Wooden boat repair question

Discussion in 'Watercraft' started by Tracy Lauricella, Aug 25, 2012.

  1. Tracy Lauricella Active Member

    Posts: 318
    Lakewood, WA
    Ratings: +33 / 0
    I've got a wooden drift boat that I bought last year. It's in pretty good shape, and I'd like to go another season before I do any major sanding and re-varnishing if possible.

    However, on the bottom of the boat, the previous owner put a large piece of heavy duty plastic (PVC most likely) on the hull. Presumably to help prevent scratches and such when dragging it over rocks. It's a good idea, and I like having it there.

    Unfortunately, it's started pulling away from the boat in the front. The screws appear to be stripped out and the plastic has warped away from the boat. What do you think the best way to fix this would be? My first thought is to hit the plastic with a heat gun and bend it back into place before letting it cool. Then use something like liquid nails to hold it in place, as well as to fill the screw holes. At that point I'm not sure if I should put new screws in, or just leave them out.

    any thoughts? Here are some pictures of the area needing repair:
    [IMG]

    [IMG]

    [IMG]


    Thanks,
    --Tracy
  2. Tracy Lauricella Active Member

    Posts: 318
    Lakewood, WA
    Ratings: +33 / 0
    well, I took the plastic off, and now I'm thinking that sanding/revarnishing the whole bottom is needed:

    [IMG]
  3. Dave Alberts Member

    Posts: 231
    Lakewood, WA
    Ratings: +24 / 0
    Tracy--
    I'm also in Lakewood... give me a call... I've got materials left over from my pram project that would work well for your boat. It looks to me like you've got a bit of work to do but should be able to take some short cuts to get you back on the water.

    Dave
    (253)584-1714
  4. Tracy Lauricella Active Member

    Posts: 318
    Lakewood, WA
    Ratings: +33 / 0
    Thanks Dave, I'm headed out now to go to the Garlic Festival in Chehailis with my wife, but I'll give you a call tomorrow.

    I decided to sand off the epoxy that was there- much of it was peeling up. I'm glad I did. I found one section where it was full of bondo and it had dry rot all around it. The Bondo wasn't holding or sealing well, and it was a half inch thick in places. When I removed it, I found the dry rot continued underneath:

    [IMG]
    [IMG]

    I have some West System epoxy (205 & 207) plus some high-density filler, but I'd love some suggestions as to what else to try. I'm thinking that cutting out the damaged section and putting in a new wood patch is the right approach.

    Thanks,
    --Tracy
  5. Patrick Gould Active Member

    Posts: 2,356
    Ellensburg, WA
    Ratings: +688 / 1
  6. Idaho steel Active Member

    Posts: 150
    Clearwater
    Ratings: +48 / 0
    More than likely that's some form of UHMW, which is a high density polyethylene. Some folks have gotten it into their heads that it makes a good shoe for wooden boats... What you have there is the inevitable result of running mechanical fasteners into the bottom of a wooden boat.

    If you had glass/resin peeling up, I doubt it was epoxy. More than likely plain 'ol polyester resin of some kind, which generally doesn't bond to wood worth a darn. When you were sanding it, did it smell like "fiberglass?"

    I agree that cutting out and patching that damage is the best way to go. I'd forget about reinstalling that damn plastic, and do a quality glass job on the bottom. Two layers of 12 oz. bi-axial over the chines, then sheathe the whole bottom in 20 oz. tri-axial. Add graphite powder to your last coat of resin. Slick, tough, and repairable.
  7. nomlasder Active Member

    Posts: 1,320
    Burien.
    Ratings: +111 / 0
    I agree, the fasteners holding the shoe let moisture in and are the cause of the failure. I suggest patching the playwood with two layers of 1/4". The first layer only as big as the rot and the second half lapped into the original plywood with at least a 2 inch lap. The glue can be epoxy or 3m5200.

    Inspect each screw hole for signs of rot. They can be driled out and 1/4" dowel glued in as filler.

    I personally am not a big fan of fiberglass but it makes for a very servicable bottom layer.
  8. Tracy Lauricella Active Member

    Posts: 318
    Lakewood, WA
    Ratings: +33 / 0
    Thanks for the information and suggestions everyone! I talked to Patrick on the phone today and discussed my plan of attack. So far so good.

    First I excavated all the dry rot. This left a pretty good gap in the chine board. I shaped a piece of wood to fit the excavated section and tapered the edges before epoxying it in place using West System's epoxy.

    [IMG]

    My original idea was to keep the patch small and bevel the edges of the hole to match. I decided instead to extend the hole to the boat ribs so I could use them as backing blocks for the patch.

    [IMG]

    That worked well, and I cut a patch to fit. I epoxied it in place, once again starting with just the basic epoxy to wet it in, then adding thickener to build a filleting paste. I used some deck screws to hold it tight against the ribs while the epoxy cures. Once it's done curing, I'll take the deck screws back out and patch the holes they left.


    [IMG]


    I still need to fill the bumper where the dry rot cut into it, and there's lots of screw holes to clean out and patch. After that, a little sanding and then I plan to fiberglass the bottom, likely wrapping the fabric up over the chines and side bumpers.
  9. Patrick Gould Active Member

    Posts: 2,356
    Ellensburg, WA
    Ratings: +688 / 1
    That was fast, and it looks great. My boatbuilder buddies would probably get many hours of discussion out of the wisdom of extending the patch. I think it's the way to go, and in case anyone else is second guessing the move keep in mind that this boat has floor boards so there will likely be no one stepping in the area of the patch. This should be plenty strong.

    Tracy - consider getting some low viscosity epoxy, it'll be an extra expense but will wet out the glass much better and give you a longer work time. Don't forget to mask off the sides if you decide to wrap the glass around the chine guard. Epoxy can drip and run after you walk away and it's easier to mask then to sand epoxy.
  10. Tracy Lauricella Active Member

    Posts: 318
    Lakewood, WA
    Ratings: +33 / 0
    Thanks Patrick. I wasn't confident enough in my woodworking skills to trust my ability to match up a decent bevel, so I figured using the ribs as backing boards would be a safer approach.
    I'll pick up some of the slower curing epoxy this week, and thanks for the reminder on masking!
  11. Idaho steel Active Member

    Posts: 150
    Clearwater
    Ratings: +48 / 0
    Boy, there's the voice of experience! I heartily concur! I would add, that a carbide scraper works a lot better than sanding. Don't ask how I know...

    Looks good so far. If you're going to glass in the chines, bi-axial tape is way easier to deal with than attempting to wrap the bottom cloth around.

    Raka has great epoxies, and every type of cloth you can think of. They are great to talk to as well. Just a thought.
  12. Tracy Lauricella Active Member

    Posts: 318
    Lakewood, WA
    Ratings: +33 / 0
    Can you explain a little why the tape is easier? (I've not done a lot with fiberglass before; just a small pram project a while back.) The bottom of the drift boat is flush with the chines/sideboards. I figured I'd take off the aluminum strip on the sideboards and then run the bottom cloth down over the sideboards about half an inch or so. What does the tape do easier?

    Thanks again for all the information.
  13. Patrick Gould Active Member

    Posts: 2,356
    Ellensburg, WA
    Ratings: +688 / 1
    The biaxial tape has strands that run at 45 degrees to each other. You could tape the chines first and then put a layer of cloth on the bottom. I've taped the chines on many, many boats with standard 6oz tape. It seems to work pretty well. In this case I think it wouldn't be too hard to just glass the bottom and wrap it up the chine guards. The benefit would be that at trim stage you could just cut away the excess cloth and end up with a perfect straight edge. Putting a radius on the chine guard is key. You can just use a router bit if you have one or a block plane and sandpaper otherwise.
  14. Patrick Gould Active Member

    Posts: 2,356
    Ellensburg, WA
    Ratings: +688 / 1
    BTW: Boat repair is a results oriented activity, there are many way to tackle a given problem. Once you're past the basics the right way is the one that works for you and looks right.
  15. Idaho steel Active Member

    Posts: 150
    Clearwater
    Ratings: +48 / 0
    The reason I like the bi-axial tape in this application is the way it "hugs the curves" so to speak. It just rolls out nice and clean. In the past, I have had some issues with wrapping the bottom cloth, where it wants to bunch up and fold. This can be remedied by using your pinking shears to make relief cuts in the cloth. I also like to put a couple layers of glass on the chines anyway, since that is a structurally critical area. The chines also take the majority of the abuse in any boat, and bi-axial is much stronger than standard cloth.

    However, as Patrick correctly notes, this is all about results, and if you find a technique that works for you go for it. I grew up with power boats and rocky beaches, so I have a tendency to want to over build...
  16. Patrick Gould Active Member

    Posts: 2,356
    Ellensburg, WA
    Ratings: +688 / 1
    All of the above is true, including the part about wrapping the bottom. It can be tricky so have some sharp shears handy just in case.
  17. Tracy Lauricella Active Member

    Posts: 318
    Lakewood, WA
    Ratings: +33 / 0
    I put the first layer of fiberglass on today. First step was to sand and prepare the surface, then hit it with a coat of epoxy. When that was still a bit tacky, I put the cloth on and started applying resin.

    Of course, as soon as I started putting resin on, the wind kicked up. (It had been calm all day) Scrambling around to wet out the fabric while the wind kept trying to flip it up was an interesting process.

    I got it covered though. I used two 8" runners over the chines, and a single wide piece up the middle.

    There were some areas that I couldn't seem to fill properly though. They don't appear dry, but there's clearly a little bit of air underneath the mat. It looks to be caused by unevenness in the boat surface.

    What is the best way to take care of this? Also, before I put the next layer of cloth on, should I put several more layers of epoxy (so the first layer of cloth no longer has a visible texture) or just apply the next fabric layer as is?

    UPDATE: After doing some reading, I'm going to add the second layer of fabric while the first one is still tacky, for the best bond.

    Here's how things are looking now:
    [IMG]


    A big thanks to Dave for letting me buy his leftover supplies!


    --Tracy
  18. Dave Alberts Member

    Posts: 231
    Lakewood, WA
    Ratings: +24 / 0
    Tracy--
    getting the air out can be tough, but IMO, it is very important. If there are voids, I suggest letting the epoxy set solid and then grind out the voids before applying the next coat, or more glass cloth. I should have mentioned, I have several different rollers that help a lot to get the air out and work the resin into the cloth, and position the cloth where you want it. If you want, come by and I'll get them for you to use. I'll be up untill 9:30 or so if you want to come by tonight. Give me a call.

    Dave
  19. Tracy Lauricella Active Member

    Posts: 318
    Lakewood, WA
    Ratings: +33 / 0
    Thanks Dave.

    I put another layer of cloth & resin down, and there are still voids. I tried to get them out, even working the resin into the voids with my gloved fingertips, but no luck. I suspect it's just due to the cloth bunching up.

    Once it sets, do you think I can just grind down the voids, feather the edges and apply patches?
  20. Dave Alberts Member

    Posts: 231
    Lakewood, WA
    Ratings: +24 / 0
    That's the way I would do it... As I said, the rollers I have make the job much easier. If you catch it before the epoxy completely hardens, you can use a utility knife to cut out the voids... If not an aggressive grinder works well.