Subject: Re: [harryproa] Re: Gaff easyrig?
From: Mike Crawford
Date: 3/23/2009, 3:15 PM
To: Gardner Pomper


  You are completely right.

  But then the mast may have to deal with compression, bending, and torsion from the top down at a concentrated point.  That's a different mast design, and will require a much beefier mast with more cross section higher up.  It's not the end of the world, but it does get away from Rob's smaller-lighter-simpler-faster design theory.

  I personally also like the idea of fewer points of concentrated stress, as well as fewer points for failure.

  That said, I *love* the wharram gaff-rigged soft wing sail.  I just haven't yet figured out how it could work well on a harryproa (both physically as well as aesthetically). 

  My other great boating desire is a Wharram Tiki 38.  Unfortunately, while it can do 15 knots lightly loaded, it will never compete with a harryproa, has many more points of failure, will cost more to create, and won't be demountable and transportable in any realistic sense.  I'd actually rather have the Tiki in many ways, but some some of these criteria are showstoppers that prevent it.

       - Mike
 

Gardner Pomper wrote:
Actually, I thought that this might help the jib luff tension, because with a top gaff, you could run a stay down behind the main leech and have a counterbalancing pull there. I assume the problem with the easy rig is that the masthead gets pulled forward upwind and the jib luff luffs.

- Gardner


On Mon, Mar 23, 2009 at 2:23 PM, Mike Crawford <jmichael@gwi.net> wrote:

  One other item which I won't bother adding to the group:

  Jib luff tension would be an issue with a masthead jib boom.  Downwind that area high up would be great.  Upwind, the tension would put huge loads on the mastead boom, which might not be able to keep the luff taut enough for good performance.  The easyrig is already challenged in terms of luff tension (need to balance it with mainsail leech tension, as with some lightweight catamarans), and this would make it moreso.

       - Mike
 
 
Gardner Pomper wrote:

Ok, thanks all. I think I understand better now. It seems to me that the basic response is that you can get a relatively rectangular main from other methods, requiring less complication and weight aloft. My idea with the masthead boom was to increase the size of the headsail to 75% or so of the main, but it doesn't sound like the headsail is important enough to change systems.


Thanks to all. I do want to go sailing, not do research, but I am also always on the lookout for new ideas, which is how I ended up on this forum anyway.

- Gardner

On Mon, Mar 23, 2009 at 10:30 AM, Mitch <mitch.sailing@gmail.com> wrote:

Hey folks,
I think you're underestimating the versatility of carbon - specifically battens. if you look at what development classes are doing (AC, Int 14s, many multis) there's no traditional gaff, with an uphaul, etc, but there is one big batten that acts like a gaff to the sail and makes the main close to rectangular.

The other thing I learned after 15 years of sailing Int. 14s as a development class - is to hold the innovations down to a reasonable number so you know what actually is working.  If too much is new/innovative, you don't have a control point to compare to. Pick one area of innovation - Hull, Rig, Sails, Foils, and work to optimize them before you try the next part of the equation. And don't forget that the software is likely the most important part of the entire package!  Time in the shop is not time sailing.
Greg



On Mon, Mar 23, 2009 at 6:34 AM, Gardner Pomper <gardner@networknow.org> wrote:


I looked at the web pages some more, and it looks interesting. By having an "uphaul" from the top of the mast, it looks like you can make that top boom alot lighter, since the ends are supported, and you can raise and lower it. Plus, it has a little sailtrack to make the jib self tending at the top as well.


Think this helps get around enough of the weight aloft issues to be worth while?

- Gardner

On Mon, Mar 23, 2009 at 8:47 AM, Gardner Pomper <gardner@networknow.org> wrote:
Hi,

Thanks for the link. That is pretty much what I was talking about, although I thought it would end up with a bigger jib.  I thought I had seen something like this somewhere, but could not remember where. I noticed that he has a drawing of a 54' motorsailer, with about a 40' mast on it. I'll have to send him a note to see if it ever got built.

- Gardner


On Mon, Mar 23, 2009 at 8:33 AM, pkeck2 <pkeck2@yahoo.com> wrote:

Not sure if you've seen these, or if they were mentioned in another post...but someone did something very similar to what you're talking about, albeit on a much smaller scale:

http://balancedrig.com/

Phil



--- In harryproa@yahoogroups.com.au, Gardner Pomper <gardner@...> wrote:
>
> Hi,
> This is probably a dumb question, but what is the problem with a "gaff"
> easyrig? By this I mean an easy rig with a boom at both the top and bottom
> of the mast, so that both the jib and main are rectangular in shape, instead
> of triangular? Everything I read indicates that a triangular sail is
> inefficient, and that more sail area higher up is better. I have seen solid
> wing sails in this configuration.
>
> I know weight aloft is a bad thing on a monohull, because it intensives the
> pendulum effect m the inevitable heeling, but on a multihull, which should
> never lift a hull (cruising, not racing proa) it doesn't seem like it will
> matter until you are in alot of trouble anyway. Plus, having a rectangular
> sail should lower the center of effort considerably, to keep you out of
> trouble.
>
> Anyway, basic explanations of why I am wrong would be appreciated <grin>
>
> - Gardner Pomper
>





__._,_.___
Recent Activity
Visit Your Group
Yahoo!7 360°

Start a blog

Public or private-

it's your choice.

Y!7 Toolbar

Get it Free!

easy 1-click access

to your groups.

Yahoo!7 Groups

Start a group

in 3 easy steps.

Connect with others.

.

__,_._,___