Pronounced heeling to port
Minus her port keel
Her rudder
A Pardox rudder
On December 11th 2011 I wrote* about a Macwester
30 twin keel yacht, or at least, I thought she was a Macwester 30, but the
author of two related comments said he believed she was a Macwester 28.
Whatever the case, I saw the same yacht alongside the quay at Hullbridge last
Sunday afternoon. By the way she was settled on the mud I knew she had lost her
port keel. I spoke to a person I assumed was the owner, and he informed me the
keel had come off when the yacht was on her mooring. He said he had temporarily
sealed the hull with expanding foam, and that he was waiting for high water so
that she could be taken ashore for inspection at the Up River Yacht.
What intrigued me was not so much her missing keel, but her
relatively small rudder which is small in comparison with the area of her
underwater lateral profile. I suppose the same could be said of many yachts,
but Paradox is an exception, since her large rudder acts as a keel by providing
lateral resistance. Generally, the further aft a rudder is from the centre of
lateral resistance, the more leverage it has for turning the boat. Obviously,
if a rudder is ridiculously small, it will have little effect. Therefore there
must be an optimum proportional area relative to the lateral profile area of
the hull according to where the rudder is located. The speed of a vessel, the
amount of heel, whether it is a balanced rudder, and how it is hung in relation
to being vertical on its axis will also affect how a rudder performs.
James 3:4 ‘Look also
at ships: although they are so large and are driven by the fierce winds, they
are turned by a very small rudder wherever the pilot desires.’
Links
*Macwester 30?
Macwester 28
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