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post #739 of Old 02-20-2011 Thread Starter
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On design Keels and rudders

Some very interesting information about the JPK 1010 that probably is relevant for other similar cases:

They have compared a 1010 in IRC set up (Keel without a bulb and a single rudder) with a 1010 on Ocean Racing configuration, with a bulbed keel and two rudders. Boats in the water at the same time with wind conditions between 13 and 20K.

They have found out that close to the wind the speeds are about the same but over 15/16K the bulbed version, that gives more righting moment, permits to close more on the wind and gives more power with a slightly better speed.

Downwind the speeds are the same but the twin rudders give a safer and easier ride and that with a reduced or solo crew means faster.

With a complete crew, the rating favors the non bulbed keel/ single rudder version. JPK is going to maintain that version, but as with a short crew the twin rudder and the bulbed keel is clearly a better option, they are going to make both versions, according to the boat use.

The difference in rating between the two boats is not big (in 2010 was 1/6000 and it is going to be even more reduced this year).

So now you know the advantages and disadvantages of a single and twin rudder and what solution to chose

The JPK 1010 is a relatively narrow boat (3.39M) and the use of twin or single rudder has nothing to do with the boat being too large for a single rudder to be effective on the water at large angles of heel.

Last edited by PCP; 10-23-2013 at 12:07 PM.
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