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steps for design a IOM hull

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Old 12-03-2009, 09:57 AM
  #1
tatolazo
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Default steps for design a IOM hull

HI:

I have the drawings for a new hull IOM class. Now i need to find the exact location for the keel and rudder.

1.- Should i first find the center of lateral resistence in the hull with or without the keel/bulb and rudder in place??
2.- After that. Could I keep the distance from the center of lateral resistence in the hull to the center of effort of the sail measured form another IOM?? ( since the rigs are all the same size the center of effort of the sails does not move in the rig) or this distance between keel and mast will vary because of the shape of the new hull??

I just need to have clear the logical steps to achive exact or more eficient location of the mast and keel - rudder

Hope you can comment about it.

Tato Lazo
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Old 12-03-2009, 10:32 AM
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jphart
 
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Default RE: steps for design a IOM hull

Tato:
Everything changes with a new hull. Taking dimensions from another boat will give you a start for trial and error. All three components of lateral resistance are in play, hull, keel, rudder, and the hydro-dynamics of their interaction ie. lift or disturbance from a keel bulb. I believe that there are some modeling programs usedby naval architects to solve your problem. Try to contact: www.westlawn.edu they're a school of yacht design and may be able to help or redirect.
Good luck, it's a long way from nice lines on paper to a sailing boat, but when it all comes together, it's worthwhile.
Jim Hart
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Old 12-03-2009, 10:51 AM
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tatolazo
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Default RE: steps for design a IOM hull

JPHART:

exactly. It is a whole new thing starting from the beggining with a new hull.

The location of rudder is pretty much the same. I am using the same fin area and shape configuration that in my prior model that is running quite well. , but the thing is in first place if i need to use in place the rudder and fin in the hull to find its center of lateral resistance??

Once this first step is clear to me, the following is just a trial and error.

Thanks

Tato Lazo

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Old 12-04-2009, 12:52 AM
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larrykin
 
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Default RE: steps for design a IOM hull

Hi,
my advice is to try and make contact with Claudio at RC Universe.
[link=http://www.rcsailing.net/forum1/showthread.php?4991-IACC120Cup/page30]R/C Sailing Forums[/link]
Ask him the question and I'm 100% positive he will know the answers. If not he will point you in the right diection. The guy is an RC yacht legend and fountain of knowledge.

Larry L.
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Old 12-04-2009, 09:41 AM
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tatolazo
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Default RE: steps for design a IOM hull

Larryking.

Thanks, I will contact him, .

Tato Lazo
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Old 03-12-2011, 05:47 PM
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ron ward
 
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Default RE: steps for design a IOM hull

the center of lateral resistance is essentially the fore and aft location of the the C/g. in full size boat design it is easily found bybalancing a scaleprofile of the hull with fin/keelbulb, 1/2 the rudder profile attatched and the waterline drawn on. take the profile, stick a pin through the profile at the waterline and into a wall. keep movingthe pin fore and aft on the waterlineuntill theprofile balances with the waterline dead level. the pinhole will represent the CLR along the waterline. it works the same for models, as well and it doesn't matter if the profile hangs rightside up orupsidedown on thepin.
once the CLR is established.....
location of the COE will be a percentage of the waterline length. aCOE anywhere from 6 to 12 percent of the WL ahead of the CLR...called "lead"will give a decent amount of weather helm,.... under most circumstances. very high aspect ratio sail plans will needcloser to 6% leadand lower aspect ratios will require closer to 12% lead, maybe a bit more in light winds, as the boat will heel less. that last bit of "correct lead" can only be found by sailing the rig and moving the mast fore or aft.
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