I did a quick 'back of fag packet' check on the Kingfisher 20 with JR and again found that it would probably suffer from weather helm. Chris E has confirmed this, so it seems that the information being used in the early days was not so good, and and it would appear that the designs weren't adjusted after the first ones were built. Pity, but now we seem to know and perhaps not replace aged bits with the original copies. It should be possible to draw a cambered rig with enough balance to get a better sailing experience without moving the mast.

Has anyone sailed a Bermudan Kingfisher 20, and if so, did it suffer from significant weather helm? If not, then it would appear to be the JR and not the hull, as Edward questioned.

Cheers,  Slieve.

Michael, moving the rudder to the transom will not necessarily move the CLR aft. I know Paul suggests including the rudder in the CLR calculation, but as the rudder moves it is not a constant and therefore not everyone includes it. However I believe moving the rudder to the end of the waterline should improve the effectiveness of the rudder, and if partially balanced should give a better sailing experience.

Slieve.

Slieve McGalliard wrote:

Thanks for the photos Mike.

Personally I've never been 100% comfortable with PJR's method of establishing lead, even though it is a well established procedure. The actual Centre of Pressure on a flat junk sail seems to be further aft than that of a cambered sail, so that positioning the Centre of Area with a fixed lead over CLR (or more correctly CLA) of the hull will not necessarily give a consistent result. From the available photos it appears that the C of A of Emmelène is further forward than that of Butterfly, and if the C of E is further aft on the flat sail then it is to be expected that Butterfly will have more weather helm than the split rig boat, which apparently has near neutral helm. The question must be that although Buttercup is manageable and enjoyable to sail, could it be significantly better if adjustments to rig balanced were brought closer to the more modern thinking?

When Blondie and Jock wrote their most excellent book, PJR, they were working on remarkably little information. The boat designers who tried to produce boats using such information had little to go on, and as we know their boats had advantages, but the performance was not outstanding. Many years later we have the advantage of all the JRA newsletters and the easy flow of information (and miss-information) with our high speed communications, and therefore have a big advantage over the early pioneers. We are not arrogant, but we are much better informed and should use that information. Perhaps now is the time to re-evaluate those early designed boats and rather than updating parts of the rig to the original specifications we might gain from using our new found knowledge to apply the latest thinking and see if we could achieve the full potential of the boats.

We know we are able to produce rigs that fully compete with the well developed Bermudan rigs, so it would be good if everyone could benefit.

Rags Nierop designed nice boats and their owners like them, but somehow the junk rigged versions seemed to miss the mark. Kingfisher's rudder extension appears to be a sticking plaster attempt to solve a weather helm problem on the K26JR, whereas placing the rudder at the end of the waterline would undoubtedly improve the steering, and re-balancing the rig might produce something really special. Perhaps Richard is experiencing the start of this with his experiments on Tammy Norie.

We live in exciting times.

Cheers, Slieve.

Thanks Slieve, some good points to ponder.

Cheers, Michael

Slieve McGalliard wrote:

Hi Michael,

No, not intended to be arrogant. But questioning, yes.

I did say that the diagrams that I had measured were not necessarily accurate, and that I did hope that I'd made a mistake. I am also hoping that this will encourage others to look at the designs to check my crude calculations. There do seem to be those who accept poor performance from their rigs, and it is interesting to see that Richard in Tammy Norie may be getting improved performance by adjusting his rig away from the original set up.

The fact that Chopsticks became virtually unmanageable when a professionally designed and built rig was fitted, and received rudder surgery to bring it under control does ask questions. From the information I got after the event it seems that the problem fell between mast position, sail balance and camber shape so the rudder surgery may have been one solution but not necessarily the one to bring out the full potential of the boat.

It's interesting what you say about Butterfly. Can you give details of your present rig as it might help us understand what is going on? Mast position, Rig type, Flat/ cambered, how cambered, total area, controls, etc? 

There is a lot to learn, and it is only by asking questions that we will gain knowledge.

Cheers, Slieve.

Hi Slieve, I didn't mean you! I meant all of us. It is beyond my mathematical ability to do more than a simple cut out and balance to get CLR, same with the CE. I'll try and put a photo of the flat cut old style sail on my page together with a drawing enlarged from the brouchure Did it! photos of sail and my finding CLR cut outs on my member file Hope people can see it  

Mike

Hi Michael,

No, not intended to be arrogant. But questioning, yes.

I did say that the diagrams that I had measured were not necessarily accurate, and that I did hope that I'd made a mistake. I am also hoping that this will encourage others to look at the designs to check my crude calculations. There do seem to be those who accept poor performance from their rigs, and it is interesting to see that Richard in Tammy Norie may be getting improved performance by adjusting his rig away from the original set up.

The fact that Chopsticks became virtually unmanageable when a professionally designed and built rig was fitted, and received rudder surgery to bring it under control does ask questions. From the information I got after the event it seems that the problem fell between mast position, sail balance and camber shape so the rudder surgery may have been one solution but not necessarily the one to bring out the full potential of the boat.

It's interesting what you say about Butterfly. Can you give details of your present rig as it might help us understand what is going on? Mast position, Rig type, Flat/ cambered, how cambered, total area, controls, etc? 

There is a lot to learn, and it is only by asking questions that we will gain knowledge.

Cheers, Slieve.

David Tyler wrote:

Slieve McGalliard wrote:

As with the Coromandel, I have just run the measuring stick over the few rough Kingfisher 26 drawings I could find and again seem to find that the junk rigged version has heavy weather helm built into the design. Are we to assume that those who planned these rigs had no regard or understanding of rig balance, and probably worse, that those who have been sailing them have not questioned the balance and performance?

If this is the case, are we going to find that a lot of the other older professionally rigged junks are also suffering from the same malaise?

I just hope that I've made a mistake somewhere, and that this is not the case.

As for the coromandel, please show your drawings and calculations. I own one (Butterfly) and she has a little more weatherhelm than my previous Corribee (Trivial pursuit) which had a larger skeg, it is in no way excessive in practice! I have made the usual cut out of the underwater elevation to get the balance point which we call the CLR. If I put the rig in position, taking a conservative half width position for CE the lead is 8 percent. Could do with being more but still ok. I think we are confusing individual boat variables , sails etc, and calling the guys who made the design incompitent. A tad arrogant I say!