Hi Rob,
All the discussion about round CF masts ,omer wing sail etc.has set me to thinking . I like simplicity of an unstayed mast and the easy management of the junk rig sail especially at sea. But how to keep the steering simple?
So I was thinking a two mast omer style rig where the carbon masts are built with a rudder /daggerboard on the bottom of the mast or attached to an existing rudder/ daggerboard.. When you shunt and turn the sails one becomes the other and away you go. It would still incorparate dual wheel steering for obvious reasons . An articulated rudder could be added for better response.
So there you go, I think there is merit to this idea. I don't think the
complexity of going through the bottom of the hull would be any different than a regular rudder.
The compexity of running a Harry proa would certainly be allieviated .
Best Regards,
Peter
Materials cost is higher on the wing if it has a sheer web and/or foam cored sides. This is partially offset by needing less carbon as it is a thicker section and the load bearing shape is square rather than round.
The wing also has more labour, for pretty much the same reasons.
Food for thought: Last weekend we had 50 knot gusts and sustained 40 knots. El is moored to a jetty out the back of the house so may not have seen this much, but at one stage the breeze was funnelled between 2 houses and it was hooting. The wing mast (6m above the deck) was bending a bit, and with me sitting on the ww hull it was lifting it and the loads on the mooring lines were higher than I could hold. If it was not tied to the jetty, it would have capsized.
rob On Fri, Feb 1, 2013 at 12:52 AM, fvonballuseck <fvonballuseck@gmail.com> wrote:
Hi Rob
does that mean that price difference between wingmasts and round masts would come down .... or am I being optimistic here?
Fedor
--- In harryproa@yahoogroups.com.au, Rob Denney wrote:
>
> >
> > ****
> >
> > Rob,********
> >
> > I think you have seen this already:********
> >
> > http://www.onesails.com/wingsails.php********
> >
> > My question is would the round section mast be easier/cheaper to build
> > than the normal D section like you have been doing? Notice the diameter is
> > the same all the way up, could you make this by going over a pvc pipe
> > mandrel or such? I think it would be hard to keep the carbon in line
> > though. Maybe an open mold would be better?********
> >
> > Thanks,********
> >
> > Jerry Barth****
> >
> >
> We are building round and wing section masts, not D's, although there is no
> reason why we couldn't. Non tapering is more windage when reefed and
> probably more weight aloft as the wall thickness at the top is at the
> minimum for both tapered and non tapered.
>
> Male mandrels are lousy unless you have a very good filament winder (ie
> machine, not hand) as the fibers do not get laid tightly so get out of line
> when the bag or wrapping is applied. The off axis layers also get crimped
> as the diameter is reduced under pressure. Building it in 2 pieces in a
> female half mould and joining them would be a better job, and in one piece,
> much better. If the mast is more than say 10m long, then either infusing a
> dry laminate or pressure moulding a wet or prepreg one would be preferred.
>
> rob
>
> > **
> >
> >
> >
>
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