Subject: Re: [harryproa] Re:: How to build hulls
From: "StoneTool owly@ttc-cmc.net [harryproa]" <harryproa@yahoogroups.com.au>
Date: 6/5/2018, 12:11 PM
To: harryproa@yahoogroups.com.au
Reply-to:
harryproa@yahoogroups.com.au

 

    High aspect ratio obviously is a good thing, until you look at the negatives.   On a cat, you have only so much righting moment, and they do NOT come up from a knockdown as a rule.... depending on the degrees of the knockdown.   The other negative is the rate at which the strength and weight must go up on a free standing mast as the height increases.   The leverage is all concentrated against the mast partner.... The longer the handle, the greater the stresses.    A  monohull has the safety valve of heeling and dumping wind energy by reducing sail area as it heels.  The multihull has far less margin of safety.
    This of course is all amplified when single handing.  It's a big factor in how much sail one dares to carry under any given circumstances.  

                                                                                                            H.W.


On 06/05/2018 09:14 AM, '.' eruttan@yahoo.com [harryproa] wrote:
 



| Didn’t mean size - should have been clearer, I was referring to aspect ratio. I think junk rigs tend to be short because they hoist too much hardware and lines (and weight) aloft.

Interesting. I had not considered that.
How much heavier is a junk rig?

But even so, as I understand wings, and to a lesser degree, sails, one is better with a higher aspect ratio than raw square footage, and, if one moves to a more square planiform, one drops the effective coefficient of lift, for the same foil.

I had assumed most junks had low aspect ratios because they were refits for existing masts. Or the mast choice was restricted

If one can build ones own mast, and wanted to fit a junk rig, could one not raise a higher aspect ratio, higher performing junk for almost the same weight as short square one? Probably have a lower or identical com and coe too?


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Posted by: StoneTool <owly@ttc-cmc.net>
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