[Rhodes22-list] Ro, Ro, Your Boat...

[Robert Skinner]

Reference:

Wooden Boat Volume 192, Setember/October 2006, page 54

"A Different Way to Ro -- Complex Japanese traditional 
oar makes sculling simple"

The article describes a long oar (~18') that is built
in two major sections and affixed to the transom with
a simple rounded and domed pin.  The inboard end of the 
oar is attached to the bottom of the boat with a rope,
allowing the oar handle to move in an arc.

The mounting method allows the oar to rotate about its
long axis as well as moving back and forth laterally.
The transom pin transfers the longitudinal force vector 
to the hull, and the rope prevents the oar handle from
rising up as the sweep pushes against the water.

The inboard component of the oar is fastened solidly to
the sweep, but bent downward.  Thus, when you push 
sideways on the oar handle, the torque on the oar 
rotates the sweep so it gets a bite on the water.

The person using this oar has only to move the handle
back and forth to drive the boat.  All but lateral
forces are controlled, so the operator's effort can
come mostly from the large muscles in the legs as he
stands beside the oar.

The angles used in the design of the oar are critical,
and the article gives dimensions for all components.

As I read the article, several things came to mind:

1.  The pin used in Japan could be replaced with a
removable oar lock set in a permanent block on the 
transom.  The block could be made of almost anything,
wood or plastic, and could be thick enough so it 
would require no holes thru the transom except the 
mounting bolts.  The hole for the oar lock could be
open at the bottom to drain freely.

2.  There is no reason why a long oar couldn't be
built with sections of aluminum tubing connected with
an off-the shelf paddle to test the concept.  The 
hole in the bottom of the oar would be replaced by
a collar on the oar in the prototype, possibly by
a gymbrel in a final version.

3.  For a prototype, the rope that would ordinarily 
be attached to the cockpit floor could be attached to 
a board that you stand on.  In the finished version,
a fold-down attachment such as a hatch handle could
be set in the floor.

4.  The Japanese design makes no provision for using
the oar to row backward, as the forces would lift the
oar off the pin.  I'd want something to keep the oar
in place so I could use it to slow the boat down when
approaching a dock, etc.  If the oar lock mentioned
above were secured in its socket with a pin, and there
were a bail over the top of the oar, then the oar 
could not rise and come loose, or get lost.

As regular paddles are limited by their length when
used to scull, and longer oars would generally have
to be made for the boater's own situation, why not
go for an elegant and powerful solution.  The Pardeys
used a long sweep instead of a motor on a blue water 
29' TALEISIN (IRRC), and Lyn describes its use.

http://www.landlpardey.com/
info%40landlpardey.com

If you want a copy of the article, contact:
Woodenboat
41 Woodenboat Lane
P.O. Box 78
Brooklin, ME 04616-0078
207-359-4651
-- 
Robert Skinner