Engine stringers?

Discussion in 'Powerboats' started by gbaaron, Feb 27, 2005.

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  1. gbaaron
    Joined: Jun 2004
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    gbaaron Junior Member

    Replacing the stringers in a 20' baja, starting with the engine stringers.
    The original design looks like it has a two by six board glassed in for the base and then plywood laminated to the top & sides for thickness. Should I use this design or is there something better. has stock 260hp merc. will have 375-400hp when done.

    Thanks.
     
  2. PowerTech
    Joined: Feb 2005
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    PowerTech Senior Member

    I put clear fur wood stringers in my boat wraped in byaxle it is strong.but you could use divinacil foam wraped in byaxle and that would be strong as heck to.
     
  3. Suggest to build as Carlwun post but for the hull stringers. For engine stringers cores better to use a softwood coated three times with epoxy before glass with biaxiall, You could have also an absorption of engine vibrations and less risk of fatique cracking. Use softwood because in a remote case of water infiltration this could have less expansion then hardwood.
     
  4. gbaaron
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    gbaaron Junior Member

    Thanks for the reply. Should I use the original design with the 2 by 6 or use all laminated plywood?
     
  5. Need to look at the boat type; for a 20 ft 6 by 2 looks a little heavy. Send to me a link to look at the boat. Anyway laminated with epoxy is better than timber.
     
  6. gbaaron
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    gbaaron Junior Member

    Here are some pics of the engine stringers.
    Were they are fastened to the transome 2X6, and wider were the engine mounts are.
    The other pic is a cutaway after removed from boat
     

    Attached Files:

  7. My advise is that You could use laminated plywood to reach the same thickness and dimensions of the stringer on the engine section. Glass them with biaxiall cloth after a few layer of450 gr/mq mat an polyester resin. But is just my advise, laminated softwood glued with epoxy, three pieces of 3/4 " per 6" or so each, then coated with epoxy will be better. You could then glass all with epoxy resin and biaxiall, but don't use mat or use mat without binder, like the constinuous strand one. You will have real strong engine supports and stringers. You could leave others hull stringers in foam core glassed with isophtalic polyester resin or vynil ester (better). Did You use epoxy resin before? Do You can find it or could be a problem?
     
  8. Jeff sky
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    Jeff sky New Member

    Anytime you have to replace stringers or engine mount box please do it right remove all !!!! dry rot and look at this new system called seacast same stuff used to replace transom with worked great for me will add picture later
     
  9. gonzo
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    gonzo Senior Member

    You can simply rebuild them to the same as the original design. They lasted decades and the original builder was not really careful about sealing the wood. Polyester works fine on these repairs if you clean the surfaces properly. Epoxy has better properties, but won't give you any advantages since the rest of the boat is polyester.
     
  10. DSR
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    DSR Junior Member

    I agree with Gonzo,

    Timber with plywood laminations is a common practice for engine stringers and gives you a good strength-to-weight ratio with the plywood lams helping to prevent the timbers from splitting, especially if there is crossgrain present in the stringers (such as cutouts for clearances for the engine and other items), and higher horsepower applications.....
    Just my 2¢. :)

    Dave
     
  11. ondarvr
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    ondarvr Senior Member

    This is good advice, your attention to detail will be much better than in the original build, so it should be stronger and last longer. The wood rots because it gets wet, it typically gets wet from sloppy workmanship, like exposed wood, unsealed screw holes, etc, the type of resin makes no difference in this type of failure. While epoxy is a better product, it frequently doesn't make much of a difference in which product you use.
     
  12. PAR
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    PAR Yacht Designer/Builder

    Welcome to the forum Jeff.

    Speaking of attention to detail, this is a thread that's over a decade old. There are plenty of more current threads with similar information or you may wish to start your own, with specific questions about what you may need.
     

  13. DSR
    Joined: Mar 2017
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    DSR Junior Member

    Wow!! Didn't even notice that, I just saw it pop up on on the recent posts..... That's funny!! :p
     
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