Once more on oars

[Peter Malcolm Jardine]

I am going to make a set of oars for Dove, the dory ketch. I am sure as a dory she will row well, albeit a mite heavy compared to a rowing dory. Bristol bronze sells a set of traditional oarlocks with extra length so that the sockets can be flush at the gunwale, and the oarlock will give the height necessary to accomodate the coaming on the cockpit. I am thinking spruce, with a spoon blade. What is the ratio between boat width and oar length? Any comments on construction? Laminations? woods? purty pictures?

[Bob Smalser]

...dory ketch.... heavy...

What is the ratio between boat width and oar length? Any comments on construction? Laminations? woods? purty pictures?

I'd make them powerful and fairly robust for heavy work. Shaw and Tenney's 7:18 formula makes for a strong, well-balanced oar but you have to get used to crosshanded rowing if you aren't already.

Spruce, ash, Doug Fir. Ash is the most robust; spruce has the best strength to weight ratio. I'd probably use the local spruce in a full scantling as I think ash is unnecessarily heavy, and not get very fancy. Light, racing oar designs and heavy work don't mesh.

[Peter Malcolm Jardine]

I was thinking spruce, and try to pick a couple of nice pieces locally. I have your threads and the others kind of memorized Bob, thanks for your comments..... so be be totally ignorant of the process Dove is about 4 feet wide... How long ?

[Bill Perkins]

Peter ; not your question ; but for a boat with side decks ,as Dove has , I like oarlocks that have some provision for attaching a lanyard to the lock above deck , like Bristol Bronze's Raised Ribbed Horn oarlock , if those are high enough. I guess you could carefully tie a lanyard to the body of the "Traditional " lock with maybe a dab of epoxy as a bedding .

The lanyard runs from the lock, over the side deck , to be made fast inside the boat . With one hand you can then grab the lock ; bring it inboard ; and tuck it somewhere safe like under a short length of shock cord placed under the deck for the purpose .The lock can also be quickly deployed one handed .

Locks secured with a short chain or line and toggle to the very bottom of the lock are practical for open boats but a nuisance for decked ones I think . Every time the oarlock needs to be removed you've got to grope for the toggle below deck with one hand while pulling the lock out with the other . Same thing when mounting the lock . If you bobble it for any reason it's gone overboard . I'm assuming that you're not going to risk those nice pieces without lanyards of some kind .

[Bob Smalser]

I was thinking spruce, and try to pick a couple of nice pieces locally. I have your threads and the others kind of memorized Bob, thanks for your comments..... so be be totally ignorant of the process Dove is about 4 feet wide... How long ?

What's the exact distance center to center between oarlocks and their approximate height above the waterline? High-freeboard boats benefit from more length, and rowing from atop a coaming is higher than normal.

http://pic20.picturetrail.com/VOL12/1104763/4518261/60037718.jpg

[Bruce Hooke]

In case Bob was not explicit enough in his comments...I'd skip the spoon blades. Spoon blades are for lightweight, high-performance rowing craft, not large, heavy dories...

[Don Z.]

From Shaw & Tenney:
http://www.shawandtenney.com/images/oardiagram.jpg
http://www.shawandtenney.com/images/boatdiagram.jpg

Shaw & Tenney Oar Length Formula for Correctly Fitted Oars
Inboard length of the loom equals ½ 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

[Canoeyawl]

Rowing a heavy boat does not always follow the “rules”
Ships used to be rowed from the orlop deck; I wonder what the specs are for those oars?
My little yawl (4000lbs) rows standing up with 8-1/2 foot spoons. Although a straight blade oar would work I had the spoons and tried them and they work fine.
This was all a surprise to me, as the plan was to follow convention and I have a lovely new pair of 10-1/2 foot workboat oars leaning in the corner for 10 years now. They just won’t work for this job.
If you can beg or borrow some different oars to test you may save a bit of work.
The technique for rowing a heavy craft is very different from a skiff. Short powerful strokes are the order of the day. If you get hung-up on the finish, that oar can hurt you.

[Peter Malcolm Jardine]

Dove is 4 foot 10 inches in beam, with 14 inches of free board where the locks would go. The coaming is 4 inches. The Bristol bronze oar lock raises the oar 3 3/4 inches above the deck. According to my calculations, which could be wrong, the inboard length of the oar is 29 inches, and the total length is 103 inches. Does this make sense?

[Thorne]

Sounds sorta short. My dory skiff is 4'3" at the widest, with about 8"-12" of freeboard. I found that moving to 8' oars from 7' oars made a huge difference.

With your additional freeboard and beam, sure sounds like you might want to try 10' oars. As suggested above, why not put in the oarlocks and try some borrowed oars before you build/buy? You could even try to temporarily clamp oarlocks into place if unsure of the exact position.

This is all assuming rowing from a sitting position -- standing will require longer oars, different oarlock positions, and probably the tall oarlocks.

[Bob Smalser]

... the inboard length of the oar is 29 inches, and the total length is 103 inches. Does this make sense?

I get 31" inboard length and 9' 3" overall, which sounds better.

I'd whip out a couple of rough blanks out of DF with temporary buttons at 30" from handle end, LOA of 9'6" and try them for fit. With your freeboard I don't believe your thumbs will overlap and you can probably play around some with inboard length and even a LOA of 10'.

[Joe ( Cold Spring on Hudson )]

Just be careful not to affix the oarlocks or anything with stress to the oak coaming, thats there the last owner put some blocks and cracked it bad.

Oh and how about some PICTURES !!!!!!! ;)

[Ian McColgin]

Just reinforcing about the spoon blades. Negatory. Note the article about the dory stroke in the current WB which, I'm happy to say, agrees with my deep prejudices.

Spoon oars really feather poorly compared to a symetrical blade, which really gives a power blast as you start the feathering as you move the oars up through the water at the end of the stroke - especially if you've reduced the shaft experimentally to get a bit of bend and spring back on that part of the stroke.

Interestingly, and like a traditional kayak paddle, a narrowish face with a central rib, edges thinner, is quite dynamic and has huge lift.

[Songololo]

Here is are two online utilities (from a sail and oar website) that will calculate the lengths of the various oar components based on boat width ... they are in French but fairly straight forward to follow (Google language tools helps :)...

http://cnsl.naoonet.free.fr/construction_amateur/avirons/calcul_aviron_oeil.htm

http://cnsl.naoonet.free.fr/construction_amateur/avirons/calcul_aviron.htm

Haven't used them myself ... calculations not checked ...

[Tom Hoffman]

Peter, I am far from an expert, I needed a couple of sets of oars for my Whitehall I had just completed. I just couldn't justify spending $200+ per pair.

Joel Herzel was kind enough a couple of years back to respond to my post regarding this topic and provided me with a copy of his article. " Hollow Core Octagonal Birds mouth oars". I followed his instructions as closely as possible and ended up with two sets of oars approximately 120" long. I have since cut them down to just under 108". They work fine for our boat. Here is a link to the pictures of the boat and oars and construction of them.

http://community.webshots.com/user/slvrgost

If you would like to try your hand at a pair or two, send me an e-mail and I will send you the article. It is quite detailed and easy to follow.

Regards,

Tom.......

[Peter Malcolm Jardine]

Joe: No, oarlocks will be installed at the gunwale, with long shafts on the oarlocks. Yes I need to get some pictures.... :) I have done some work on various things.... new seat at the back of the cockpit, a pennant/fly ...nylon with a dove silhouette on it, etc...Thanks all for your replies. I would like to use DF if I can find some...or Sitka?

[Peter Malcolm Jardine]

Joe: No, oarlocks will be installed at the gunwale, with long shafts on the oarlocks. Yes I need to get some pictures.... :) I have done some work on various things.... new seat at the back of the cockpit, a pennant/fly ...nylon with a dove silhouette on it, etc...Thanks all for your replies. I would like to use DF if I can find some...or Sitka?

[Bruce Hooke]

I wouldn't bother with fancy Sitka Spruce of oars. Just find some good local spruce and go to town.