What's the average cruising speed of an asian sailing junk (non-motorized) in miles per hour?

Question

I'm interested in the traditional asian sailing boats called 'junks'.

Here are a few photo links of various junks which can be found by searching "sailing junk" on the Flickr website:
http://www.flickr.com/photos/52329227@N00/91698345/in/photostream/
http://www.flickr.com/photos/28032494@N00/175053466/
http://www.flickr.com/photos/stu_plaw/62771991/
http://www.flickr.com/photos/darryn/53050741/

I would like to find the typical cruising speed of these type of sail boats, or the approximate speed range that these sailing junks can travel.

Answer 1

Displacement hull speed is what ships travel at (unless a planing hull with a huge sail, a hydrofoil, or massive horsepower is involved).

It is approximately (in knots) the square root of the waterline (in feet).

That last photo seems to have a waterline length of 30-35 feet. So it could do 5-6 knots (6-7 mph) under favorable wind conditions.

Going "off-the-wind" would depend on how much of a keel and rudder they have. They could probably make a 1 or 2 knots headway with a quartering headwind.

Beating straight upwind (tacking back and forth)? I don't know, but I don't see a streamlined enough hull nor enough of a weighted keel to do that very well.

Answer 2

Due to the design of the vessel, it's average cruising speed under sail is only about 5 MPH. With a good (heavy) following breeze, it can exceed a whole 8 MPH, but would be tricky to handle if they had to do any maneuvering. They have a bulky bow, and rounded hull. They're designed for slow, continuous travel, and can carry a lot of cargo ot can be outfitted for extended cruising, with staterooms.

Answer 3

The actual speed is a function of the waterline length, about 6 mph would be the hull speed. Generally a displacement boat will not exceed its hull speed.

Answer 4

Probably its natural hull speed.