transom repair opinions

Discussion in 'Materials' started by swade, May 21, 2012.

  1. swade
    Joined: Jun 2010
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    swade Senior Member

    Finally back to making progress. made a cardboard template today.

    Did some test fitting with ply scraps. no way 2 x 3/4 and a 1/2 sheet will fit in there after reenforcing and bonding the ply. I used a piece of cardboard as a filler figuring by the time i add 4+ more layers on the inside, seal the ply, then epoxy them together with 1/16 trowel maybe i'd be somewhere therabouts in additional thickness

    So may just go with 2x3/4 or may wing it and have a 1/4 piece of ply on standby just in case.

    Sometime this or next week i'll cut my plywood from my template, seal it with the epoxy, and maybe within 2 weeks get a block of time to lay everything in. I think i'll try to do it all in one session instead of multiple.
     
  2. swade
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    swade Senior Member

    Me again =)

    I could use a 2nd opinion

    I know i have a 2 inch gap (see pics also notice there's a rounded over area of 1/2" with along the back at the bottom of the gap), Looking at what size ply to use, doing some test fits i think i've figured out

    4 x 1/2 ply layers = 1 7/8 thick

    or

    1 x 3/4 + 2 x 1/2 = 1 5/8


    4*1/2 gives me the closet allowance for filling the gap, thickest transom and most layers for strength. Problem is i'm not sure how much thickness goo bonding the each layer of ply is going to add, and 4+ layers of 12oz biaxel no mat) on the back. (though i guess i could test that with scraps).

    The problem this creates is i want to have everything cut fit and sealed before layup day ... but this may not be possible and i might have to layup renforce everything, then bond my layers and test fit and do it all in two steps.

    Motor is a 4 stroke 130 if that matters with the transom thickness.

    Probably i better test but figured i'd see if could get some input. I know there's specs on wetted cloth thickness but can't seem to find it but i'll google more.
     

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  3. PAR
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    PAR Yacht Designer/Builder

    A single layer of 12 ounce will be in the .02" range, which is pretty damn skinny. You don't need the fabric between the plywood layers. You could just butter each layer with thickened epoxy (apply with a 1/16" notched trowel) and use drywall screws to hold them together as the goo cures (remove when cured or use stainless which can remain).

    Rather then try to precisely fit the plywood, I'd wedge open the transom slot, knowing there'll be a good bit of epoxy ooze out, once the wedges are released and the transom skins compress the plywood/goo sandwich. Don't get me wrong, try to get it close, so you don't need so much epoxy, but don't get crazy about it, as you'll have some waste oozing out everywhere, if done properly.
     
  4. swade
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    swade Senior Member

    thanks par! the wedging makes a heck of a lot of sense...that's the way to go. It's little bits of info like that one that isn't obvious from reading various topics on this.

    I'll bet that will work and I'll probably end up with 4 1/2 inch sheet layers which should be pretty strong from my reading.
     
  5. PAR
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    PAR Yacht Designer/Builder

    Do lots of dry runs, dropping the panels into the slot, round over edges if you have to, so it's good fit. It doesn't need to be tight, just light contact or slight gaps that can be filled with a smear of goo. You'll get it. Epoxy will help lubricate the piece as it goes in too, but then you're married to what ever fits you got, so lots of dry runs until you're satisfied, then butter her up.
     
  6. swade
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    swade Senior Member

    Hi Par thanks again.

    I plan to do quite a bit of test fitting tomorrow. Then maybe epoxy this up tuesday. We'll see ...man it seems we've had an unusual amount of rain this year.

    I understand it's recommended to seal the plywood before hand..

    So I have probably 4 1/2 layers of marine ply. I seal all sides before hand with unthickened epoxy. is that *all* sides first? I'm assuming not just the exterior sides (that will bond with inner and outer laminate) but also the sides of the ply i'll be bonding with each other together.

    I assume i let the sealing stage cure before hand? I'm shooting to re-enforce the inner liner and get the core put on in one shot. If sealing and let cure first, do I need to tooth the sealed ply before bonding my sheets together (or bonding to the inner and outer) with the thickened epoxy?


    sounds like a tedious question but i've searched like heck and never see that explained out.
     
  7. swade
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    swade Senior Member

    well i may have answered that question. Rechecked the transom docs on bateau2.com, they mention to pre-wet the ply with unthickened epoxy to let it soak it up, and while still wet butter it up.
     
  8. swade
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    swade Senior Member

    omg what a royal pita, it's in. If this thing was worth more than the landfill charge i'd have paid someone =) ...and truth be told it should have probably gone to the landfill and I was about to many times, i just figured why not screw up on this one.

    In hindsight, maybe it's me, I'd have gone in through the inside. I found myself with tons of questions trying to fill the flange gap going this route even in the end. People say this is easier but I dunno...i think i would have preferred the inside knowing what I know now as you're assembling not trying to work/fill a gap.

    I ended up going 2 stages, I did the biax and 1st sheet. No way I was going to get 4 x 1/2 pieces in then after the biax, so i ended up with 3 x 1/2 and a 3/8 (or 1/4 can't remember) piece I bonded outside, then droped those as a unit in on the 2nd step.

    Mistake #1, that gap is a pain. Laying the biax, i tried to to the inner wall and wrap the flange corners in one piece, no experience with the biax so it was a nightmare...i won't even go into the vertical surface mess. I quickly realized I should lay the backwall then tab around the flange corners, but it was still pretty messy trying to work in that gap. Problem always on these 1st time things is you realize your screwup and start over compensating and rushing trying to beat the clock when you should slow down and think a bit.

    Mistake #2 I made was not allowing enough looseness in the fit..i should have left a bit looser fit, and used more goo to fill flange glass to core gap. I was hoping to really slightly force it in there so there would be good pressure all around as it was tough trying to wedge the flanges open much and still get stuff in.

    In the end I did a hail mary over a long lunch and was a *bit* off and had to force it in, I got pretty close couldn't have been off more than an 1/8 or a 1/4 from bottoming out on one side but i had to really force it. I had plenty of peanut butter filleted down there to bed it and there will be some ooze from the pressure so i'd be surprised if there were voids. But i'm going to core drill the outboard holes,etc and i'll check my laminate done in the gap...I know the pieces i did outside came out good.

    After the biax and even 1 layer the whole transom felt like concrete already.

    Mistake #3, I'm not sure about this. I guess from working with resin and mat on a couple small things here and there I didn't even think of it and cut my biax to pattern. By the time it got to the boat it wasn't a pattern. In hind sight now i think i probably should have cut a big square much larger and worked it on then trimmed it afterwards. It did end up looking ok to me, with the (i think) 4 or 5 layers I didn't have much in the way of air bubbles despite the mess i got myself into. I just kept working it with a squeegee untill it looked nice and flat.

    Next thing i learned was how tough this biax was on a vertical surface, i quickly decided to drape it over the transom top figuring i'd grind that off easy enough but it was touch and go for sure as it kept wanting to roll off the wall!

    So lessons learned.

    So now ill check the work tomorrow, also have a bit of tidying up top with biax to do, and i have to bond the cut out glass back on and do my bevelling and tab that back together and we'll see how it all feels...already feels like you could hook a tow rope and tow it across state from the back.

    Also the tool i've come to like from this project, that used dynabrade strip belt sander I picked up, it took nothing to cleanup my mess in the flange gap between stages with that thing.

    Thanks for all the advice so far. I'm sure it's not 100% but my guess is i probably got at least 90% of the way there and the epoxy and biax for sure seems to have tons of strength to make up for a newb mistake here and there.
     
  9. swade
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    swade Senior Member

    All grinded / beveled out now! I used a flat edge while I beveled to ensure i had a somewhat even bevel on both sides of the outer laminate cut.

    I'm debating what to do with the transom trim cap piece like this one back there on the well:

    http://www.boatdesign.net/forums/at...37618101-transom-repair-opinions-0051004a.jpg

    It's some black plastic piece which i had to destroy to get off. I guess just to hide the joint. I'm thinking on just 5200'ing the joint there after everything is back together and leave it, or wrapping the biax around that transom well cap/hull corner (so tab the cap there to the transom hull) and just have the whole thing finished off. Guess it doesn't matter either way, i'm leaning towards just wrapping it.
     
  10. PAR
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    PAR Yacht Designer/Builder

    Yes, some black 3M 5200 will do a nice job of filling the cut on the rubber portion of the run rail. You could also buy a replacement piece and just butt the new piece it with a clean square cut.

    The deck cap needs the same things as any repair: replace what has been structurally compromised, the fill with an easy to sand fairing compound, sand you brains out, paint and buff.
     
  11. swade
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    swade Senior Member

    No pics as i've only had a brief bit to work on it in the mornings. But the update is all glassed up, got the cap piece put back on patched up and tied in.

    Was a bit concerned today mixing fairing about working times with the epoxy as i ran out of the slow cure 2:1 from fgci on the repairs, i had to get their 4:1 (from a local store close by that stocks their product) which is cheaper i noticed. But after the 1st run it was pretty predictable and as soon as I mixed my fairing goo i spread it out on an aluminum hawk...it gave me enough time plus it's cooler temps right now.

    I got the first fairing coat on today, it's pretty striaight, will see after i block it in a day or 2 or next week.
     
  12. swade
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    swade Senior Member

    back!

    crazy. 7 months since i updated this. kids, holidays, yada yada, I won't make the mistake again of having a project i can't have at the house. Boats been in a lot, motor in my garage. Was going to ditch the boat and motor separately only i'm too lazy to go pull the wiring harness and stuff..and the time i'd make for getting rid of all that is about the same i have left to finish. Reason i'm back is i need the motor out of the garage to make room for other projects and i want to start looking for something simpler flats or bay boat. That and i'm stubborn.

    So..i wrestled the last bit of motivation I had and brought it over for a couple of hours and sanded my initial fairing coat. Overdrilled the outboard holes and the core laminate was solid everywhere...it's a brick...man i drained two full lion batteries in my drill with a new speedbor bit doing just 4 holes, i had to do it at the lot with no power, and still had to charge and go back the next day to finish 1 hole.

    1 more fairing coat, wetted then filled the oversized holes (love the epoxy shelf life!). One thing is man the filled holes got hot, even taped over, the epoxy kicked off and expanded out the holes. Looks ok though I think will see maybe tomorrow... just wasn't expecting that.

    Tomorrow quick sand and hopefully that's fair enough, drill the holes in the oversized ones. With luck i'll be down to just shooting paint maybe friday then mount so we'll see! or i'll see you guys in 6 months lol
     
  13. PAR
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    PAR Yacht Designer/Builder

    Way to go wild man, keep it up and how about some pictures when you get a chance . . .
     
  14. swade
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    swade Senior Member

    Thanks for the encouragement. I couldn't leave all that advice you've given hanging. Capacitor blew on my compressor today so a slight setback...but i'll have this shot in a week. It's 99% fair today. Will try to get some pictures.

    Have this lingering in my mind, I have a can of matched gelcoat (it may not still be good i have to check), is that going to work or do I need to use paint? fcgi epoxy docs says: Thin films cured in open air will blush.

    But it will be sanded and washed. I'm sort of inclined to try it. If I need to go paint do i use 2k? I have supplied air,etc to spray it, just easier to shoot it with gel and wet sand and polish. Plus I'm trying to avoid having something color matched which the gelcoat i have is. If not gel i'll probably shoot that repair section and nonskid areas in grey to set it off a bit.
     

  15. PAR
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    PAR Yacht Designer/Builder

    If gel coating over an epoxy repair, you'll need a tie coat. If gel coating over polyester or vinylester, then just regular surface prep. Most opt for paint over epoxy, unless you go for the new epoxy gel coats, which are costly.

    No you don't need to use an LPU (2 part polyurethane), but it's the hardest and toughest paint going. Next on the list are the single part polyurethanes, which are a lot cheaper, but not as durable. Running neck and neck with these are the new versions of the WR-LPU's which is a water based polyurethane. These cost more then the single part polys, but considerably less then the solvent based LPU's.

    My understanding is all of the epoxies from FGCI will blush, regardless of film thickness. They may now have a non-blushing formulation, but I'm unaware of it. In this regard, you should assume that all epoxies will blush, regardless of formulator. This is because most folks don't have the climate control necessary, to insure there's no blush or other contaminants on the surface, so it has to be cleaned and abated anyway.
     
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