Mike
11-12-2009, 03:10 PM
I intend to make my own oars and spars for the Tender Behinds I am building (see my Blog) and have done a bit of research on the subject.
There is plenty of advice available on the Web, of course, some of it better than others. Overall, I plan to use the advice given on just two sites, one by Jim Michalak and the other on a website called 'Sizes' as follows:
Jim Michalak's Boat Designs (http://marina.fortunecity.com/breakwater/274/2001/0215/index.htm#ROWING%202001B)
118 E Randall, Lebanon, IL 62254
Rowing 2001B
I decided to rerun these rowing articles that first appeared here in the winter of 98-99. I've left out some of the details that appeared in those issues and added other details.
MAKING A SET OF OARS....
I'm going to show drawings for 7' oars which are about the most useful length for me.
561
WHAT KIND OF OARS....
The oars I make are really derived from the patterns of the late Pete Culler. They are characterized by having heavy square looms inboard of the locks and long narrow blades in the water. An example is shown in Figure 1.
The square looms are easy to build, help balance the oar, help locate the oar in the locks, and keep the oar from rolling around on the wales.
The long narrow blades go against modern thinking of spoons, but for long distance rowing, long and narrow is the way to go. The average mortal can only pull so much of a load, in spite of what an Olympian might do. The Culler blades can match the mortal's pull. They might slip a bit when starting a heavy boat from a standstill, but once up to speed, the have full grip on the water. They balance better. They are less fatiguing. They have less windage. By the way, the oars of traditional Irish caurrahs have no blades on their oars. Neither do the paddles of some traditional kayaks.
WHAT YOU NEED...
Oars are made from four materials - wood, glue, leathers and varnish.
For wood, I use 1x6 pine boards. The pattern shown in Figure 1 will just barely make an oar from a 1x6. I try to buy a single board long enough to get out both oars. For example, for a pair of 7 foot oars, I buy a board 14 feet long if I can. That way the oars will be a close match on weight, stiffness, and color I like to use soft wood like pine, It is easy to work and makes a light oar. It need not be clear wood although clear is easier to work Small solid knots are fine and look good too. I've never worried too much about grain because the sticks get laminated and tend to stay straight. But the straighter the grain the better.
For glue I prefer plastic resin "Weldwood" glue and doubt if there is anything better for making oars. Pour some in a cup and squirt in cold water until it has the consistency of normal woodworking glue like "Elmer's. I've found it to quite true that this glue will not set properly until it is a t 70 degrees F for twelve hours like it says on the can. But don't hesitate to use epoxy if you already have it on hand.
For leathers I don't use leather. I bind the 8 inches just below the square section of the loom with synthetic mason's twine, about 3/32" diameter. It lasts for years.
For varnish I use ordinary oil based spar varnish.
Now let's talk tools. The tool I use the most in making oars is a bandsaw and I hate to say that because it's not a cheap or small thing that everyone will have. The problem is that you've got to saw a 2-1/4" thick blank. Hand saws will work and the effort should get you in shape for rowing. After all, oars were invented long before the bandsaw. But I see Dave Carnell has built oars using his table saw and others have built oars with a sabersaw.
HOW TO BUILD...
First cut the 1x6 boards to the proper length. lay out the centerline with a straight edge. Then draw the pattern for the center piece, the one with the blade, around the centerline. Cut out the center lamination following the line closely with your saw, because the outer laminations of the blank are made from the off fall and there isn't much extra.
You can draw patterns of the outer pieces and cut them out. But it's easier to glue the pieces directly to the center piece and trim them after the glue cures. Trial fit the outer pieces. You may have to trim them for the proper shape where they blend into the blade area of the centerpiece. When you are satisfied, butter them up well with glue, and clamp them in place. You may need to tap in a a light temporary nail to keep the pieces from sliding around on each other because almost all glues are quite slippery until they start to set. Try to get glue squeezed out all around. And be sure the blank is resting straight while curing. Walk away from the blanks until the glue has cured hard.
After cure, trim the outer pieces to match the centerpiece. Use a plane and sander to work these pieces to their final lines, being careful that these faces remain square to the other two unworked faces.
Now cut the two unworked faces of the handle and loom of the oars to their final dimensions. Draw centerlines down the two worked faces and lay out the shape of the handle and loom. Cut to the lines and sand smooth. At this point the cross section of the oar from handle to loom is square.
The oar drawing shows how much of the loom is left square. The rest is to rounded. You start by drawing lines on handle and loom that allow you to make the cross sections octagonal. You can draw them using the gadget shown in Figure 2. Then cut down to the lines with a half round rasp where the lines blend to the square section of the loom. Then use a drawknife or plane to remove the rest of the material down to the lines along the shaft. Now she's eight sided. To round it you're supposed to sixteen side it and then round it out. To tell you the truth, I leave mine eight sided, including the handle and the area which fits in the rowlock.
562
Lastly you need to trim mass out of the blade. I plane the blade down so its edges are 1/4" thick. Then I use the front roller of my belt sander to hollow the blade slightly on either side of the center, leaving a ridge in the center.
I think the only critical part of these oars strength wise is the 1-1/4" section where the blade meets the loom.
Give the oars a good overall sanding, but leave the handles rough.
Wrap the rowlock area, from the square section down 8 inches toward the blade, with mason's twine. Wrap it tightly and use knots to secure it.
Give the oars three coats of spar varnish. That includes putting varnish on the twine binding. It will go a long way towards holding the binding in place. Don't varnish the handles.
An easy and effective "button" can be made be added to the bound area, to provide a stop which will locate the oar lengthwise in the lock, by wrapping it tightly with three wraps of 1/4" shock cord, and tying the cord with a square knot. If the tension in the cord is right, it will stay firmly in place while rowing and yet allow repositioning up and down the bound area to change rowing leverage when required.
And from Sizes:
http://www.sizes.com/tools/oars.htm
oars
The handles of a pair of oars should overlap by 4 inches, that is, the inboard portion of each is 2 inches longer than half the distance between the rowlocks. The distance between the rear edge of the rower's seat and the rowlocks should be about the distance between the inside of the rower's wrist and the inside of the elbow.
An oar is a lever with its fulcrum at the oarlock. The oarlock's position relative to the oar is set by the location of the button, the ring that keeps an oar from sliding through the oarlock. Shaw and Tenney (Orono, ME), one of America's premier makers of oars, recommends a ratio of 7:18 for all boats designed for efficient rowing, from skiffs to shells. To achieve this, the inboard portion of the oar must be 7⁄25ths of the overall length of the oar. So, for example, if the distance between rowlocks is 42 inches, the distance from the end of the handle to the button should be (42 ÷ 2, + 2 =) 23 inches, and the overall length of the oar (23 ÷ 7, × 25 =) 82 inches or 6 feet 10 inches. Stock oar sizes from 6 to 10 feet are in 6 inch increments, so round up to 7 feet.
563
For a utility boat not really made for efficient rowing, such as a dinghy, round down instead of up. Longer oars will do no good and just be more cumbersome. But in any boat, if an oar continually pops out of the oarlock, the oar is too short.
The point at which the oar would balance if it were supported on a narrow rail should be on the outboard side, but within a foot of the button.
I would not use pine for the oars and intend to use either spruce or Douglas fir. I like the idea put forward by Jim Michalak and, if you visit his website via the provided link, you will see he offers some advice on rowlocks and the gunwale fittings too.
Best wishes
There is plenty of advice available on the Web, of course, some of it better than others. Overall, I plan to use the advice given on just two sites, one by Jim Michalak and the other on a website called 'Sizes' as follows:
Jim Michalak's Boat Designs (http://marina.fortunecity.com/breakwater/274/2001/0215/index.htm#ROWING%202001B)
118 E Randall, Lebanon, IL 62254
Rowing 2001B
I decided to rerun these rowing articles that first appeared here in the winter of 98-99. I've left out some of the details that appeared in those issues and added other details.
MAKING A SET OF OARS....
I'm going to show drawings for 7' oars which are about the most useful length for me.
561
WHAT KIND OF OARS....
The oars I make are really derived from the patterns of the late Pete Culler. They are characterized by having heavy square looms inboard of the locks and long narrow blades in the water. An example is shown in Figure 1.
The square looms are easy to build, help balance the oar, help locate the oar in the locks, and keep the oar from rolling around on the wales.
The long narrow blades go against modern thinking of spoons, but for long distance rowing, long and narrow is the way to go. The average mortal can only pull so much of a load, in spite of what an Olympian might do. The Culler blades can match the mortal's pull. They might slip a bit when starting a heavy boat from a standstill, but once up to speed, the have full grip on the water. They balance better. They are less fatiguing. They have less windage. By the way, the oars of traditional Irish caurrahs have no blades on their oars. Neither do the paddles of some traditional kayaks.
WHAT YOU NEED...
Oars are made from four materials - wood, glue, leathers and varnish.
For wood, I use 1x6 pine boards. The pattern shown in Figure 1 will just barely make an oar from a 1x6. I try to buy a single board long enough to get out both oars. For example, for a pair of 7 foot oars, I buy a board 14 feet long if I can. That way the oars will be a close match on weight, stiffness, and color I like to use soft wood like pine, It is easy to work and makes a light oar. It need not be clear wood although clear is easier to work Small solid knots are fine and look good too. I've never worried too much about grain because the sticks get laminated and tend to stay straight. But the straighter the grain the better.
For glue I prefer plastic resin "Weldwood" glue and doubt if there is anything better for making oars. Pour some in a cup and squirt in cold water until it has the consistency of normal woodworking glue like "Elmer's. I've found it to quite true that this glue will not set properly until it is a t 70 degrees F for twelve hours like it says on the can. But don't hesitate to use epoxy if you already have it on hand.
For leathers I don't use leather. I bind the 8 inches just below the square section of the loom with synthetic mason's twine, about 3/32" diameter. It lasts for years.
For varnish I use ordinary oil based spar varnish.
Now let's talk tools. The tool I use the most in making oars is a bandsaw and I hate to say that because it's not a cheap or small thing that everyone will have. The problem is that you've got to saw a 2-1/4" thick blank. Hand saws will work and the effort should get you in shape for rowing. After all, oars were invented long before the bandsaw. But I see Dave Carnell has built oars using his table saw and others have built oars with a sabersaw.
HOW TO BUILD...
First cut the 1x6 boards to the proper length. lay out the centerline with a straight edge. Then draw the pattern for the center piece, the one with the blade, around the centerline. Cut out the center lamination following the line closely with your saw, because the outer laminations of the blank are made from the off fall and there isn't much extra.
You can draw patterns of the outer pieces and cut them out. But it's easier to glue the pieces directly to the center piece and trim them after the glue cures. Trial fit the outer pieces. You may have to trim them for the proper shape where they blend into the blade area of the centerpiece. When you are satisfied, butter them up well with glue, and clamp them in place. You may need to tap in a a light temporary nail to keep the pieces from sliding around on each other because almost all glues are quite slippery until they start to set. Try to get glue squeezed out all around. And be sure the blank is resting straight while curing. Walk away from the blanks until the glue has cured hard.
After cure, trim the outer pieces to match the centerpiece. Use a plane and sander to work these pieces to their final lines, being careful that these faces remain square to the other two unworked faces.
Now cut the two unworked faces of the handle and loom of the oars to their final dimensions. Draw centerlines down the two worked faces and lay out the shape of the handle and loom. Cut to the lines and sand smooth. At this point the cross section of the oar from handle to loom is square.
The oar drawing shows how much of the loom is left square. The rest is to rounded. You start by drawing lines on handle and loom that allow you to make the cross sections octagonal. You can draw them using the gadget shown in Figure 2. Then cut down to the lines with a half round rasp where the lines blend to the square section of the loom. Then use a drawknife or plane to remove the rest of the material down to the lines along the shaft. Now she's eight sided. To round it you're supposed to sixteen side it and then round it out. To tell you the truth, I leave mine eight sided, including the handle and the area which fits in the rowlock.
562
Lastly you need to trim mass out of the blade. I plane the blade down so its edges are 1/4" thick. Then I use the front roller of my belt sander to hollow the blade slightly on either side of the center, leaving a ridge in the center.
I think the only critical part of these oars strength wise is the 1-1/4" section where the blade meets the loom.
Give the oars a good overall sanding, but leave the handles rough.
Wrap the rowlock area, from the square section down 8 inches toward the blade, with mason's twine. Wrap it tightly and use knots to secure it.
Give the oars three coats of spar varnish. That includes putting varnish on the twine binding. It will go a long way towards holding the binding in place. Don't varnish the handles.
An easy and effective "button" can be made be added to the bound area, to provide a stop which will locate the oar lengthwise in the lock, by wrapping it tightly with three wraps of 1/4" shock cord, and tying the cord with a square knot. If the tension in the cord is right, it will stay firmly in place while rowing and yet allow repositioning up and down the bound area to change rowing leverage when required.
And from Sizes:
http://www.sizes.com/tools/oars.htm
oars
The handles of a pair of oars should overlap by 4 inches, that is, the inboard portion of each is 2 inches longer than half the distance between the rowlocks. The distance between the rear edge of the rower's seat and the rowlocks should be about the distance between the inside of the rower's wrist and the inside of the elbow.
An oar is a lever with its fulcrum at the oarlock. The oarlock's position relative to the oar is set by the location of the button, the ring that keeps an oar from sliding through the oarlock. Shaw and Tenney (Orono, ME), one of America's premier makers of oars, recommends a ratio of 7:18 for all boats designed for efficient rowing, from skiffs to shells. To achieve this, the inboard portion of the oar must be 7⁄25ths of the overall length of the oar. So, for example, if the distance between rowlocks is 42 inches, the distance from the end of the handle to the button should be (42 ÷ 2, + 2 =) 23 inches, and the overall length of the oar (23 ÷ 7, × 25 =) 82 inches or 6 feet 10 inches. Stock oar sizes from 6 to 10 feet are in 6 inch increments, so round up to 7 feet.
563
For a utility boat not really made for efficient rowing, such as a dinghy, round down instead of up. Longer oars will do no good and just be more cumbersome. But in any boat, if an oar continually pops out of the oarlock, the oar is too short.
The point at which the oar would balance if it were supported on a narrow rail should be on the outboard side, but within a foot of the button.
I would not use pine for the oars and intend to use either spruce or Douglas fir. I like the idea put forward by Jim Michalak and, if you visit his website via the provided link, you will see he offers some advice on rowlocks and the gunwale fittings too.
Best wishes