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Thread: strip planking+fiberglass inside

  1. #1
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    Default strip planking+fiberglass inside

    Hello ,I am at the beginning stages of a a boat building project :3 "sailing whale boats" for the sea scouts in my country,to replace their 60 year old fleet.we are planing to build them of strip planking ,douglas fir on laminated iroko backbone with laminated frames ,fiberglassing with biaxial on the outside .my dilemma is whether to fiberglass the inside too,or just epoxy coat and paint.
    not fiberglassing the inside is what we will prefer but I need more advice ,I am attaching some photos of the boats as they are today ,about 15 years ago they were fiberglassed on the outside to keep them alive ,

    thank you .

    6817_152446598150_540658150_2603579_2447957_n.jpgCarmelit_Whaleboat.jpg

  2. #2
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    Default Re: strip planking+fiberglass inside

    Glassing both sides will create a much stronger hull.

  3. #3
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    Default Re: strip planking+fiberglass inside

    Glassing both sides is for “strip built” boats. Canoes and light rowing craft .
    Strip “planked”, are heavier boats with frames, vertical inside fastenings. These boats do not really need any glassing ,outside or inside.
    Glassing the inside between the frames would be pointless .... and daft.

  4. #4
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    Default Re: strip planking+fiberglass inside

    Quote Originally Posted by wizbang 13 View Post
    Glassing both sides is for “strip built” boats. Canoes and light rowing craft .
    Strip “planked”, are heavier boats with frames, vertical inside fastenings. These boats do not really need any glassing ,outside or inside.
    Glassing the inside between the frames would be pointless .... and daft.
    Absolutely. No need for glass inside. Outside biaxial does provide some diagonal stiffening – the need depends really on the thickness of the strip planking and how it's fastened.

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  5. #5
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    Default Re: strip planking+fiberglass inside

    Fibreglassing the inside (with a lighter weight layer than the outside) improves puncture resistance significantly, as well as abrasion resistance - maybe an issue for your application?

  6. #6
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    Default Re: strip planking+fiberglass inside

    In case of a Narwal attack .

  7. #7
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    Default Re: strip planking+fiberglass inside

    Quote Originally Posted by wizbang 13 View Post
    In case of a Narwal attack .
    Bowsprits, rocks - lots of things are out to get you.....

  8. #8
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    Default Re: strip planking+fiberglass inside

    Those boats are too nice to have shoddy strip planking to skin the hulls. Douglas fir might be competitive price wise more educational, and will, certainly, use fewer fastenings! And, there is little cause to have a lot of sticky kids helping either! Strip planking uses a lot of glue and nails! And the glue can cause all manner of mischief with allergies and other health problems in the future!

    Teaching traditional skills shoulld be a part of Scouting on the water or land in my humble opinion!
    Jay

  9. #9
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    Default Re: strip planking+fiberglass inside

    “Shoddy strip planking” ....
    Jay, All boat building is toxic . You know that.
    I did not read that the youths are going to build them, but use them.If they are going to build them, teach them to be neat.
    Like... sail them, not relentlessly repair and pump them.

  10. #10
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    Default Re: strip planking+fiberglass inside

    thanks all for your comments,we are going with a more "modern" way of boat building because building and maintaining a carval built boat will be not realistic ,so strip planking and epoxy is the best compromise, the use of this boats goes some 80 years back from the early british navy whale boats ,this is a photo from the late 40 early 50 of last century
    51165011_10219031757452047_4722504433886298112_n.jpg51844984_10156230549604422_6780527954674843648_o.jpg
    and as for Narwal attack we have Iron Dome :-)
    the plan is to have the kids involved ,following the build,helping but the majority of the work will be done by me and a small crew

    thanks again

    Itai .

  11. #11
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    Default Re: strip planking+fiberglass inside

    So how thick is the planking? If it's thick enough to edge nail it glass on the interior will serve no purpose. If you do edge nail I can tell you with absolute certainty that pre-drilling the strips is well worth the effort. Nailing also holds the strips together while the glue cures without being in the way like clamps so you can keep on stripping.

    Beading and coving is also worthwhile since it helps with alignment and done en masse it is faster and easier than hand beveling.

    I expect that your planking will be 1/2 to 5/8 thick. If you go with a full 7/8 you will be able to increase the frame spacing by 50%. 7/8 fir will be hard to twist and edge set at the same time though.

  12. #12
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    Default Re: strip planking+fiberglass inside

    My boat (an 18' beach cruiser designed by Don Kurylko) is strip planked with 1/2" thick by 1" wide strips, edge nailed and epoxy glued. I glassed the outside to add some abrasion resistance for beaching, but did not glass the inside. Seems fine so far (3 years).

    Tom
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  13. #13
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    Default Re: strip planking+fiberglass inside

    I think the trade off is glass on the inside vs ribs.
    Probably a fairly heavy +/- 45 makes almost all the internal structure irrelevant.
    Take the weight of the ribs, deduct the weight of the fiberglass, and add the remainder to strip thickness.
    Smoothing the inside enough to do the laminating is the biggest PITA
    SHC

  14. #14
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    Default Re: strip planking+fiberglass inside

    Glass the outside and epoxy seal the inside. It's an open boat and you don't want rain water soaking into the planking.
    I built a 20' full keeled sailboat years ago(full decks and cabin). Strip planked and outside glass. Worked out fine.
    If your planking is thick enough, you can epoxy the strip planks together and also edge nail the strips. Don't really need any glass. The only reason I glassed mine was for absolute water tightness.
    I was born on a wooden boat that I built myself.

  15. #15
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    Default Re: strip planking+fiberglass inside

    Quote Originally Posted by SHClark View Post
    I think the trade off is glass on the inside vs ribs.
    Probably a fairly heavy +/- 45 makes almost all the internal structure irrelevant.
    Take the weight of the ribs, deduct the weight of the fiberglass, and add the remainder to strip thickness.
    Smoothing the inside enough to do the laminating is the biggest PITA
    SHC
    Exactly.
    The only thing I'd add is that a strip planked boat that is glassed inside and out could be built to last forever. the wood provides the fore & aft strength and the glass provides the crossways strength plus a heavy moisture and chafe barrier. If weight isn't the first concern, this is a great construction method. Lots of long-lasting race boats built this way too.

  16. #16
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    Default Re: strip planking+fiberglass inside

    Quote Originally Posted by Russell Brown View Post
    Exactly.
    The only thing I'd add is that a strip planked boat that is glassed inside and out could be built to last forever. the wood provides the fore & aft strength and the glass provides the crossways strength plus a heavy moisture and chafe barrier. If weight isn't the first concern, this is a great construction method. Lots of long-lasting race boats built this way too.
    Hello Russel.
    my concern with glassing inside and what prompted me to start this thread is if water does get in the wooden core it will lead to problems that will shorten the lives of this boats.
    is this a legitimate concern from your experience ?
    thanks
    Itai.

  17. #17
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    Default Re: strip planking+fiberglass inside

    Quote Originally Posted by Jay Greer View Post
    Those boats are too nice to have shoddy strip planking to skin the hulls. Douglas fir might be competitive price wise more educational, and will, certainly, use fewer fastenings! And, there is little cause to have a lot of sticky kids helping either! Strip planking uses a lot of glue and nails! And the glue can cause all manner of mischief with allergies and other health problems in the future!

    Teaching traditional skills shoulld be a part of Scouting on the water or land in my humble opinion!
    Jay
    Ditto! Enough said on the subject over the years. It's beyond me why these plastic resin sheathing myths persist. If they want a fiberglass boat, they should build a fiberglass boat. Nothing wrong with that. They have forums for those, too, I think.

  18. #18
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    Default Re: strip planking+fiberglass inside

    The only thing I'd add is that a strip planked boat that is glassed inside and out could be built to last forever. the wood provides the fore & aft strength and the glass provides the crossways strength plus a heavy moisture and chafe barrier.

    ROTFLMAO!

    And when "the fore and aft strength" wood swells and shrinks as the moisture content changes, the "glass providing the crossways strength" cracks. So much for its "heavy moisture barrier."
    Last edited by Bob Cleek; 02-04-2020 at 07:43 PM.

  19. #19
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    Default Re: strip planking+fiberglass inside

    Quote Originally Posted by wood1 View Post
    Hello Russel.
    my concern with glassing inside and what prompted me to start this thread is if water does get in the wooden core it will lead to problems that will shorten the lives of this boats.
    is this a legitimate concern from your experience ?
    thanks
    Itai.
    You can bet your ass it is!

    Epoxy sheathing is not a complete moisture barrier. Epoxy is moisture permeable. A good sheathing job on a boat that is dry stored will go a long way to stabilizing things, but the simple fact is that moisture abhors a void. If youi've got a dry piece of wood, moisture is going to want to go there. You will have nicks, dings, and imperceptible cracks over time. You'll have screw holes through the sheathing for whatever reason (e.g. keel and stem chaffing strips, caprails, rub rails, etc. etc. etc.) The wood moves as it swells and shrinks; the sheathing doesn't. The structural system continually is trying to tear itself apart, with varying degrees of success. Once the water finds its way beneath the sheathing, and it will, the sheathing will keep it there, nice and warm in the sunshine and you're on your way to a fungal decay science fair project. Sometimes this takes a while. Sometimes it happens amazingly fast. Sheathing a strip build kayak or dinghy that you will be keeping in the garage between day sails is one thing. A whaleboat is quite another.

    Last edited by Bob Cleek; 02-04-2020 at 07:46 PM.

  20. #20
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    Default Re: strip planking+fiberglass inside

    A strip planked / epoxy boat does not need any glass for strength in any direction or dimension.
    Waterproofing or abrasion resistance... that’s it
    Mine has no glass. ... show me a stronger 34 foot wood boat.
    pfft .. you guys.

  21. #21
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    Default Re: strip planking+fiberglass inside

    Quote Originally Posted by wizbang 13 View Post
    A strip planked / epoxy boat does not need any glass for strength in any direction or dimension.
    Waterproofing or abrasion resistance... that’s it
    Mine has no glass. ... show me a stronger 34 foot wood boat.
    pfft .. you guys.
    And your boat really doesn't need sheathing to keep the water out, either, does it? As for abrasion resistance, your good helmsmanship and a fender or three should take care of that.

  22. #22
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    Default Re: strip planking+fiberglass inside

    Correct .
    being a round sided double ender she just needs the one fender actually.
    Bob , you post a photo of a crap rub rail, butted. That is where the problem started, and that looks like ply ... or osb!
    Last edited by wizbang 13; 02-04-2020 at 08:08 PM.

  23. #23
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    Default Re: strip planking+fiberglass inside

    Quote Originally Posted by wood1 View Post
    Hello ,I am at the beginning stages of a a boat building project :3 "sailing whale boats" for the sea scouts in my country,to replace their 60 year old fleet.we are planing to build them of strip planking ,douglas fir on laminated iroko backbone with laminated frames ,fiberglassing with biaxial on the outside .my dilemma is whether to fiberglass the inside too,or just epoxy coat and paint.
    not fiberglassing the inside is what we will prefer but I need more advice ,I am attaching some photos of the boats as they are today ,about 15 years ago they were fiberglassed on the outside to keep them alive ,

    thank you .
    Take a look at Paul Gartside's website. He has a lot to say about strip building, large and small, but what I am thinking of is his recommendation for 2 or 3 cold moulded layers instead of glass on the outside. Read the whole article, you'll find it under FAQ, More on strip planking: Paul's opinion.

    Jamie

  24. #24
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    Default Re: strip planking+fiberglass inside

    Consider how much extra trouble the cold molding over the strip planking adds to any future repair, not to mention the actual initial installation. IMO, it is fixing something that ain’t broke.

  25. #25
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    Default Re: strip planking+fiberglass inside

    Bump - any updates on how this project is going Itai?
    Larks

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  26. #26
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    Default Re: strip planking+fiberglass inside

    I would recommend building it as you describe - strip-planked on laminated frames with biaxial fabric set in epoxy on the exterior. No fabric is required on the interior unless you foresee a problem with chafing and scraping in the bilges from gear and equipment stored in the boat. I would also recommend that the exterior fabric sheathing be laid on at 45 degrees to the centreline - it is stronger this way. I presume that you are going to replicate the existing boats, and not build to a new design; is that correct? If so, consider using the book Elements of Boat Strength by Dave Gerr to calculate scantlings of planking & structure. The book is available from the WoodenBoat Bookstore.
    Hope for the best, but plan for the worst.

  27. #27
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    Default Re: strip planking+fiberglass inside

    Quote Originally Posted by wood1 View Post
    .my dilemma is whether to fiberglass the inside too,or just epoxy coat and paint.
    There is no point in epoxy coating the inside if you are not using it to glue cloth to the wood. Epoxy alone is not a paint system, It checks and cracks along the grain.
    Use a marine primer and marine paint system on the inside.
    It really is quite difficult to build an ugly wooden boat.

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  28. #28
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    Default Re: strip planking+fiberglass inside

    Hello all ,
    thanks for your replies ,the project is on hold for now because of the covid 19 situation,not the best time to start fundraising.

  29. #29
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    Default Re: strip planking+fiberglass inside

    Douglas fir might be expensive in your part of the world. There are producers of high quality plywood in Israel. I know of a youth group that built a pilot gig in glued lapstrake. Actually a CLC kit. It worked out well.

  30. #30
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    Default Re: strip planking+fiberglass inside

    hello jim,
    yes douglas fir is not cheap here as are all the good imported lumber,
    and unfortunately
    all the plywood factories closed years ago ,indeed it was a premium product ,now it is almost impossible to buy marine plywood in israel.

  31. #31
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    Default Re: strip planking+fiberglass inside

    Quote Originally Posted by wood1 View Post
    Hello all ,
    thanks for your replies ,the project is on hold for now because of the covid 19 situation,not the best time to start fundraising.
    Sorry to hear that, I hope you manage to get it back up and running again soon.
    Larks

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    “It’s risky”, said experience.
    “It’s pointless”, said reason.
    “Give it a try”, whispered the heart.

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  32. #32
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    Default Re: strip planking+fiberglass inside


    Built this 18' steam launch about 20 years ago. Strip composite, 1/2" Monterey Cypress planks, 6oz glass outside, 10oz inside.
    One thing I really like about this method was the resulting clean and easy to clean interior.

  33. #33
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    Default Re: strip planking+fiberglass inside

    Hey, that's beautiful!

  34. #34
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    Default Re: strip planking+fiberglass inside

    http://forum.woodenboat.com/showthre...at-Restoration

    I saw your photo of this beautiful boat and was intrigued by the floors you've installed, and it appears to have the sort of invisible laminated fiberglass frames that I have in my boat. My keel needs to be replaced, and I think a bit heavier than my last one (it's aboout 5/4 wide by 6/4 deep) and scarf jointed in only 14 feet LOA. Would adding some floors like you have be a good way to tie the new keel into my existing structure? Interested in your thoughts! Please check out my link above.

    Thank you!
    Jim

  35. #35
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    Default Re Gary's photo

    Gary,
    I saw your photo of this beautiful boat and was intrigued by the floors you've installed, and it appears to have the sort of invisible laminated fiberglass frames that I have in my boat. My keel needs to be replaced, and I think a bit heavier than my last one (it's aboout 5/4 wide by 6/4 deep) and scarf jointed in only 14 feet LOA. Would adding some floors like you have be a good way to tie the new keel into my existing structure? Interested in your thoughts! Please check out my link here:

    http://forum.woodenboat.com/showthre...at-Restoration

    Thank you!
    Jim

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