Shaw and Tenney - Maine Crafted Since 1858

How to properly Size Rowing Oars

How to properly Size Rowing Oars

Rowing with the correct length and style of oar makes all the difference in your rowing experience.

A great boat is no fun to row with the wrong oars and a fine set of oars, properly fit to the boat, make rowing almost any craft enjoyable.

"I need help sizing my oars" is the question we are most asked at Shaw & Tenney. We have been offering our advice on that question since 1858 with the same philosophy; you need the correct leverage ratio, 7:18. We have seen dozens of articles and dissertations on the "right" way to size oars taking into account a multitude of factors. Bottom line, you need the proper leverage ratio, everything else will fall into place. Of course there are a few exceptions we will note but the Shaw & Tenney oar length formula works for the vast majority of boats.

Oar Sizing, oar in guide boat.

To help our customers size their oars correctly, we've been using the same formula since 1858:

The Original Shaw & Tenney Oar Length Formula

Measure the distance between the center of the port and starboard oar sockets, which hold the oar locks on each gunnel. This is called the "span" between the oarlocks. Divide the span by 2, and then add 2 to this number. The result is called the "inboard loom length" of the oar. Multiply the loom length by 25, and then divide that number by 7. The result is the proper oar length in inches. Round up or down to the closest 6" increment.

This length will provide an oar where 7/25 the length is inboard of the oarlocks and 18/25 of the oar is outboard of the oarlocks. It is the ideal ratio to row almost all boats. Sized correctly, when rowing on your return stroke your hands will be 1 to 3 inches apart and you will be pulling directly towards your abdomen.

If you prefer an overlapping grip, add 6" to the calculated oar length, however the vast majority of rowers prefer a non-overlapping grip.

Oar Sizing Formula, How to size oars by Shaw and Tenney

If you have more than one rowing station in your boat, measure both. Typically they will require two different length oars which is fine if you're going to be rowing tandem and need two sets. Otherwise you'll need to compromise the correct length to work properly in both stations. If you are rowing more than 75% in one station size the oar to that length.

The same math applies to locating your chaff gear, we offer traditional leathers or whipping (rope wrap). The center of the leather or whipping is placed at the 7:18 leverage fulcrum by multiplying the overall length in inches by 7 and dividing by 25.

Sizing Oars, stitching oar leathers.

Trouble with Improperly Sized Oars

Here is an example of the consequences of having the wrong oars, in this case too short. Customers will often call and say my oars are popping out of my oarlocks I need some round oarlocks to fix the problem. Our response, "your oars are far too short". As a result they are rowing with their hands too far apart, outside the plane of their torso (incidentally this becomes painful quickly because it is all arms and no back). To get the blade in the water they have to pull up towards their chin on the power stroke, and pop, out comes the oar.

Conversely oars which are too long have problems too. There is excess outboard weight which tires you quickly. You are rowing with a leverage ratio which is too high requiring more effort for no gain in performance. Finally the oars may not clear your knees on the return stroke.

Exceptions to the Oar Sizing Rules

As mentioned earlier there are a few exceptions to the 7:18 ratio for certain types of boats. I'll cite a few, all of which we make oars for. Adirondack Guideboats, based on longstanding tradition, typically always have a 24" loom length for 7'-6 and 8' oars. Monomoy lifeboats use 12' oars at all rowing stations of varying spans, in their original capacity for lifesaving ( they are now raced in several US cities) speedy deployment was more important than leverage ratio.

There are also situations where the proper oar length cannot be used. The oars can be too long to store in the boat or under the thwarts. A boat may be too wide to row with a pair of oars and a single oars person. We recommend 10'6" as the longest pair of oars used by a single rower. The oars may be sized for rowing from a standing position or for a large sailboat with significant freeboard.

Hand made wooden oars by Shaw and Tenney

However for the vast majority of rowing craft The Shaw & Tenney Oar Formula will calculate the proper oars length.

As always feel free to call us and were happy to help you determine the correct oar length and select the best blade style for your boat.

Soon to follow: Selecting the Best Style of Oar for your Boat

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How to Size Your Oars

To determine the correct length oar for your boat measure the distance between the port and starboard oar sockets. Then apply the Shaw and Tenney oar length formula to determine the oar length that will provide the correct 7:18 leverage ratio. This length will provide an oar where 7/25 the length is inboard of the oarlocks and 18/25 of the oar is outboard of the oarlocks. It is the ideal ratio to row almost all boats. Sized correctly, when rowing your hands will be 1 to 3 inches apart and you will be pulling directly towards your abdomen. If you are popping out of your oarlocks when rowing your oars are far too short. If you prefer an overlapping grip, add 6” to the calculated oar length. If you have more than one rowing station in your boat, measure both. Typically they will require two different length oars which is fine if you’re going to be rowing tandem and need two sets. Otherwise you’ll need to compromise the correct length to work properly in both stations. If you are rowing more than 75% in one station size the oar to that length. As always feel free to call us and were happy to help you select the correct oar length and blade style for your boat.

The Original Shaw & Tenney Oar Length Formula

To help our customers size their oars correctly, we’ve been using the same formula since 1858: Measure the distance between the center of the port and starboard oar sockets, which hold the oar locks on each gunnel. This is called the “span” between the oarlocks. Divide the span by 2, and then add 2 to this number. The result is called the “inboard loom length” of the oar. Multiply the loom length by 25, and then divide that number by 7. The result is the proper oar length in inches. Round up or down to the closest 6” increment.

How to Size Your Paddle

For traditional wooden paddles the ideal length for the Stern paddler is the bridge of your nose or 6 inches less than your height. For the bow paddler the paddle reaching the cleft of your chin or 9 inches less than your height is correct.

For our Racine paddle if you are over 5’6” tall select the 63-1/2” length and the shorter paddle if you are under5’-6”tall.

When paddling solo we typically recommend a bow length paddle. For Canadian style solo most paddlers prefer an even shorter paddle.

For paddling canoes when standing (yes our mother let us do this) a 69 inch or 72 inch paddle is usually about right.

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