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Thread: What size oars?

  1. #1
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    Default What size oars?

    Howw do you choose the proper length oar to use. What is the proper distance between hand grips?

    What is the relationship between oar length and beam?

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    Quote Originally Posted by JohnPlatou View Post
    Howw do you choose the proper length oar to use. What is the proper distance between hand grips?

    What is the relationship between oar length and beam?
    There are many ways to do this..
    And none are wrong... As for 8 foot dinghy with a 12 foot oars, it may looked kindly odd
    1) is half the length of boat
    2) twice the beam width plus 6"
    As for the distance between hand grips...
    Depend on the person.. Myself I like to leave a space about a width of my fist..
    Some preferred the ends of the grips slightly overlapped about a inch, I don't like it because of pinch zone....

    This is just a general idea how to fit for oar... I use an 2X2 lumber to get a feel "how big" of oars to get... My 16 foot grand banks dory used 8 foot oars, while the dinghy get 6 foot... A Jonboat may have between 6 to 8 foot....
    save a nose, pick a banjo

  3. #3
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    More info will help. Oars range from huge 3-man galley slave variety to long & thin racing scull to short & heavy workboat styles.

    What boat dimensions, waters, style of rowing, storage space, etc?
    "The enemies of reason have a certain blind look."
    Doctor Jacquin to Lieutenant D'Hubert, in Ridley Scott's first major film _The Duellists_.

  4. #4
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    From the Shaw and Tenney web site. A=distance between the oar locks+2" in inches

    Length in inches = A/7 x 25

    Used it on several different boats and works for me.
    You have to be very careful when you don't know where your'e going or you won't know when you get there- Yogi Berra

  5. #5
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    Shaw & Tenney Oar Length Formula for Correctly Fitted Oars
    • Inboard length of the loom equals ˝ the span between the oarlocks + 2"
    • Total length of oar equals 1/7 of inboard length multiplied by 25
    • Leverage Ratio is 7:18
    • Distance from the center of leather to end of grip equals 7/25 of the total length of the oar
    Thank you Ron Carter, for Shaw & Tenney link.
    I think it is simple to make 7:18 ratio, taking the inboard available length as base.
    Last edited by Syed; 01-25-2007 at 09:56 AM. Reason: missed an e in Tenney

  6. #6
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    A lot seems to depend on the other factors, such as waters rowed, distances rowed, and type of boat. For moving a heavy workboat short distances in heavy swells, short fir or ash oars are best. For recreational rowing in still water in a lightweight long pulling boat, long spruce oars are best.

    Storage is another factor -- if you can only store 8' oars on the floorboards of your boat, making them 8.5' may not be the best idea...

    Distance between the inboard ends also varies by rower - many have the ends meet (I like this) and others prefer an overlapping grip, i.e. the oars overlap at the ends by the length of the grips or possibly a bit more.
    "The enemies of reason have a certain blind look."
    Doctor Jacquin to Lieutenant D'Hubert, in Ridley Scott's first major film _The Duellists_.

  7. #7
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    The Shaw & Tenney equation is certainly a good starting point. One point to note in that formula is that the +2" in the equation for the inboard length of loom is based on rowing with overlapping grips. If you don't like to overlap your grips you should probably figure the inboard length of loom as simply half the beam at the oarlocks.

    If you are going to experiment with overlapping your grips it may be best to go for plenty of overlap because the worst pinch zone is created when there is no space between the ends of the grips but also no overlap.

    The ideal solution to picking oar length is to borrow oars that seem to be about the right length and try them out, but for most boats the Shaw & Tenney formula will get you close. The cases to watch out for are the cases where your boat is far from average...for example, unusually large or unusually high or low sided...

  8. #8
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    I hear what you say about the 'pinch zone', but since my oars have leathers but no buttons/collars, I actually like the ends to touch as this helps me center the oars when rowing.

    As above, much depends on the boat, the waters rowed, the oar design, and of course the rower...
    "The enemies of reason have a certain blind look."
    Doctor Jacquin to Lieutenant D'Hubert, in Ridley Scott's first major film _The Duellists_.

  9. #9
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    Quote Originally Posted by Thorne View Post
    ...and of course the rower...
    Yup. The point I was trying to make was that someone should not be scared off from rowing overlapping by the pinch problem experienced when the oar grips are just touching because more overlap can actually help the pinch problem. I was not trying to suggest that someone who likes the just touching approach shouldn't stick with it. That is how I often end up rowing...

  10. #10
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    The distance between the grips should be up to you . Some row cross handed some don't.
    The "7 units on the inside, 18 units on the outside" is the accepted formula but, I don't know why there must be 2 additional inches.
    There is an additional caveat that the pivot point should always be, at least, 1 " inside the oar's balance point.
    And, since most calculations don't fall at half-foot increments, as do oars, you have a choice of rounding up to the next length for performance or rounding down for pleasure rowing.
    Last edited by Cuyahoga Chuck; 01-26-2007 at 11:59 AM.

  11. #11
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    Chuck,

    The problem is that the 7/18 ratio is based on how much inboard length you have, which is in turn dependent on the amount of overlap. So, you can't apply the 7/18 formula without deciding how much overlap you want...

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    Quote Originally Posted by Cuyahoga Chuck View Post
    And, since most calculations don't fall at half-foot increments, as do oars, you have a choice of rounding up to the next length for performance or rounding down for pleasure rowing.
    Hadn't thought about that since I make all of my own oars and paddles. Longer is usually better all things considered, but as Thorne pointed out oars that are too long to stow can be a bit of a problem too.
    Last edited by Ron Carter; 01-25-2007 at 11:03 PM. Reason: fat fingers again
    You have to be very careful when you don't know where your'e going or you won't know when you get there- Yogi Berra

  13. #13
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    Here's an interesting web article by John Welsford on oars, oar length calculations, etc -

    http://www.woodenboat.net.nz/Workshop/worksindex.html

    He discusses his own method of securing oars using adjusting lines instead of buttons/collars. He also flattens/shapes the grips a bit to put the blade in the preferred position.
    "The enemies of reason have a certain blind look."
    Doctor Jacquin to Lieutenant D'Hubert, in Ridley Scott's first major film _The Duellists_.

  14. #14
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    After a number of threads on the topic I have come to the conclusion that your oars should match your boat. I don't think there is one universally applicable mathmatical ratio.

    What size and shape is your boat?
    Yachting, the only sport where you get to be a mechanic, electrician, plumber and carpenter

  15. #15
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    Default Shaw and Tenney Oar Length Formula

    To clarify: The Shaw and Tenney Oar Length Formula calculates the proper 7:18 leverage ratio with a non-overlapping grip. The 2" addition in the equation compensates for the angle of the oar to the water, not to provide an overlap.

  16. #16
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    John,

    If you are strong and your boat is fast the Shaw and Tenny formula will get you oars that are too short. I will let you decide if your strong.

    If you boat is 16' or longer, and 48" wide or less then it is fast, even if it is heavy.

    Good luck with the oars.
    Yachting, the only sport where you get to be a mechanic, electrician, plumber and carpenter

  17. #17
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    this thread is old and it is a pain in arse.... everyone have posted almost the same ideas...
    Whoever start this thread should close it....
    save a nose, pick a banjo

  18. #18
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    Default oar lenght

    still useful

  19. #19
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    i've found this thread helpful — i'm glad it's up! and john welsford's approach was very intriguing.
    "All you needed was a favorable wind for everything that dry land provided to become superflous, disposable. Voices, noise, people, smells, the tyranny of the clock had no meaning here." — Arturo Pérez-Reverte, The Nautical Chart

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