I really like the yuloh on my boat, which is built light (the yuloh) because it's only a 20 foot boat. When studying about making a yuloh I read work by Jerome (Jay) Fitzgerald (several books, easily found by googling his name and sailing), who used his on a heavy displacement cruising sailboat that I think is something like 45 feet long. He built the handle end out of a 4 x 4, talking about how hard he leans into it.

I used to sail a Falmouth cutter 22, which is a pretty heavy boat. I had the perhaps bad habit of sculling with the rudder, using the tiller, to do things like get the last little bit into a harbor, or around an obstacle when the wind died and the current was problematic. This boat displaced something like 7000 pounds, loaded. Getting the boat started moving by rudder-sculling, at first you would think nothing was happening, then gradually the boat would start to move through the water. Once it had gotten going, with just moderate effort I could keep it going at 1.5 knots. That's just with the rudder, nevermind the possibilities with a proper yuloh.

With the present boat, if I start gradually with the yuloh it's the same thing – no instant movement, but pretty soon it starts to go. Or if I'm feeling particularly energetic, I can get it moving right away, using more vigorous strokes. But it doesn't seem to matter to the boat – a more paced approach, or the quick version – it gets going either way, gradually or more quickly.

We used the design guidelines laid out by Slieve, and it seems to work quite well. The article by Bob Groves, about the yuloh on Easy Go, was also quite helpful. That article can be found here.

Cheers,
Shemaya

A longer lever from the fulcrum on the handle side, would seem to increase the power but also the range of motion. With a curved handle you could accomplish the increased angle  of attack described in the previous post by just moving farther away from the fulcrum as the boat picked up speed.

I don't know but that is an interesting thought, similar to changing gears on a bicycle.

I think I will start another topic along the bicycle line of thought as I have wondered about it before.

While the amount of HP a human can produce may be the limiting factor, from my experience with rowing sailboats, the length of the oar, the size of the blades, the distance of the fulcrum, the body position seated or standing, technique, etc. has a great deal to due with how well the boat responds to the HP generated.

Surely there are yuloh designs that would improve the application of that limited HP.

Lets focus on one man operating the yuloh. What properties of the design would help create more power to move a higher displacement sailboat?

I have rowed a 2 ton displacement sailboat with a set of oars, standing up, facing forward, fisherman style, 338 miles through the Erie canal. So my view of what is possible as far as rowing sailboats is outside most peoples comfort level.

What would you consider the upper limits?

I would think the difficulty would be in getting the sailboat up to speed, the inertia would help keep it moving along with less effort, from my experience.

Longer lever arm, broader blade, longer blade, multiple blades on one arm, what would it take to increase the power?