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[the red dragon]

Hi All,
Does anybody remember "Krispie" ?, if so can you help with a problem I have.
In the middle 70's I built a RC version of "Krispie" and took the splendid looking model to my local pond, it would not sail, after a number of "try this, try that's " from various boaters at various ponds I gave up on it and it went into the attic and I took up powered boats.
Last year, now knowing more about Yachts than I did then, I decided to it on the water again, still the same problems, mainly related to into wind issues.
I have established the static CLR of the hull and calculated the CE of the sail plans and found that it sails quite well when the dynamic CE is about 5.5ins forward of the static CLR, this gives a silly position of the mast and sails on the hull, and no where near where the plans show them to be.  
I have calculated that if the Jib is increased to a mast head size, the same as the Main, the CP should move forward and give a correct looking sail plan that works.  
Any comments and suggestions would be welcome.
Geoff Jones.


Title changed.

[andrewh]

Hi, Geoff

I seem to remember that Krispie was a fairly conventional 36R, so the rigging etc would follow the usual general layout.  Unfortunately I have never seen anything but the build words - never pictures

She MUST sail.  Evidently you have the mast and keel installed, so as you say the main option is balancing the sail plan.  
Presumably the problem you are seeing is excess weather helm?  As the wind gusts the boat tries to weathercock into the wind?
Increasing the jib area should help this, as you surmise


Can you let us see a side on view of the whole rigged yacht, pleaase?
andrew


Title changed.

[redpiperbob]

Hi Jeff
picked this up from the My Hobbystore web site

Krispie MM1404
Designer: Vic Smeed



This 36in. Restricted yacht has proved very successful with both R/C and vane steering. Many examples were built following the original's unorthodox double diagonal planking using cereal packet card, but all-timber planked and g.r.p. examples have won many races

 All the best for the New Year
Bob

Featured in "The Model Boats Magazine" Dec 1976 - June 1977
 

Title changed.

[steamboatmodel]

There were two or three built and sailed around here back in the 70s. They followed the published plans and had no problems. Do you still have the plans to check back against?
Regards,
Gerald.

[the red dragon]

Hi All,
Thanks for your replies and interest in my problem.
Now Christmas and the New Year are over I will get some photos of my "Krispie" on and off the water and details
of the sail plan dimensions
The position of the calculated static CP useing the plan dimentions is 1.75" into the main from the mast c/l. And the   
actual CLR is 20.75" from the bow.
I know these change when under way, but to achieve a balanced Yacht I have had to move the mast forward from
the plan position by 1.25" and it looks as if it could do with more.
I could repostion the rack but if it is any further forward the jib boom will overhang the bow if it is to clear the mast,
this is what I mean by it looks silly. 
I have calculated that a jib the same height as the main will move the static CP forward to 1.00" into the main from
the mast c/l and put the sail plan over the hull more in line with the overall plans But before I go to the expense of
two new sets of sails as the existing material is no longer available just to replace only the jibs, I would like to know
what is the real problem.
Regards,
Geoff.

[the red dragon]

Hi,
I forgot to mention another indicater that the CP needs to go further forwards is if the mast is raked forward
when it is at the forward limit of rack.
Geoff.

[roycv]

Hi all, I use the 'Tucker' formula of C of E should be 4 % ahead of the CLR, the 4 % is 4% of the waterline length applied at the waterline.
Does that make sense?
I have changed the sail configuration of a yacht to this formula and it sailed with no further adjustment.
good luck, Roy