Position of thwarts and thole pins

I have a copy of W. E. May’s book Boats of Men of War.  It is an excellent book that I recommend.  Amongst other items in the book are a fair number of reproductions of draughts of ship’s boats.  One showing an 18′ cutter seemed to have a very small height between the top of the thwarts and the bottom of the chocks for the thole pins.  Out of curiosity, I measured each of the draughts where I could identify the chock-to-thwart distances reliably.  Here is a summary of my results:

Boat Year Length Beam No. of thwarts Double banked? Thwart spacing Vertical height between thwart and chock Horizontal distance from chock center to aft edge of thwart
Barge 1809 32′ 7′ 6″ 7 Yes 3′ 0″ 9.9″ 7.5″
Pinnace 1815 37′ 6″ 8′ 9 Yes 2′ 11.5″ 10.5″ 10″
Yawl 1799 26′ 6′ 6″ 6 No 2′ 7.5″ 9″ 10.6″
Cutter 1764 28′ 6′ 7″ 8 No 2′ 2″ 8.2″ 9.8″
Cutter 1786 28′ 7′ 1″ 8 No 2′ 3″ 9.1″ 10.6″
Yawl 21′ 6′ 5″ 6 No 2′ 4.5″ 7.9″ 11.6″
Cutter 1800 18′ 6′ 6.5″ 4 No 2′ 10″ 6.2″ 9″
Launch 1779 29′ 8′ 7″ 7 Yes 2′ 10.8″ 7.2″ 9.2″
Launch 1804 33′ 9′ 10″ 8 Yes 2′ 9.2″ 8.4″ 9.7″
Launch 1815 35′ 10.5″ 9′ 8.5″ 9 Yes 2′ 11.6″ 10.2″ 10.5″
Gig 1815 25′ 4″ 5′ 7″ 6 No 2′ 7.3″ 6″ 9.8″

Having only 6 inches between the thwart and chock seems too small, even if the rower is sitting on the far side of the boat.


Oars – David Steel, 1797

I obtained a reprint of The Art of Making Masts, Yard, Gaffs, Boom, Blocks, and Oars by David Steel, from 1797.

This is an Gale ECCO reprint.  That is, an original copy in the British National Library was photographed on to microfilm.  The microfilm was later digitized.  That digital copy has been printed.  The print quality of spotty — some things are hard to read, this volume appears to be missing many of the plates related to mask making, and some plates are very eccentrically split between multiple pages.  Despite this, it is better than not having a copy.

I reproduce the section on oar making below:


The different parts of oars are described by the engraved figures, and their dimensions by the tables.

Ships’ sweeps and oars are made of hand-masts, or rafters, suited to the size and length, as per table.  They should be chosen straight-grained, free from large knots, shakes, or rind-galls.  They are first sawed, or jambed in a snatch-block, and hewed nearly to their size; then raised on horses, and completed by the drawing-knife, spoke-shave, or plane.  Open handles are nailed to the sides of the loom in the direction of the flat of the blade, made of oak, about one inch and three-quarters deep, and two inches and one-quarter thick, hollowed to admit the hand easy between that and the loom: the length of the handle is one-third the length of the loom.

Ships Oars - Steel

Barges’, lighters’ and ships’ boats’, oars are made of fir-rafters, similar to ships’, without handles to the sides of the loom.

Barge oars - Steel

N.B. The looms of boats’ oars are often made round.

Oars and sculls for barges, wherries, and skiffs, are made of ash (and sometimes of fir) rafters, which should be chosen tough, straight-grained, without shakes or large knots.  The rough wood is taken off with an axe, and finished in a neat manner on horses by drawing-knives, spoke-shaves, and planes.  A leather button is nailed on the foreside, about two inches from the loom, and that edge rounded, to work easily in the rowlock: the lower end of the blade is strapped round with tin to prevent its splitting.

Wherry Oars - Steel

Sculls for wherries, skiffs, &c. for choice and make are similar to wherries’ oars.

Wherry Sculls - Steel

N.B. Oars or sculls made of fir exceed the dimensions in the above tables one-eighth of an inch.  The price of fir oars is seven shillings less than ash oars, and fir sculls three shillings and sixpence less than ash sculls.

On Oars

I recently read Eric McKee’s book “Working Boats of Britain: Their Shape and Purpose”, London: Conway Maritime Press Ltd: 1988 (reprinted from 1983), ISBN 0-85177-277-3.  It is a very good book, and I highly recommend it to those who are interested in boats.

Of first note, the book is very much about boats and not ships.  Moreover, it is about working vessels, rather than pleasure craft.  This gives it a focus that is much more in line with my interests than most books.

There are many superlative details in the book, but of especially interest is the section on rowing geometry and on oars.  I highlight only a few of the points from pages 135-139.

  • Oar lengths tend to be twice the beam of the boat when used in fresh water sculling, a foot shorter than this when rowing side-by-each, and up to three times the beam when pulling (using a single oar).  McKee notes that David Steele says that these lengths are 2 1/2 and 3 1/2 times the beam in the early 19th century.
  • Blade area tends from small, short, and wide in protect inland waters to large, long, and narrow in open rough water.  There is a chart on page 136 that shows typically blade areas versus length and conditions.  A 10′ oar used in river conditions has a blade than averages 3/4 sq.ft in area, whereas in open water the area the average is more like 1 1/4 sq.ft.  The area varies 1/4 sq.ft.
  • Freshwater blades are roughly 1/5 the total length of the oar.  Saltwater blades range from 1/4 to 1/3 of the length, with the longer for rougher conditions.

McKee lists a number of points for the geometry of thwarts, thole pins, and foot placement.  When constructing a new pulling boat, it would be good to consult his figures.

I note that his figures are what actual working craft use, not some theoretical model, racing shell, or pleasure skiff.