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Author Topic: rudder centre or off centre?  (Read 866 times)

Dublo 1

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rudder centre or off centre?
« on: May 03, 2011, 09:04:18 pm »

Hi there everyone, this is my first ever post on any forum and I hope its my first of many on mayhem. Have recently got back into boat building after a lay off of some thirty years!! I have gone straight into large gas power boats with hulls from PMB [mercury cat] and complete rehash of venoms king of shaves. So far have been happy with the results, however I have built aeromarines challenger 48 with zen 7,near enough to plan but although the boat is stable and quick it does not like turning [at any speed] I have tried all the usual tricks but for whatever reason all so far have failed. I have used the offset position for the rudder as in the plans and am wondering should I reposition it to the centre of the prop as in my cats.Any suggestions would be much appreciated.Thanks.
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omra85

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Re: rudder centre or off centre?
« Reply #1 on: May 03, 2011, 10:09:43 pm »

Hi Dublo
I have the AM Challenger 43 and 48.  Both have the offset rudder as per the plans and both turn well, bearing in mind that you'll never get them to turn like a multi boat..
Have you fitted a decent, solidly mounted servo with a solid linkage?  The 48 has a 15Kg pull one with a 2mm stainless rod linkage (one side only).
No racing boat likes turning at slow speed and will turn sharper the faster you go - (that's my excuse anyway  ;)  )
You should not be able to move the rudder when the stick is neutral and you will need 25 to 30 degrees of throw each side on the rudder blade at "full lock".
Cheers
Danny
PS I admire your courage - the Zen 7 is FAR too powerful for the 48!!  You'll be lucky if you can turn in less than 20 yards radius without it falling over  O0 {-)
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Dublo 1

  • Guest
Re: rudder centre or off centre?
« Reply #2 on: May 04, 2011, 01:01:41 am »

Danny, Many thanks for your info, servo is mounted rigid and rated at 18 kg so I've at least got that right. As for angles will have to check but again thanks for your help. Zen 7 came by way of Ebay [in would you believe a Vantex challenger as a straight engine swap] and yes you,re right , it is too powerfull but its all I've got to go in at the moment. Will swap engines with one in Mercury cat [260pum] if i can't get it right, and frighten myself to death with that instead!!
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