Re: [harryproa] Re: BD sailing

We will probably have them at the edges of the board near the waterline.

For pulling it up out of the water that may be less than ideal.

Traditionally there is an uphaul fixed at the leading edge as far away from the pivot as possible.

This means there is a line in the water at all times.

If we need an extra uphaul at the tip of the board to lift the board out of the water we could let it go when sailing so it has least drag and pick it up out of the water when the board has to be pulled up. This is what the early fishermen did over here with their leeboard uphauls when they went home in a hurry.

I will post some photos when the board is in place.

Rudolf

----- Original Message -----

From: k_s_oneill

To: harryproa@yahoogroups.com.au

Sent: Monday, October 26, 2009 4:34 AM

Subject: [harryproa] Re: BD sailing

I am very interested in how you arrange the control lines. Any drawings or pics you post would be greatly appreciated. I'd be glad to post a drawing of how I run the leeboard control lines on my boat, but it sucks, it would only be a guide to what to avoid.

Kevin

--- In harryproa@yahoogroups.com.au, "Rudolf vd Brug" <rpvdb@...> wrote:
>
> The guards keep the board parallel to the cl and prevent drifting sideways.
> They are just pieces of wood glued to the hull. The lower one taking the sailing loads, the upper keeping the board from floating sideways. The lower guard could end up 3m long in the final version so it supports the board at variable angles.
>
> rudolf
>
>
>
> ----- Original Message -----
> From: robert
> To: harryproa@yahoogroups.com.au
> Sent: Sunday, October 25, 2009 12:19 PM
> Subject: [harryproa] Re: BD sailing
>
>
> On second thoughts,
> With a pin at that position to hold it, why does it need the guards?
>
> --- In harryproa@yahoogroups.com.au, "Rudolf vd Brug" <rpvdb@> wrote:
> >
> > Hi,
> >
> > The owner agreed to experiment a bit more with the board.
> > We will repair the leeboard and have the pivot right between the upper and lower guard.
> > That way the leeboard will not move away from the hull.
> >
> > Regards,
> > Rudolf
> >
> > ----- Original Message -----
> > From: rob
> > To: harryproa@yahoogroups.com.au
> > Sent: Monday, October 19, 2009 4:04 AM
> > Subject: [harryproa] Re: BD sailing
> >
> >
> > Hi Rudolf,
> > I am going to have to sit on this for a while to make sense of it. I feel all we can do is simply work empirically until we really understand it. ie rudders further apart, more to lw , bigger and /or centreboard. After I finish my marking I will have a bit more brain space to work on it and draw some clear pictures of all the possible forces. I don't necessarily think this will provide any solutions but will make my sleeping easier without it running around.
> > Now to go and drill some holes in some plywood strips to finish off the moulds.
> >
> > --- In harryproa@yahoogroups.com.au, "Rudolf vd Brug" <rpvdb@> wrote:
> > >
> > > Hi,
> > >
> > > I don't claim to have all the answers, but it seems that from a standstill the rear rudder does most work to get the boat to bear away. With just 2 rudders the aft rudder has to move the entire midsection of the boat across the water against the pressure of the sails. At this stage the forward rudder is somewhere near or at the pivot around which the boat is turning. So it doesn't steer the boat much.
> > > The leeboard compensates the sideways load and provides a pivot
> > > to turn the boat with the aft rudder.
> > >
> > > regards,
> > > Rudolf
> > >
> > >
> > > ----- Original Message -----
> > > From: rob
> > > To: harryproa@yahoogroups.com.au
> > > Sent: Sunday, October 18, 2009 1:08 PM
> > > Subject: [harryproa] Re: BD sailing
> > >
> > >
> > > On further thinking:
> > > I can't get an integrated understanding of all these points. Why further apart rudders allow the boat to sheet in and sail away as does a leeboard. I can't see why having the rudders further apart can make such a difference to simply angling the rig to a fairly fine angle, getting a lift and driving the boat providing there is enough rudder area. The only difference I can see is the distance to lw of the COE being a smaller prop0rtion of lever arm when using the wider apart rudders or the leeboard,
> > > regards,
> > > Robert
> > > --- In harryproa@yahoogroups.com.au, "Rudolf vd Brug" <rpvdb@> wrote:
> > > >
> > > > Hi,
> > > >
> > > > As I see it things seem to be pointing in one direction.
> > > > This is how I feel it works on bigger boats like BD.
> > > >
> > > > Rudders closer to the mast loose steering effect. Shunting is getting more difficult.
> > > > Rare Bird's and the old BD set up seems the minimum distance from the mast to steer well and sail
> > > > with acceptable rudder angle. Arttu's boat shunts easily with rudders further apart(5.3m)
> > > > The old set up didn't allow us to sheet in and sail away.
> > > > The leeboard we tried indicates that a central(ish) leeway preventer improves steering and shunting.
> > > > All this seems to lead to the conclusion the best solution is to have normal size rudders as far to the ends as possible with a leeboard or 'luffboard' next to the mast. Rudders have to be kick up and the front one lifted out of the water always. As they have to be near the ends I would prefer in hull rudders. I am working on those, it seems possible.
> > > >
> > > > regards,
> > > > Rudolf
> > > >
> > >
> >
>

__._,_.___

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