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14 January 2014

Schoon 'er Ketch?

 
Three masted junk cat schooner









Junk cat ketch


Schoon 'er Ketch?

Anke and I really like multi-masted rigs. 

Schooner, ketch or yawl all grant the engineless a range of means for balancing the vessel underway or stand-still maneuvers. In the many, tight corners we like to explore or tuck ourselves into, these abilities come in mighty handy!

Mid-cabin layouts often have a keel-stepped mast somewhat forward of amidships. This may feel salty, down below, but often means sharing the bunk with a balk of lumber who likes it in the middle. I mean, I'm a tree-hugger, and all, but...

And besides, that forward-of-mid-ships-ish position for the mast means it's CE is even more so. It's very close to the CLR and therefore has very little leverage to crank the boat around. Individual sail CEs further towards the ends of the hull are much more effective.

In this respect, a ketch or yawl beats a schooner, whose main (after) sail's CE has a short lever arm. In LUNA, we addressed this with the small 'driver' set at the aft transom... being far from the CLR, even it's small area is effective for cranking the stern one way or the other.

Note: Actually, it would have been more effective with about twice the area... it couldn't quite hold the head up when drifting, under driver alone.

 
T32x8 layout, showing potential mast positions (circles)


The layout we're using for the T36x8 gives us the full range of possiblities, assuming masts set in above-decks tabernacles (standard layout eliminates schooner). Note that the positions at the fore and aft decks can be stepped in timber tabernacles whose beams are strongly mounted to bulkheads.

The schooner layout presents challenges, however. The pilot house helps support an aluminum, deck mounted tabernacle, but it's a high-stress affair with larger sails. We're considering a timber tabernacle with one, over-sized, deeply buried post running down the bulkhead. It would impact the dinette seat, or we can through-bolt one from the galley side with considerable overlap. The other post would pierce the deck, but have to clear the opening cut-out between galley and salon.

Okay... comparisons then, schooner vs. ketch:

First, Anke and I are going to cross a yawl off the list. Not because it's a bad rig... but to get the sail area from one sail means a whopping big one, set on a tall mast. We prefer to handle smaller sails, smaller masts, and maintain a lower combined CE. Plus, cat yawls tend to develop wicked weather helm, a real problem in gusty, high wind areas.

Three masted cat schooner:

Pros:
  • Schooners are just cool.
  • Principal sails are close if not equal in size (both smaller than equivalent ketch main).
  • Under stowed main, we get a modest cat yawl... a good heavy weather format.
  • The driver has many uses (riding sail, manipulation, can add weather-helm when desired).
  • Was handy and efficient in tight quarters on LUNA (square boat approval!).
  • Principal sails are solidly sheeted inboard (no boomkin).
  • Principal masts are located on centerline.
  • Sheets don't threaten to foul the smokehead.
Cons:
  • Driver takes extra mast, step, rigging and handling.
  • Driver is less effective than ketch mizzen (aft sail).
  • Main boom is higher and harder to reach.
  • Main sheets sweep the cockpit.
  • Main tabernacle blocks some view from pilot house, and takes up mid-deckspace.
  • Main tabernacle is structurally less robust.

Cat ketch:

Pros:
  • Both tabernacles solidly mounted, and buildable from inexpensive timber.
  • CE of after sail is well placed for manipulations.
  • It's boom is low and easy to reach.
  • One less mast to worry about.
  • No rig intrusion into the interior.
  • Forward view is unimpeded.
Cons:
  • Main (fwd sail) is significantly larger (can't reduce and still fill 'airspace' above decks).
  • Main mast is likely taller (discuss another time).
  • Mizzen is off-center (neither critical nor optimal, in my opinions).
  • Mizzen is sheeted from outboard (boomkin... hard to reach, and vulnerable).
  • Unequal sails (meaning can't mix and match in a pinch... minor point).
  • Sheets (may) threaten to foul the smokehead (minor point).

Our conclusion is that it's a close call. 

We were  very happy with LUNA's rig. The only issue I see as important is the integrity of the mid-ships tabernacle on a larger boat (bigger sails, stiffer hull).

SLACKTIDE is a pleasure, as well. The only issue I see is that the main sail (fwd) will need to have very long boom and battens across the long mid-deck, or we leave an overlarge gap between sails.

Chances are, once we've settled on the sail planform, that will make the decision for us.

Stay tuned!!


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About Me

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Anke and I live aboard SLACKTIDE, our T26x7 ketch. We sail by wind, tide and muscle in the waters of mid- to northern Southeast Alaska. We try to maximize the joys of life, and minimize the chores. ........ We live between the communities of SE Alaska, but drop in to visit with friends. Lately, we've worked, every other winter, care-taking Baranof Wilderness Lodge in Warmsprings Bay. This has given us a window on Web. ........ We're working toward a subsistence lifestyle, somewhat impeded by addictions to coffee, chocolate and cheese. ........ We think TEOTWAWKI is looming, and while we won't be ready, we'd at least like comfortable seats.