23 Bertram/Carribian Stringers and transom

Discussion in 'Fiberglass and Composite Boat Building' started by crankit, Sep 5, 2012.

  1. PAR
    Joined: Nov 2003
    Posts: 19,126
    Likes: 498, Points: 93, Legacy Rep: 3967
    Location: Eustis, FL

    PAR Yacht Designer/Builder

    The physical properties are similar between the two epoxies. $22 a liter seems the full retail price. Have you contacted DuckFlats?
     
  2. crankit
    Joined: Oct 2007
    Posts: 30
    Likes: 0, Points: 6, Legacy Rep: 10
    Location: Aus

    crankit Junior Member

    I've made some progress over the holidays on this rebuild and yesterday I glued in the transom.

    I used epoxy thickened with fumed silica and troweled a thick coat onto the outer fiberglass, coated the new marine ply core with epoxy then set the new core in place with 2x4 using threaded rod and nuts through the drive hole and clamps.

    A few issues of note. I'm pretty sure I laid on enough thickened epoxy and the clamping pressure should have been sufficient because I did have ooze out on the sides, But I forgot to use a notched trowel before I set the core in place. Should I now be overly concerned about voids. At the moment I'm really worried about this and I can't believe I forgot about using the notched trowel.
     
  3. michael pierzga
    Joined: Dec 2008
    Posts: 4,862
    Likes: 116, Points: 0, Legacy Rep: 1180
    Location: spain

    michael pierzga Senior Member

    A notched trowel is the correct tool. In future use it.

    When laminating , normally I use West epoxy because it is availble locally. . Last month I did a vertical repair, structural cloth, with Epiglass Epoxy,

    The viscosity of Epi was very thin. Keep a heads up that all your resin is not running downhill when tabbing in with heavy structural cloth.
     
  4. PAR
    Joined: Nov 2003
    Posts: 19,126
    Likes: 498, Points: 93, Legacy Rep: 3967
    Location: Eustis, FL

    PAR Yacht Designer/Builder

    It's difficult to tell if you'll have void issues, but undoubtedly there'll be some, as trapped air, etc., but ooze out all around is a good sign , so focus on that. I was pretty pissed when I lost my favorite watch cap, some time ago and found it, making a repair to our rental house last week, while I took down some drywall I hung 7 years ago. There it was, looking like the day I left it. Crap happens, move on . . .
     
  5. crankit
    Joined: Oct 2007
    Posts: 30
    Likes: 0, Points: 6, Legacy Rep: 10
    Location: Aus

    crankit Junior Member

    Yep, Gonna have to let that one go. One things for sure, It's not coming out. That epoxy has got it stuck down hard. Live and learn I guess hey Par.

    One other point I should make is that I found the epiglass needed a lot of fumed silica to get it thick enough. I mixed over 1part silica to 1 part epoxy and even that didn't seem like enough for fillets. Was a real pain in the *** because it would keep running away from me. Then when it kicked it kicked off within a min or two and yet didn't seem all that hot to the touch. Wasn't at all what I was expecting.

    I think when this batch runs out I will try that Boatcoat that Par mentioned in a previous post. Or perhaps I should have used PL Adhesive for the fillets.
     
  6. SamSam
    Joined: Feb 2005
    Posts: 3,899
    Likes: 200, Points: 63, Legacy Rep: 971
    Location: Coastal Georgia

    SamSam Senior Member

    Since you removed all the stringers and inner support for the hull, make sure the hull hasn't changed shape before you re-install everything and lock in the shape.
     
  7. PAR
    Joined: Nov 2003
    Posts: 19,126
    Likes: 498, Points: 93, Legacy Rep: 3967
    Location: Eustis, FL

    PAR Yacht Designer/Builder

    Mix milled fibers into your epoxy first, until about as thick as you want, then add the silica. Ditto the hull shape distortions Sam mentioned. It can happen easily when removing the internal structure.
     
  8. crankit
    Joined: Oct 2007
    Posts: 30
    Likes: 0, Points: 6, Legacy Rep: 10
    Location: Aus

    crankit Junior Member

    Thanks for the tips:)
    Just regarding the hull distortions - What i did was I dropped a plum from the the corners of the stern, along the keel and marked points on the cement, then drew strait lines representing the keel and stern. From there I've marked out points in the cement then on the hull that I measure from. I'm not sure if this is the way the pros do it or not but it's all i could come up with. I'm open to better ways of doing this.

    There is also a section of the hull between 2 strakes on one side that I think must have been stretched from my uncle putting it on a trailer without keel rollers and only using the multi rollers along the hull to support the entire weight. I'll take some pictures tomorrow.
     
  9. SamSam
    Joined: Feb 2005
    Posts: 3,899
    Likes: 200, Points: 63, Legacy Rep: 971
    Location: Coastal Georgia

    SamSam Senior Member

    Looking at the hull from the outside, things should be 'fair', that is straight, flowing surfaces with no bulges or depressions. Bulges are sort of rare unless you have something like an engine laying in there, but if the hull skin is vaguely flexible, you have to be careful that your own body weight doesn't make bulges and distortions while you are in there. Depressions from trailer rollers happen easily. They can happen immediately after the internal structure is removed, and although they are temporary, they can become permanent when stringers are glassed back in, or even with all the internal structure in place they can happen slowly over months as the boat sits on the trailer, supported incorrectly, and they are permanent.

    Long straight edges will help find problems, reflections of a trouble light moved around at night, when its dark, will also show distortions.

    Another thing to look for is twist, especially if the hull gets moved on the trailer after the internal structure is removed. Constantly climbing in and out on one side can do it or just working and walking around inside can do it. You can check that by standing off to the side, looking at and getting the two gunnels in line and seeing if they are parallel, or putting some straight 2x4s athwart-ship across the gunnels and standing behind the boat and looking to see if the top edge of the 2x4s are parallel.

    Luckily you didn't take the deck off the boat so you shouldn't have to worry about the beam spreading, the sides bowing, the bottom sagging and the deck never fitting back on.

    I see where you have the chines supported with jack stands, that's good (as long as you didn't jack in any twist). If you do find any depressions caused by years of sitting on the trailer wrong, you can possibly correct them now by rigging ways to put pressure on them (weights or 2x4s wedged up to the shed rafters, etc) before you instal the new innards.

    One place I worked at, we made 30 ft power boats of a shape like yours. The support system for those was the crane would lift the hull from the mold and set it on 3 upended metal barrels, one under each corner of the transom and one under the keel up front. The two supports at the stern were leveled with each other with wood stacked up, which allowed me to use a builders level inside, at least athwart ship. I don't remember if the bow barrel was leveled with the other two, but I think we just got that eyeball close and used measurements, strings and squares etc for fore and aft stringer, bulk head installation and deck building work.
     
  10. crankit
    Joined: Oct 2007
    Posts: 30
    Likes: 0, Points: 6, Legacy Rep: 10
    Location: Aus

    crankit Junior Member

    Here are some pics of the of the depressions. At first I thought that maybe this boat had a hook as something intended from the factory but after researching the manufacturer and history of this model I found that is not meant to be.

    [​IMG]

    [​IMG]

    In this picture the red lines should give an idea of where on the boat the strakes are you see in the previous photos.

    [​IMG]

    Also I've tried not to take all the stringers out at once. So at the moment only the main inner stingers are removed. The little Incy wincy stringers marked in red lines are completly rotted and would not have offered any support at all at the time my uncle and grans had it on the trailer. Please ignore the red circles, There another job that I need to fix. Lukily the stringer that was replaced first seems to be strait along the hull directly beneath.

    SamSam, I'm thinking of using some old tractor batteries for weights and maybe I'll make up some new adjustable stands to put a bit of pressure In the places that seem a little low. What I'm unsure about is whether I should do it now and let it sit for 2 weeks or to do it just before installation of a new stringer. Does the hull need time to move back?
     
  11. michael pierzga
    Joined: Dec 2008
    Posts: 4,862
    Likes: 116, Points: 0, Legacy Rep: 1180
    Location: spain

    michael pierzga Senior Member

    I guess its convenient to work on the boat while its on a trailer.

    I don't like it. I prefer to block up, establish level and work.

    Makes measurements easy.
     
  12. crankit
    Joined: Oct 2007
    Posts: 30
    Likes: 0, Points: 6, Legacy Rep: 10
    Location: Aus

    crankit Junior Member

    There is actually no weight on the trailer and if you look closely at the rollers you'll see that they're all loose. All the weight is being supported by my stands. I'm keeping the trailer there for safety.
     
  13. PAR
    Joined: Nov 2003
    Posts: 19,126
    Likes: 498, Points: 93, Legacy Rep: 3967
    Location: Eustis, FL

    PAR Yacht Designer/Builder

    'Glass has a memory, so weights will not work, unless you leave them in for years un touched. This is a fairly common problem with trailer boats. You'll have to re-fair the aft sections, which is a lot easier if the boat is upside down, but possible with it blocked up on a cradle too. The "run" on that boat will have dead flat sections, so it's straight forward work, as opposed to compound curves, but working on your back under the boat isn't a pleasant chore.

    Putting in the stringers now will be fine or you can wait. The stringers stiffen the hull locally and will help in the re-fairing process, making the areas stiffer, so it's easier to get the hull "blocked" to shape once the filler goes on.
     
  14. michael pierzga
    Joined: Dec 2008
    Posts: 4,862
    Likes: 116, Points: 0, Legacy Rep: 1180
    Location: spain

    michael pierzga Senior Member

    Yah...OK. Boat might be a bit high off the ground.

    An elevated work platform on one side or at the transom makes life nice. Easy in and out access to the boat , a handy work surface and a good place to store the days materials.

    Climbing In and out of a project , three million times a day, wears me out.

    You are lucky in that you have a nice big hole in the back of the boat. Great for vacume cleaner hose and power cable feed. .

    Before you start your glass work it would be good to give the inside a good soap and water clean to remove any contaminates like oil, salt.
     

  15. Landlubber
    Joined: Jun 2007
    Posts: 2,640
    Likes: 125, Points: 0, Legacy Rep: 1802
    Location: Brisbane

    Landlubber Senior Member

    crankit,

    Try AA fibreglass, I use them all the time, nice people and a reasonable price, go for the epoxy.

    WE just finished doing the same thing to a Haines 17, all new stringers, transom and support knees etc etc. The boat was TOTALLY different after it was finished, no more slop.
     
Loading...
Forum posts represent the experience, opinion, and view of individual users. Boat Design Net does not necessarily endorse nor share the view of each individual post.
When making potentially dangerous or financial decisions, always employ and consult appropriate professionals. Your circumstances or experience may be different.