I use a single Speer foil leeboard. I outlined how it works earlier. Laurent C. has twin daggerboards, which you can see here starting at about twenty seconds:
http://www.youtube.
Since they face different directions and only work on one tack they don't have to be symmetric on any axis. His are a NACA foil which has a "twist" in the tail, and the slots are angled a few degrees to windward. They're balsa core and carbon, made by a professional foilmaker (Phil's Foils? I'm not sure). Very stiff and light.
One thing to think about on a Harry is the jib boom hitting the forward (up) board. On an una rigged Harry I think it would be fine, it seems to work fine on his boat, but they have to be handled on each shunt. That's the only way I can keep up with him to windward, since my leeboard doesn't require any movement on a shunt I shunt faster than he does, even with two sheets vs one.
Again, this is only one example and I'm not trying to be a know it all, just thought it might be interesting to see before you spend money on stuff.
Kevin
--- In harryproa@yahoogrou
>
> Hi Arrtu,
> in light of Rudi's work with a single leeboard,
> is there any reason not to have just one and reduce work in a shunt and the extra drag of the extra slot in the bottom,
> regards,
> Robert
>
> --- In harryproa@yahoogrou
> >
> > Hello,
> >
> > We have two rudders 0.5x1.2m. We were able to sail over the Baltic and
> > back home with our setup. Upwind sailing was possible and the more wind
> > (speed)the easier it was. With both sails up we were able to sail higher
> > up to the wind. Upwind sailing with main only was easier when reefed,
> > better sail area/foil area ratio. The angle was poor when reefed, but
> > shunting was no problem. We had wind about 25knots.
> > Fast downwind sailing was also a bit uncomfortable. When the bow
> > submerged the stern tried to wander sideways. The helmsman had to stay
> > alert.
> > Light wind shunting is tricky.
> > I am going to add performance and make life easier by building two
> > daggerboards 1.5x0.5m symmetric sections. They will be situated +-1.8m
> > from the mast next to hatches. They are a going to be canted outwards
> > going thru the hull bottom in the center line. The daggerboard case will
> > make stairs down in to the hull.
> > Bulkheads for safety are needed.
> >
> >
> > Regards,
> >
> > Arttu
> >
> >
> >
> >
> >
> >
> >
> > > Hi,
> > >
> > >
> > > The second time we raised the jib I purposely kept sailing the same
> > course -close reaching- and didn't change the sheeting angle.
> > > Speed was something like 8 knots. The jib was hoisted while sailing.
> > The power and speed increase was noticeable, and along with it the boat
> > went out of control.
> > > I think power of the sail will always push the bow down causing the
> > bow to be the deepest part of the hull.
> > > Maybe the bow acts as a pivot in that situation and causes the boat to
> > turn upwind without lots of leverage at the other end?
> > > Another thing I noticed was that the front rudder had load on. In the
> > old set up the front rudder was hanging loosely in it's casing. We were
> > able to lift it at speed which I remember well as I was surprised by
> > that.
> > >
> > > regards,
> > > Rudolf
> > >
> > > ----- Original Message -----
> > > From: heinrich_meurer
> > > To: harryproa@yahoogrou
> > > Sent: Thursday, October 08, 2009 10:35 PM
> > > Subject: [harryproa] Re: BD sailing
> > >
> > >
> > >
> > >
> > > I was wondering why the problem increased with the jib put up. One
> > would expect the opposite. So what you are saying is that when you put
> > up the jib the bow gets more depressed while sheeting in moving the
> > lateral trim of the hull forward? Would the cure then possibly be to
> > sheet in very slowly to keep the bow up? Did the luffing become more
> > managable once you were up at speed?
> > > Heinrich
> > >
> > > --- In harryproa@yahoogrou
> > > >
> > > > Hi,
> > > >
> > > > The things that changed are :
> > > > Distance rudders from centre was 4600MM, now 3800MM. Also they moved
> > sideways 800MM to ww.
> > > > Fitted the electric drive with batteries weight max.
> > 120kgs.(probably less)
> > > >
> > > > Rudders are smaller but the other setup worked also with blades
> > partially raised.
> > > > Also we sailed with only two of us, with the old set up there was no
> > problem sailing with six persons sitting in the cockpit, so well to ww.
> > > >
> > > > Thanks Robert, yes I was thinking just that. I am going to try to
> > temporarily fix an old rudder blade in the middle as a dagger board. I
> > think the bow down attitude of the boat with full sail up might be the
> > cause.
> > > >
> > > > regards,
> > > > Rudolf
> > > >
> > > >
> > > > ----- Original Message -----
> > > > From: Rob Denney
> > > > To: harryproa@yahoogrou
> > > > Sent: Thursday, October 08, 2009 11:08 AM
> > > > Subject: Re: [harryproa] BD sailing
> > > >
> > > >
> > > > G'day,
> > > >
> > > > Very disappointing. Could you make a list of the things that have
> > changed, please, so we can try to figure out the problem. eg, sails,
> > rudder location, rudder size, weight in ww hull, differences in water
> > drag, etc etc.
> > > >
> > > > Ta.
> > > >
> > > > regards,
> > > >
> > > > Rob
> > > >
> > > >
> > > >
> > > > On Thu, Oct 8, 2009 at 3:14 PM, Rudolf vd Brug <rpvdb@> wrote:
> > > >
> > > >
> > > >
> > > > Hi,
> > > >
> > > > Yesterday we have been out sailing BD with the new rudder set up.
> > > > Wind about 16 knts. After hoisting the sails we pulled the sheet and
> > the boat luffed.
> > > > Pulled the other sheet to get the right bow pointing downwind and
> > sheeted in again, the boat luffed.
> > > > After a few attempts I descided to take the jib down, and we got her
> > going.
> > > > Rudder angle was about 10 deg. so no high speeds.We tried shunting
> > and we had to get BD going really downwind to be able to build up enough
> > speed to keep her from luffing straight into the wind.
> > > > After some time we set the jib while sailing on a close reach. Once
> > the jib started pulling the boat luffed into the wind the rudder only
> > putting the brakes on.
> > > > We took the jib down and proceeded without it. The front rudder has
> > to be pulled up at least half way to keep the rudder angle 'down' to the
> > 10 degres I mentioned. Front rudder all the way down makes it hard to
> > keep the boat from luffing into the wind.
> > > > We also tried the front rudder tilted out of the water entirely
> > which made made for very nervous steering behaviour.
> > > > Returning to the marina we were very disapointed.
> > > >
> > > > As we brought BD to the marina after the launch we had to negotiate
> > some bridges and a lock all less than
> > > > 1 metre wider than the boat. I noticed that steering was less
> > precise compared to the old set up. Reaction is slower and seems more
> > abrupt, probably because the late reaction causes one to turn the rudder
> > further than usual.
> > > > Reactions please,
> > > > Regards,
> > > >
> > > > Rudolf
> > > >
> > >
> > >
> > >
> > >
> >
>
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