My adult life has been spent investigating fatal accidents; Airplanes, boats, even a spaceship; the Challenger! I'm retired from the NTSB. Eighty percent of all of those accidents were caused by bad decisions. The rest were a lot of fun to figure out.
I don't want to discourage anyone from exploring beyond the walls of convention. Even Mother Nature does it! I'm fortunate to live within a few hours drive of some of the greatest old boat yards and bone yards, where old dreams lie abandoned, rotting. They are witness to our genetic compulsion to "do it my way." I study them. There are ferrocement junks with circles of rusted rebar where one batch of concrete hardened before the next could be mixed. Steel
hulls with cracked chines where an over-heated interior
bulkhead contracted and wracked too many panels
to be fixed without starting over. And yes, a couple of A frame rigs. I know, at a visceral level, these could be a thing of beauty. They solve the complex engineering challenge of designing a bulkhead to carry the ten to thirty ton compression
load of a mast supported in mid air. They open up interior
space and deck
space right where the helmsman should be. They permit
creative new approaches to converting wind
across the bow to miles beneath the keels.
I omitted an important point in my previous, excessively long treatise. A frames can also eliminate the structural challenge of providing a centerline forestay that needs to originate in midair, be under so much tension that the sail attached to it doesn't bow to leaward to varying degrees, to be anchored aft in an equally robust structure. That can be accomplished by staying the structure to each bow and stern, using existing structural rigidity. Picture two beams or logs
, with cross beams lashed as tight as possible. Lift
one bow, and the other is relatively undisturbed. Perfect rigidity is not a reasonable expectation, which is OK, the steady hull
continues through the water
in something like equilibrium rather than trashing its standing waves and slowing down. Now stand an A frame on this raft, supporting the feet on the logs
where there is already a lot of strength, and keep it upright with a rope
from the top to each bow and stern. This gives you more things to hang sails
on, and some very interesting new aerodynamic considerations. The most interesting of these is about the spanwise flow from three pyramid sails
converging at the apex. Can it be converted to miles behind you?
Gone are the huge engineering challenges of building three truss bridges or cantilevers to support a conventional fore-and-aft sailplan, whose principle reccommendation is "that's what we do on half-a-marans!"
One nagging problem remains: this structure is now fully triangulated. Its a pyramid. A little wave goes under the port bow, trying to lift it. The port stern goes down because it hinges at the mast base on that side. This loads up the port backstay, jerking the apex aft and to port, snapping the starboard forestay, trying to lift the starboard bow, depressing the starboard stern, pulling the starboard backstay which cracks the port forestay like a whip, and starts all over again. As the second lookout on the Titanic is reported to have said, "this could be bad."
Putting this A frame on a monohull
accomplished only one thing. It eliminated the side stays. Instead of a single stick (or seven) that only had to be kept in column to hold up for a long time, you've created a complicated engineering challenge that costs more than twice as much to build, can't be found on the shelves of your local boat builder's super store, and created twin towers that must not only deal with the local breezes, but with the disturbances created by the other tower. Putting this A frame on a catamaran
is even harder, because there's nothing but air where you would want to anchor
that whole fore-and-aft thing!
An aside: A sail, like a wing, benefits from a thick cross section at the leading edge. A wingsail is more efficient than a single surfaced foil because the air going over the outside of the curve has farther to go than the air on the inside, so it goes faster there, creating a greater pressure differential. A mast is not a bad thing if it has a foil shape and pivots to form the best shape. And the air behind a fixed mast is not dead. Its still working, just not as well.
speaks to those who chose not to repeat it. The cantilever wing on airplanes in the 1930's was a major breakthrough. The flying wires and struts (the masts and shrouds) of earlier aircraft created drag that increased exponentially with wind
speed and circumference (sort of.) so fewer wires, further apart meant more speed, less gas, smaller tanks
, more speed, more passengers or bombs, etc.. The closer together these wires were, the greater the drag. Hold your hand out the window at fifty miles per hour with your fingers closed. Now open your fingers wide. the same frontal area has more drag because of the interaction of the flow around each obstruction. Lesson: keep the aerodynamic complexity of your rig to a minimum. It is what moves you, and great care reaps small but valuable rewards.
But the A frame rig still appeals to me; I'll keep doodling, and I hope someone solves this conundrum.
Now about black boats: Thanks for the opportunity to have fun with this one, Steven. Paint
it any color YOU want, and repaint it whenever YOU want. Or figure out a way to marinize that digital billboard and have it change colors continuously, like an octopus in heat! (now there is a creative divergence from Mother Nature's conventional practices!) I apologize for the Winebago crack.
Kerry: Reread everything I wrote after "More suggestions, serious ones this time." I'm not demanding anything; I'm asking for solutions, inspiration, and serendipity. The first is about the mainsail
. It doesn't have to hang on a rigid luff. In fact, It doesn't have to stay in the middle of the boat all the time. You could have two or three set aside for various wind conditions or combinations, that only need to be raised with a single halyard
, flying free. By letting the boom pivot forward of the CEP, it could be self balancing, permitting a single sheet to control it. It could be set close to perpendicular to the longitudinal axis of the boat in a run, or even used to back the boat. And who says you couldn't run a sail up each leg of the A frame?
I'm very serious about regenerating electricity. My present boat is outboard
powered, and the gear
reduction of the lower ends, combined with the the prop being optimized for thrust rather than being driven, means I can't experiment
with regeneration (and still have something to sail at the same time.) Somebody get to work on this; I've got to get that 700# generator
out of my aft stateroom!
HenryV: I am very excited about the SMG A frame cat. The legs are set inboard enough to permit
easy access fore and aft. The rig looks great. But I was crushed to see that they chose to do without boards or even mini keels. Bummer! History
spoke with the Catalac
I don't see you on the PDQ
Forum. I had a 32 (hull #30) for several years. It was a very fine sailing boat, and one I would have recommended to Steven.
Finally: has everybody noticed that there aren't a lot of little Procyons running around local hangouts?