Best finish to resist impact for bright wood

Discussion in 'Wooden Boat Building and Restoration' started by socalspearit, Mar 6, 2022.

  1. socalspearit
    Joined: Apr 2021
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    socalspearit Junior Member

    Does anyone have any thoughts on the best possible finish for bright wood to resist blunt impact?

    I'm building this very specialized custom freedive/spearing rig for commercial use. Here is the original very long thread: Custom 19' all weather, minimalist, strip plank composite 'go fast' https://www.boatdesign.net/threads/custom-19-all-weather-minimalist-strip-plank-composite-go-fast.66022/page-13#post-925889

    My concern is heavy blunt impact from dropped weightbelts and very heavy anchors (it's just a 19.5' boat but for what I do I use a 30lb kettlebell for an anchor so I can stand right over deep structure in a current with barely any scope). The deck surface will be a laminate .6" thick, composed of 1/4" western red cedar on the underside bonded to 1/4" white oak on the top. Sheathing the underside will be either 1 or 2 layers of 6oz glass and/or 6oz plain weave carbon fiber. The white oak on top I specifically want for its hardness and I plan to finish it bright. Before I start doing tests I wonder if anyone has experience with something like this. Obviously the white oak will be at minimum sheathed with some layers of epoxy and clear ureathane but I'm wondering if adding a layer of glass on top of the oak would give better results against something like a dropped weight belt or would it just be too brittle and likely to dent/chip?

    SpearIt_One_v5 v1-a.jpg SpearIt_One_v5 v1-EXPLODED-B.jpg PXL_20220305_155425369.jpg PXL_20220305_155418340.jpg
     
  2. bajansailor
    Joined: Oct 2007
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    bajansailor Marine Surveyor

    I think that when you are diving nobody is going to be admiring that beautiful natural wood finish inside the hull.
    So why not just use easily removable non skid matting?
    Maybe something like this?
    https://therubbercompany.com/matting-flooring-decking/boat-marine-matting/
    And then you can put the varnish work on display after you return home and wash down the boat (I am assuming you will bring it home on a trailer, rather than than leaving it afloat in a marina?)
     
    BlueBell and hoytedow like this.
  3. socalspearit
    Joined: Apr 2021
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    socalspearit Junior Member

    It will live in the marina. Between guiding/teaching plus my own hunting and training I'm currently on my inflatable 1 - 4 times a week year round. I don't often to any major cleaning on that and I don't want to start. I hose it off, give the engine a quick flush, and if I'm traveling and away I haul it out onto my platform and cover it to keep it out of the sun. New boat I intend to do similar--quick hose off, flush the engine, and probably put a cover on the console although that may not be necessary as my spot only gets a few hours of sun per day and covers tend to create condensation and ultra humid air which I find destroys even supposedly waterproof electronics very quickly!

    Rubber mat is last resort and even then I'd probably rather just let the deck get beat up and refinish possibly at some point. They mats work fine but on a boat used like this will be a huge chore to keep clean. My inflatable has a rubber runner on the deck to the protect the airfloor and the space between the runner and the airfloor always has something ugly growing on it that grows back with in a day or two of cleaning. A finished surface would needs just 60 seconds with a hose on most days whereas the mat will be like a sieve for all kinds of smutz and nastiness--broken pieces of shells and lobster parts plus random bits of kelp, and something stubborn will quickly start to grow between the mat and the deck. I am definitely going to run tests with it but I also got this SoftSand additive which if it works as advertised seems like a possibility to have on the floor, railing, and gunwale on the stern port side where divers are meant to climb in and out. I got a few different colors so I will need to test, but I think a careful mix of the black and tan on top of the oak may look okay (the oak is stained dark). I like the oak for impact and structural strength and putting a bright finish on it isn't a big deal for me.
     
  4. fallguy
    Joined: Dec 2016
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    fallguy Senior Member

    Gonna be nearly impossible. Anything you put on the wo is not gonna tolerate much abuse. The wo is super hard and the finishes get smashed on impacts and flake off. I'd probably use teak oil and be done with it.
     
  5. socalspearit
    Joined: Apr 2021
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    socalspearit Junior Member

    What about a different wood? Since it would be a veneer on such a small boat it wouldn't be absurd to even go with actual teak. Is there a tropical type hardwood that would hold a finish and stand up to that kind of abuse?

    EDIT: did some research... live oak is probably available here on the west coast or at least at a specialty lumber shop, and on the Janka scale looks to be awfully hard...
     
  6. Blueknarr
    Joined: Aug 2017
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    Blueknarr Senior Member

    Nothing shy of 1/4" steal plate will keep the core undamaged from a 30# anchor dropping from waist high.

    More than 10oz fg cloth will prevent the wood's grain from being visible.

    So if you want wood grained sole- ten oz fg and ten coats of traditional varnish. This will be the easiest option to maintain and perform cosmetic repairs.

    When you get tired of the maintenance- look into urethane bedliner.
     
    fallguy likes this.
  7. Rumars
    Joined: Mar 2013
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    Rumars Senior Member

    There are several choices, drying oils, traditional spar varnish and PU varnishes. Drying oils will not chip but their UV and abrasion protection is 0, if you want the wood not to grey out, frequent recoating is necessary. They can not be used over epoxy, only bare wood.
    Traditional spar varnish compromises UV protection for flexibility. Flexible is what you want, but they are not very impact and abrasion resistant. Use over epoxy can (but not necessarily will) be a problem. Will need recoating at least once a year.
    PU varnish has the best UV and abrasion resistance, but can be pretty brittle, especially the two pack ones. Works well over epoxy. What you want is a single pack super flexible PU varnish, and the only one known to me is Coelan.

    There are common woods that are harder then live oak, for example, ipe, cumaru, ekki. All are difficult to glue because of their high oil content, G-Flex and special methods needed. Jatoba is comparable to live oak in hardness, simpler to glue then the others. The live oak will not be a walk in the park either when it comes to glueing.
     
    Will Gilmore likes this.
  8. fallguy
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    fallguy Senior Member

    Stick with your plan and use an oil once or twice a year.

    Nothing is gonna stand up well to dive gear abuse.

    Another tack would be to make the sides bright finish and paint and mat the sole. Gear bumps will be less damaging. It'll look gorgeous with some black Chris Craft mat.
     
  9. kapnD
    Joined: Jan 2003
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    kapnD Senior Member

    Why so dead set on building the craft in wood?
    Especially when you’re looking for low maintenance/hard use!
    With two batteries, 18 gallons of fuel, dive gear, humans and all their accessories, you’re starting out heavy.
    I’d opt for thinnest possible okume ply, 6 oz reinforcement, and epoxy with paint.
    Lots of small craft on the order of what you’re building are showing up here lately, most home built are styrofoam/epoxy.
     
  10. socalspearit
    Joined: Apr 2021
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    socalspearit Junior Member

    I have gotten to like joinery and wanted to build something light and strong. I'm not sure if you read the whole post--it's a composite boat mostly all sheathed in carbon fiber and fiberglass, not a wood boat. The western red cedar is incredibly light and the better built boats I have been on or at next to in the marina some of which have seen decades of commercial use are 'solid wood boats inside a fiberglass boat' style boats, not stitch and glue. I am not sure of the weight of styrofoam and epoxy or the weight of okume but the cedar is very light, and with a 60hp engine the boat will really scoot so I feel like it should be more solid than that. I've never heard of anyone cracking the hull of a Livingston or Radon while flogging home loaded heavy in the waves but little styrofoam/fiberglass ribs it has happened to friends.

    Luckily it will be hard to drop a 30lb bell from waist high since there is no incentive to stand on this boat unless tied at the dock; you'd fall off quickly in open water and the freeboard is 13" at the bow where the anchor is intended to be hauled from. But it is present in the boat. My neighbors' decks are mostly what you describe--they're lobster fishermen so I think their decks are more about abrasion resistance than very heavy blunt impact, and generally their decks are heavy marine plywood with lots of glass and then urethane with non skid. But they aren't trying to keep anything bright of course.

    I will look into Coelan. I had a feeling that maybe something a little more flexible than a traditional might be the way to go. There's a promo shot West Systems did I think of their G-Flex where they thickly coated a piece of wood with and dropped something very heavy on it to demonstrate the qualities of the epoxy (it dents badly but maintains the moisture barrier). And thanks, I am familiar with the G-flex have been using it since the stem and forward chines are steam bent laminated white-oak, and the keel is white oak.

    I feel like teak oil will coated wood is going to need a lot of maintenance and it would certainly not look bright for long.
     
  11. socalspearit
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    socalspearit Junior Member

    I did a little research on live oak. Although it grows here (most California species are live oaks of one kind or another) it isn't milled because it is such a huge pain being hard, knotty wood that yields only very short boards. One local specialty lumber supplier told me I'd have to source it somewhere in the American SE and that nobody here ever stocks it. I do have one call out to a specialty shop that does a lot of live edge wood thinking they might have something.

    I feel like I have seen jatoba around, so that could be a possibility. I'm probably over-engineering since again, the vessel is not intended for standing operation and would be very difficult to stand on outside the harbor so anything falling on it isn't coming from a great height but I'd rather do it right the first time.

    I'll do impact tests of potential deck surfaces: 1) one with WO and oil as a control, 2) WO with a thin coat G-flex and 6oz S-glass in West 206 with two part interlux varnish, 3) WO with G-flex and Coelan, 4) WO with G-flex, 6oz S-glass and Coelan, 5) WO with Coelan
     
  12. fallguy
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    fallguy Senior Member

    6 oz glass is not going to do well unless you neat coat it about 3x...the impact will hit the fiber and the results easy to anticipate...at least give it a fighting chance with say 3 layers of epoxy; downside of course is epoxy alone not uv stable also cure test must be a week or the resin will be soft and lie to you some
     
  13. socalspearit
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    socalspearit Junior Member

    I was planning to fill the weave on all this since I don't care for the texture of fiberglass on this boat. I reckon it would take about 2 coats to fill the weave so 3x would be just thicker than the glass? Besides possibly G-flex, all the bright work will be topcoated with 207, which is advertised as having some UV resistance, then enough urethane to give it full protection. Two part Interlux is what I have for most of the boat, but while the Interlux has terrific abrasion resistance, I think it would likely crack or chip on impact. In USA there's only one Coelan distributor and they're out of stock on the website. Tomorrow I have to call and see if I can get a can. I have a ton of experience with Smooth-On and their various urethanes and they do make some flexible clear urethanes with UV resistance. If I can't get Coelan I might at least test some Smooth-On. I trust Smooth-On for an awful lot but they don't have the marine history that Coelan has.
     
  14. fallguy
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    fallguy Senior Member

    I'd go 3 coats of epoxy is all. You can do a coat at say 8am and another after lunch and another in the evening on the test piece. Give it plenty of time to cure or heat it to say 150F for 2 hours and let it cool in the heat chamber/blanket closed. Then test the next day.
     

  15. upchurchmr
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    upchurchmr Senior Member

    Paint is best.
    Forget bright and impact together.
     
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