Last summer, I experienced my
closest
encounter with disaster while sailing. A thunder storm was
growing
close and we hurried to an anchorage, dropped the 12lb Danforth anchor
with plenty of scope and backed it down to have it set well. Wind and
rain arrived within moments of setting the anchor and chased us
below. I would have preferred to have set the larger and better
holding Bruce clone anchor but the Danforth is in the bow anchor locker
and quicker to deploy. The storm blew us beam to the wind and
drug
the anchor. I did get the Bruce deployed, but if the Danforth had
broken out compared to plowing a furrow... we'd been on the
rocks.
The full story of that is in my cruising journals.
Had the boat not blown beam to the wind, I believe the Danforth would
have held. The c250 is given to considerable hunting while riding
at anchor in any appreciable amount of wind. If the wind grows
strong enough, instead of turning on the end of a swing and going back
the other way... she will sail as high as she can and heel over and lay
beam to the wind straining at the rode. Mine did it on a starboard tack.
The solution to this problem is no mystery to the mariner, it is a
riding sail aft. Perhaps the mystery is why the boat hunts.
My theory is that the hull sides form a foil with lift just as occurs
on an airplane wing. Thicker foils offer more lift than thinner
foils do, so a boat like the c250 with a 3:1 length to beam ratio will
have a lot of lift and be subject to sailing on their rode.
Some links to those articles and discussions:
Sailrite
Tech
Talk
On to the solution. A riding sail provides drag aft which veins
the boat into the wind. I chose the V design because the flat
sail design doesn't provide drag until some amount of hunt has started
and the offset balancing scheme doesn't make as much sense to me.
My approach is to have two riding sails. One, a more
traditional sized and made of heavy material that will withstand the
kind of winds experienced last summer. The other, a light
duty riding sail / awning combo having too much surface area and of too
light material to want flying in a storm. Both will be
constructed using the V design. The one pictured below is a test
model to verify sizing and design. If something proves effective,
I'll make or have it made out of out of canvas.
Pictures of the design for the awning / riding sail;
Side Profile Front Profile
I have finished constructing the lighter duty awning / riding
sail. It is made of blue poly tarp and cost $11. It was
made
from a 9' 4" x 11' 4" blue poly tarp and 100' of 3/16" nylon
line. It was sewn at its seams with the line embedded so it is
supported by continuous line rather than grommets at the corners.
The dimensions are; leach 8', luff 10' and foot 12'. It will be
hoisted on the backstay by use of a caribiner and the main
halyard. The tack will secure around the mast and the pair of
clews lines will go to the stern cleats. It basically is two
sails
sewn together on their luffs. I used a two inch hem border with
the hem folded over 1 inch, then that folded over the rope giving a 1"
finished hem. The leach, luff, and foot are concaved 2, 2
1/4, and 2 1/2 inches respectively so as to avoid flutter,
marked by using soup cans and a 10' piece of 1/2 " pvc pipe.
