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Thread: Kick up rudder for Shellback dinghy

  1. #1
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    Default Kick up rudder for Shellback dinghy

    I'm looking to make a kick up rudder for my shellback dinghy

    My plan so far is to make it out of solid wood, glued with opposing grain in one inch strips for stability (as suggested here)

    I was going to scale the Pooducks kick up rudder down as they are very similar shapes
    My blade was going to be 3/4" thick with 5/5" cheek pieces
    I chose these dimensions as my rudder hardware is made for a rudder 2' wide
    Here is what I have so far, my first though would be the there is not enough wood around the rotation point so an idea might be to extend the check pieces down and back another 1/2" - 1" to provide more support. Each square is 3"

    Does this seem workable?
    Any suggestions?


  2. #2
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    Default Re: Kick up rudder for Shellback dinghy

    Where is the underside of the skeg?
    It really is quite difficult to build an ugly wooden boat.

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  3. #3
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    Default Re: Kick up rudder for Shellback dinghy

    I'm not sure I understand the question.

    The above picture is one I copied from a the rudder plans for the shellback I found online, right down to the grid in the back ground and it's orientation on it. So this shape and size is intended for the shellback and will work on it.

    I also found a smallish copy of the Pooduck rudder plans which is a larger kick up version of the Shellback rudder so I was able to copy the kick up functionality of one into the other. The flat angle of the cheeks on the right, conforms to the rake of the transom. I left out where the pintles were attached.

    I am asking about the functionality/strength of the kick up part as well as whether building it in solid wood(laminated 1' strips with grain reversed) is a good idea

    Here is a picture of the shellback which should show the rudder in relation to the skeg
    shellback-sail-plan@2x.jpg
    Attached Images Attached Images
    Last edited by Toxophilite; 05-12-2021 at 01:10 PM.

  4. #4
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    Default Re: Kick up rudder for Shellback dinghy

    Quote Originally Posted by Toxophilite View Post
    I'm not sure I understand the question.

    The above picture is one I copied from a the rudder plans for the shellback I found online, right down to the grid in the back ground and it's orientation on it. So this shape and size is intended for the shellback and will work on it.

    I also found a smallish copy of the Pooduck rudder plans which is a larger kick up version of the Shellback rudder so I was able to copy the kick up functionality of one into the other. The flat angle of the cheeks on the right, conforms to the rake of the transom. I left out where the pintles were attached.

    I am asking about the functionality/strength of the kick up part as well as whether building it in solid wood(laminated 1' strips with grain reversed) is a good idea

    Here is a picture of the shellback
    shellback-sail-plan@2x.jpg
    You need to know where the underside of the deepest bit of the boat is so that the rudder will clear when kicked up. By the way, your pivot point does not look to be at the centre of the arc, unless the drawing ws badly distorted by the camera.
    It really is quite difficult to build an ugly wooden boat.

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  5. #5
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    Default Re: Kick up rudder for Shellback dinghy

    Try this
    kick up.jpg
    It really is quite difficult to build an ugly wooden boat.

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  6. #6
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    Default Re: Kick up rudder for Shellback dinghy

    That looks better and I would be very tempted to extend the rudder stock up a bit and use a mortise to accept the tiller.That way you can either use metal straps or through bolts at the top to greatly reduce the possibility of splitting.

  7. #7
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    Default Re: Kick up rudder for Shellback dinghy

    I assume you mean the cheek pieces will be 5/8" and that there will be wood in the places the blade isn't.
    I don't know what scale the drawing is. The blade above the pivot is going to be doing all the work, a Sunfish rudder has less than 3" of bearing. So you are probably alright.
    But this all seems massive.
    The Shell Back is a tiny boat with out much righting moment , and not a lot in the way of speed, so the rudder doesn't have to look like it belongs on a battle ship. I understand the constraint of using some existing hardware, but you dont need to kill it!
    The 420 rudder heads we built ( for a much faster and powerful boat sailed by teen age knuckleheads) were .165" aluminum plates fastened together by 10/24 machine screws into 1/2" aluminum threaded spacers. The gudgeons were folded up bits of 1/8" stainless.

    The key to keeping rudder heads together is the fact that the pivot bolt has to be tight. This makes the two cheeks work together. The best plan is to have an oversize hole in the blade ( like 1/2") and use a 1/2" OD 1/4" ID bushing that is slightly longer than the blade is wide. The blade should continue to pivot even when the bolt is socked down. If you are intent on using wood, I'm pretty sure you could use 1/4" ply for the cheeks and have local padding thick buildups for the pintles. There is no need to have any of this drag in the water.

    Finally have some fun and shape the blade to a 5 digit NACA section. I recommend the 63 series. It really does make a difference in how the boat sails and is a point of pride at the dinghy dock.
    SHC

  8. #8
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    Default Re: Kick up rudder for Shellback dinghy

    Hey thanks lot's of great information
    The original rudder, functional but the wrong shape and now a bit of a warped potato chip was made of 3/8 play with 3/8 ply cheeks and then 1/4 pads on either side
    I was worried that if the blade was too thin though made of laminated 1" strips would warp too. I had lots of solid wood and no marine ply and wasn't willing to buy a giant sheet to use a small section of it, though I did put an ad on the local craigslist looking for some.

    I was going to shape the blade into a nice foil which would reduce a lot of it's weight and beefiness and I was also goind to shape the \cheeks too.

    The squares in the drawing are 3" across. the shape is an exact copy of the shellback dinghy's rudder.

    There is a 4" radius around the pivot point all around and I was going top extend the cheeks down and back to strengthen the pivot point as was suggested in my first post.

    I could go with the original shape but my boat wasn't built to store the rudder behind the stern thwart like a proper shellback and I don't like the idea of removing the rudder in shallower water. I've always enjoyed kick up rudders on small boats.
    But yes I could probably make it all lighter/thinner.

    I could see if I could hunt down smaller pintles and gudgeons. I don't want to drop a bunch of $$ on it.

  9. #9
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    Default Re: Kick up rudder for Shellback dinghy

    Racelitehardware.com is your source.
    SHC

  10. #10
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    Default Re: Kick up rudder for Shellback dinghy

    Duckworks has a decent selection of rudder/tiller hardware as well--much of it is Racelite, I think.

    Tom
    You don't have to be prepared as long as you're willing to suffer the consequences.

    www.tompamperin.com

  11. #11
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    Default Re: Kick up rudder for Shellback dinghy

    Out of interest here is the drawing(low quality from internet) for the Joel White's Pooduck skiff which has a kick up rudder which I modelled mine on Note where the pivot pint is. however I plan to beef mine up a little more and now plan on going with 1/2" dimensions on all my parks, blade, cheeks etc. and 1/4" risers on either side for the pintles.
    poduck rud.jpg

  12. #12
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    Default Re: Kick up rudder for Shellback dinghy

    I took the various advice offered here and have made some progress on my rudder (and daggerboard) It will be nice to have a daggerboard that doesn't require brute strength to pull up and push down. The old one works but looks like a potato chip and has a very wobbly leading and trailing edges. there's always the doubt of whether it will be the time it just DOESN'T move and as I've been dollying from my trailer to beach launch a lot lately that would be pretty troublesome to say the least. I would've made more progress on this but there's been decent weather and I've been sailing on various lakes, arms and inlets. I rowed 6km the other day in the pouring rain singing lusty sea songs.

    Anyway kickup rudder parts are all roughed out, roughly assembled and functioning and awaiting final shaping assembly and finishing. Same with the daggerboard. I will likely be putting a layer of light glass on the daggerboard. I'm tempted to glass the forward edge of the rudder blade too.

    The rudder is a combination between a scaled down pooduck rudder and a shellback rudder made out of 1/2 thicknesses with theheavier wood being used in the blade. The daggerboard is a few inches deeper than the original but it will be straight and have a nice countour, somewhere between practical ruggedness and hydrodynamic pleasure.

    Originally I was going to make the parts monochromatic but I had a mishmash or different mahoganys, some denser and some lighter which seemed to be determined by colour. so I used denser ones on edges and where the pivot points would be. I joked withe my sister that I made it out of old cutting boards. Unforunately she didn't think I was joking and thought it was clever recycling....ooops
    It would've been much easier to make them out of marine ply. But I would've had to buy a couple big sheets for a lot of $$ (especially right now) and I happened to have a lot of nice mahogany.


    different light but rougher shape


    Last edited by Toxophilite; 06-13-2021 at 10:45 PM.

  13. #13
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    Default Re: Kick up rudder for Shellback dinghy

    one can make dungeons and pigeons from fiberglass and epoxy...if those inch thick syorebought ones do not make you happy
    cutting board was my first thought too, but this is much better than ply,
    it's a tricky thing to get right, and can take alotta futzing, but well worth the bubbles.
    bruce

  14. #14
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    Default Re: Kick up rudder for Shellback dinghy

    I was going to use the pickles and bludgeons the boat came with. I was sore tempted by the wood boat store brass unit just cause it's shiny but it's a lot of $$ to hang off the back of my boat and they're only 7/8"wide so the bronze straps would be buried anyway. Duckworks has some that would fit at prices I can afford. I have more time than $$ right now. For assembly I went with the zillion clamp approach, it seemed to work well. I didn't use too much pressure side to side just top to bottom.
    I figure if I have picnics, or do some camping, I have a variety of beautiful cutting surfaces.

  15. #15
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    Default Re: Kick up rudder for Shellback dinghy

    Besides the internet (here), which is helpful, is there a good source of information on building tillers and rudders? I was at the library perusing wooden boat building books and I was astonished that NONE of them seemed to have a section for rudders and tillers. Whole chapters on oars, sometimes two, but steering, none at all. Why is that? Is it a masonic thing?

  16. #16
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    Default Re: Kick up rudder for Shellback dinghy

    Well I can resolve the earlier question myself. I was wondering if people generally use bushings on their small boat kick up rudders. I read somewhere of a drill fill drill technique which I assumed to mean that one is essentially making epoxy bushings. Any insight on this?

  17. #17
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    Default Re: Kick up rudder for Shellback dinghy

    That's what I did with my rudder pivot--overdrill, fill with epoxy, then drilled for a 1/4" bolt that tightens with a wing nut. Seems to work OK.

    Tom
    You don't have to be prepared as long as you're willing to suffer the consequences.

    www.tompamperin.com

  18. #18
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    Default Re: Kick up rudder for Shellback dinghy

    Cool and thanks. Do you use large washers on the inside at all(between the cheeks and the blade)? or just on the outside?

  19. #19
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    Default Re: Kick up rudder for Shellback dinghy

    Friction fit!
    outside only
    Last edited by wizbang 13; 06-21-2021 at 11:50 AM.

  20. #20
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    Default Re: Kick up rudder for Shellback dinghy

    Thanks Nice weathered looking rudder!

  21. #21
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    Default Re: Kick up rudder for Shellback dinghy

    Yep, washers on outside only for me.

    I did put a couple layers of glass between the cheeks and filler block to make the slot for the blade a little bit wider in case it swelled.

    Tom
    You don't have to be prepared as long as you're willing to suffer the consequences.

    www.tompamperin.com

  22. #22
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    Default Re: Kick up rudder for Shellback dinghy

    Quote Originally Posted by Toxophilite View Post
    Thanks Nice weathered looking rudder!
    It looks rough, and it IS. Been modified, extensively , lives in the sun. Never gets to a shop.

  23. #23
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    Default Re: Kick up rudder for Shellback dinghy

    I like it! As long as it does the job.
    I'm replacing my original daggerboard and rudder mostly for functional reasons but in the case of my rudder partly for aesthetic reasons(the original design is more shapely and suited to the boat.
    Both units were pretty warped and in the case of the daggerboard VERY warped and prone to getting stuck, requiring too much brute strength or leverage to remove.
    I finished my dagger/cutting board, glassed and epoxied with the lid put on. Still have a few coats of finish to put on the top. Pretty fancy for something that mostly lives underwater but wood things are usually always pleasing. It's straight . slides in and out easily and is actually about 4" longer than the original. I had read about people getting better results doing this and figured I could always make it shorter if needed. The Joel White design was shaped to fit behind the stern thwart across the back of the boat. On my boat there isn't space there anyway for I figured I try making it a little longer. Worked great yesterday in 10-15 knot winds..I just noticed the line holding one of the mainsheet blocks is around the downhaul belaying pin!



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