hull, would this work?
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Postby seasickwhale » Sat Apr 04, 2009 1:33 pm

Hi Chris,
Chris Wicks wrote:....If I were to put the wooden mounting pad forward of the stainless steel mounting plates, this would set the OB to the fwd end of the OB hole in the hull, would this work?

This is exactly what I did for my 6hp-Honda. The mounting block now sits forward of the stainless plate - no problems at all.
Happy Sailing

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Postby Dennis » Sat Apr 04, 2009 6:37 pm

Hello Chris

It may help if you sail with the engine in reverse gear. This will prevent the engine trying to tilt in heavy seas.

I also have a 5hp Honda, but have not (yet) had the prop hit the rudder. I have tried to manually pull the outboard leg aft when the motor is in reverse (and the boat on the trailer) but there is clearance.

I also considered moving the motor mounting block forward, but it has not proved necessary (yet).

Happy sailing

Dennis
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Postby Chris Wicks » Mon Apr 06, 2009 8:08 am

Hi

When originally fitting my 5hp Honda, it seemed the clearance would be ok, albeit tight. My boat is on a swinging mooring and subject to some pretty big occasional swells (from passing Greek inter island high speed ferries).

I always engage reverse when sailing at any speed or in choppy seas and yet by the end of the first season it was clear the cavitation plate had been tapping away at the leading edge of the rudder causing the 2 halves to split. This was repaired and improved by taking the joint with GRP and applying a professional and strong repair. Then found I still had water ingress to the rudder on next season and this was due to no sikaflex applied when the rudder pintles were drilled and fitted in the factory.

Now all is well except there is some contact with the OB to the rudder so I will move the mounting bracket fwd. As yours is a new boat I'm just saying watch this carefully as the rudder damage was a mare to fix.

Honnor Marines support to help the solve this problem was outstanding I should add!

Cheers

Chris

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Re: Outboard mounting

Postby Malcbuchanan » Fri Feb 22, 2019 9:00 pm

Related Question ...how 'deep'/high' should the outboard be mounted - so mine has 25cm from the centreline of the prop to the top of the 'skeg' that runs from the stub keel to just under the rudder The outboard could be mounted some 7cm lower. Mounting it lower would increase the bending on the mounting/though offset by taking 7cm off the mounting block...maybe some increase to the risk of outboard leg hitting the rudder

anyone any measurements of the prop to skeg dimension ?

my engine is a 6hp Yamaha - standard leg length

Thanks and Regards
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Re: Outboard mounting

Postby erbster » Sat Feb 23, 2019 4:08 am

Hi Malcolm, I don’t have any measurements but I didn’t think the exact position of the prop is critical, as long as there is no risk of fouling. Like several others, I have a Honda 5hp. I wonder how much difference there is in the prop position between different models of outboard?


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Re: Outboard mounting

Postby Malcbuchanan » Mon Feb 25, 2019 9:14 am

Charles thanks for coming back - I will see what it looks like on the water - ie how far below the water the prop is, but it looks fine judging from the water level mark on the anti-foul . Regarding fouling the rudder - the swash plate is well clear so I have no concerns there
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Re: Outboard mounting

Postby erbster » Mon Feb 25, 2019 5:46 pm

Good luck. When/where are you launching?


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Re: Outboard mounting

Postby Malcbuchanan » Mon Mar 04, 2019 9:40 pm

Hi Charles - thanks for your responses

Hope to launch mid March here at Lymington

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