Thanks for the summary Nol. It's good to hear Blind Date is sailing more like it's supposed to. It's a little lighter than Rare Bird, so should sail faster, so better than 16 knots with little better than 20 knots of wind. I expect that will be achieved if the rig is optimised.
By the way, Rare Bird's only rudder problem was the breakage of an undersized and corroded rudder shaft. Prior to that the sailing was relatively effortless. Rebuilding of the rudder cassettes and shafts is now complete.
We expect to be sailing again in the next few weeks as time permits.

Cheers,

Col Campey

Rare Bird

--- In harryproa@yahoogroups.com.au, "Nol Twigt" <noltwigt@...> wrote:
>
> Blind Date developments,
>
> This is a message from the Blind Date in the Netherlands.
> I am chairman of the technical committee that was formed in April 2010 to improve the sailing performance of the Blind Date to it's full capacity.
>
> In 2009 the original rudders of the Blind Date were replaced because the construction was too light.
> The rudder blades twisted and there was so much torsion the rudder house (is that is the proper word in English?) that the disk on top got stuck in the limited room between the triangles that connect the rudder to the leeward hull. This made steering impossible. I understood that sistership the Rare Bird had the same problems.
>
> In 2010 new rudders were built and installed. These rudders were smaller (rudder blade 40 x 150 cm instead of 50 x 200 cm) and they were placed on the beams, closer to the center of the ship.
> This turned out to be a bad idea. Steering and shunting became very difficult. In winds stronger than 24 knots the ship would turn it's nose into the wind, no matter what the helmsman did.
>
> The reason for this behavior was that the COE (Center Of Effort of the sails) was behind the lateral point. Reduction of the surface of the back rudder reduced it's influence. Moving the rudder to the beam moved the lateral point to the wrong side of the COE.
> The Blind Date sailed with both rudders in a 30 degree angle steering down wind, which was really horrible. It felt like the handbrake was on and there was nothing we could do about it.
>
> The whole situation of 2010 was very discouraging. The Blind Date project was in financial problems because building the ship had taken much more time (=money) than was calculated.
> Financially not yet recovered, the new rudders had cost somewhere round 30.000 euro's.
> It was very painful to conclude that these rudders did not work properly and would probably never never do their job. In that situation the main sponsor withdrew from the project.
>
> For some weeks I invested all my spare time making an animation that explains why the new rudders made steering hard in light winds and impossible in strong winds.
> Since there was no money for a better rudder design, the only option was patching up the old rudders and placing them back.
> Blind Date builder Rudolf reinforced the old rudder blades with a strip of carbon. I placed external ribs on the diagonals of the rudder houses. Round the outside of the ribs I wrapped lots of unidirectional carbon. I will place pictures on this website as soon as I found out how that works.
>
> The result so far is that the 'new old rudders' work well in the light to moderate winds we had.
> The ship sails neutral with the back rudder working like a daggerboard. There is hardly any pressure on the front rudder. In this way of trimming it works best when the front rudder is used for steering.
>
> The speed of the Blind Date is still a bit disappointing. The ship is just a little faster than most monohulls, but not much. We reached 10 knots in 18 knots wind.
> According to the calculated Texel Rating of 115, the Blind Date should reach an average between 13 and 14 knots in these circumstances.
> My impression is that the rig is responsible for the lack of speed. In september we will improve the rig, together with the sailmaker.
>
> I am quite happy with the ship as it is now, however I agree with builder Rudolf that it would be interesting to build a new leeward hull with a little more curve in the bottom line. This will help the nose to stay above the waves and it will make turning easier. Rudolf and I also agree that it would be better to place new retractable rudders close to the bows, so they can be smaller and lighter.
> I like Rob's idea to replace the aero rig by two mainsails with the masts placed in the leeward hull, close to or even right on the beams. With this schooner rig the Blind Date can be steered even without rudders, which would make it suitable for shallow waters.
> I guess it is always good to have dreams…
>
> We realize that now, roughly 10 years after the Blind Date project started, we have finally reached the point where the ship sails in the way it was designed. All initial problems are solved. Many technical and financial difficulties were overcome.
> Thanks to Rob Denney we have a very remarkable ship that inspires creativity. Thanks to Rudolf van der Brug it is very well built. The combination of innovation and skills draws a lot of positive attention, which makes the Blind Date an interesting object for sponsoring. And last but not least the Blind Date functions very well for guests with a visual handicap, the target that initiator Jan Schippers had in mind. Jan showed a great amount of tenacity bringing his project to this point.
>
> Any step that we take from here will make it better than it was originally designed.
> In practical terms, in 2010 we had to do with two limitations. We could not use the ship in winds stronger than 24 knots and we could not sail in shallow waters.
> The priorities of the Technical Committee are to take away both limitations.
> The 'new old rudders' took away the first limitation. I think we can handle any wind now, within reasonable limits. As a result we can do a lot more sailing and chartering.
> The next challenge is sailing in unknown shallow waters, taking the Blind Date on longer trips. Hitting the bottom should not damage the ship or make steering impossible. In the traditional Dutch flat bottom yachts you can see that this quality is very important for sailing in the shallow waters that we have in the Netherlands.
>
>
> to be continued,
>
>
>
> Nol Twigt
>
>
> --- In harryproa@yahoogroups.com.au, Rob Denney <harryproa@> wrote:
> >
> > From the guys on Blind Date.
> > Hi Rob,
> > Today we made our first trip with the renewed old rudders on the Blind Date.
> > They seem to work well.
> >
> > The windspeed started and ended almost zero. In between it increased
> > to 20 knots.
> > It felt as if we would need to reef the main sail if it would increase more.
> >
> > The ship feels totally different.
> > It used to have a will of it's own, specially in stronger winds.
> > Now it listens and it speaks to the tillerman. It forgives minor
> > mistakes in steering.
> > Shunting works well. The rig forces seem to be overruled easily by the rudders.
> >
> > I think the ship works like you intended now.
> > I congratulate all who are involved!
> >
> >
> > Nol
> >
>