Subject: Re: [harryproa] Gaff easyrig?
From: Gardner Pomper
Date: 3/22/2009, 8:51 PM
To: harryproa@yahoogroups.com.au
Reply-to:
harryproa@yahoogroups.com.au

I am also wondering about how these weight aloft and stay tension arguments relate to the dynarig. I remember a fair amount of discussion of that rig when Todd was making R/C models using it, and it seems quite positive. Probably the strongest disadvantage was that it might not feather automatically. I was wondering if the automatic fore/aft canting that Rob is using with the Chinese rudders could also be used with a dynarig to shift a greater percentage of the sail area leeward of the mast?


Anyway, the dynarig has multiple "booms" along the height, as does a junk rig. Why it is ok with these rigs, but not with an easyrigh? Or isn't it ok with those rigs?

Thanks,

- Gardner

On Sun, Mar 22, 2009 at 9:59 AM, Gardner Pomper <gardner@networknow.org> wrote:
Hi,

Do you remember how heavy the boom on Rare Bird is? I would assume that one just like it, or maybe a bit lighter, would go on top of the mast. I can't attach images, I don't think, but here is ASCII art:

    bbbbbbbbbbbbbbbbbbbb
    |             M                 |
    |             M                 |
    |             M                 |
    |             M                 |
    |             M                 |
    |             M                 |
    |             M                 |
    |   jib       M     main     |
    |             M                 |
    |             M                 |
    |             M                 |
    |             M                 |
    |             M                 |
    |             M                 |
    |             M                 |
    |             M                 |
    BBBBBBBBBBBBBBBB
                  M
                  M
                  M

- Gardner

On Sun, Mar 22, 2009 at 3:07 AM, Rob Denney <harryproa@gmail.com> wrote:

G'day,

Gaff main sails are fine, but the weight of the gaff and the lump of
mast sticking up above the sail are both negatives. A gaff jib boom
needs to be pretty strong, so heavy.

regards,

Rob



On Sun, Mar 22, 2009 at 12:28 AM, Gardner Pomper <gardner@networknow.org> wrote:
> Thanks, I had not seen that. I have been leery of booms even before one hit
> my wife in the head, scaring everyone rather badly. One of the things I like
> about the harryproa is that it keeps the boom away from the crew.
>
> This picture is just a regular gaff rig main, though. I mean the easyrig,
> with both the main and jib on the same boom. Can't you put a mirror at the
> top of the mast to move away from triangular sails.
> - Gardner
>
> On Sat, Mar 21, 2009 at 11:19 AM, Kim Whitmyre <kwhitmyre@dslextreme.com>
> wrote:
>>
>> Gardner Pomper wrote:
>> > 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.
>>
>> Gardner, have you not seen the wingsail used on most of the Wharram
>> designs? It is exactly as you describe, with the exception of the lower
>> boom: it has none, but instead runs on a traveler between the hulls.
>> Here is a picture of my boat in the slip with the main up:
>>
>> wingsail <http://farm2.static.flickr.com/1023/1207431702_4244ed6a4e_o.jpg>
>>
>
>



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