Keel Fin Planforms
I’m at the stage of planning to put fins into my two new IACC 120 hulls (ClaudioD NZL 92 plan) & I’ve noted that other hull plans use different rudder & keel planforms & I would like to have a better understanding of the differences between the three most common fin plan forms you can see in IACC 120 yachts design:
A) Straight “trailing edge” keel fin (which I have on my original hulls)
B) Straight “Leading edge” keel fin.
C) Straight “Trailing & Leading edge” keel fin.
Playing around with the illustration prepared you can see that the Hull Centre of Balance (CB) would move forward.
Then “theoretically” (which I can never trust my own) I assume would need to move the position of the bulb C.G “forward” as well.
Cause & effect theory suggests that elsewhere some changes and that is Center of Lateral Resistance (CLR) to Centre of Effort (COE) would need to move forward as well (assuming all 3 fin surface areas were the same)
ok so far so good...but but the distance between “fins leading edge and the COE position” increases on B & C planforms
Here’s my questions:
1) What affect does increasing distance of the "fins front edge to COE" have on boats helm balance?
2) If helm balance is affected, how do you correct it?
3) What are the pro's & con's between these 3 different keel fin planforms?
P.S If I'm not wrong (Matthias?) all of the top boats have straight Leading & Tail edge keel fin planforms.
Last edited by K1W120; 10-27-2010 at 09:47 AM.
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You can only create, what you can imagine