Custom 19' all weather, minimalist, strip plank composite 'go fast'

Discussion in 'Boat Design' started by socalspearit, Sep 2, 2021.

  1. fallguy
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    fallguy Senior Member

    See my next post first! Weave fill is at the end!

    The right way to do this is to neat coat immediately. Two coats within the bond window.

    With these light fabrics, fill coats reduce the likelihood of sandthrough.

    use a rate of 2 oz per sqyd, plus some for the roller..I like the cheap foam rollers for this, or if you go to Home Depot, they used to sell an adhesive roller that worked great....I use a 1/4" nap regular roller for a bulldozer fast effect and then follow with the low nap adhesive roller; you can squeegee the bulldozer roller at the end if you are a tad short

    if you feel you are past the bond window now, then I'd sand with 80-120 grit; you'll hit the weave a bit; heavier grits will do some damage

    You can do any repairs after the fill coats.

    personally, I sand anything after 24 hours .. a lot depends on temperatures .. if you can't fingernail, I'd probably sand..I don't have great faith in primary bond window recommendations by mfg because I have done plenty of sanding of stuff done within the windows and there has generally been clear shear of feathering in my climate controlled building...fyi.. my testing may be imperfect; could even be dirt that messes up the bond; so make sure to clean it well, especially if you sand...I use acetone...
     
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  2. fallguy
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    fallguy Senior Member

    Oh, wait, you only got one layer on?

    For this, I would not weave fill.

    Scratch it with 80 grit, clean it, and add the next layer.

    Sorry...I misread

    Weave fill is common at the end. Two-three coats.
     
  3. fallguy
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    fallguy Senior Member

    Also, please tell me where you are in the stack. If you laid one fiberglass; the best approach is to lay both the carbon and last glass coat at the same time because the carbon likes to float...and the glass will sort of prevent that by wetting through on top...kevlar floats, too, if you have a combo

    I can also help with strategies. You mentioned cutting glass. But all the glass should be cut and ready to roll off tubes. You make a lot of sharpie references on glass and boat to get the glass located right. Even length references each meter to make sure the pull/stretch is right.Small bits of masking tape of poor quality, delicate surface tape can help with setup. Then back on the tubes, carefully thinking through the rolloff direction. Then you roll the surface with 40% of the epoxy ready to pair. Unroll the glass, and have another batch ready to go for 60% on top.. Working only one side of the boat reduces walking times greatly...which are wasted time in epoxy work. You don't allow help to measure epoxy ever, but help can mix. So, for this job, you batch label A would be 40% of glass weight in resin. B is labelled hardener and resin and 60% of glass weight to wet.

    I thought you had planned to trap the carbon between two layer of fiberglass to help with the lamination.

    Also, I have a lot of experience with limited helpers and you have to plan how to best utilize. If you only got 25% from the wife; it is on you, not her. But she could do the batch mixing and save you two minutes for each batch. You sharpie label the resin and hardener... My friend Ray, who worked on my boat a lot for some pay, died on March 3 at the age of 79, may his memory be eternal..

    Do NOT top down wetout carbon..it sucks. Always roll it off onto a wetted surface. It puddles under and is really a pain to make the sirface even under it the other way.

    gotta run; ask away
     
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  4. socalspearit
    Joined: Apr 2021
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    socalspearit Junior Member

    @fallguy
    thanks for the detailed response. I got two layers of glass on. Originally I was going to sandwich the CF between these glass layers but I decided the CF looks better if it's the last layer, structurally it's the most sound, and I'm not trying to engineer the boat to the point where it can resist hitting rocks hard at speed so a layer of 6oz glass over the CF isn't going to do much anyway.

    Anyway, on closer examination I am very unhappy with it. It didn't end up a total disaster and if this thing was a quick and dirty stitch and glue job I'd be like 'fine whatever it'll work' but so far, the boat hull is super solid and been done to a high professional caliber. It hurts and will drive me crazy to know what's under subsequent layers and paint and fairing compound if I just do a little sanding and fairing then cover it up. Very frustrating because if I'd just started out with the intention of doing a good hand lay-up, we actually would have been golden. 90 minutes to do each layer would have been plenty of time, and I'd done some albeit smaller sections by hand on the internal airboxes and gotten near perfect results. They aren't as tight as a vacuum pull but still very serviceable and professional looking.

    Besides some blisters that are small but quite numerous, I see a lot of small air bubbles that I shouldn't on a good hand lay-up. I am really thinking to hit it hard with even a belt sander and strip off a good 50% of the glass/epoxy to open up any potential air voids, test a small portion to see how fresh epoxy goes in, dremel out actual blisters and possibly even resort to a vacuum process to fix it. I want to get epoxy into those bubbles. I'd work in small sections, maybe just 20% at a time, and do a sort of infusion process--run as strong of a vacuum as I can on it with no peel ply or baby blanket, then let it pull liquid epoxy into all those tiny bubbles, tack up a tiny bit, then pull the bag off before it sets up, then sand it fair. Once these layers are fixed, just do a good hand lay-up of the CF, or maybe vac bag it but in sections. Or if I end up taking off too much of this fiber, just clean it up and do another layer of glass before the final CF. I got really greedy and took way too big of a gamble trying to do too much it once with a bag.

    Belt sander is strong tool but I actually used one for a good bit of the fairing, and because the hull was so smooth and fair before glassing it I can control it. I am really hating all the sanding that's going on in the back porch but if I really hit I'll move it somewhere that kind of dust is less offensive and go to town. Stupid to have wasted the time, money and energy but whatever, I want to get this right. It's not shown on the time lapse but I built the transom 3 times and the steam bent white oak stem twice before I was satisfied with the quality of those parts.

    PXL_20220604_031344172.jpg PXL_20220604_031441746.jpg
     
    Last edited: Jun 3, 2022
  5. fallguy
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    fallguy Senior Member

    I'd never use the belt sander on that. Festool and 40 grit perhaps.

    I won't try to tell you how to fix it.

    I have a lot of vac experience and honestly, I'd never use vac on a 2 layer layup of 6 oz....too risky to end up dry and 6 oz ends up needing weave fill. I might use it with biax under, like a db1700 with 6 oz or 4 oz over..well, I would.

    But here is the deal with vac. Best you get is 50% reduction. So 6 oz glass is 6 oz resin ends up at 3 oz resin and two lifts minimum clear is 7 oz resin vs 10 oz no vax. So you save 3 oz per yd. Your boat, call it 6sqyd is literally just over a pound of savings. So, then suggest quality? Not really, because only needed if you have lotsa funky curves. I did bag an overlay on a Boston Whaler Sport. That went well, but I bagged all the skegs and keels separately, so it was like a 4 day job. One layer only..6oz
     
  6. socalspearit
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    socalspearit Junior Member

    Okay, I am going to keep this in perspective. The blisters are semi-cosmetic and 99.9% of the work perfectly good so while I want to strip off everything with a belt sander and just start over it's a little much.

    Here is what I'm thinking to fix this, if you have feedback I'd appreciate it. Thanks again for the detailed reply above; a lot of that is what we'd already figured out (ie CF can't be wet through, cut and prep fabric for deployment, etc).

    - cut out any of those suspicious blisters with a dremel, all the way back to where the fiber is solid and fully bonded to the hull. It makes me crazy that they're most on the chine edge which is one of the worst places for that stuff. Do this first since they are very easy to spot at this stage.
    - vacuum carefully and remove dust
    - warm up each blister area with a heat gun--not too much to loosen anything but enough to be very warm
    - immediately inject and brush with 105/207. The warm substrate will loosen the fresh epoxy and help it wick in.
    - mix up a filler, 105/207 plus a little bit of g-flex, then some of the higher density West filler, like the 405 and some 406 and maybe pinch of chop strand, then inject and push this into those blister areas. Finish it just very slightly proud of the hull surface
    - wet sand everything smooth with 60 grit and 5" pneumatic sander, not being afraid to go a little into the outer layer of glass fiber but not trying to strip it off. While the epoxy was still extremely green, after I ripped off the vacuum bag stuff, I did some passes with epoxy so I'd say the weave is at least 80% filled, so I'd just cut to about 75% of the weave fill, meaning I'd remove 25% of the outer (second) glass layer. I can't source 5" wet/dry 40 grit.

    When I start the next layer of fiber, I'm going to do a hand lay-up, and as I lay down the base coat of epoxy, I'm going to have somebody walk in front of my brush with a heat gun and get the hull fairly warm, then I'll hit it with freshly mixed 105/207. Not as good boiling under vacuum to remove air bubbles, but certainly a lot easier. I'll lay each piece of fabric over and get it fitted and right before moving over and base coating the next section. I found so far with my carbon that if the base coat is just barely starting to thicken, it'll hold the CF nicely, then it can be fully wet-out with fresh epoxy and pressed in.
     
  7. fallguy
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    fallguy Senior Member

    You don't use a heat gun. It is not needed and will do more harm than good.

    To inject holes, get about 6-12 blunt nose injection needles. They are 0.064" typically. And get a couple drill bits 1/16" or same. Drill two holes in each defect. I mark them with a tape that is not pushed down. Then after you have them all prepped, mix a small amount of epoxy and inject them and place the tape over the injection holes to keep the epoxy from draining out if not level.

    Next day, come back, pull the tape, sand it flush and there may be a couple indents to fill since epoxy shrinks.

    I had to fix a panel with a couple hundred of these one time. They require two holes because the air likes to get trapped otherwise. So a hole on each end or far apart from each other works best. And I tried other ways; this was my favorite.

    I'd never use a heat gun in layup. You speed roll the substrate and then roll the fabric off a tube. If the carbon is going to show, then you can't use a sharpie for reference lines, but you could probably try a tiny piece of electrical tape or delicate surface tape.

    For your boat, here is about how it would go.

    Fabric is ready, let's say 6 yards long by one yard, so 6 sqyd piece of 5 oz glass. Forty percent is used to roll the substrate or 15 oz, plus 4-6 oz roller loss. Or for 2:1 epoxy, I'd make a 21 oz batch for batch A. Batch B is the heavier batch at 60% or 18 oz. I'd roundup to 21 again, or 18 it and squeegee the roller, but I hate to run short. Only mix batch A.

    Roll this on where planned. Dump it, roll it, etc. It should take you 10 minutes max. Unroll the fabric. One person needs to anchor the fabric by holding it in place while the other unfurls. This takes 3 minutes max. Then the anchor person mixes batch B while the other person rolls the fabric with a preferred roller. This is important because the fabric needs a single pass. This is not for perfection, just a once over. Have the mixer start when you feel you are two minutes from completion. For your boat, a 6" bubble buster roller 3/4" would take you about 5 minutes max for the first pass. Just a go over it all pass, no wetout goal.

    Then start to pour the epoxy. This varies a bit if the area is flat or vertical. I like to use a paint pan here. Dump mixed epoxy into a tinfoil lined tray and roll it on. This part will take you 15 minutes. The helper may only be holding the paint tray, but that is a major help.

    By my work estimate, this job for each piece of fabric is 33 minutes.

    Please don't mess with a heat gun; they typically scorch fiberglass inside the epoxy and you have to fix. For a carbon final layer, you'll wreck it if bright finishing.

    After it cures, knock down any high or bad spots gently by hand; weave fill two coats, spray it with Duratec Sunshield iff you want to see the carbon.
     
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  8. fallguy
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    fallguy Senior Member

    Also, I don't like hot tacking cf. It is too easy to deform.
     
  9. socalspearit
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    socalspearit Junior Member

    @fallguy
    Thanks again for all the details. I like your injection method, I can certainly see it working quickly for much of this. Tomorrow I'm going to clean up the space and get back to work. In its entirety the vacuum process left my hull in what feels like a minor disaster but when examined in sections everything is not so bad and very fixable with some time. Any blisters over the white oak parts I'll probably grind and fill with an epoxy mix of high density filler and chop strand since I went to the trouble of building white oak into the keel and chine edges specifically for impact resistance, and anything over the cedar I'll try an injection method since epoxy is still much harder than cedar.

    Once I get it cleaned up I'll reassess but I may not wall-to-wall CF the entire outer hull since the CF is only meant to show in the bilge and a few inches over the waterline, and while it does add some structure it really isn't necessary that it be CF since the wood interior is so solid on its own. If I do it in parts, I could very easily vacuum process small sections of the bilge area, maybe break that into 6 sections, to be tested and done one and at time. In small parts with a vacuum I could get perfect chine corners on the final CF layer and make sure to get epoxy deep into the pores of the existing two layers of glass that make me cry. All that would be left would be the sides above the waterline and those are flat sections easily done by hand with glass, which could be easily matched and fitted against the CF edge, and that seam where CF meets glass could be easily faired since that seam would be underneath paint anyway.
     
  10. socalspearit
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    socalspearit Junior Member

    @fallguy
    I looked up the Duratec Sunshield. Looks interesting, do you know if it can be topcoated with a urethane? My bottom paint is a clear teflon two part urethane.
     
  11. fallguy
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    fallguy Senior Member

    No.

    Stick with the urethane. I did not know the plan.
     
  12. socalspearit
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    socalspearit Junior Member

    I spent the morning on it. It's nowhere near as bad as I thought--I just have very no experience working with fiberglass in this way. It's adding some time and elbow grease but should have zero impact on structure, longevity, or cosmetics. Wet sanded with 40-80 grit and little $50 pneumatic random orbital doodad off Amazon. Just now hosed it off. Most of the blisters opened up under the sanding and I'm going to slice them all with an xacto to make sure the water drains and it dries fully before I fill those. The S-2 glass even at 60z weight is INCREDIBLY tough, so even with 40 grit and the pneumatic sander there is zero chance of accidental sandthrough. I may do a top layer of that over the CF on the exterior, which is mostly on the bottom.

    Also, if anyone following this thread is looking for Coelan (impossible to get now) I found a NZ company called Uroxsys makes something similar, which is now distributed by Awlgrip under their name of 'Awlwood.'
     
  13. socalspearit
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    socalspearit Junior Member

    Much better results with the vacuum process this last week. I am doing just one layer at time of CF under vacuum, and only working in sections--three major sections to get most of the hull and then I may split the stern with its airboxes into a few small sections. My wife and I are getting better--we're doing each section as a 'proper' hand-layup then bagging it before the epoxy sets. I was a little freaked out when I stripped off the bag materials on the first CF run and I discovered some ripples in the carbon, but they were mostly just epoxy ridges, and then once I started working with the CF I discovered I could actually sand well into the CF, and once wetout it's still cosmetically perfect. Everything on the boat that will live below the waterline is getting the CF applied under vacuum, and then the remainder (up to the outwales) I will do a CF layer by hand since those are straight sections that will be underneath paint and not live underwater. The carbon will never show to more than 4" above the chine.

    Working with the CF though I am discovering that it is butter soft in comparison the S-glass, so I am definitely going to put one final layer of 6 oz S-glass over the entire exterior hull, and probably vacuum bag that as well, working one side of the boat at a time. It'll add time and certainly a good bit of money but unless the boat rams into a breakwall at speed the S-glass will protect the carbon weave for the lifetime of the boat and should make it easier to sell even many years from now. The carbon looks better without the S-glass but at the end of the day it's mostly the bottom of the boat (which will be seen by divers) and I'll feel better about it knowing that it has a layer of S-glass on it.

    PXL_20220614_030442616.jpg PXL_20220620_024700298.jpg
     
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  14. fallguy
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    fallguy Senior Member

    Generally speaking, one does not run the vac line on the part. Hard to tell in the pictures exactly if you did, but looks a bit like it.

    glad it is going better
     

  15. socalspearit
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    socalspearit Junior Member

    Thanks, we weren't running the vac line over the part. Because these were such large sections and my CF is already 50" wide and I'm working with 60" peel ply, I did sometimes have to double up the peel ply and so the unfinished edge was sometimes pressed into the part, leaving a few embedded fibers that have to be pulled and sanded out. If I just fold that edge up and back an inch I could avoid that, I'm thinking it might crease a tiny bit but in the grand scheme that would be minor. Is there a specific or standard way to deal with that?
     
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