Subject: Re: [harryproa] Re: Predicting performance?
From: Gardner Pomper
Date: 5/28/2010, 11:38 AM
To: harryproa@yahoogroups.com.au
Reply-to:
harryproa@yahoogroups.com.au

 

Ok, I both of you guys think it is a good idea, I will take another look. You always seem to have very sound reasoning and good experience to back it up.
 
I am going to try to get my plywood daysailing proa mostly finished this weekend, and try to get it in teh water in a couple weeks. I have windsurfer masts and sails for it, which is what I am going with first, but it would seem like a good test platform for a different rig.
 
So, a couple questions: those internal frames look like alot of work. Is there any reason that I can't make them out of cored panels? I can pad the edges with soft foam to keep from chafing the sails. They would be really quick to just cut out of a larger cored sheet. If any flex is required, it would seem like it would only be at the leach, and I could use a short hinged stick there (just a foot or so), so the the internal frames are in 3 pieces instead of 2, and still save a ton of labor and weight.
 
Second question: how would I figure the panel shapes to make the sails?
 
Thanks,
- Gardner

On Fri, May 28, 2010 at 9:17 AM, Mike Crawford <jmichael@gwi.net> wrote:
 

Robert,



<< you could get away with rice bags and still have a reasonable shape>>

  Precisely!  I'm not sure if it would be a premium racing rig, but while cruising, it seems to me that the average sail shape, particularly in light winds, would be superior to a bermuda rig. 

  To get the right sail shape with a single skin takes time, in terms of adjusting leech/outhaul/vang (no vang with fixed boom), and money, in terms of sail cloth, track, and battens. 

  Plus, the battens that work at 40 knots will be to stiff for five knots, and the battens that work at five knots will be too flexible for 40.  I'm tired of yanking on my boom to get the battens to switch over in light winds.  I like to sail, but I'm not the kind of guy who would keep three sets of battens on hand in order to have just the right strength for the day's winds.  So I have a medium-stiff set that functions in all winds, but really isn't good for light or heavy weather.



<<The strings need not be a big source of drag with dyneema but one would need some gloves.>>

  Agreed.  Though I'd probably try to use dyneema on all the individual lines, feeding into a single wider-diameter mainsheet (one shet per bow, of course) that would be easier to handle and cleat.



<<Some people swear by junk rigs and this makes more sense to me than a straight junk.>>

  Particularly if you want to go upwind.  I'll daysail much more often than I go cruising, so going upwind is a big deal.  A friend of mine says one spends 70% of one's time sailing upwind, and I have to agree.  If I just go out and back for the day, the windward phase is noticeably slower, and covers a lot more distance, than the leeward phase.

        - Mike



On 5/27/2010 7:29 AM, robert wrote:
 

Hi Mike
I am with you on this rig: you could get away with rice bags and still have a reasonable shape; the sheet loads are lighter; it's easily reefable; if the top section rotted out, it would be easy to replace without wrecking the lines of the sails; there's no sail track to buy or jam; and the battens can be low tech. The strings need not be a big source of drag with dyneema but one would need some gloves. I will have to make up my mind before I start trying to set up for making the masts. A simple tapered section makes the most sense and it wouldn't need the bearings of a lot of other rigs.
Apart from not being common I am not sure what the problems with it are for a cruising rig. Some people swear by junk rigs and this makes more sense to me than a straight junk.
Robert



__._,_.___
Recent Activity:
Visit Your Group
.

__,_._,___