Mountain Buzz banner

41 - 60 of 194 Posts

·
Registered
Joined
·
3,751 Posts
Discussion Starter #41
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.
 

Attachments

·
Registered
Joined
·
3,751 Posts
Discussion Starter #42
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."
 

·
Registered
Joined
·
3,751 Posts
Discussion Starter #43
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.
 

Attachments

·
Registered
Joined
·
3,751 Posts
Discussion Starter #44
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!
 

Attachments

·
Registered
Joined
·
3,751 Posts
Discussion Starter #45
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.
 

Attachments

·
Registered
Joined
·
3,751 Posts
Discussion Starter #46
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.
 

Attachments

·
Registered
Joined
·
3,751 Posts
Discussion Starter #49
I'm going to cross-post one of my own from another thread to keep my oar design info in one spot:


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.
 

·
Registered
Joined
·
3,751 Posts
Discussion Starter #50
Progress update:


Started by roughing out the handles. Had an oops moment and started the cuts 90º 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.
 

Attachments

·
Registered
Joined
·
3,751 Posts
Discussion Starter #51
I'm super excited about this part:After reading everything I could get my hands on by master oar-builder Pete Culler, and master dorymaker/riverman Brad Dimock, I decided I wanted dihedral concave faces.

Remembered an article I'd read awhile back about coving wood on the table saw. This was a crazy idea 20 years ago, but is a somewhat common technique today.
https://www.rockler.com/how-to/cutting-coves-table-saw/

Don't tell my dad, but I actually tried this 30 years ago on his table saw when I was trying to make a concave base on an old wooden water ski. 14 year-old me learned that fiberglass is not friendly to table saw blades. I didn't set up a good double fence so the cove on that water ski had some visible kerfs in it. The double fence is the key to keep the wood from wandering.

So I made this sled. The rails in back are 5/8" high so the edges of the blade can ride on them and let the neck/shaft of the oar ride through and not rise up.

(Note that the face taper was already done on these blades with my friend's huge jointer--first pic).
 

Attachments

·
Registered
Joined
·
3,751 Posts
Discussion Starter #52
I also did a tapered rip on the cedar/spruce blades:


Top of oar will be 5 3/4" and bottom will be 6 1/4" once we add a tapered spacer and ash blade edges
 

Attachments

·
Registered
Joined
·
3,751 Posts
Discussion Starter #53
If you can't visualize it, here's how the oar sits on the coving sled. Blue is the sled, red are the small blocks to align the oar shaft, green is the saw blade, oar blades are black dashed lines
 

Attachments

·
Registered
Joined
·
3,751 Posts
Discussion Starter #54
Used my table saw with the blade at 45° and only 3/16" deep to bevel the ends of the square tops. Cleaned them up with a chisel, then they got completely sanded with 60-grit followed by 120-grit.



You don't want to use higher than 120 grit before epoxy, because the finer grits will "burnish" the pores of the wood and epoxy won't soak in. 60-grit is perfect for "structural" work, but you can see the swirl marks under the epoxy so it needs a finer sanding.
 

Attachments

·
Registered
Joined
·
3,751 Posts
Discussion Starter #55
After sanding, they got epoxied. Cured the first coat overnight, quick sanding, then another flow coat last night. This will cure out, get a quick fine scuff, then ready for varnish.

Tips of the blades still need to be fiberglassed, so varnish is aways off, but I wanted to get the epoxy soaked in to protect the wood from dings.
 

Attachments

·
Registered
Joined
·
3,751 Posts
Discussion Starter #56
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.

Fixed my oops. 1/8" thick strips glued on:
 

Attachments

·
Registered
Joined
·
41 Posts
Thanks for Posting and sharing the Process-Your oars are looking nice!!
Your posts have motivated me to build my own oars after nearly a decade of procrastination.
I just ordered some 10' lengths of CVG from my local supplier today. Ill be doing the square tops as well, but would like to add some carbon fiber fabric to the blades and probably under the rope wraps.
Been reading about some carbon Fiber sleeves....this may be the ticket.

I saw your link to the Fiberglass sleeve...Do you think you'll go this route or stay with the natural wood?
 

·
Registered
Joined
·
3,751 Posts
Discussion Starter #58
Thanks Stelz!


After seeing CBRob's oar snap under his rope wrap, I definitely plan to reinforce it. It appears his rope crushed the outer wood fibers over time, and then being in the oarlock at that single point puts a lot of strain on the wood.





I have a little bit of CF cloth, and a lot of fiberglass; I will probably do a single layer of CF and then 2-3 layers under the rope wrap. I already have the flat cloth, and will just wrap it around the shaft. If I were going to do the full length of the shaft, I'd definitely go with the sleeve, that looks really easy to do.

With 4 oars, I may do two with rope wraps and two with leather collars.


Tips of the blades will definitely get glass. I boat shallow-ish, rocky rivers and my tips do strike bottom. Probably (6) narrow layers x 6oz glass.


Edge - I was thinking of doing a dynel edge bead like Sawyer...but my old oars have gone 14 years with ash edges and no major dings...so I'll probably just epoxy/varnish them.


Face - Both the fir and the jatoba are hard, dense woods. I'm not worried about major dings or delaminations, so I won't glass the entire face of the blades.




My friends' blades have spruce and cedar. They'll get wall to wall glass on the blade faces both for ding protection as well as to hold the laminate together (cedar tears easily), as well as the tips.

I hate to admit it, but I like the look of dings and battle scars, especially if they're superficial. I felt bad about the first dings on my old oars, but now I'm really proud of them 14 years later...they have lots of "patina" and still look nice.
 

·
Registered
Joined
·
3,751 Posts
Discussion Starter #59
Here's another interesting thought. I tried to make curves in the CVG strips cancel each other out, but still ended up with some slight taper.

You can see my centerline pencil marks across the width of the blade. A couple of them ended up off center when I planed off the tip of the curve.



You can also see the glue joint. Notice the glue joint is not centered in the first one on the left? When I was planing the taper into the shafts I noticed a pretty good curvature on that one. I planed away the curve, and the centerline moved....but now I have a very straight oar.
 

Attachments

·
Registered
Joined
·
3,751 Posts
Discussion Starter #60
Ill be doing the square tops as well, but would like to add some carbon fiber fabric to the blades and probably under the rope wraps.
Been reading about some carbon Fiber sleeves....this may be the ticket.

I saw your link to the Fiberglass sleeve...Do you think you'll go this route or stay with the natural wood?

Thanks for asking, too. I hadn't quite finalized what I'm doing with the blades and tips. Helpful to have to think about it, and once I've heard myself say it, then I have a decision made. :D

One of my last decisions is on tip shape. Rectangular tips are more traditional (for rowboats and dories) but rounded tips are what are most common for whitewater oars (Frank's, Sawyer, Smoker, etc.) I've somewhat wanted to go square...but then I look at the damage on my old oars and it really has been ~90% on the blade tips. I think squared corners would invite the most damage....probably will go full round or semi-rounded (big flat oval).
 
41 - 60 of 194 Posts
Top