MingMing 3

RE American Express.... "he heard an extremely large waves coming, AND CLIMBED BACK OUT OF THE COMPAIONWAY".......

When i faced 80 knot winds, i was down below in a survival suit and life jacket wondering if i would ever see daylight again. When daylight came and i could see the waves, I wished it was dark. I paid even more attention to details after that experience.

 

Less freeboard, more water over the deck.
More freeboard, more water energy pushing the hull sideways.
At what point does a keel become a "trip lever"?
I met an old man from Denmark sailing a Colin Archer type, it had far less ballast than i imagined, but his experience was the boat would heel so far in beam on breakers with solid water sweeping over the bulwark , but offering less resistance than if upright. I thought his small wheelhouse and windows was vunerable, but he said no windows had ever broke.
Beamy but also deep, but not "stiff" in a modern sense.

 

I found a quote from a builder of a Bolger Micro the other day which they piled lots of sail area on, and claimed over 10 knots. I found that difficult given the displacement curve on the flat bottom, until he mentioned 6 people in the cockpit. I get the impression it was then planing on its flat aft section with its bow pulled up out of the water.
Not going to race one across Biscay though.......

 

American Express I like a lot, and sailing the old Mini Transat i have i want more of the same but even better and more comfortable:

(If i recover financially and emotionally)

a 1 Ton WindSurf board for an old fogey

Mast centered (1/2) and the Centers (Gravity, Flotation and Buoyancy) well together.

Big Freeboard. Ballasted with a daggerboard that can be pulled aft with a lever, hoist and winch. 200 liters water ballast to Beating Upwind. And two Rudders two.

 

Do you include your rudder areas as part of leeway prevention or a percentage of sail area? I always recall the first rudders on Aqua Quoram where too big as they prevented the boat from broaching earlier, than wiping out at a higher speed.

 

Pretty sure i posted in the past "Explorer 15" plywood yacht with a ballasted bulb swing keel, with small external stub for beaching. Google/Bing searches have become worse than useless.
I have a sales brochure somewhere, it was expensive for a dinghy with a lid and not really a surf inspired design, despite the trick keel.

 

(Principles of Yacht Design, Second Edition)

Note that without wetting the stern (which the Wave will wet) the Center of Flotation is about 60% LWL

(... like my windsurfboard with a huge stern ...)

(If you want a modern sailboat you have to center the mast and move the daggerboard aft. American Express 1979 led the way)

 

"rudder areas"

I have calculated the yaw moment of the heeled and yawed hull 3-6 degrees at the speed of the Carene by three ways and made an arithmetic average and without taking into account the orbital speed of the wave as it is a small boat and we assume it is in the same part of the wave. And 1 rudder blade without moving it should be able to place the Center of Lateral Resistance aft of the Center of Gravity. On the other hand I have calculated the Balance upwind.

In the end it turns out that the two blades together have an Area equal to the effective Area of the centerboard which is counting a rectangle from the bottom of the Bulb to LWL.

Yes, the blades are very large. I have to rethink the matter.

Beating Upwind only uses 1 blade, and i want it to be deep. And on the other hand it must be big for mechanical safety.

A nice tangle and puzzle.

---

Hull Speed (5.99 m LWL: 19.64 feet): 5 kn
(Theoretical Hull Speed: 6 kn)

Carene (144-164 D/L) Speed: ca. 7.7-7.5 kn, which with Waves are 8-10 ... 12-14 ... 16-18-20

 

Surfboard.......with cabin....



"Peter Pan" one-off sail canoe from Sweden. Met in Gibraltar. Circumnavigated. Flat aft sections.

 

In this old uphill 'photo' with plenty of wind the rudder blade produces 625 Newtons with 3 degrees plus 6 degrees of Leeway

The Water Ballast on windward side transforms +100% the small sailboat and instead of 400 Newtons of forward force (with 15 degrees of heel) we have 800 Newtons (!) of forward force, and so we overcome the AeroDynamic resistance of the hull and keep going uphill at 5 knots.

 

Waterballast can definately be beneficial in fixed tanks. Cant say i was keen on shifting 25L jugs fore-n-aft/side to side, but some hull forms perform better for it.

 

848 Newtons

Drive Force with 200 liter Windward Water Ballast and 15 degrees Heel

30 knots Wind @ 10 meters high

Second reef in the mainsail

 

American Express 1979 loaded 225 liters, Norton Smith says he was surprised at how much he used the magnificent invention. For a small sailboat, it's a great solution.

 

On a boat with minimal hull height and beam, it shows it can still work for smaller types.
I was/am considering flexible fresh water tanks in sealed (but accessible) compartments that as emptied, flood with sea water to act as ballast, or low air pressure into the flexible tank to evacuate most of the sea water when not required. That will suit for regular trailer use, or replaced with steel/concrete ballast castings combination if kept afloat.

For your downwind sleigh ride to the Algarve you can go light, but the water ballast will certainly help getting North again.
There is a Setka 5m in Cabo Verde probably for cheap, but getting back to Europe is uphill unless via the rum islands.