Two Piece Oar

[Bobcat]

I want to make about a ten foot sculling oar, but have it break down to stow. Any thoughts on how to join the two pieces? I am thinking of a metal or PVC sleeve and a pin. Would it work? Is there a better way?

[htom]

Find a different place to stow it.

Well, maybe there isn't one. Perpendicular clothespin scarfs, maybe, with a sleeve over it and pins.

[JimConlin]

PVC is heavy, weak and flexible. I'd think of an aluminum or glass composite ferrule joining spruce oar parts.

[Thorne]

Most of the spars I've tried extending have broken at the extension -- so whatever you use, see if you can 'taper' the stiffness off at the ends. Perhaps using fiberglass strips wound around the oar at either end of the metal sleeve?

Won't an extension cause real problems with a sculling oar == I thought they were supposed to flex evenly...

[skuthorp]

Maybe redesign the oar, a year or 3 back there was a propulsion system designed involving a sinuous metal strip that 'skulled' a pedaled kayak. Maybe an oar shaft with a length of flexible stainless steel that could slot in and fix with bolts or pins? The shaft may not need to be as long as a conventional oar, and could possibly be curved slightly as the effort would not be so much, I think?
Maybe you could dispense with the oar and use a modified rudder setup?

[Peter Malcolm Jardine]

I have been thinking about a similiar problem in making oars for my dory ketch... by the book they would be 108 inches long, and it would be easier to stow them in two pieces.

My suggestion is this: (after some thought) a piece of 2" brass pipe, with the ends brazed over with a piece of 3/8' brass plate. before the brass plate is brazed in place, a extra thickness on on plate would be placed in the middle of the diameter, then drilled and tapped with an appropriate tap...probably 3/8 fine thread, or even 1/2 inch. On the other assembly a bolt brazed into the middle of the other plate. The two would slip over the oar for a reasonable distance...maybe six inches or a little more, then screw together. The strength of the two surfaces of two inches diameter should be quite tough.

The other arrangement i have thought of is a brass sleeve as a socket, then a very close fitting sleeve on the other end with a tension fit. I have seen this done on Kayak paddles, and it was successful, although the torsion on an oar is greater.

Both suggestions involve some machine work, and I am not sure of how much weight they would add to the oar.... which is a consideration on an oar used in a faster hull. I am still debating my own choices

[Bob Smalser]

I want to make about a ten foot sculling oar, but have it break down to stow. Any thoughts on how to join the two pieces? I am thinking of a metal or PVC sleeve and a pin. Would it work? Is there a better way?

Use heavy-gage brass pipe and bed the wood faying surfaces to a perfect fit using epoxy. Commercial 2-piece oars go bad quickly when enough play develops between wood and metal and the wood is progressively broken down.

[Tom Hoffman]

Instead of going to all this trouble. Make your own oars. I have an article that will teach you how to make a hollow core octagonal oar, either flat blade or spoon blade. It was authored by Joel Herzel, and he was kind enough to send it to me.

It makes a light long 9' - 10' oar. The big plus is that they are very cheap to make. I made 4 oars for less than $30 total.

If you would like the article and pics showing the jigs, email me.

Tom...

[Wooden Boat Fittings]

The other arrangement i have thought of is a brass sleeve as a socket, then a very close fitting sleeve on the other end with a tension fit. I have seen this done on Kayak paddles, and it was successful, although the torsion on an oar is greater.

Kareela's (kayak) 8'-8" paddle is made this way. It's lasted about forty years so far.... The joint is a close enough fit that I have to clean the verdigris off the faying surfaces and grease them at the start of each season in order to get the two pieces to fit together at all.

There's a difference though, in that a kayak paddle is normally supported with a hand each side of the joint, whereas the oar will (presumably) be supported only on one side, by the rowlock. Since you don't want to be left holding the loom while watching the blade drifting astern, I think you might want some form of positive locking on the joint, not just a friction fit.

Having said that though, whenever I've used Kareela's paddle for sweep strokes (both hands at one end,) there's never been any loosening of the then-outboard joint whatever. Also, although the whole loom has bent considerably under those conditions, nor has there been any damage at the joint (or anywhere else for that matter.)

Mike

[skuthorp]

Mike, if the metal joint is off-centre on the shaft, and the fulcrum is below the joint, would that make a difference in the wear on the joint?

Gotta go now, away for a few days.

[Ian McColgin]

Kayak paddles are not subject to anything like the bending, flexing stresses as oars. I despair of a good solution for the reasons Bob noted. This crushing is not a problem in double bladed paddles since the joint is not between load and fulcrum.

[Wooden Boat Fittings]

.
Jeff, I don't see that it would make much difference either way, apart from differences due to the respective lengths of the moment arms. (And except of course if the joint is inboard and comes apart, when you haven't just lost half the oar. And avagraybraikmate.)

Ian, I wouldn't entirely disagree. But as I note above I haven't found bending stresses to be a problem with sweep strokes with Kareela's paddle, when the joint is definitely between load and fulcrum (and the bending of the 1¼" dia loom is quite obvious to the eye.) I may say that Kareela has a long straight keel with no rocker so I use this stroke a good deal, and I've had many opportunities to be amazed at how well the paddle takes the strain.

Please note that I am talking about kayak paddles here though, not oars.

Mike

[Bobcat]

I appreciate all the replies. I am coming to the conclusion that there is a reason why I have never seen a break-down two piece oar, aside from the cheesy oars used on cheap inflatables. I have two kayak paddles that come apart, but there doesn't need to be as much strength in the middle of a kayak paddle as in the shaft of an oar.