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Neutral Helm


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#1 olsurfer

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Posted 20 March 2017 - 08:16 PM

Will a trimaran with daggerboards in the amas that are positioned about 1.5 ft ahead of the mast and no centerboard in the mainhull, have a very heavy helm and easily "get in irons"?



#2 Derekkelsall

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Posted 20 March 2017 - 09:12 PM

I would expect YES, but would need to see a profile of boat and rig.    This might be a case for trim boards in the transom.

 

Happy boating,

 

Derek.



#3 msouth

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Posted 20 March 2017 - 10:01 PM

Take the wideness of the trimaran into the calculation, it will balance out as the force of the rig is not 90 deg to boat moving direction
It is more forward in direction.

#4 juniordave nz

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Posted 20 March 2017 - 10:44 PM

The weight of your helm depends on where you have the pivot of the rudder and whether the centre of lift is in-line with the pivot (neutral), or behind the pivot (weather). It also relys on the fact that the centre of effort of your sail plan is behind the main foil. The distance behind the main foil will impact the force that is taken by the rudder. If the centre of effort is 5% behind the main foil, then it will take 95% of the force and the rudder 5% and so on.



#5 Graham M

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Posted 21 March 2017 - 12:20 AM

http://www.antrimdes...maran-erin.html  

 

This might be helpful.



#6 olsurfer

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Posted 21 March 2017 - 05:18 PM

http://www.antrimdes...maran-erin.html

 

This might be helpful.

This boat is a good candidate for discussion. The webpage above does a good job of explaining the design parameters and it would be great to talk with folks who has sailed her for some first hand experience. For a boat launched in 93, she was visionary but as time moves on, how have those design choices held up? The webpage shows the races she has done well in and that speaks for itself, but when using the formulas to calc COE and the like, she is outside those boxes. I get that it's about lifting the bow but is there trade offs in this design?






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