Trailer Design Feedback

Discussion in 'Sunfish Talk' started by wev162, Jun 27, 2009.

  1. wev162

    wev162 New Member

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    I recently acquired a Jet Ski trailer on CL for $150 that I've repurposed for my Sunfish. In the interests of getting on the water this summer, I decided to modify the Jet Ski bunk system and pad them with foam swimming "noodles" to hopefully cushion the boat. The rear six feet of the boat are hanging off the trailer (Basically everything behind the cockpit), do you foresee this creating undue stress on the boat?

    I appreciate any feedback on my efforts so far!
     

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  2. davavd

    davavd OldNSlow

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    Having recently repaired some damage done to my boat by my first, less-than-adequate, bunks, I can speak with some experience. I would try the boat further forward on the trailer, with the bow almost to the winch. That should leave less hanging off the back and decrease the weight on the rear bunks. Anything you can do to increase the area of the bunks will mean less force on the hull. I also think that the keel and the chine (where bottom meets side) are probably the strongest parts, though a lot of boats seem to have keel damage.

    Attached is a picture of my 2nd (hopefully last) trailer set-up, which just hauled my boat 5 hours without damage.

    [​IMG]
    The cross pieces are treated 2x cut to fit the shape of the hull and padded with plush carpet over 1/2" thick closed-cell foam.
     
  3. LQT420

    LQT420 Member

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    Try removing all but the main leaf spring on each side of the axle (ie - suspension). When you stand on the empty trailer it should sink down 4" to 6". This will give the more cushion to the hull when trailering as a standard jet ski trailer with a suspension rated for 600lbs would be way too stiff for a 130lb Sunfish.
     
  4. wev162

    wev162 New Member

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    Looking at your picture, it seems like your rear support is only about 6" farther back than I have mine setup. It's hard to tell from the pictures but I've only got about 3 or 4" of clearance between the bow and the winch so I don't have much room to shift it forward. I'd prefer a little space between them to avoid knocking the bow off the boat if I had to brake hard. The Winch is mounted to a rather substantial pedestal welded to the frame of the trailer so I can't easily remove it.

    I'm really hoping to get on the water this summer without much more effort, any thoughts on the least amount of work to use what I have so far?
     
  5. wev162

    wev162 New Member

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    Well the trailer was apparently a deluxe model, it has a Torsion suspension so there aren't any leaf springs to remove. I don't think there is a way to adjust the load rating.

    Link to Manufacturer Specs: http://www.tritontrailers.com/products/Model.aspx?CatID=29&SubCatID=41&ModelID=334&info=features
     
  6. Webfoot

    Webfoot New Member

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    Well, here's what I learned from a 1971 boat, newer boats may be different.
    The weakest part of my boat hull was under the cockpit, there was nothing between the bottom of the hull and cockpit. This caused the hull to oil-can and epoxy resin spikes on the bottom of the cockpit to punch through the hull from the inside. I sprayed expanding foam inside the hull between the cockpit floor and hull. This part of the hull is now the strongest and where I place the trailer bunk supports. Behind the cockpit I have three foam blocks so this is also a safe place for the trailer bunks.

    On a wood hull, the keel would be the strongest area. All the Sunfish keel consists of is a fiberglass hump. Placing weight on the keel concentrates stress in the keel area. I don't have the trailer rollers touching the keel, they do not do anything.

    Best trailer I found is a 12/14' with coil springs and shocks for $150. Using bigger trailer tires made it ride even better. My Harbor Freight trailer with just leaf springs is terrible. Hit a washboard road pulling a rowboat and the trailer bounce to high I could see the whole inside of the rowboat.
     
  7. Wavedancer

    Wavedancer Upside down? Staff Member

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    On my (problematic; but that's another story) Trailex trailer, designed for Sunfish, the stern of the hull is 4' 6" from the rear support bracket on the trailer. Or, in other words, the bailer is quite close to the rear support bracket.

    I believe that the preferred way to support a Sunfish is with brackets that are perpendicular to the boat (and the internal structural foam).

    I wonder how many miles/bumps the noodles are going to last. But do go sailing ASAP :)!
     
  8. wev162

    wev162 New Member

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    Here are some quick day time pictures that might show things a bit better.
     

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    • Creative Creative x 1
  9. davavd

    davavd OldNSlow

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    That actually looks OK to me - I'd go sailing.
     
  10. Wayne

    Wayne Member Emeritus

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    I don't think you are correct when you refer to the boat's construction as "epoxy". These boats are made of glass fiber reinforced polyester. The cockpit is bedded in pads of polyester resin. Ultimately, because of the double bottom and internal cockpit walls that area of the hull has the greatest reinforcement. Perhaps your hull experienced some sort of dramatic trauma causing the cockpit tub to catastrophically break free, leaving jagged edges at the broken bonds resembling "spikes".
    [​IMG]

    When setting up a trailer to carry any lightweight boat, observe where the largest unsupported surface is ... that's the area to avoid loading. Right angles and curved stringers provide resistance against flexing. Flat regions, even with styrofoam backing, are the most vulnerable to constant pounding. Set up your bunks or cradles to carry the weight at the boat's most rigid point, the area as close to the chine as possible. NEVER carry weight on a roller, a roller's curve concentrates all the force along a very narrow line. Rollers can be ok as guides, but once the boat is loaded a roller should have daylight between it and the hull.
     

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  11. baldessariclan

    baldessariclan New Member

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    Another trick you can use is to let a lot of air out of the trailer tires -- maybe run them as low as 10 - 15 psi. This will take additional shock out big bumps in the road and help protect your boat. Normally this sort of thing would be a big no-no, but these boats are so light that the tires don't flex muxh even at low pressures, and thus don't overheat at highway speeds, and shouldn't hit/pinch on the rims when you hit those big bumps. The heavier the trailer, though, the more pressure you'll have to keep in your tires.

    I would tend to think that multiple rollers supporting the keel, located at "strong points" (i.e. front and back walls of cockpit, daggerboard trunk, mast step) shouldn't be too hard on the boat, so long as they are used in conjunction with bunk boards. The more support locations you use, the better.
     
  12. 67stang

    67stang Member

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    Great thread ! I am currently focusing on my trailer too. I am aborbing all of the input from everyone. If I can add one thing though, looking at the rear shot of the "noodle" set up, it looks as though the noodles could move around, and with the straps tightening the boat to the noodles, if one noodle starts to shift, the strap needs to be tightened down to adust to the change. And since there is no bow stop, the boat could easily shift, ( causing a possible dissaster on the roadway?) just from one noodle movement.
    IMHO, I like the idea of perpendicular padded supports. putting too much preasure on un supported areas, could be problematic. Think about how much preasure is needed to keep the boat on the bunks, if the bunks start to press in ward on the hull, I think it could be the start of hull damage.
    Here are some pics of mine, no PT here,( things could change as I go, maybe later when I'm more permanent) and I don't plan on putting it in water that deep.
     

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  13. minifish

    minifish New Member

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    I think too much of the boat is hanging over the back without support which is why I think the boat needs to come forward on the trailer if possible. I would take the winch off so you can move the boat further forward. You don't need a winch for this boat.
    Then mount cradles which are perpendicular to the hull (look at the pic davavd posted) one cradle mounted where your most forward set of pool noodles are and one set mounted across the supports for the jetskis. If you can, try to have three cradles, two sets on the supports for the jetskis and one forward of those. I would build the cradles to go all the way to the edges of the hull.

    Where your pool noodles are on the hull is going to constantly flex with each bump no matter how soft the trailer rides which won't be good for it. And if you store it on the trailer, you'll eventually get dents in the hull.
     
  14. btsunfish

    btsunfish New Member

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    I think the boat needs to be moved forward. It overhangs the rear of the trailer too much to reasonably expect anyone driving a tall vehicle (think semi) to be able to see the brake/running/turn lights at a regular highway distance. Nothing will hurt your Sunfish more than having her aftermost 6 feet ripped off by a bread truck.
    Just my two cents...
     
  15. daanno

    daanno New Member

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    My first thought after I looked at the pictures was not the problem of having the rear of the boat sheared off ( a very valid concern) but the issue of the weight. With that much of the boat behind the axle there would be almost no weight on the tongue. Low tongue weight would cause a massive amount of fish-tailing. Personally, I'd vote for moving it as far forward as you can. As others have mentioned, lights and hull stress are concerns too. It would be tragic to get to the lake and find out you only have the front half of your fish. :eek::eek::eek:
     
  16. predator

    predator Fear the 'fish!

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    Great thread.

    I just got my boat and used the stock Northern Tool trailer. I adjusted the width and height of the bunks to put them parallel and just inside the outermost edges of the hull, and the keel just resting on the rollers.
    After reading this I'll add some more padding on the bunks to raise it off the rollers a bit and modify the springs.

    I drove it 8+ hours on I-95 and don't think anything broke or dented. I'm anxious now to get home and check it! There were a few serious bounces along the way, but all the straps were still tight.

    Here's a pic. I can't wait to get it in the water!
     

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  17. Webfoot

    Webfoot New Member

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    Ok, it was spikes of polyester hanging down, that I am sure of. They probably construct the boats a better today then they did in '71". Anyway, I could looked in the inspection port and see the gap under the tub which is still firmly attached to the deck. I could reach under the tub and feel the spikes which were directly over the impact craters the pushed through the hull out from the inside. The hull at this point was able to oil-can nicely into the spikes. The other side of the hull had the bailer unit which was keeping the hull from flexing. I also had stress holes in the bottom of the tub from lack of support. Good old expanding foam took care of my problems. From what I understand, they use to use some sort of 'Glue Disk' or 'Caulking Disk' way back when to attach the tub to the hull. It coule be the spikes were the remains of a failed application.
     
  18. Zeppo

    Zeppo Member

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    Predator, I was driving down I-95 myself, and guess what I found on the side of the road? Yes.... the aft 4 feet of your Sunfish. But what the heck.....cut a few inspection ports here and there and fixing it will be a snap. Cheers
     
  19. NightSailor

    NightSailor Captain

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    I recommend you transport your boat upside down supported by the deck.

    Alternatively, you can transport it on one side.

    Do not transport it on it's bottom. You will ruin it.
     
  20. wev162

    wev162 New Member

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    I've heard the recommendation to carry the boat upside down before, why is this better for the boat than bunks supporting the hull right side up near the chines?

    Any advice on how to carry spars/mast when trailering a SF upside down? I've looked at buying an 8' PVC tube to carry beneath the boat attached to the trailer frame but it would have cost almost $150 to buy enough 8" PVC to carry the spars.

    Any cheaper alternative methods for carrying them beneath the boat?
     

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