Tuesday, April 20, 2010

What the $^&#@ is a leeboard?

There's no simple answer to that question. A frustration saving device, an oops we forgot something measure, a whoa it works widget. Get ready for your weekly dose of salt.

During the gruelling test sail, which proved to not be so gruelling, we found that it was difficult to sail closer than six or seven points off the wind without crabbing (sliding sideways). This effect, known as making leeway, can prevent us sailing upwind with any efficiency. The solution? Check the instruction manual. In our case, the US Navy published a guidebook called the "Deck and Boat Book." While many references are given to sailing boats without centerboards, there weren't many solutions except "pull the weather oars" (those closest to the wind). We did that during the test sail, and it worked, except there must be some way to do this without rowing.

As it turns out, there was.

The standard acquisition Monomoy Pulling Boats built between 1871 and 1904 were built without centerboards. This was specifically written into the contract because "through-hull openings [such as those for centerboards] have proven sources of structural failure, particularly on those boats which are frequently landed upon shore." The Norfolk Naval Shipyard Boat Shop records have frequent entries of centerboard boats being repaired having "ctrbd trunk sprung" - at least four such entries annotated as "failed hoisting loaded". Hmmm. That seems to make sense. The keel would be slotted for the centerboard - as illustrated in the extant drawings of centerboard versions. That means it would have been something of a weak spot, and even properly reinforced, the longitudinal flexing of the boat when hoisted could have caused the centerboard trunk planking to spring or seams to open. Very interesting.

So we know why the navy chose to opt out of centerboards. I'm still on topic, bear with me.

As we have seen, boats without centerboards are crap tacking into the wind. Any sailor can tell you more or less the same thing. So what did the navy do about it? Compensate.

The original 1871 contract specified no centerboards, but the 1873 revision added the following:

"Boat equipment... to include ten oars, one steering oar, one leeboard [emphasis added], sailing rig complete with spars, cordage, sails and associated appliances."

There it is! Leeway - centerboard. No centerboard - leeboard. After two years churning out boats, they figured out that something was needed to prevent excessive leeway. Leeboards hang off the lee gunwale and acts as a fin, retarding the crabbing motion of the boat when tacking. No through-hull openings, no structural alterations. Sailors probably figured out that improvised leeboards worked well, and officers passed the feedback to the shipyards. Granted, there is no evidence of that, but knowing how the navy worked and how close the ship to shipyard relationship was at that time, one can interpolate. After all, in those days captains spoke directly to the shipyard leaders, rather than to middle men as they do today.

So folks coming out this weekend to train for Conquer the Chesapeake 2010 have something new to play with. The Dockyard crew has been building a leeboard for our Monomoy based on drawings from the Norfolk Naval Shipyard Archives. Look for it in photos, or see it yourself on the waterfront at Naval Station Norfolk this Saturday.
That's all for now, back to the grind and time crunch.

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