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Hobie 21se crossbeam issues  Bottom

  • New to me Hobie 21se has a lot of play in the crossbeam to socket connection, the taper pin holes are wallowed out and I believe the bearings are shot.

    Rather than try to rebuild and reengineer this connection my plan is to find an aluminum binding agent/epoxy and glue the cross beams into the sockets (don’t ever need to collapse boat). I know aluminum is a tough metal to adhere to so I’m concerned an epoxied joint will break free with stressed from sailing. Once bonded I may get some construction rivents and add a few per side to help with the hold. What does everyone think about this approach?

    Also does anyone have pictures of the crossbeam bearings? I haven’t had a chance to pull my hulls apart yet. Text me pics if you want 860-967-5667
  • I can’t comment on your specific issue as I’m unfamiliar with the 21.

    I epoxied the crossbars on my 16 because I had some excessive play between bars and castings. I just used thickend West System and after a full year of sailing it seems to still be a tenacious bond. I obviously reriveted but I wouldn’t be surprised if it would have held up with epoxy alone.

    West System has some newer application specific stuff called G/Flex that may be better suited for aluminum.
  • I have heard of people welding the cross beams in place, but not epoxy. Might be better to shim and then bolt. The original bushings are small curved plastic pieces that are riveted to the crossbar. Good luck, they sure are fun boats.

    --
    Scott,
    H21SE in Southern CA
    --
  • I would not recommend trying to weld in such close proximity to fiberglass. Anodized aluminum is difficult to weld in the first place but the real problem would be just how fast aluminum transfers heat within aluminum. I am sure that the heat from welding this thick material would destroy the connection between the aluminum and hull.... icon_confused

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    Bill 404 21SE
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  • QuoteNew to me Hobie 21se has a lot of play in the crossbeam to socket connection, the taper pin holes are wallowed out and I believe the bearings are shot.

    i admit i don't know this boat at all but:
    why not just tap out the taper pin hole to the next size up and use a regular bolt?

    what bearings are worn out? (i don't see them mentioned in the assembly manual - https://static.hobiecat.c…al_assets/21SE_Manual.pd)
  • I attached the 21se parts manual. Shown is a part number for an oversize tapered pin. First step would be to
    check with hobie on availability for this pin and the bearing strap kit. That should solve your problem. Second
    step would be to have a local machine shop make you some oversize pins.

    https://static.hobiecat.c…66-1856821231.1556545584

    --
    Pete Knapp
    Schodack landing,NY
    Nacra 6.0,I20,P18, P16,H16
    --
  • outboard/inboard bearing strap kit # 321 30001 icon_wink

    These rivet to the both the front and rear crossbar.

    If my memory serve me right, you will need 1/8"? countersunk stainless steel rivets

    And perhaps you can order the next size larger taper pins from McCarr Master.....and thread them yourself.

    --
    Bill 404 21SE
    --
  • Thanks for all the help guys, I finally got some time to take boat apart to see what was going on. It looks as if the taper pin holes are quite worn but the bearing strap kit is intact. When brand new was there some “slop” between cross bar and socket. With cross bar inserted I can move free end an inch or two, this calculated to about an 1/8” of play at inner bearing strap.

    I’m concerned even with new taper pins and bearings I will still have movement due to worn socket. As I don’t ever plan to collapse boat I still think I may try to glue/epoxy the beams into the sockets. Any product recommendations? Thanks

    https://i.imgur.com/PfvZBC5.jpg

    https://i.imgur.com/1qrcuCv.jpg
  • Often the holes are larger than the bolts on the new boats, but things stay put. The beam may sit well if you seat it in a thick vat of silicone, tighten down, and call it good. 5 minutes. Don't forget to put Tef-gel on the bolts to prevent the galvanic corrosion present on your beam from getting worse and to prevent your beam bolts from seizing in the threads.

    Below is some more information, but I really think the enlarged holes are a non-issue so long as the beam is seated in silicone. I replaced beams once with new ones from the factory and the holes were very large. Yet, the beams never move. Boat is super stiff, nothing ever moves. This was on an Inter 20.

    If that does not work, you might solve the problem by using epoxy to create a more form-fitting seat in the deck for the beam, without actually bonding the beam. Many racers fill the entire beam seat with epoxy, grease the beam (lard, I dunno; see old Catsailor threads for more info), and tighten things down to get a perfect fit. I would clean both surfaces thoroughly with acetone and sand to scar and clean again. There are many epoxies to choose from. West system products work very well. They produce reliable secondary bonds when many other things out there simply don't work. Cost is a consideration. Buying WS epoxy, hardener, and adhesive filler (to make it thick) is going to cost a pretty penny. You could use West System 610 (under $20 for large caulking gun size tube). It would be very good for this job for several reasons. It's thick like gel right out of the tube. Importantly, it mixes as it comes out of the tube. Thus, you will not have a pot of mixed epoxy flash on you before you are ready to seat the beam. You will want to get it straight before the epoxy sets, or else it will be a bad situation. To improve epoxy working time, you could work during a cool time of day (inside with AC would be best), shade the beams, and place the epoxy tube in a container or ice water (taking it out as you apply). I've done the ice water thing with other WS stuff, but you may want to try with 610 first to ensure it hardens, etc (although I'd be shocked if it did not).

    You'll want to be sure epoxy does not creep too far into the holes or grab the bolt threads when you are seating the beams. You might put silicone around the holes and bolt threads before you put the epoxy down. After you seat the beams, you can remove them, apply some proper silicone (to waterproof and keep beam even more snug), and tighten the bolts.



    Edited by traphappy on Jul 27, 2019 - 12:51 PM.
  • sam recently posted a tuning guide for under his tramp
    there are some directions how to on how to seat a boat too and has some good data (they call it "setting the beam" http://www.microwindracing.com/boat.html

    imho: i would not try to permanently affix anything on a boat - they all need to be taken apart at some point to be maintained - so i wouldn't "5200" the boat together (unless sailing over the Niagara falls - if so, go for it)
  • The beams on the 21SE are telescopic. Basically a tube inside a tube that slide apart and then they are held
    into place with large tapered pins that pass through holes drilled in both tubes. You can see in his pictures the
    bearing saddles that are riveted to the inner tube that are supposed to take up slop but still allow the tubes to
    slide. If it were me and i felt there was too much slop, I would drill the rivets out of the bearing saddles and make an aluminum shim to go under them to tighten things up. I would also see if the oversize tapered pins
    are available. Using epoxy to make the beams permanent will make selling the boat in the future difficult as
    most won't be comfortable towing the boat full width. Good luck with it. The 21Se is an awesome boat. You should bring her back home in September for the Roton Point Regatta.

    --
    Pete Knapp
    Schodack landing,NY
    Nacra 6.0,I20,P18, P16,H16
    --
  • I towed my 21 wide for over 20 years plus and only "bumped" a toll booth basket on the Ohio Turnpike.

    By saying bumped I mean knocked it completely off the wall.... icon_rolleyes

    I only tow it dismantled now. icon_wink

    --
    Bill 404 21SE
    --
  • QuoteThe beams on the 21SE are telescopic. Basically a tube inside a tube that slide apart and then they are held
    into place with large tapered pins that pass through holes drilled in both tubes.

    Gotcha - i wasn't aware of that
    could you just drill a new set of holes and add a through bolt to keep it in place (and still be able to telescope for transit by removing the bolt?
  • Larger Taper pins and shims under the bearing strap sounds like a good solution to tighten everything up and keep the telescoping beam functional.
  • I’m not able to find taper pins in size I need so I’ve come up with a solution using a large bolt and some tapered sleeves I can have turned at work. Any thoughts/comments?
    https://i.imgur.com/XAcXlyf.jpg

    My major concern is enlarging the holes in the beams. Should I use a tapered reamer with same rape as the pins? This may be hard to find correct size but it would ensure nice contact with pins and beam. Does anyone know if original holes in beams were cut with same taper as pins? Or were the normal holes with slightly smaller diameter as pin was inserted?
  • curious why they can machine taper sleeves and not taper pins? Are the oversize Hobie pins not available?
    What size are you looking for? Mcmaster carr shows threaded taper pins up to and over 1 inch. Your idea
    should work since you plan to leave the boat stretched. It will be a bit of a pain removing the tapered sleeves as you will have to try and drive them out from the inside. I would not get too hung up on the tapers matching
    perfectly. I would find a tapered reamer and try and match the sleeves to it. The soft aluminum crossbars
    will allow the taper to set in. I don't know if Hobie matched the pins with tapered holes. Try asking over
    on the Hobie forum you might get an answer. Sounds like you have some creative ideas to solve this problem.

    https://www.mcmaster.com/taper-pins

    --
    Pete Knapp
    Schodack landing,NY
    Nacra 6.0,I20,P18, P16,H16
    --
  • I suspect the original holes were almost certainly drilled with a tapered reamer to match the pin. If you have access to a tapered reamer, I would definitely go that route since it will give a much better fit to the pin, but they are pricey.

    I think your tapered sleeve concept looks pretty slick. Probably better than the original design since if the holes in the beam are not perfect or if they wear out, the sleeves can be brought in so both sides of the crossbar maintain full engagement between the sleeve and the individual sets of holes. This should reduce wear and slop.

    Just a thought with regard to removing these sleeves/bolts, if you use a fully threaded bolt, you could thread the thru hole in the sleeve that gets installed at the head end of the bolt and thread that sleeve onto the bolt. The sleeve on the opposite end (nut end) just gets a straight thru hole. When you want to remove the sleeves, back off the nut a few turns and then give that end of the bolt a tap with a mallet. This will drive the bolt and the head end sleeve out of the crossbar. Once those are removed, you can come back from the other side of the crossbar and drive the other sleeve out.

    sm
  • Hobie.com forum has more details as well. The plastic bearings can be removed from the cross beams and you could replace them with Delrin strips, machined down (sanded) to your custom thickness. That would take out the slop. I believe the holes are tapered, but the custom tapered sleeve idea above with 316 stainless bolts and locknuts would be an elegant way around the tapered hole business. Those tapered sleeves would have to be stainless also...

    --
    Chuck C.
    H21SE 408
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