Photo of a 50 year old Glasspar transom, what's a good test?

Discussion in 'Fiberglass and Composite Boat Building' started by apson, Jul 18, 2011.

  1. apson
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    apson Junior Member

    1960 Glasspar: stringers and transom questions

    I'm curious how I should decide whether or not to replace an old transom. I'm taking this 1960 Glasspar Marathon down to the hull to replace stringers and before I order epoxy I'm trying to decide whether or not to do the transom. I haven't gotten into the bilge, yet, so I cannot see the very bottom of the transom. The top looks like decent wood, though. There are very few hairline gelcoat cracks on the outer skin near where the outboard mounted -- and this was a BIG outboard for this little 14' boat: A 1961 Merc 700 FGS (210 lbs). The clamp for this motor wore some pretty serious indentations into the inner side (and tore right through the splash well).

    [​IMG]

    If I can't find any rotten/hollow areas in the bilge, would it be a bad idea to replace the inner skin with something heavier? The way the splash well fits in there is about 1/8"+ of unused space; it's sort of a silly design. I could easily fit a nice thick layer of fabric there I think -- and tab it around the sides and bottom of the hull. The inner skin there seems very thin!

    My other question is whether or not anyone thinks it would be possible to do stringers and floor without pulling this entire cap off. The old floor is very rotted and I think will be pretty easy to get out. I was thinking I might be able to just carefully flex this athwartship seating area up 1/2" - just enough to glass the top of my deck once I slide the piece in:

    [​IMG]
     
    Last edited: Jul 19, 2011
  2. IMP-ish
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    IMP-ish powerboater

    Is it easy to remove the drain plug tube to check the condition of the transom core at the bottom?
     
  3. apson
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    apson Junior Member

    Thus far I've been afraid to remove them because I don't know the best way to go about it as they're flanged on both sides. There are three drains in the transom: 1) The splashwell drain tube which you can see in the pic mounted in the middle center of the transom 2) the deck level drain (same type of standard drain tube), and 3) a small threaded screw in the very bottom of the transom which serves as a bilge drain. I've had the boat out on the water twice for a couple hours at a time and every time I pulled this screw out to check for water it was bone dry.

    Any other screws going through the transom were severely rusted. I worry about those points.

    Is the best way to check these common problem areas to just probe to see if it feels like wood or cardboard? Will it be that obvious?

    Also, I'm not sure how to treat the holes I plan to re-use. I'm sure there is a lot on the subject on this forum but I've yet to get there.
     
  4. PAR
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    PAR Yacht Designer/Builder

    Drill a test hole. If it's good, then plug it and move on. From your pictures, I can see both plywood and hull shell delamination, so you can pretty much bet the transom core is shot after 50 years. The lower outboard mount holes are a good location to look for transom core issues. Usually, if there are substantial dents at these bolt locations, it's because the core beneath the 'glass skin has collapsed from rot.
     
  5. apson
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    apson Junior Member

    Cutting away final perimeter.

    I just finished getting most of the floor out. Most spaces were being held by carpet alone...aye! I have about 1" of floor left on the entire perimeter as I'm scared of accidentally cutting through the hull. Of all the posts I've read I'm not sure I've seen this part covered. Can I put a blade on my 4.5" grinder or should I just set my circular saw to 1/4" and go very very slow? Then just grind away the rest? It does appear that I can do the stringers and floor on this boat without removing the cap after all. If I wasn't able to remove the existing floor by hand (i.e. if it weren't completely rotted) I'm not sure this would've been the case as it gets pretty tight under those seats.

    I just ordered my supplies from US Composites. I got the 2 gallon thin epoxy kit, 7 1/2oz E Glass for the floor, 6" 1708 tape for the stringers and possibly transom tabbing, and a few yards of 1708 for inside the transom if I end up doing it. Also Aerosil-Cabosil as a structural filler and some SM Fairing Compound for some repairs to the cap before I paint it.
     
  6. apson
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    apson Junior Member

    Thanks for moving my post...sorry about that.

    I have the floor out and a closer look at the transom below the deck shows much more rot than the top. It looks like I'm doing the transom after all. The bummer is that so much of this wood is good it's going to take hours to get out. I should've found one in worse condition.

    I need to take the cap off. BUT, everyone I've seen post photos of a glasspar citation or marathon restoration hasn't mentioned how they got the cap off beyond drilling the rivets. I understand that the rivets have to be drilled but my marathon has cloth that was laid connecting the cap with the hull. If you see the attachment "cap_cloth.jpg" there is some fiberglass bridging the hull to the cap. I'm not sure where or how (with what tool) to cut this. There's about 5" clearance.

    Hopefully the tool I need to buy this can also be used to cut away the glass on the inside corners of the stringers, too. Does such a tool exist? Dremel? Also, I live within 2 minutes of a Harbor Freight :)
     

    Attached Files:

  7. PAR
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    PAR Yacht Designer/Builder

    Send the 1708 back and get 12 ounce 45/45 biax tape for the tabbing. You'll use 1/3 as much epoxy as you would use with the 1708 and it'll be a stronger, lighter laminate too.

    If close to the hull, then use a hand saw, which is much less likely to hack through the hull shell. With power tools, you can't feel the hull, but a hand saw you can. Leave a 4" flange around the perimeter of the sole (what you're calling a floor), so you have something to bond to.

    Well, you posted as I was. You don't have to remove the cap, just cut it at the transom. Yea, this sucks, but you were going to paint her anyway right? Not much flange on the sole. Yep, 50 year old transoms are usually shot.
     
  8. apson
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    apson Junior Member

    Thanks PAR, I will try to find that 12oz tape. 1/3 the epoxy...that will be some serious savings.

    I'm not sure I can handle cutting the cap off back there...that makes me pretty nervous. What about just removing the rivets and propping it up? Maybe I'd rather put my limited skills to use cutting that glass tape where nobody can see under the cap. On the other hand I will be repairing a car stereo hole(s) so perhaps I could work the cap repair into the same phase. To put those rear pieces back on the cap would you feather the joint edges, glass from behind, fill and fair? I could epoxy in a couple strips of wood as a guide, too...so the pieces line up maybe.
     
  9. PAR
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    PAR Yacht Designer/Builder

    I use a reciprocating saw and just plow down right through the cap, steering to break the deck line too. It's a typical repair, feather it back several inches, fill and fair when the cores replaced. I do this to save the skins. I use all sorts of thing to get things to line up until the goo kicks off, popsicle sticks, duct tape brads, shims, dead cockroach bodies, whatever it takes. The idea is to remove the cap over the transom core so you can drop the new core down into position and bond it in.
     
  10. apson
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    apson Junior Member

    I follow ya. I think I've been trained to pull the cap by so many others who've done so with my boat (or it's big sister the 16' Citation). It seems like they're taking the cap off like it's a lego piece so I'm so confused as to whether their caps just aren't glassed on like mine or if they're just more tenacious with their boat restoration. I need to replace my rub rail, too, so it's off and all the rivets are exposed begging me to drill them out. On the skin, my inner transom skin is toast. It almost seems like it wasn't even saturated with resin in parts; like a mesh I can peel off easily by hand...I can see through the weave, even.

    I've emailed Andrew Gott who restored a boat very similar to mine to ask him if his cap was just riveted or riveted and taped. See the bottom of this page: http://www.agott.com/glasspar/rest1.html

    Like legos...drives me crazy ;)
     
  11. PAR
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    PAR Yacht Designer/Builder

    It may have leaked at some point and an owner decided he would lay some tape in there to seal it up. I've seen this done before, though most just use goo in a tube or smear thickened resin on the seam instead.
     
  12. apson
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    apson Junior Member

    I wondered that too but it even has the Glasspar speckled inside hull paint on it. Hard for me to imagine them doing this on the assembly line, though. I would've imagined once the cap was out of the mold all painting ceased.

    I got one of those Fein multimaster knock-offs at Harbor Freight on sale for $30. I just tried their HSS plastic/wood/metal cutting blade on the stringer reinforcements and it really seems to work and with a decent balance of aggression and precision. I'm going to try some more once I get suited up. I'm very curious to see how long this blade lasts on fiberglass. If I can't figure out a safe place to cut that tape under the cap I'm going to take your advice and cut it for full transom access.
     
  13. IMP-ish
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    IMP-ish powerboater

    For what it's worth (two cents on a good day) I'd take a properly glassed hull to deck joint any day. My least favorite are the many boats that use only screws to connect fiberglass to thin fiberglass. Really easy to disassemble. But over time they work the holes in the fiberglass bigger and gradually work themselves loose.
    Are rivets alone much better, or does the fg here hint they still work loose over time?
     
  14. MyFlamingo
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    MyFlamingo Junior Member


  15. apson
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    apson Junior Member

    Last edited: Jul 25, 2011
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