Subject: [harryproa] Re: Gaff easyrig? |
From: Mike Crawford |
Date: 3/24/2009, 10:42 AM |
To: harryproa@yahoogroups.com.au |
Reply-to: harryproa@yahoogroups.com.au |
Yes, I do keep coming back to the dynarig. It is appealing. I am,
however, concered about how it will behave if caught aback. I hope to
build a small one for my test proa this summer (if I ever get the
rudders and crossbeams built). This balanced rig is designed to work with the wind from either
side of the sail as for the Easyrig. The Maltese Falcon appears to get
much of its benefit from being single sided - that is the wind only
works on one side of the sail. This allows the sail to be asymmetric
with permanently curved spars.
I worry about what will happen with a dynarig during a shunt when the
wind picks up.
With an una rig or easy rig, you can go completely neutral by
loosening the mainsheet and allowing the rig to weathercock. At any
time, at any point of sail. This is one of the reasons why I'm a fan
of a proa with an unstayed rig; no matter what you're doing, you can
quickly stop dead with a neutral rig, and/or back up.
With the dynarig, the full area of the sail goes perpendicular to the
wind during a shunt. That might not be a big issue in moderate winds,
but if you get a gust at that moment, especially if the ww hull is on a
wave, the results could be most unsavory. Even if you don't get
knocked down, that's a lot of stress on the rig when the boat isn't in
a position to defuse that stress by sliding leeward.
An illustration of this is at:
http://au.groups.
The group discussed this a bit last summer, but I don't recall anyone
offering a logical argument as to why the dynarig would be safe in this
situation. There were opinions about it not being a problem, of
course. Todd was most in favor of the rig, and said that it was not a
problem during his many tests (which were a great addition to this
group; I'm sorry he's not yet participating again).
The Maltese Falcon can deal with this in one of two ways. Either:
a) turn only one mast at a time -- it's a huge ship, and can easily
handle 1/3 of the sail area going perpendicular to the wind, or b)
press a button, furl the sails, turn the masts, and then press another
button to unfurl.
Given that a fast/light/inexpens
Then there are the issues of weight aloft, concentrated points of
stress at the battens, added complexity, and less-convenient furling.
I'd love the efficiency of a double-sided sail with perfect camber,
but my spending will likely vote with a system that is much simpler.
It's hard to beat a mast with a bolt rope luff for sheer simplicity and
ability to repair damage one's self. Reliable track and slides/cars
follow closely behind.
- Mike
Gardner Pomper wrote:
I do like the thought of an asymmetric sail on an asymmetric hull (a
proa).
--- In harryproa@yahoogrou
>
> This balanced rig looks a little like the modern iteration of the
square rig
> used on the Maltese Falcon (http://www.symaltes
> sail centred on an unstayed mast. In fact the Hoyt balanced rig
previously
> discussed on this forum (http://www.garryhoy
> like a square rig, albeit a little asymmetric..
>
> Geoff Lowe
> Infotools Limited
> +64 9 488 1772
>