Laminate Sample #26: Cedar Strip-Planking with E-glass / Epoxy Skins

[@tomlogan2102]

I wish I could give this video two thumbs up. I love cedar and fiberglass. It’s a powerful combination. Thanks so much for the work you do. Sorry to say somethings so cliché… You are totally underrated.

[@pabloricardodetarragon2649]

I agree totally. It's not the last fashion in high composites, but that works pretty well and it's very durable if the skins are thick enough to be totally waterproof and that a good epoxy resin had been used. The 1988 trimaran F 40 Adrenalin was made of 3/8 red cedar, 200 gr carbon fiber. The complete boat long 12.18 m with a width of 12.18 was at the limit of the rule: 1800 kg, similar to the kevlar carbon multis of the time. It was sailing on 2017 at Phuket, 30 years later. I know cruising boats about 40 years old in excellent shape. It's a simple method using a light wood (cedar, paulownia (300 kg/m3...), light pines) and even stronger woods at a very stressed zones, which can be made DIY on a male mold in a simple shelter with little investment in tooling. It's rather cheap and easy, but needs lot of hours of work. A good naval architect will modulate the thicknesses, varieties of woods, and amount of fibers to get the best of it. Great advantage it's impervious to delamination, that simplifies the structural calculations. You can even make big wing masts with the method. Many canoes, and small power boats were made. Lots of multihulls and plenty of strong cruising boats have used successfully the method. For boat building it's one of the best methods for one off boats, and you can obtain excellent ratios weight/strength/durability for a fraction of the cost of an advanced composite.

[@ExploreComposites]

Yes! I've seen pictures of Adrenalin but wouldn't have guessed that light! I am a huge fan of simple wood construction for one-off boats but don't do much of that anymore - some day. Really want to get my hands on some Paulownia too - around here in eastern North America northern white cedar is about the lightest thing we have.

[@charlesmoore456]

Great video! Steve and Alix from Acorn to Arabella sent me here. They are using this technique in their boat.

[@ExploreComposites]

Oh neat - I saw their cabin housesides. Not sure it would be my choice but it uses cheaper material and has very strong corners without posts and fasteners. I’m sure if they sheathe it that it will work great! Strip planking is very versatile and is an ideal way to quickly build one-off curvy stuff - like boats.

[@dejayrezme8617]

I've been wondering if you could vacuum infuse strip planking? Maybe have the edges slightly rounded so as to provide flow channels. But I have no idea if the resin would flow into fiberglass between wood strips pressed against a mold surface. PS: Thanks for all the videos!

[@ExploreComposites]

Short answer: yes, totally. But the process would be challenging! Flat things would be easy-ish but for curves, the strips would have to be pre-glued and removed from the former, have holes drilled and then sheathed with infused skins. Not sure how you'd mold a shape and infuse both sides. A rolled treatment that makes little crush lines in the edges of the strips could work as a resin channel - but would take lots of testing to nail it. Plenty of boatbuilders infuse glass or carbon sheathing over strip planked or cold molded panels but only one side at a time. Not sure how they seal it but it seems to work!

[@kizzjd9578]

I rekon if you had strips of glass or carbon between each timber strip, it would probably soak in. Would be a mission to lay up though and also ensuring that you have proper resin penetration as well.

[@Fulcrum205]

That would be heavy and ugly as the vacuum pressure would push the glass into the gaps between the strips. That would be weak as well because your glass fibers would not be parallel to the core surface. Correct way would be to fair the strips with a low density filler, then bag and infuse the glass skin.

[@pabloricardodetarragon2649]

It's a lot of complication for uncertain results. The light woods are very porous and will soak tremendous amounts of resin in the infusion process. Furthermore the strip planking is a simple cheap manual method and the cost of the consumables and equipment of the infusion will be unsustainable.

[@Fulcrum205]

I'm not understanding why you want to do this. Resin infusion is about be able to wet out your laminate while keeping a very low resin to glass ratio. This keeps the structure light. Vacuum is there to compress the interstitial spaces in the fiberglass and remove any off gassing. Infusing strip planking doesn't make any sense. You are going to have to fasten everything together, seal the back side, then bag and infuse the resin for why? Wood strips arent going to compress any appreciable amount under vacuum. You could just brush a low viscosity laminating resin on the strips and let capillary action carry it into the seams. For strip planking I would just buy a Raptor 18ga Brad nailer and a couple gallons of gorilla glue. Then you can just brush your strip, tack it on, and grab the next one. Mist the whole thing with a little water at the end and it will be ready to sand the next day. Strip planking is slow enough with having to rip and scarf eleventy-million strips. Don't add a bunch of extra time building vacuum bags and sealing air leaks. If you've got a full mold don't bother with any of that. Just lay up fiberglass and foam core in your mould.

[@paulbriggs3072]

You state that the cedar is not strong or stiff for its weight whereas in reality for its light weight it IS strong and stiff compared with other species. Usually for removing soft polyurethane glue you use a sharp scraper then sand.

[@ExploreComposites]

Paul, you are right - I was comparing it to other "fibers" like glass or carbon instead of other woods. Cedar is very respectable structurally and the fact that it is so light makes for a unique type of ply/core situation. Totally agree on the scraper too - I was just being lazy here and blasted it with the sander!