PVC Pipe Oar Design

Discussion in 'Boat Design' started by pcfithian, Jan 21, 2013.

  1. alan white
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    alan white Senior Member

    I encourage you to make the oars to your own PVC design if that is what you want to do. Post the results and we'll all see what happened. You're obviously not into it for the money, so no harm at all in some experimentation. Have fun!
     
  2. moTthediesel
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    moTthediesel Junior Member

    In our business we have a bunch of aluminum row boats for our guests to use. We always bought wood oars to use in them, but over the last few years, we have found that the commercially available oars have gotten both very expensive, and of very poor quality.

    The "Feather Brand" oars commonly sold in the USA are glued up from basswood, and in our rough livery use we have found them to last no more than a year or two, at a cost of $30 each. So I designed a cheap all PVC replacement made from "Big Box" store parts that can be put together in minutes at a cost of less than $10 each. Yes, they are ugly, heavy, and flexible, but they move the boats around and they are very durable - almost (but not quite) indestructible.

    I don't have any pictures to show here, but they are made from a 5' length of 1" schedule 40 inside of a 5' length of 1-1/4" sch 40, with a blade made from 6"X1/2" foam PVC trim lumber. The grips are made from short 3/4" PVC pipe glued on the end with a reducing bushing. The oarlocks are the cheap and readily available clamp-on type.

    Would I recommend them for use in the Henley Regatta? Would I spec them for use on a classic pulling boat or St. Lawrence skiff? Hell no, but there are horses for courses, and for rough utility purposes, PVC oars can make sense.

    Tom
     
  3. blisspacket
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    blisspacket Junior Member

    Consider birdsmouth construction using cedar; blades from cedar shingles, the bottom edge strengthened with folded glass tape. Handles from pine closet rod. Mine have been in service two years, mildly abused, going strong.
     
  4. pcfithian
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    pcfithian Junior Member

    Well, it's so cold outside and in my shop that I decided to look at the equations before doing any work on this.

    You guys are right, the deflection will be huge. See attached for calculations.

    The internal X brace does reduce deflection, but not by much. Comments welcome on the math.

    Looks like I'll be making these out of Spruce or DF. I'm off to to the lumber yard to find a nice piece to cut up for the shaft.
     

    Attached Files:

  5. peterAustralia
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    peterAustralia Senior Member

    20 pound load is not enough, when the wind is working against you, you will find yourself using all your strength to work those oars, try 60 pounds minimum

    In the end, it is up to you,,,, you can experiment,,, see if it works,,,,, and afterwards then we can all say we told you so when it does not work (this is a joke)... apart from a little time and money wasted, no lasting harm will be done with your oar project
     
  6. michael pierzga
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    michael pierzga Senior Member

    Common power ratio used for oars..


    http://[​IMG]
     
  7. peterAustralia
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    peterAustralia Senior Member

    thats a nice formula, I note that the article uses overlapped oar handles, I like them so that the handles meet just half an inch apart, makes it a fraction less hassle as you do not have to worry about getting your timing right.

    I have a table saw and a bandsaw, but dont have a lathe. So to obtain those turned handles is difficult. I can make the loom using pine and a power planer, then I turn a sanding belt from a linisher inside out and move it back and forth. Very very quickly the oar gets round. A combination of power planer and inside sanding belt is very effective and very fast (you have to wear gloves when using the sanding belt as it cuts your finger tips to shreds)

    Not having a lathe, the handgrips are difficult to manufacture, anyway my last pair of oars work very very well, the previous 2 pairs are reasonable but not great. Practice makes perfect

    I reckon 100 years ago there were no outboard motors, so there would have been tens of thousands of people building small rowing boats just to get around and do a little fishing, then outboards came along and a lot of those skills were lost. Now with the internet information is getting easier to obtain.

    Think that old sketch shows oar blades which are 6 inches max width, me I prefer narrower blades at under 4 inches, but maybe my oars are a fraction too long so I have to compensate with narrower oar blades. On my new boat oars are 8ft long and rowlock to rowlock distance is 51 inches.
     
  8. Village_Idiot
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    Village_Idiot Senior Member

    Methinks aluminum tubing would be better than PVC - lighter, stiffer, but much more expensive these days, and would require welding. Also noisy, cold and brittle compared to wood. Yep, wood is the way to go - also good for pushing off rocks, docks, whacking things, etc. OK, I'll stop rambling...:p
     
  9. michael pierzga
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    michael pierzga Senior Member

    Square section oar shafts are common and much easier to make. Thier is little reason for oval section oar shafts.
     
  10. SamSam
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    SamSam Senior Member

    Oars and paddles that float are handy.
     
  11. alan white
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    alan white Senior Member

    Just to add to the how-to part. I round the looms by using a spoke shave and block plane (at least to 8 sides). The tool is very easy to control and can take off just a whisker or a good bite. When it comes to sanding, I use a sander belt that I tear open and I "saw" back and forth by hand until smooth, pulling down alternate sides.
    Go from 20-50 grit and finish with 50 grit, then sand with grain til final smoothness--- or use a RO sander.
    It might take three hours to make two oars this way, then varnish.
    Hand grips can be shaped with a rasp, then sand paper.
    No one can teach how to do precise work with hand tools. You either are "handy" in that way or not. I suggest trying hand tools to begin with, and see if you've got a knack for it and if not, depend on power tools if necessary.
    You'd be surprised how accurate and satisfying hand tools can be given the chance.
     
  12. Petros
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    Petros Senior Member

    the only place the oars need to be smooth and "pretty" is where you hold it. No real need to make the rest so smooth other than pride. Making the paddle smooth will help efficiency a little, but not really a noticeable amount.

    looking at those deflection calculations seems about right. Now also look at ultimate strength, doug fir wins again, by a long way. If you make a doug fir shaft hollow, it is will be much lighter and almost as strong and stiff.
     
  13. alan white
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    alan white Senior Member

    Are you comparing spruce to fir or ash to fir (or some other woods)?
    I ask because I have always assumed spruce was about equal to fir in such applications. The fir would weigh maybe 20% more but could be thinner although the end result would be somewhat of a wash.
    I haven't seen a set of fir oars (that I know of) but spruce is definitely considered the most suitable for reasons of strength to weight and possibly it has a bit less tendancy to suffer from cracking under strain.
    I am not too aware of species of fir or spruce (or ash) that grow outside of the USA.
     
  14. Petros
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    Petros Senior Member


    I was comparing the deflection calculation that the OP did for D. fir vs. PVC pipe, and PVC pipe with plywood web stiffeners.

    Doug Fir is actually much stiffer and stronger than spruce, and much more rot resistant too, but it is heavier. Rot is not too much an issue if stored out of the weather. Sitka spruce has one of the highest strength to weight ratio, so it can be made lighter and as strong, but you have to make it larger than a doug fir paddle to get the same strength, and it would cost more than doug fir (you would have to design specifically for equvalent strength or stiffness). Doug fir as almost as good a strength to weight ratio, and much stronger ultimate strength, and cheaper, but sitka spruce is the best strength to weight ratio of almost all the woods. Sitka spruce is not that common a species of spruce btw, always verify you are actually getting sitka spruce if you buy it. Ash is fairly strong, but it is even heavier, so its strength to weight ratio is not as favorable as spruce or d. fir.

    If you are building light weight boats or oars, both sitka spruce and doug fir can make similar weight at the same strength, but you would have to adjust the size to match strength. Doug fir is much less costly and eaiser to find, so dough fir has become a common substitute for boat building and even in homebuilt wood aircraft.

    boats and paddles have been made from anything and everything as far as wood goes, even bamboo. so use what you can get, any fairly clear fine grained wood will work out fine. It was just we were comparing d. fir vs. pvc plastic on this thread.
     

  15. rwatson
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    rwatson Senior Member

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