The Life of Boats

WoodenBoat Magazine #240: The Geometry of Rowing

By John C. Harris

This is an article I wrote in 2014 after years of frustration with oars being the wrong length in fixed-seat boats. (The article is concerned ENTIRELY with fixed seat boats. Sliding seat craft are another kettle of fish.)

There are many sources offering a standard formula for oar length, but nearly all of them are based on a single variable: the boat's beam at the oarlocks. I'd known since I was a kid, splashing around in oddball rowing craft, that the problem was a polynomial equation. Many factors are at play: the type of boat, the seat position, and especially the freeboard, or height of the oarlocks above the water. I spent weeks measuring traditional small craft that were known to be comfortable rowers. Many points of data were entered into a spreadsheet, and patterns began to emerge. I wrote and illustrated the article while on vacation with family, earning myself many demerits in the process.

There's a sentence in the concluding paragraphs that bears repeating: "The formual works well for the middling spectrum of traditional smallcraft." In other words, you're all set if it's a rowboat of normal proportions in the 8-foot to 18-foot range. If the formula spits out 14-foot oars or something similarly impractical, you've probably got a strange case on your hands, and you should pause to wonder why.

(Click below to enlarge the article or click here to read it on WoodenBoat's site.)


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