Oar Length and Finish Question

The oars are for 14 ft. rapid roberts. The oar locks are 64 inches apart and I set my seat as high as I could get it. How long should I cut my oars? For the finish should I epoxy the paddles for strength and varnish all of the oar?

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Permalink Reply by Jason Knight on February 6, 2010 at 4:13pm
Correct me if I am wrong guys but 8.5' oars would work well with a 14' boat. Epoxy and varnish on the oars is good. After the oars are finished wrap and stop the oars with a rubber donut.

-jk-
Permalink Reply by Rick Finnell on February 6, 2010 at 6:48pm
Thanks Jason, finished sanding and shaping them today. I have enough sawdust and shavings to do all my flower beds. Thanks again , fun project.
Permalink Reply by Lawrence E. Long on February 7, 2010 at 5:14am
Rick: There is a formula for oar length- I will dig it up if you want. Boat length is not the factor to consider- you are right to consider the distance between locks. It sounds like you will be making your own oars- If so make them 9 ft long, try them on the boat- and you can shorten them by4-8". I made mine and found they were a littlwe too long and cut off 6" and redid the handle. For the tips- to avoid splits and rock bangs I covered the tips about 1-2" up the blade with dynell fabric set in 3 shots of epoxy. Paint the tip your favorite color and do the rest of the oar (except the handle-leave unfinished) with a coat of epoxy and 2-3 coats of marine varnish.
Good luck
Permalink Reply by Charles Ray Heater on February 7, 2010 at 9:48am
Cyrus and myself have tried a a lot of ideas in regards to the oar tips. We have settled on storing the oar tips in a bucket of linseed/turpentine mixed 50/50. We found that doing this keeps the tips soft and supple to abuse from splintering. Be sure to radius the corners and sand them when the wood oars are new then keep them soaking in the bucket until needed.
Permalink Reply by Rick Finnell on February 7, 2010 at 11:02am
Ray, what you'r saying is to leave the radius raw wood, like up the paddle how many inches?
Permalink Reply by Charles Ray Heater on February 7, 2010 at 2:31pm
Rick:

We remove any finish on the tip up about 6 inches. The raw wood absorbes the oil better this way.
Permalink Reply by Rick Finnell on February 7, 2010 at 3:37pm
Thanks when i epoxy i will tape the end of paddle.
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Permalink Reply by Dave Z on February 8, 2010 at 6:08am
Lets see, the old forumula is....
half the distance between oarlocks, divide by 7, then multiply by 25. You'll find it on various oar-maker sites too.

Yields 9-1/2 footers for your boat.

How it is devived, lets see..................

You have two oars. you don't want the handles to hit, right? The span of one oar inside the boat should be half the distance between the oarlocks. 64 inches/2 = 32".

A typical leverage ratio for rowing oars is 7:18.
The typical distance from the oarlock to the end of the grip is 7/25ths of the total oar length.
Therefore, total length is 1/7th of the inside length of the oar (32"/7) multiplied by 25.
114.28" equals roughly 9.5 feet. Seems a little long.

For drift boats, I have used a different formula. Roger knows it. I have it written on my shop wall at home and can't recall it here. I'll post it later.

Yeah, boat length has nothing to do with oar length. It's all about the beam at the oarlocks and how high the sides are.

My oars are actually just varnished. I have a set of Gulls and a set of solid ash oars I made. They are hung vertically from the rafters when not in use. How many time shave I banged my head on them? Don't ask.
Permalink Reply by AJ DeRosa on February 8, 2010 at 6:59am
Any time the question of "how long for my boat" comes up on these forums the old formula thing usually comes out. Formulas might be a starting point but as Dave has shown they are not the final answer.
As Dave mentioned there are many factors to consider and nobody has come up with the factor of individual preference. The white water guys seem to prefer longer oars for power, fishing guys might want a little shorter for tight spots. How high is your seat relative to the freeboard? How tall (or short) are you? These are the other variables that come into play. Consider this; when you are rowing with the blades in the water are your hands at eye level, oars too short, or are they bumping your knees, oars too long.
As is usually the case, trial and error is a very good teacher. I have the unfair advantage to try several different lengths for each new boat we build since we have a quiver of oars from 8' to 10'to choose from. Easy to throw in a couple pairs and try them out. You may or may not have this luxury. Borrow some from your friends and have at it.
Another approach to consider if you are building your own oars ( and a tip of my hat to you if you are ) is to turn your grips extra long so you can trim them to suit your particular comfort zone. Obviously you want to start out too long and trim down. I have done this on several sets of oars with very good results. You can trim from either end as well. Shortening a few inches from the blade side is not out of the question but the double long grip gives you a better range for fine tuning to your particular sweet spot.
Permalink Reply by Kelly Neu on July 9, 2014 at 10:15am

Hi Dave,

Wondering if you could share your driftboat oar length calculations?  Seems like the equation above tends to come out a little long for most of my boats.  Curious what the difference might be.  Thanks for all your great posts.

-Kelly

Permalink Reply by Brad Dimock on February 13, 2010 at 6:39pm
I'm with Ray on oar tips. The debate is whether to try and make them to strong to break, or too limber and supple to break. I go with the latter--soak them in turp/linseed all winter and between trips. That keeps them super-light and knife-like when feathering through waves, and they just don't break. Making the tips heavier and fatter goes against my inherent laziness, and they'll never be stronger or harder than the rocks. I claw my way along the shore as much as anyone, and the untipped oars hold up just fine.

As far as finish for the shafts, I do not recommend epoxy or varnish. In the long run (I'm thinking a decade or more) all that will crack and peel and give you endless headaches, endless sanding, endless recoating. I use an LTV (Linseed/Turpentine/Varnish, equal parts) or the old boat soup (Linseed/Turp/Pine Tar/Japan Drier). Give the oars a one-minute sanding if they're getting hairy, slop on the glop, rub it dry. It's quick, the oars always look good, and they'll never blister or peel. Works well in conjunction with the above oar-tip system as well.

Length? I agree. Try the formula and see how it works. Be ready to adjust. Too long is way worse than too short, though.
Permalink Reply by Gopher Dan on July 10, 2014 at 8:20am

Sit in the boat with some long 1x2"s or extra lumber, with some small sections of spare plywood clamped on the end and see what angle you like best.  All the formulas I saw yielded oars that were too long.

My boat is 14'8" from tip to stern directly down the center line with 69" from oar block hole to oar block hole, and I went with 9' and they seemed perfect.

A lot of it depends on how high the seat is and if you have standard or high sides on the boat.  I found in my scenario 8.5' oars would have come in closer to my chin than my chest and would have been too short.

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