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Sailing an SJ23 With Centerboard up.

Whoa Nellie, here, just a little bit...

It is true that an SJ23 will sail with the centerboard completely housed.  The righting moment does not appreciably change either, because the center board only weighs 30 pounds or so, and offers little in righting moment, per se.  On the best of days, an SJ23 makes a lot of leeway, but you accept that to get the benefits of a shoal draft and trailerability.  Besides, we can motor upwind.

An SJ23 will also be a much more restful sleeping place at anchor without the clunking of the centerboard slapping the inside of the trunk all night with each little duck wake that goes by, if the CB is housed completely.

HOWEVER: In a turn or a tack, the boat  pivots around the Center of Lateral Resistance (CLR).  The CLR is the balance point for all stuff underwater, and is located along the centerboard when it is fully deployed.  For the purposes of this discussion, you can visualize this by looking at a side view of an SJ23 as it sits in the water.  If you take a cut-out of everything under the water from that view, and balance it on a pencil, the balance point is functionally the CLR, or "everything that keeps it from going sideways".  Things change a bit as the boat heels, and as the forward motion force vectors come into play, but ultimately, the boat wants to pivot around the CLR when it changes course.  The deployed centerboard leaves no question to the inanimate boat regarding the course it should follow in a turn: the boat literally "trips over " or twists around, if that is more clear, the centerboard in the water, because once the boat begins to turn, the relatively broad area of the centerboard suddenly becomes a very substantial force of resistance.  In a broader profile where the CLR is less definitive, such as the case with the housed center board and only a shallow full keel, the boat wallows through any turn, gently following the long keel.

In a confined space, such as is often found near launching and docking areas, tight-radius turns are often required and critical to both safety and the avoidance of embarrassing events that cause damage and repair headaches.  The centerboard should remain fully deployed as soon as it is safely launched with sufficient draft, prior to using the engine, and then until safely at anchor, when board slap is bothersome, and raised fully.  In the morning when you continue with your sailing, the board should again be fully deployed until it is returned to the trailer.

There are upwind conditions in heavy air where raising the board a little bit, which moves the CLR aft, will help balance an excessive weather helm.  However, if excessive weather helm upwind is a common condition on your particular boat, you can also increase the rake of your mast, which moves the center of Effort (CE) of the sail plan aft and more in balance with the CLR. This makes you feel less pull on the helm.  Also note that the centerboard saddle in the keel slot can be moved aft in the trunk slot by simply removing two lag screws and sliding the bracket fore or aft, as dictated by the helm balance.

I would suggest the following drill for anyone who owns one of these boats or any similar boat with a centerboard/keel combination.

• The drill: In safe, unobstructed water, preferably with a reference structure such as a dock or float and no other expensive things that you might have contact with, do a set of turning manoeuvres, both in forward and reverse.  Do one set of manoeuvres with the CB down, the other with the CB up.  Note both your turning radius and helm response.  I strongly suggest you do the first set of manoeuvres with the CB down.  I won't tell you what you might experience, but you may have a profound Archimedes moment.

Just sayin'...

In really tight manoeuvring situations, on our boat, we  are also known to use both the outboard's tiller as well as the rudder to tighten our turning radius and do challenging placements of the boat.  Using both outboard and boat tiller in concert takes a bit of practice, but it ensures that the rudder spends less time in a stalled state, working efficiently, while the prop thrust can work effectively to lever the stern strongly against the CLR that is several feet forward on the centerboard.  The important lesson here is to have lots of practice in non-emergency boat handling so that you can handle those little surprises.  And we all have surprises.  The most common for us is probably the outboard stalling while approaching the dock at 4 knots or so.  Now what? Want fries with that?

As far as the concept of raising the CB downwind for greater speed, back in the 60's in the 14's we used to do that a bit.  Can't say that we ever saw strong evidence one way or another for greater speed, other than it allowed the helmsman a little easier time to kick the ass-end of the boat around a bit in heavy air.  These days, in the 14's, the centerboard is now a dagger board, it is always completely down, and the boats are faster yet.  If the argument to raise the centerboard is about reducing total wetted surface drag, the centerboard in the half-raised position presents nearly the same wetted surface as when completely submerged, so that is a weak rationale.  The only viable argument to raise, therefore, is to make it easier to steer.  But remember: when you actually STEER, the boat should go where you steer it.

Cheers, and keep sailing, not fixing stuff, and enough blather here. Gleno

P.S.  As one of the building crew, I probably would have counselled a softer, less committal approach to dealing with a stuck keel.  I might have done nothing at all, in hopes that I would get lucky and it would fall out on its own, or if pressed, I might have chosen as a very soft, sacrificial plugging matrix, like marshmallows, Styrofoam packing peanuts or sawdust and Elmer's glue where you or a subsequent owner could have an easier pathway back to the OEM condition, if you did not like the result.  Epoxies can be a devil to undo.  Good luck, and please post a full report if you go back to the OEM configuration.  Gleno
 

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