best material for stringers?
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best material for stringers?

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    Senior Member flatwater's Avatar
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    Default best material for stringers?

    Hi all, it's been a while since I've been here....enjoying the summer with the Stevens. However I've been going "easy" on it because I know the stringers aren't 100%, and I plan on replacing them this winter. I thought I'd do a bit of searching now and start to gather up materials for it. I contacted a local boat shop and they suggested using laminated wood (plywood staggered and screwed together). Would this be the way to go or should I use single pieces of hard wood (like cedar) for example? I searched around on the site but didn't drum anything up. I'm sure it's on here somewhere if someone could post a link that'd be great. My boat is a 1973 17' Stevens v drive. It has a 454bbc...and is used as a nasty ski boat every week. Any help would be great, thanks guys,

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    Senior Member hellnback's Avatar
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    I used #1 fir
    It may be OLD ,it may be Slow ... but at least it's MOBILE !!!

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    RPB
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    The best stringers are not wood. Just finished making (experimenting) with several different composite stringers utilizing various technologies, comprised of epoxy, Kevlar, carbon fiber, and other materials. Excellent deflection and stiffness and wont rot.
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    Senior Member flatwater's Avatar
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    Quote Originally Posted by hellnback View Post
    I used #1 fir


    hellnback, that would be a type of hardwood?

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    Senior Member flatwater's Avatar
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    Quote Originally Posted by RPB View Post
    The best stringers are not wood. Just finished making (experimenting) with several different composite stringers utilizing various technologies, comprised of epoxy, Kevlar, carbon fiber, and other materials. Excellent deflection and stiffness and wont rot.
    Sorry my computer is acting up a bit.... I thought keeping the stringers somewhat flexible would help the rest of the boat move and flex. Having the stringers solid and not being able to flex sounds like it would cause the "weak link" to fail? I'd like to see pictures of your test boats. I'd LOVE to use Kevlar, but I don't think that would be in the budget!

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    Senior Member phughes SS-13's Avatar
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    Default Got Wood??

    Fir is not a hardwood, it is a pine. I have used air dried Ash with excellent results (that's a hardwood). Air conditioned wood is important, regardless what type of wood you use. I don't think it would be wise to use kiln dried wood, too brittle. I used the old stringer as a template to cut the new one to fit, glassed it into place then put the final wrap of carbon fibre over the entire length. Turned out awesome. Do one side at a time, and take extreme care in supporting the hull. Do not assume the trailer will support the hull correctly. If the hull is allowed to sag or belly or twist while the stringer is out then you glass in a new one, that new dimension to your hull is there to stay. Let us know how it goes.

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    Senior Member phughes SS-13's Avatar
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    Default Still Got Wood

    Although I have never made a stringer of composite, I have used composites in many other areas. I would not hesitate to use high density composite and carbon fibre to rebuild stringers. I love the stuff and it is so easy to work with, coupled with epoxy and it is a repair that is permanent.

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    Senior Member flatwater's Avatar
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    Quote Originally Posted by phughes SS-13 View Post
    Fir is not a hardwood, it is a pine. I have used air dried Ash with excellent results (that's a hardwood). Air conditioned wood is important, regardless what type of wood you use. I don't think it would be wise to use kiln dried wood, too brittle. I used the old stringer as a template to cut the new one to fit, glassed it into place then put the final wrap of carbon fibre over the entire length. Turned out awesome. Do one side at a time, and take extreme care in supporting the hull. Do not assume the trailer will support the hull correctly. If the hull is allowed to sag or belly or twist while the stringer is out then you glass in a new one, that new dimension to your hull is there to stay. Let us know how it goes.
    Yes, I understand the importance of supporting the hull. I plan on removing the boat from the trailer and putting the boat on a "rack" with 4 caster wheels (so I can move it around the shop. I will "fit" the bottom of the hull and support it as much as possible. It'd be great to find some type of memory foam to sit it in, that would harden...hummmm? Anyway I'm sure I'll think of something. Time is on my side, so I have no excuse to rush anything. Although I have done some fiberglass work, I will need some pointers along the way. I will provide pic's and bring you guys along step by step. Who knows, it might even help someone else out along the way. My ski season ends around October here, so it won't be until after that. Thanks for the replies! if you have anymore suggestions, lets hear em!

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    Quote Originally Posted by RPB View Post
    The best stringers are not wood.
    I also have to agree , considering there are so many good products out there at the moment like coosa's Bluewater 26 which i have used in the past Coosa Composites, LLC - Manufacture of high-density, fiberglass-reinforced polyurethane foam panels and this one is a product that i happen to favor the most because it is Coosa's biggest competitor with better priceing ( Thermo Lite Board ) and sometimes offering second's at a fraction of the orginal price ( $ 50 a sheet ) Water Resistant, Fiberglass Reinforced Composites | Stringers and Transoms | RV Repair | Boat | Flooring | Plywood Replacement | Marine Bulkheads and then there is this one which is very new to the market , and being introduced in Professional Boatbuilder which is a trade Magazine for those working in design, construction , and repair which is Seaboard *Endurabond * which is a new material that supposedly will provide good structural properties for marine applications and a product that i will be trying in the near future www.totalplastics.com
    Last edited by OFFSHORE GINGER; 08-23-2013 at 10:03 AM.

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    Senior Member OFFSHORE GINGER's Avatar
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    Brian , i apologize for not getting back with you sooner ( pm ) and the reason being is .........................i often do not pay much or any attention to to my mail box because i do not like the format or make up.
    Last edited by OFFSHORE GINGER; 08-22-2013 at 08:42 AM.

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    Senior Member flatwater's Avatar
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    Ok, I apologize....perhaps the thread could have been better titled "What is best, solid wood or plywood".... I understand that using a composite type of material on a race boat, or in a high performance application would be necessary, however the main use for my Stevens is slalom skiing. I ski at 38 mph.....boat total speed is 50ish...and used on flat water. The most abuse the boat sees is the hole shot and some tight corners, so I think I can get away with wood stringers for a replacement. I've been searching the net finding out what people use. I see lots of things about PT Plywood, and Exterior Plywood, being cut and lap jointed, screwed together with resin and a layer of fiberglass in between. I see a lot of sold wood from Douglass fir, birch, spruce, ash, etc... It looks like as long as you ensure your wood is protected, there is a wide variety of material to use. I have also be reading up on the installation of the stringers to the hull and the need to have a gap between the stringer and the hull it's self. The use of a loc tight construction adhesive is used with 1/4" foam spacers, then some "peanutbutter" compound to smooth out the transition to the floor for the mat to sit nice. Also read that replacing one stringer at a time is a good way to go in order to maintain original boat structure and to have a base line of measurement. So as far as material goes, this is my thought.....if I went with a solid one piece of say Doug fir for example, would it be as strong as the staggered pieces of plywood? I see the plywood being much like an "engineered" floor joist, that replaced regular 2x10's on the last house I built. Also would the solid piece of wood have more squish to it when attaching hardware as opposed to the plywood? Don't mean to overthink things....just want to get it right the first time gents. thoughts?

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    Senior Member OFFSHORE GINGER's Avatar
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    To tell you the truth every Boat Co that i have ever worked at has used Marine grade Ply for there stringers .

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    Quote Originally Posted by OFFSHORE GINGER View Post
    To tell you the truth every Boat Co that i have ever worked at has used Marine grade Ply for there stringers .
    Thank you.....

  16. #14
    Brian B dryhoze1's Avatar
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    Default Stringers

    For the stringers on a Stevens or any other flatty for that matter, I would Not use marine grade plywood for stringers. The compression with stringer washers and backing plates on solid lumber is bad enough with these old boats. Get some nice DF or ash. Support the bottom very well & use the old stringers as templates. If marine grade plywood was better, I'd think Hondo ,Stevens, Sanger ,Litchfield & many others would have used it ! Just my .02
    Last edited by dryhoze1; 08-23-2013 at 08:32 PM.

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