newbie transom help please

Discussion in 'Fiberglass and Composite Boat Building' started by gainey, Jun 28, 2013.

  1. gainey
    Joined: Jun 2013
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    gainey New Member

    Hi everyone,

    I have just picked up this boat for free, it need some work the first thing is the transom needs to be replaced/repaired. I have no experience in fibre glass at all, so if you can help step by step that would be great.
    I have looked at the bote cote, and also looked at the seacast version. Basically I am not sure which way to go and exactly how to do it, I will attach some pictures, I am not sure whether to:
    1. cut the fibreglass of from the outside back of the boat or attempt to cut it from the inside
    2.their is a small crack on the inside at the lower part of the transom
    3. cut the cap off from the top, and then dig the wood out as best I can and then leave the 2 firbre glass pieces front and back and then fill it with the secast expoxy

    my understanding is that I cut the (either inside or out) fibreglass of then take the wood out and then put marine ply back in (but paint it with bote cote) and then fibre glass back over that.......is this right. I am very new I don't know how/what to fibreglass, and I am not sure if I am on the right path if anyone can help by telling me:
    1.where and how to cut the fibreglass
    2.if I need to cut or can I use the seacast
    3.what products to buy to paint/coat with
    4.how to firbre glass
    5.cost is an issue, I am in no rush just looking forward to the project and my kids using the boat.

    I will post the pics, but please help me if you can I am in Australia nsw, so hopefully I can get the products that you suggest IMG_0260.jpg

    IMG_0253.jpg

    IMG_0257.jpg
     
  2. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    Welcome to the forum.

    There are lots of previous threads about this process, with several very recent success stories, just unfolding. Read though as much as you can, to familiarize yourself. Next download the free user's guide from westsystem.com and the epoxy book form systemthree.com. These will cover more details and tricks, of course geared toward their products, but the information is the same for all epoxies.

    As to which technique (there are a few different approaches) to employ, you'll need to make this call, based on what you have, it's arrangements (some methods are better then others) and other details.

    This is a long one, recently finished up (now he has to do his sole - damn):

    http://www.boatdesign.net/forums/materials/transom-repair-opinions-43168.html

    Lastly, there's no such thing as a free boat, as you're about to find out.
     
  3. RTM
    Joined: Jun 2013
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    RTM Junior Member

    I rebuilt the transom on a bass boat. The transom looked similar to yours. I cut the glass skin on the outside leaving about a six inch perimeter on the sides and bottom. The plywood core was soggy and rotted and I removed it rather easily. I had to scrape the rotted wood off the interior skin. Then I cut out a new plywood transom using 3/4" exterior plywood 2 layers. I coated the interior skin with a layer of 1 1/2 oz. mat while it was still wet I covered it with a layer of plywood transom, ran some screws through the plywood and the interior skin to hold them together. After this cured I removed the screws, laminated a couple or three of layers of mat and roving woving to the outside of the plywood and while this was wet I screwed the second layer of 3/4" plywood to the first using stainless steel screws. Now another layer of mat, roving woving, and more mat over the old glass around the perimiter. Grind all the old gelcoat off the old glass. Finally, grind, sand prime and paint the transom and it will be like new. I ran a 150 hp Suzuki outboard on this boat with no problems. I was really a simple and straightforward job.

    rich
     
  4. swade
    Joined: Jun 2010
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    swade Senior Member

    Just to clarify the sole is on a different boat, in the time doing the transom I realized a simpler center console was more sensible, no upholstery, sealed decks,etc). But yes, got that cut out already! waiting for rains to subside!

    Gainey i'm a newbie but will give you my opinion from what I learned mostly from doing mine in that link (with par's advice).

    First if i do this again, i'll probably prefer to go inside assuming it doesn't look like a ton of fairing work, reason is finishing is a bit easier, and IMHO before you go outside you better be 100% certain the ends of stringers, knee braces aren't rotten. Otherwise you'll be cutting the outside only to find out you need to cut the inside. So first access those. If it's typical...they put the wood down, glass over, water in core of transom transmits to the other areas and visa versa.

    Good news is if you go through with it, your transom will be like a rock.

    Personally i considered seacast and i'm sure lots like it. In the end it looked like the same amount of work to me, and a properly done core, and holes done in any core should last quite awhile...I mean seacoast ain't cheap how long do you expect/want that boat to last? 10 years, 5? 20? I'm no expert but i'm sure i could pull the one I did across the state by the transom, that epoxy + biax is some wickedly strong stuff over a couple of canted layers of ply, and if you spend the time to do holes correctly

    you'll end up with:

    1) encased transom core. remember it's not when built at the factory! water can wick from stringers,etc
    2) do the holes right and the wood transom i'd expect to outlast the rest of this boats lifespan.

    Let's put it this way, if i do another, i'll do it exactly the same. Except i may go the inside route...advantage i see to inside, you aren't filling a tight fitting gap and your able to access the stringer, knees,etc, and you can finish with gelcoat (even though i can never get gelcoat to match old stuff.). Choice i think depends on how complicated the back is. Fitting in the gap was a bit of work, by going inside you don't have to worry so much about fitment. to me it wasn't simple figuring out how to fill a randomly width GAP, i knew i'd have glass, i knew i'd have multiple layers of ply with epoxy between them. Even though i test fitted, the last bit went in with a sledge =)

    On your boat, i'd seriously consider from the inside, everything is square! easy fairing! I didn't go from the inside only because i thought the whole rounded outboard well,etc would take a ton of time to fair to not look obvious, and even though I figured a bit of stringer damage the glass was really thick, in the end i lucked out, wasn't that much stringer wise in hindsight. But if it had been, from outside would have been wrong choice.

    Whatever keep in mind how you're going to finish it. By going outside, someone like par would recommend epoxy to make up strength, that typically means no gelcoat. Going inside you can finish with something more gelcoat compatible. THough i never have luck matching old anyhow so you'll see in mine how i came up with color schema on a whim.

    hope that helps.
     
  5. stylemismatch
    Joined: Mar 2010
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    stylemismatch Junior Member

    I hadn't been to this forum in ages, just happened on it while looking for some other information. I might be a little late to this discussion but will add my little bit of experience just in case it might be helpful. (I've rebuilt three boats now, so have a little knowledge to share).

    I don't see any advantage in cutting out the outer skin to replace a transom. It's going to be very difficult to make it look good when you're done, whereas if you cut out the inside skin you won't have to mess with that at all.

    PLUS (and this is very important), every boat I've ever come across that had a bad transom also had other issues that needed to be addressed as well which you won't have access to if you don't pull the cap. More than likely there are some rotted stringers in there as well. (At least you'd be able to inspect them to determine for sure if they're ok).
     
  6. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    This is a good point, but removing the outer skin is the easiest way, especially if the splash well is complex. Finish work is no more difficult on the outside of the hull then the inside. You still have to fair, smooth, paint or gel coat.

    It's true most that come here with a bad transom core also have soft soles, rotten stringers, etc., so look it over good, before you pull out the sawsall.
     
  7. gtflash
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    gtflash Senior Member

    I am facing a transom also on 8meter open boat. interesting discussion.

    I have read many threads on here. I have partial rear access, but really think from outside seems a more time effective method.

    Par I have read the thread you linked to several times, the only bit of info i cant find is, how much tabbing is required on the outside skin, between old transom face and new??

    I wanted to maintain a gelcoat, and have quite a bit of resin already. I wondered if it was possible to lay up an apppropriate shaped gelcoat on a flat gloss surface then few layers of 1708 with polyester resin, then once cured, lay epoxy buttered or biaxial, in ply face down and weight down, then other ply, then other ply, then bi axial 4 or 5 layers. In theory it seems this method i have dreamt up would mean i could gelcoat repair the outside, and almost just tab the inside to hull and new knees with epoxy and bi axial..... Is it a silly idea?
     
  8. PAR
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    PAR Yacht Designer/Builder

    I don't think your premolded tabbing will work, mostly because you'll be relying on secondary bonds and a well loaded area.

    You can perform the the appropriate repair then apply gelcoat conventionally, so I don't see the advantage of your method.

    Aside from the novice getting good, matching results with gelcoat, the other question is tabbing weight. This is application specific, though if you have to error, do so on the too much side. You should be able to tell by what's there and what's removed. You'll want similar laminate thicknesses, if not a little more.
     
  9. swade
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    swade Senior Member

    Also helps to read over the west system book about repair, there's a section there detailing how far to grind back to get strength of original laminate, lots of info there in regards to tabbing,etc. In hindsight i should have started there, par would have had less to type on my thread =)

    That said i was a bit under what was in the book due to the euro transom kinda thing, i went as wide as i could and still be able to get the core out and grind in the gaps. but the epoxy and 1708 makes up a good bit of strength there as well I guess..
     
  10. gtflash
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    gtflash Senior Member

    apoligies gainey, muscling in on your thread. I like the look of your boat, what is it?

    Par, i appreciate your experience. I am quite good at gelcoats now, and intended on using peel ply, but take on board the 2ndry bonding point. I honestly thought it would reduce sanding the whole face of gelcoat, and reduce gel over epoxy issues.

    I have succesfully bonded gel over epoxy, but only recently so not sure of its longevity still.

    With regard to tabbing, . I mean tabbing width or bevel not thickness, 12:1 as west say?
     
  11. PAR
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    PAR Yacht Designer/Builder

    4" on each side of the seam will do (as the minimum), with staggered overlaps. The more the better, less wouldn't be recommended.
     
  12. gtflash
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    gtflash Senior Member

    4", thanks Par.

    When people talk of outside in transom, does that mean they leave the inside skin on still? I always presumed it meant removing the whole lot, so the boat was open.
     
  13. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    Yes, cut the transom off, leaving a 4" - 6" flange all around so you can bond the skin back on, without having to go around the corner with tabbing. This allows you to leave the gelcoat on the hull sides and bottom intact.

    The skin will probably just pull right off, if there's a good bit of rot. I've had them fall off after cutting. You can cut with about anything - a circular saw, router, but my personal favorite is an angle grinder with a tile cutting blade. Another tool that's slower, but more precise and much less dust is a multi tool (those vibrating thingies) with a tile or grout cutting blade.

    Once the outer skin is off, the rotten core is available to knock out. Much of it will fall out, but a chisel, a grinder, a power plane and lots of elbow grease will remove the core, leaving you a view of the inner skin/liner/splash well.

    Once the core is out, grind the inner skin, the inside of the outer skin and the hull shell back to good, clean laminate and now you're ready to reinstall a new core.
     
  14. gtflash
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    gtflash Senior Member

    made a start on mine today...... funny ol transom. Was originally rigged with twin 150 mercs

    sandwich is 1/2" grp on outside, then ply, then 1/4" grp on inside skin. But only to the bulge, whcich was a half round foam, left to right horizontal stregthener. Under that is grp ply grp sandwich again, which i havent cut out yet, then another foam horizontal. I Cant make up my mind if i should match it, or grind flat and 3 layers of ply. Hell of alot of layup around the half round. chewed my grinder discs to bits

    Other problem is the deck, do I cut deck to tab transom to hull? Im happy to as all will be covered with new rear outboard well, but seems the strength is in this boats deck and hull construction

    Thanks in advanced GT
     

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  15. gtflash
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    gtflash Senior Member

    PS I went inside out in the end
     
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