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Hull Flex - How Much is too much?  Bottom

  • Hi, I bought my 80' H16 a few months ago and have had a few issues so far. I already did a crude bottom job on account of a big crack in the keel and am in the middle of patching up the portside stern due to a crack that was taking on water. When the boat isn't sinking, it is loads of fun though.

    To the point of my post: I do notice that when the bay is rough the downwind hull flexes a couple inches. I don't think it is relative to the upwind hull, I think it is relative to itself. I've searched forums and it seems that this situation is somewhat normal but I don't know if mine is so bad that it is unsafe. I am worried due to the other issues I've had. From reading other threads, it seems that the area in front of the piles is critical. On my boat the area is a little softer than the rest of the boat, but I can stand on it. I don't make a habit of it but it don't feel like I'd break through or anything.

    Should I go ahead and put other hulls on (I have some available) or just deal with the devil I know for the rest of the summer? Or is there a way to reinforce something to avoid the flex if it is actually an issue?

    On a slightly related note, what is the best practice for installing threaded anchors for the rudder mounts?

    Thanks so much, this forum has been a ton of help for months before I even felt like I needed to post anything.

    Best,
    Paul



    Edited by pauldelv on Jun 04, 2012 - 09:13 PM.
  • pauldelv
    Thanks so much, this forum has been a ton of help for months before I even felt like I needed to post anything.


    Welcome to TheBeachcats.com (as a poster).

    Hard to diagnose your boat from a description, if your hulls are truly soft then you could be in danger of having the bow break off or fold in under load, dismasting you. It's a risk/reward situation, do you sail hard in waters that could be dangerous, like offshore or through the surf? Do you carry a lot of weight? Things that contribute to how much risk you have.

    You could sail lightly and watch for cracks or signs of collapse and change out the hulls in the off-season if you think it's safe, but please err on the side of caution especially if you sail where it would be hard to get to shore or find help.

    --
    Damon Linkous
    1992 Hobie 18
    Memphis, TN

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  • When it comes to the H16, hull flex becomes normal. First thing to check would be your pylons, the foundation posts that pop up through the hulls, if there is any failure on any one of the pylons, hull flex would increase, signs to look for would be stress fractures on the hull around the pylons indicating that the base of the pylon has come loose, you could remove the tramp frame and test each pylon for play, any looseness would be negative. Pylons seldom fail but yes, occasionally they do.

    Next, check your tramp frame, especially at the corner castings, the entire frame is held together at these castings, check your pylon nuts and bolts to ensure they are tight.

    Check that your dolphin striker post and rod are tight, the stresses on the mast and sails are relieved through them out to the tramp frame.

    And finally, make sure the tramp is as tight as you can safely get it, may surprise you to know that the tramp is vital to stiffness, loose tramp, loose boat. But be careful, the old vinyl tramps could be dogged down super tight as they were much stronger than the mesh tramps, which tend to stress and tear around the grommets if too tight.

    Many posts on tightening up H16's by epoxying the corner castings or using cables between the posts and pylons, the truth of the matter is that H16's flex, and whether this is by design or chance, that flex helps the H16 absorb some of the pounding when sailing through waves or rough water.

    If everything checks out ok, just sail it like you stole it

    firedevil

    --
    TurboHobo
    H14T
    H16
    P18
    G-Cat 5.0
    P16
    --
  • ~~ Damon & Turbo summed it up nicely..... Go out and have fun with it this season, work on it in the off season, and take care of the soft spots. It'll get worse as time goes on and STAY OFF IT...... Before your boat folds up under you, It'll look so ugly It'll scare ya. A friend of mine had one do it to him !!!!!! icon_eek

    --
    ~ Vietnam Vet 69-71~ 17 Hobie w/big jib, ~18 Hobie mag,~DN Ice sailor,
    and other toys.......
    ~~ I live in NY state on the north shore of Oneida lake in
    Bernhards Bay. ~~~~~~
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  • Thanks a lot guys. If the flex is in fact coming from the frame/tramp, I am totally fine with it. Suboptimal performance isn't a concern so long as the boat stays together. The boat won't have more than 350lbs on it and i don't plan to go offshore, at least not in huge surf. The bay I sail on gets rough, but I am never more than an earshot from something.

    From the sound of it I should spend some time looking for stress cracks and loose piles and then pay close attention to whether the flex is actually within the hulls themselves or part of the whole system.

    Would it help to put some glass under the lip along the bows or on the deck in front of the pylons?
  • http://www.thebeachcats.c…ictures/?g2_itemId=10751

    Look at the pic above, note that the pylon itself has 2 points of support, the base and the hull deck, if the base goes, you can throw the hull away, on the hull deck there must be as much support as possible hence the cone shape collar around the pylon, the stress loads are distributed evenly through the deck. Now imagine if the deck just forward of the pylon is soft from delamination.... boah

    The injection repair process has been discussed much on this website, quick and easy repair, back up and running in a jiffy, just do a search on delamination repair and spend week days doing some armchair reading...... idee

    --
    TurboHobo
    H14T
    H16
    P18
    G-Cat 5.0
    P16
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