Subject: Re: [harryproa] Re: Can you cut a carbon mast in half, then repair it?
From: Rob Denney
Date: 4/29/2009, 9:52 AM
To: harryproa@yahoogroups.com.au
Reply-to:
harryproa@yahoogroups.com.au



G'day,

Definitely doable.  Not sure which wil be the first boat to use it, but there are 3 thinking seriously about it. 

Gardner.  Built it in one piece and if you ever shipo the boat, cut it in two and rejoin it using the same laminate as the mast on the outside of the join with a n overlap of at least 100 times the mast wall thickness plus tapering the laminate.  Not optimal, and may mess a little  with the bend characteristics, but won't break.

Certainly try the other rigs, it would be good to see how they worked and costed compared to the standard rig.

regards,

Rob

On Wed, Apr 29, 2009 at 8:55 PM, proadude <rbmaui@yahoo.com> wrote:


Hi All,I was away for a while...a long while,but I just got back and in to a very interesting subject-a two part mast!?...or,what Rob was talking about before,the telescoping mast!!I wonder what has happened to this idea,and I do think that this is the answer for the future free standing mast for the proa,and not only proa boats...so,what is the progress in this area Rob?Is it "doable?
Regards



--- In harryproa@yahoogroups.com.au, Mike Crawford <jmichael@...> wrote:
>
>
> A two-pat mast seems to be the best bet.
>
> A telescoping mast would also be a great fit, but that's a more
> complex design, and you would lost anti-turtle flotation in one half the
> mast. I do believe that a telescoping mast could be done, but I also
> wouldn't want to be one of the early adopters.
>
> Robert's idea of a gunter would certainly work. However, I'd
> personally rather have a rig that makes it easy to raise and stow the
> sails in any wind, either with roller-reefing or using slides/cars and
> lazy jacks. It would probably be more time-consuming to go from sail
> cover to gunter and back again, especially if single-handed.
>
> I'd have a pro design a two-part mast, though. There is some serious
> stress in an unstayed rig, and while it's easy to design for, it does
> have to be designed for. A joint introduces other stresses, so I'd want
> it designed by a professional who has access to good Finite Element
> Analysis software.
>
> Cutting a mast and rejoining it could be done, but it probably
> wouldn't be pretty, and more importantly, you'd lose the ability to pass
> stress through nice, long, continuous carbon fibers. That said, if the
> patch were thick enough and long enough, it could work. I'd still want
> someone to do FEA, though, to make sure how long and thick the patch
> would have to be.
>
> - Mike
> / /
>
> Gardner Pomper wrote:
> >
> >
> > Hi,
> >
> > Still trying to figure a good rig for a boat that wants alot of sail
> > area (Rare Bird-ish), but can still be shipping in a container. The 2
> > part masts sound doable, but difficult. I was wondering if it makes
> > sense to just build a regular 1 part mast, 50-60 feet long, then cut
> > it in half, if I do end up shipping the boat in a container. It will
> > cost at least $6000 to ship the boat, so I can't imagine doing it more
> > than 2-3 times in my life (who knows, maybe I never will). Does it
> > make sense to just cut the mast, stick it in the container and then
> > repair it at the destination?
> >
> > Thanks,
> > - Gardner
> >
> >
>


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