Lets Talk Trailer Bunk Placement...

Discussion in 'Sunfish Talk' started by brianZ71, Mar 4, 2012.

  1. Repete

    Repete Sunfish1909

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    I run with John Howards design as well. A key to his design is that is also incorporates the use of keel rollers as the actual load points. The tailor fit bunks help with on and off of a nicely waxed boat. These bunks should be equal if not just a hair less in height to allow the keel rollers to engage the load. Yes, bearing on outer bunks only will flex the foam blocks free over time. My '79 boat already has some "oil drum" , but it was a pre existing condition. Guess what my next project is ;) .
     
  2. Charlie Braun

    Charlie Braun New Member

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    I can't find the photo essay - I think maybe it's disappeared? Anyone have any ideas where I can find some info on how to build the bunks below? They look like they're worth the effort. I have to get a hull crack repaired after my latest 4 hour trailer with standard 2x4 bunks that were in the middle of the hull.
    Thanks,
    Charlie

    [​IMG]
     
    Last edited by a moderator: Sep 15, 2013
  3. Wavedancer

    Wavedancer Upside down? Staff Member

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    Apparently, there are problems with the yahoo site, as of today. Perhaps if you check back in a while, you might be able to access the photo essay once again.
     
  4. danpal

    danpal Active Member

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  5. Geophizz

    Geophizz Member

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    The bunks have to be under the chines as much as possible, because there's virtually no structural support at the flat sections of the hull. I would stay away from any type of bunk that goes across the boat, as I've seen boats nearly cracked in half like so many eggs from bouncing on crosswise supports.

    The only drawback that I've found to John Howard's design is that it can be difficult to get the boat off a dolly onto the trailer by yourself. You have to lift the boat over the highest spot of the bunk at the rear. It is awkward and sometimes the boat slips and falls onto the edge of the bunk. I think that shortening the bunks in the rear by about a foot would solve the problem.
     
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  6. oldpaint

    oldpaint Active Member

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    Interesting point. When I retrieve my sf I plan on reconfiguring it to the John Howard design but I think it might be improved by ending the fixed bunks on a crosspiece of appropriate height at the rear of the trailer's fenders. I'd then use regular bunk supports which allow pivoting up and down at the rear. The bunk on them would be a continuation of the curves of the fixed portion but would allow for easier loading and unloading. It would be easy to build: just do the full length bunks then cut across them at the break point and have them rest on the same crosspiece that the forward section ends on. The crosspiece might have to be notched for the bailer.
     
  7. danpal

    danpal Active Member

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    I've found that this isn't really much of an issue. The bunk carpeting makes it really easy to slide the sunfish along the length of the bunk. The dolly I use is homemade and pivots so the bow rests between the bunks and I can slide the sunfish onto the trailer. The dolly I made is very similar to Jim Manta's dolly except I added an additional crossbeam above the axle. I also upgraded the wheels to Harbor Freight 13" wheels since the plastic wheels tended to wobble.

    upload_2013-9-16_16-56-54.png
     
  8. oldpaint

    oldpaint Active Member

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    I did build a removable trailer bunk system based on the John Howard design. (When I'm not hauling the sunfish I take the cradle off the trailer and use it with a plywood box as a utility trailer.) It has 1x8 pressure treated carpeted boards sitting on treated 2x8's. The cross bracing is treated 2x4's. I've been playing with webbing crossing from the top of the port bunk to the starboard side bunk to support the keel, but its not shown in these pictures. Also the bolts holding the cradle to the trailer aren't tightened, since I wasn't traveling anywhere, just taking a few pictures.
    cradle stored on garage wall.jpg Sunfish on cradle.jpg Bunk normal position.jpg Ready for Launching.jpg
     

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  9. tag

    tag my2fish

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    Very nice work, oldpaint!
     
  10. Geophizz

    Geophizz Member

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    Nice work Oldpaint! How did you get the back of the bunks to flex? I wanted to do that on mine, but could never figure out how to make it work right.
     
  11. danpal

    danpal Active Member

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    Yeah, and I'd also like to see how you incorporated the plywood box for the utility trailer (something I've been thinking about for a while).
     
  12. signal charlie

    signal charlie Active Member Staff Member

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    The hinged end is a great idea, as well as the cleats!

    Thanks for the pics.
    Kent
     
  13. oldpaint

    oldpaint Active Member

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    Thanks Tag
    Geophizz, The mounts for the bunks came with the trailer (from 1993 or so) and are pivoted, if thats what you mean. The same bunk mounts are used in the utility box pics below. To get the curve correct, I built the cradle in one piece, a lot of trial and error work, When I was happy with it, but before carpeting, I took off the top 1x8 (lag bolts hold it on) sawed that and then sawed the curved 2x8. All of it was done by eye, hmm that looks pretty good ,rather than following a plan.
    Danpal, here are some pics:
    port side overall utility box.jpg
    bunks utility box.jpg
    tailgate open.jpg
    Just a box with a tailgate. The picture above shows the 2x4 cross bracing for the top. The bracing sits in a joist hanger made for removable railings. the 2x4 also has right angles mounted at the top extending out 1/2 inch to catch the side of the trailer and hold it in. Both straps go over the two 2x4s and its very rigid. There is a 2x4 in the middle of the bottom to serve as a keel for the roller near the bow of the box. (that roller is so low the sunfish doesn't touch it) I also carved a piece of 2x4 on the front to serve as a prow to catch the bow roller bumper thing by the winch. I have to move the winch location back when I use the box because its only 9 ft long, not 13'9''.
    Thanks Kent appreciate that. The cleats aren't my idea, Geophizz came up with that.
     
    Last edited: Oct 12, 2013
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  14. oldpaint

    oldpaint Active Member

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    I forgot to mention that I had to slot one of each pair of screw holes on the end of the trailer that the bunk mount u bolts go through so the mount is plumb. This is visible in the utility box bunk mount pic above. For the Sunfish I use the outermost pair of holes.
     
  15. Light and Variable Winds

    Light and Variable Winds Well-Known Member

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    Just a mention that rollers elsewhere than the keel will put a serious bend in the hull. I do have to change my ramp design next spring! :confused: P7290019-004.JPG
     
  16. signal charlie

    signal charlie Active Member Staff Member

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    I'd avoid any load on keel rollers other than loading and unloading. If the boat is strapped down and the load concentrated on the roller, the fiberglass will crush and get soft....and the boat will take on water...and you'll wonder "where did that water come from..."
    Ask me how I know and OBTW don't forget to inspect the keel when you buy a Craigslist boat... :)
    Kent
     
  17. Light and Variable Winds

    Light and Variable Winds Well-Known Member

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  18. vela

    vela New Member

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    Do you have plans/ specs for this?
    How are the wheels on sand?
     
  19. danpal

    danpal Active Member

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