Sculling and Dingy Oars
20 Aug 14 -- The Sculling Oar.I am often asked about what our plan is for an engine. It is apparent that most people want to have as big an engine in their boat as possible. I respect that. I have nothing against engines though I don't understand the big engine facination. I would like to have an engine (a small one to be sure) but I have not figured out how to address all the particulars yet. I have often thought we could install a Beta Marine 14HP-16HP engine. I have dropped by and met with the Beta Marine folks at least twice. I have measured for one. I have a plan to install a propeller shaft slightly off-center, exiting the hull perpendicular to the rudder post and just above the top of the rudder (there is some interesting information about this in Skene's Elements of Yacht Design and Chapelle's Yacht Design and Planning). I have discussed folding propeller requirements with Martec. But, until the boat is in the water I can't be sure if there is enough room below the surface of the water for a propeller to work efficiently since I don't know exactly where the LWL will be. However, I admit that I would hate to give up the room we have without an engine, or the lack of endless complications, expenses, nasty smell, and significant tool and parts requirements. And, until the boat is in the water and I am sure what will and will not work there is no sense wasting any more mental energy thinking more about it. We have discussed outboard options. My friend Ben Zartman has a 8 HP four stroke Yamaha high thrust engine that propels his 19,000 lb gaff rigged Cape George 31 at 5 knots on smooth water. I have sailed on his boat and the capabilities of that little engine are very impressive. However, I would like to avoid an engine permanently hanging off the back of the Far Reach. I have sketched swing side mount engines as used by Yves Gelanis on his Alberg 30 Jean du Sud. Its a pretty neat system. But, it seems complicated and will take a couple of weeks of hard work to figure out how to adapt it to the Far Reach and a bundle of money to build. What are we going to do you ask? My answer, I really don't know. Currently, we are thinking about buying a 10' roll up inflatable with a small outboard (6hp - 9.9hp) so we have a second dinghy and a way for our kids to get around. It occurs to us we could employ the inflatable as a "yawl boat" to move the Far Reach around until we determine if we can make a small diesel fit as described above. A yawl boat seems like it would work, others have done it, though it would certainly not be convenient. I have talked to Larry Pardey about this predicament a couple of times. For 40 years they moved both of their boats with a sculling oar--Serrifyn at 10,500 lbs and Taleisin at 19,000 lbs. So, it is doable . . . at least for them. While we sort out what to do engine wise, I thought I could build a sculling oar and see how it works. I have researched it a fair amount. I have exchanged emails with Douglas Brooks who is an expert on the Japanese Ro sculling oar (similar to a Chinese Yuloh) and who has written articles about it for WoodenBoat magazine as well as many other maritime publications. I have also read about Bob and Kathy Groves use of a Yuloh to move their 14,000 lb Benford 34 Easy Go (though they did finally install a diesel, sadly just before their boat was lost last year). For the time being, I have decided to build a simple "life boat" style sculling oar using ash as described in the Self Sufficient Sailor (see gallery below). A yuloh, and ro as well, is very long and I imagine quite too. Though I understand them to be very powerful and efficient I think they would look odd on the modern western style Far Reach. A simple style sculling oar should not take a lot of time to build--four or five hours for a few days to knock out. I have little expectation that it will really work for us but I think it is worth seeing what it can do if for no other reason than to conduct an interesting experiment and develop an informed opinion. This would certainly be a better option if the Far Reach were on a mooring--which is what I would prefer. However, I have not been able to find any decent mooring fields that have sailing room any where near where we live in eastern North Carolina. So, there you have it . . . we have a few options to pursue--a diesel inboard, an outboard on a swing up mount, a yawl boat, and a sculling oar. Somewhere in there, we will find a workable solution.
Below:
1. I milled some rough cut ash to about 2 1/4" thick.
2. I traced the pattern out using the dimensions contained in the Self Sufficient Sailor.
3. This is hard to see but it's the blade taper.
4. I carefully cut well outside the line to remove the excess from the plank that will comprise the blade end of the oar.
5. I traced the blade taper on the edge of the plank and removed the excess with a power planer.
6. I marked for a 10:1 scarff and cut the excess off with a circle saw.
7. Next, I used my scarffing jib to cut a perfect 10:1 bevel on each part of the oar.
8. I mixed up the Aerodux 185 resorcinal glue 5:1 by weight as specified.
9. I added the hardener.
10. I brushed on the resorcinal adhesive.
11. Then, I clamped it hard.
It took the better part of the day but the sculling oar is mostly complete. It's about 16'5" long and will eventually, I think, be about 15' 6". The work was fairly straight forward though it was very hot and that made it a long day. After removing the rough cut oar from the clamps I knocked the dried excess resorcinol off with a belt sander. After that I used my 7-10-7 gauge to mark the loom and then proceeded to remove waste to turn the loom into an 8 sided shaft. After roughing it out I refined the octagon with a low angle block and smoothing plane. I also worked on the bade for a while though it will require some finish work tomorrow. Next, I used the power plane to knock the peaks off the 8 sides and turn the loom into a 16 sided shaft. After that, it was grunt work . . . spoke shave, sanding paper, long board, etc, I was drenched in sweat. I think it turned out pretty well. It is perfectly straight. I still need to refine the blade and cut the handle. I probably leave it wild till I am sure of the correct length. It was a fun project. Some people paint the blade white to protect it from checking. Others oil it. I am not sure what I will do but will definetly not varnish it. Probably, I'll oil the heck out of it then leave it to see what happens.
It took the better part of the day but the oar is about 80 percent complete. It's 16' 5" long. I suspect the final length will be about 15' to 15' 6".
Below:
1. After I unclamped the scarf I move the rough shaped oar outside and laid it across three saw horses.2. I knocked the excess dried resorcinal off with a bel sander. The scarf joint was very tight.
3. I use my 7-10-7 guage to draw the lines that I would cut back to make the four sided loom eight sided.4. I could have used a power planer but I chose to use my draw knife to cut the first four bevels.5. It was exceptionally hot so I set up the portable canopy to create some shade.6. It took some time but I cut the loom to eight sides. After using the draw knife to get close, I finished it off with a low angle block plane and a smoothing plane.7. With eight good sides it was time to cut down the peaks and make the loom 16 sided.8. I shaped the blade a little more and then began the arduous task of sanding the loom smooth.
I fussed around with the sculling oar attempting to figure out the best position for the oar lock. I will write more on this if it all works out. I had the round (2 3/4" diameter) oar lock itself cast from the Pardey patterns a few years ago at the same time the bow rollers were cast. Click here and here for more info on that project. I had to find an oar lock socket that was appropriate to the larger oarlock and heavier oar it would have to accommodate. Most are designed to take a 1/2" diameter pintle. However, I found a socket for a 5/8" diameter pintel made buy Davy and Co in the UK and sold through R & W Ropes. Then, I had a local machine shop mill the pintle from an bronze propeller shaft off cut. For now, I installed a 5/16" diameter 316 SS bolt.
The oar lock and oar lock pad.
The oar lock can rotate back and forth or swivel as required.
After making the oar I still needed to complete the shaping of the handle. To do that, I had to determine the length of the oar. I initially made the oar 16'5" long knowing it would eventually be shorter. I took the oar up on the boat and positioned it in the new oarlock. I used a protractor to get the angle correct--40 degrees to the water--and a laser level to ensure I had the majority of the blade below the LWL. Then, it was a matter of figuring out where the best to scull would be. Turns out, that on top of propane locker (the aft cockpit seat) is the best place. I offset the oarlock to starboard so the tiller would be directly forward so I can move it with my foot if needed. I may need to install a small removable teak plank athwart the aft end of the cockpit flush with the top of the propane locker to provide a larger platform but I'll wait till later to see what is actually required. Anyway, I cut the oar to 14'10" long to put the end of the oar between my chest and waist. I fudged a little two and left it a few inches long--"just in case." Next, I began to shape the handle. I used my small trim saw to make a series of wrap around kerfs in at the end of the oar making sure to set the saw blade depth a little shy of what I wanted for a handle diameter. After making the cuts I used my draw knife to remove the excess wood. Next, I used a spoke shave and cabinet makers rasps to work the final shape and then finished the handle off with a lot of sanding. I was pleased with the results.
It looks ugly but I made a series of cuts with my small trim saw.
I used the draw knife to carfull remove the wood down to the bottom of the kerfs.
I used a spoke shave, cabinet makers rasps, and sand paper to complete the handle.
I determined where I wanted the composite sleeve to fit. I sanded the loom with 80 grit. I cut two sleeves of the 7oz carbon fiber biaxial cloth for the oar. I put the smaller one on first (to create a taper), then pulled the longer one over the top. I wetted out the sleeve using a foam brush and West Systems Epoxy (105 resin and 207) clear hardener. The 207 has some UV inhibitors and cures blush free. I wore latex glove and really worked the epoxy into the carbon fiber then futher tipped out the sleeve with the brush. I let the epoxy tack up and applied another coat and so on and so fourth till I applied about five coats of over about 8 hours. The purpose was to fill the weave. I left the epoxy to cure for about two days then scrubbed it down with a 3M maroon scrub pad and water to ensure there was no amine blush. Next, I sanded the new epoxy coated sleeve with 220 and a 3M maroon pad. Then, I applied four coats of MinnWax one part Spar Urethane that has good UV and abrasion resistance. I sanded between each coat. I did this on the recommendation of the West Systems tech branch. It dried very clear and hard. The carbon fiber shows perfectly and it is very shiny (though I am not sure it is the right look for the Far Reach. I'll worry about that later though. I am sure the loom is very strong now and should pretty much incapable of warping or breaking.
Two layers of 7oz carbon fiber biaxial sleeve and about five coats of epoxy to fill the weave. Three coats of one part Spar Urathane for UV protection.
I purchased the cabron fiber sleeve from Soller Composites.
This is the carbon fiber after the first coat was tacked up. I applied four more coats on top of this one allowing each coat to tack before applying another.
I sanded the cured epoxy with 220 and a 3M maroon pad in preparation for applying four coats of Spar Urethane.
There is no mistaking the high tech look of carbon fiber.
It was time to install the oar leather on the sculling oar. It was my first attempt. I found some info in Greg Rossel's book, The Boat Builders Apprentice. There is also a helpful video on Off Center Harbor by Shaw and Tenney that is very good. I used #6 waxed nylon thread and two sail needles. The key was making sure the leather was square to start with. Then I marked each end of the leather around the loom in case there was any taper. I drew a line between the marks and cut it with a razor knife. I prepunched the holes insetting them about 5/16" and 1/4" apart. I soaked the leather in warm water for five minutes. The first and last loops are double loops to draw the leather down tight. All the rest are base ball stitches. The needles go from inside to outside. There was nothing to it. Simple. I hung the oar in the boat shed to let the leather dry.
I used the base ball stitch on the oar leather.
I was particularly pleased that the stitch remained straight down the loom. It is very tight.
Square Loomed Oars for the Dinghy
New Oars for out Fatty Knees Dinghy.I needed to make new oars for out 10 year old 9' Fatty Knees, Sweet Pea. We have sailed and rowed this little boat extensively and hold it in very high regard. Anyway, the original oars were cheaply made and a little short. I have wanted to replace them for awhile with a set of much tougher and more robust square loomed ash oars. I had some 8/4 rough ash on hand and decided now was a good time to make the oars. The photo gallery below pretty much describes the steps. I still need to cut the handles and install the round closed oar locks over onto the looms--I'll use a hack saw to cut the oar locks open at the top, bend them open, insert them over the loom and bend them back. The original oars were a little short at 7'. The Sweet Pea is 9' long and 54" wide. The new oars are about 8'1" long and should stow inside with a about 5 inches or so to spare. The square looms inboard of the oar locks will provide some weight to help counter balance the outboard end of the oars and thus make rowing a little less fatiguing. For a reference, I turned to my copy of The Boat Builders Apprentice by Greg Rossel to gain some insight on oar construction. This book has a lot of information about building wooden boats, spars, oars and the like.
TextI made the oars in the boat shed under the stern of the Far Reach. You wouldn't think that making two oars would generate so much saw dust.
Below:
1. I milled the boards as flat as I could without taking them down below the dimensions I needed for the square looms.2. I made a pattern for the balde from some scrap 5 mil ply. I shaped the patter for one half othe blade then flipped it over to trace the other side. That insured the blade was reasonably symetrical.
3. I don't have a band saw though I wish I had bought one long ago. I used a circle saw and bosche jig saw to cut the shape out.
4. I drew tapers for the full oar from the oarlock end of the square loom to the end of the blade. When I made the loom pattern it was also tapered as well.
5. I used a hand power planer to cut the taper in the blade--thickest where the blade meets the loom and thinest at the end of the blade.
6. Next, I shaped the blade with a power planer followed by the block plane and spoke shave.
7. I used my home made 7-10-7 guage to draw the lines for turning the square lower 2/3ds of the loom to a round shape.
8. I cut the corners to make it eight sided. That's the purpose of the 7-10-7 guage--to lay out the lines. You can mark them by hand (which is what I did on the bow sprit). I used a draw knife to take the corners down to just out side the lines, then transitioned to a spoke shave and block plane.
9. After making the looms eight sided, I used the spoke shave to take each corner down to make the loom 16 sided.
10. Next I used the spoke shave and cabinet makers rasps to round the looms. I cut some 2" diamter PVC pipe and split them open and slid them on the loom to check the fit for the round oar locks.
I spent most of my boat work efforts the past week completing the oars for the dinghy. In order to get more balance to the oars I refined the shape of the blades and worked to thin them down. Before I could get the oar lock on the looms I also needed to thin the looms down some more too. I spayed the looms with some automotive sanding primer and used it as a guide while working the loom with a spoke shave. The paint helped me maintain a fair and consistent taper. In fact, I needed to thin them down quite a bit and I sprayed and shaved them about a half dozen times. After each shaving I sanded with 120 grit abrasive paper on a very soft pad. Once I achieved the final taper I desired I then sanded the looms with once more with 120 grit abrasive paper until they were very smooth and consistently fair. To get the 2" round bronze oar lock onto the loom I used a technique described to me by Lin and Larry Pardey. I used a hack saw to cut through the oar lock at the top, placed the oar lock in the vise, and then cold bent them diagonally open. Once I had them open wide enough I slipped them on the oar loom. I carefully place the oar lock back in the vise and then gently bent them back closed. There is a very small gap of about 1/32"-1/16th" and though I think it is plenty tight with a little more work I think they would be flush. It was actually pretty simple. It is also apparent to me that cutting them open will not degrade their strength based on what they need to be able to do. In the next few days I'll sew on some leather to protect the oar loom where they will ride in the oar locks.
The dinghy oars are essentially complete. I need to taper the handles a little more and sew on the leathers.
Below:
1. I used automotive paint primer to spray onto the loom as a guide to maintaining a fair and consistant taper of the loom.
2. Using the paint as a guide was very effective. I was surprised how well it worked.
3. As the temperatures plunged I moved the oars from the boat shed into the shop.
4. I mainted a centerline mark as I thined down the oar blade. You can see where I cut the oar lock open.5. I bent the oar lock diagonally in the vise. I did not heat it up but worked it cold.6. Once the oar was on the loom I bent it back closed. Nothing to it.
7. If you compare this photo to some of the earlier ones you can see how much more the looms have been thinned and tapered.
8. I have a little more work to do on the blades and then seal the end grain of the blades with either shellac or epoxy. I plan to leave the oars bare.