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Left to right, Vireo, Flint and an Adirondack Guide Boat (T. Clarke)

Sunday, April 10, 2016

Where Do the Oarlocks Go?

This post is about rowing geometry for fixed seat rowing.

Colin Angus has a very complete description, with detailed measurements, of rowing geometry for sliding seat rowing.

John Welsford, in an article for Duckworks Magizine titled "Some Thoughts on Rowing" includes the following information for rowing geometry for fixed seat rowing (as well as much more excellent advice):
  • Distance between oar locks: Minimum of 3’ 10” (117cm), and an average of 4’ (122cm) to 4’ 4” (132cm)
  • Oar lock to back edge of seat: Minimum of 13” (33cm)
  • Bottom of oar lock height above seat: 8” (20cm) to as high as 11” (28cm)
  • Seat height above ‘heel rest’ on foot brace: 6” to 8” (15cm to 20cm)

Paul Truszkowski’s rowing geometry for his Michalak Vireo is:
  • Distance between oar locks: 49.5:, 126cm
  • Oar lock to back edge of seat: 13”, 33cm
  • Bottom of oar lock height above seat: 12.5”, 32cm
  • Seat height above ‘heel rest’ on foot brace: 8”, 20cm
  • Bottom of oar lock to waterline: 13.5”, 34cm
  • Length of oars: 96”, 244cm
  • Overlap when oars are level: 4”, 10cm
  • Paul's height with shoes he normally wears when rowing. 6’ 1”, 185cm

Rowing Geometry for my own Ross Lillistone Flint is:
  • Distance between oar locks: 53”, 134cm
  • Oar lock to back edge of seat: 10”, 25cm. The oar locks are closer to the seat because I like to make a deeper recovery (forward angle of oars at the catch: 50 degrees) and shorten the end of the power stroke (35-40 degrees aft)
  • Bottom of oar lock height above seat: 10”, 25cm
  • Seat height above ‘heel rest’ on foot brace: 10”, 25cm
  • Bottom of oar lock to waterline: 14.5”, 37cm
  • Length of oars: 96”, 244cm
  • Overlap when oars are level: 3”, 76mm
  • My height with shoes I normally wear when rowing: 6’ 1”, 185cm

An effective ‘rule of thumb’ for adjusting the foot brace is to sit on the seat in your normal rowing position, extend your legs until your thighs are level, then position the foot brace against the bottom of your feet.


Pictured below is a Rowing Geometry Worksheet you can download from Dropbox and then ‘model’ your own rowing geometry based on you, the size of your boat and the length of the oars.

A Rowing Geometry Worksheet you can Download and Use

Our next post will be “An Easy-build Oar Cruiser”

10 comments:

  1. My boat has a locking slide seat, so it can be rowed fixed or slide. Trying both ways many times I am sure that I can row longer, and keep up speed better, using slide seat leg strength. John Welsford says he prefers fixed, but having met the man I think it is because he has more upper body strength than I do. Has anyone else tried both and decided fixed was better?

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  2. Hi Rick, there's a post coming up toward the end of May in which I feature a number of sliding seat/rigger systems. I've included yours, with a photo of the 'stop' that converts sliding to fixed.
    Intuitively, switching back and forth has to extend your endurance, since your using different muscles with different 'loads'...

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  3. I haven't try mixed system yet but I plan to use it on Batto this summer. I imagine fixing the seat for a while might be useful in maneuveres, tight marinas, navigation locks etc.

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  4. Welsford's rationale (one of them) is that it's much easier/safer to row in rough water with a stationary seat and with your feet spread apart.

    Wojtek, have you come up with a way to have a sliding seat system and yet still sleep aboard?

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    Replies
    1. Batto is 18 ft long. If I move the sliding seat unit aftward, and myself forward, there will be enough room for sleeping aboard. To be checked out.

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    2. This comment has been removed by the author.

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  5. I've not found alternating fixed and slide to extend endurance. My back is injured, that is the weakest link for me, so sticking with legs for propulsion is usually best.
    Changing up by alternating with standing rowing is working, I'm practicing more and getting better at this:
    https://www.flickr.com/photos/ricks_boats/25315151144/in/album-72157664888616306/

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  6. Rick, what is the standing oar lock post made of? It looks like three pieces of increasing diameter. Stainless steel?
    What's the difference between the "support block" and the "extension support block"? One has to be fixed to the hull, right?

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  7. The post is a long piece of 1/2" stainless rod. It fits into the forward oarlock socket. Since the socket can't take the stress of that long lever, the rod extends down to an added support on the stringer below. At the top of the rod is a 1/2" ID Oilite bushing, this becomes the new raised socket. A couple pieces canvas/phenolic tubing hold it together.
    This started with a discussion of the Italian Pattini rowing catamarans on the WBF. They row standing, seeing how fast they go in races made me realize that standing rowing (done right) is not just for puttering around a harbor. Check out my WBF thread on making and testing these:
    http://forum.woodenboat.com/showthread.php?203433-Stand-up-rowing-a-Walkabout
    You should do a column on this, I think it has great possibilities for oar cruising!

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  8. Hi Rick, sorry for the delay... In Florida for a couple of days...

    Thanks for specs on raised par locks.... Good idea re a post on rowing forward, I've added it to the list...

    Thanks...
    Tom

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