DIY square top oars - Page 5 - Mountain Buzz
 



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Old 07-27-2018   #41
 
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Let's talk flex

Holy crap, 2" is STIFF!
My old oars were 1.75" diameter--all the way from handle to root of blade. I thought I wanted something slightly stiffer/stronger. Not sure if I want something this stiff!



Carlisles and Cataracts are 1 7/8" OD. Carlisles aren't worth comparing. These shafts are currently stiffer than Cataracts, which are stiffer than my old wood oars.


Sawyers are generally 2" OD. Sawyer Squaretops (and non-square fir wood core dynalites) are 2" OD up at the handle through the rope, and then taper from about 1.75" below the rope to a bit more than 1.5"

Smokers (ash) are over 2" OD at the handle, 2" OD at the rope, and taper to maybe 1.75" at the blade neck. This continuous taper puts most of the flex in the blade and out at the neck of the blade.


Oar design and construction goes back hundreds of years farther than whitewater rafting. We're pretty hard on our oars, but are we harder on our oars than a whaling longboat or other workboat?


Jim Michalak, in both his book (Boat Building for Beginners (and Beyond)) and at www.jimsboats.com/ January 1st 1999 shows some relatively small scantlings at the blade neck:



R.D. "Pete" Culler also has quite small blade necks. Even if we scale a 8' oar up to 10', a 1.25" neck is only 1.5".







I think I'll land close to these dimensions by Don Kurylko:
More photos of Don Kurylko's new boat - Page 23



As my blades will be slightly larger, I think I will shoot for 1.75" deep in the direction of force (perpendicular to the blade) and 1.5" thick parallel to the blade to shave weight.

Blades will taper out to 0.5" at the tip, and the edges will be 3/8" thick, tapering up to the spine in a diamond shape, very similar to Kurylko's MYST oar design above.
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Old 07-27-2018   #42
 
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More good discussion on oar shaping from Brad Dimock:
fretwaterlines: Oar quest
fretwaterlines: Oars, oars, and more oars

A student's blog from Brad's oar class:
Whitewater Dory: Oar School

How Gull oars are made:
fretwaterlines: Down Und Oars

How Van Fancy Oars are made:
fretwaterlines: Fancy Oars


Scott Thybony's Grand Canyon Commentary: The Oar Maker | KNAU Arizona Public Radio

"The goal," Brad says, "is to see how much wood you can get off the oar stock and still retain the strength and the stiffness you need. You get rid of the weight, scoop it out ounce by ounce until you have the spring and the flex you want." "Do you take aesthetics into consideration when making an oar?" I ask.
"It's secondary," he answers. "But it's like a beautiful boat. A beautifully shaped dory will almost always row beautifully." The oar maker stands next to a fine set of oars with the blade tips painted sandstone red. "If it's a beautiful oar," he adds, "it will likely row well, too."
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Old 07-30-2018   #43
 
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So...I'm going to go something like this in my final dimensions.




Like I said, 2" x 2" (2" dia. round) is pretty heavy.


I took my solid 2" diameter shafts and tapered them down so they're still 2" up at the oarlock, but 1 5/8" in the plane of the blade, and 1 7/8" across the blade. I'll lose a bit more when sanding and final shaping.

Then routed the faces again. This is pretty cool. If you taper the width and still use that 1" roundover bit, then the top and bottom rounds intersect each other. You end up with a smooth football shape, which is incidentally exactly what I want. There is a VERY noticeable difference in balance and swing weight.


And I haven't yet touched a jack plane or spokeshave. haha.
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Old 07-30-2018   #44
 
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Then I glued up my blades.


I had originally planned to glue them all up at once, but found that balancing 4 pieces of wood on each side of the shaft was difficult. I did the top ones on the shaft first, and glued up the bottoms loose.


Then after the glue green cured, I glued the bottom ones on and clamped them overnight.


And I did actually start with a plan of what these will look like. The veneer accents aren't required (didn't have them in previous sets), but my friend Jeff had this gorgeous African jatoba cherry that he offered up. Thanks Jeff!
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Old 07-30-2018   #45
 
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But MT4Runner, what about the square tops?

Say no more, fam. They're getting clear VG Douglas Fir parallel to the blades, and Jatoba perpendicular to the blades (echoing the veneers in the blades).

As the veneer is 3/16" thick, the overall square will be 2 3/8". Nice and massive.

Fir is glued up, then I will sand it smooth and glue on the jatoba tonight.
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Old 08-06-2018   #46
 
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Pulled the clamps and planed the blades down on the big jointer. Blades are 5/16" thick at the tips (they will be glassed). Now I need to use the hand power planer to take the body of the blades down to 5/16" at the edges--section will be diamond-shaped.

Ready to bevel the square tops.
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Old 08-06-2018   #47
 
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Good stuff. Thanks for continuing to share the process.
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Old 08-07-2018   #48
 
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More oar blades

The cedar is all cut from a single board.
The striping is natural.
Each blade side is made of only 3 pieces of wood!

Going for a Polynesian look on the other set; blades are cedar with thin spruce strips.
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Old 08-24-2018   #49
 
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I'm going to cross-post one of my own from another thread to keep my oar design info in one spot:


Quote:
Originally Posted by MT4Runner View Post
I have a stern frame with 66 inches between the locks, a day frame with 74 inches between the locks, and my big 4-bay Frame is 84 inches. 9.5' and 10' wood oars.

I can swing the 10 footers in my day frame, but it is not as comfortable as the 9.5' oars.

Common rules of thumb for oar stop placement are 2/7 the length of your oar, 30%, and the 1/3 2/3 Rule.

2/7 needs a counterbalanced oar with light blades, I like 30% for most situations, and 1/3 works with heavy blades and wide oarlock spacing

For a 10 foot oar, 2/7 is only 34.2" of oar inside the locks, 30% is 36", and 1/3 is 40".

For a 9.5 foot oar, 2/7 is only 32.4" of oar inside the locks, 30% is 34", and 1/3 is 38".
These will have the oar stop set somewhere between 36" (like my current unweighted oars) and 38" from the handles. I think 40" will be unnecessary.

I'm seriously considering leathers greased with beef tallow.
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Old 08-24-2018   #50
 
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Progress update:


Started by roughing out the handles. Had an oops moment and started the cuts 90 off and didn't get the 1 1/2" x 1 1/4" block I wanted. I started with the depth for the 1 1/4" face but cut on the 1 1/2" face (deeper cut). Fortunately I didn't take a full bite and they're roughed at 1 3/8" x 1 1/4". I think I will glue on a 1/16"+ piece of veneer to take it back up to 1 1/2" before I carve them further. General dimension feels good.
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