Calculating CLR, LWL, including the rudder..

ningcompoop

ningcompoop

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Hi all. Just wondering, when calculating the CLR of my little boat, do I include the rudder in the underwater profile, and when measuring LWL, does that include the rudder also? I'm just checking, as I did this some time ago, and having just looked at it again, I'm suprised how far back the CLR is from the CE - don't have any obvious lee helm.
 
LWL normally excludes rudders.
The rudder is normally included in CLR estimates, sometimes its area is arbitrarily halved though!
You can't calculate CLR (or CE) without a serious hydrodynamics program, but if you estimate it graphically, you would expect the CLR to be behind the CE.
Both CE and CLR move according to heel, speed etc etc. Simple estimates are a useful starting point, not a lot more!
 
Hi I'm surprised at the lack of response to your question.I think that you do include the rudder in your CLR calculation as it is an active part of the lateral resistance. The rudder would be included in the LWL if it is continuous with the waterline. Ie if there is no gap between the rudder and the hull.
You can have an interesting time if you load up the free software for DELFTship at:
http://www.delftship.net

There is a procedure where you can put a profile of your own boat in the background and drag the computer generated model to fit. You then have all the data available.
 
Thanks for your replies - and yes, it was more of a graphical estimation than a calculation! I wasn't planning to go anywhere special with the calculations, just satisfiying my own curiosity, initialy brought on by a particularly fraught afternoon when I over-reefed the mainsail and discovered I was unable to tack!
I have looked at the Delfship program before; now that looks like some serious displacment activity! I'm saving that for a very rainy day!
 
No I don't think so...
LWL is about the hull form and wavemaking, so transon hung rudder would not be included.
LOA generally excludes pulpits and rudders in rating speak, but includes everything in marinaspeak.
 
[ QUOTE ]
OK - I'll forget my profession..... /forums/images/graemlins/grin.gif

Marina-speak is a different language I agree ... where they will measure everything to gain that last penny.

[/ QUOTE ]

Not sure what you mean? I would have thought most of your professional type vessels would have the rudder under the hull not transom hung, so would be within LWL? I assumed the OP was talking about a transom hung rudder.
Int 14's and Moth's definitely don't include rudder in their 14 or 11 feet, but I guess they view from a different perspective anyway!
Cheers,
 
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