View Full Version : The centre of lateral plane.

Gavin L
01-29-2001, 12:30 AM
I am shortly about to remove the long shallow keel on my Long Micro and replace it with a deep fin with a bulb and an unbalanced rudder with a short skeg.My question is should I include my large powerful rudder in the calculation for the centre of lateral plane. My feeling is that I should and I would welcome some discussion.

01-29-2001, 05:19 AM
I am only cursory familiar with the long micro but I understand the basic construction is plywood egg crate design. That fin keel could place a lot of stress on the hull and general structures. Might I suggest you contact the designer for advice!

01-29-2001, 06:59 AM

Contact Phil Bolger (if you haven't already) about altering the keel structure. Make sure you also indicate (obviously) whether the sail plan is as the original design called for because that will make a difference in any alterations to the hull.

Tom Lathrop
01-29-2001, 08:40 AM
Ditto the above, but will try answering your question. With an unbalanced rudder, do not include its area in the lateral resistance (CLR) calculation. Do include the skeg. If you include the rudder, your arm and back will quickly wear out trying to hold the tiller. A loaded rudder also requires very strong construction and hull attachments.

Bolger's St Valery design (see earlier posts by this title) did include a large part of the rudder in lateral resistance but it is highly balanced to remove the load from the tiller. My own boat (S2 7.9 Grand Slam) has a balanced rudder. It balances very well and requires little steering effort but the rudder blade has sheared off twice (from sailing loads, not hitting anything) in its 18 year lifetime.