Project boat: transom, stringers and floor

Discussion in 'Materials' started by enecolt, Jun 1, 2015.

  1. enecolt
    Joined: May 2015
    Posts: 5
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Fort Lauderdale

    enecolt Junior Member

    When we decided to go for this project we never thought we will see so many different opinions on the internet about what materials to use, at this point my intention is to share with you our plans and get some opinion from the experts!!!

    Boat is a Grady White center console 20.4 built in 1984

    Major overhaul replacing transom, stringers and floor

    For transom we will use Seacast or Arjay polyester filling specifically designed to replace plywood as a core material

    For stringers we had a debate between original material (1/2" plywood) or using just one piece of wood board (spruce), because the stringer is tall 13"-14" and 14' long, spruce was our selection

    Floor will be laminated foam

    What resin to use: originally we thought well it s a no brainer lets go epoxy, but we have to paint the transom, and floor with gelcoat and it is not compatible with epoxy. Then we get to know all the repair shops around use polyester even at the store they told us why epoxy it is not necessary.

    Any thoughts an ideas will be welcome, thanks
     
  2. enecolt
    Joined: May 2015
    Posts: 5
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Fort Lauderdale

    enecolt Junior Member

    Am I asking too much, just wanted to get an opinion, thanks!!!

    Stringers, is spruce better or equal than plywood

    Epoxy or Polyester?

    Foam floor?
     
  3. Mr Efficiency
    Joined: Oct 2010
    Posts: 8,820
    Likes: 574, Points: 113, Legacy Rep: 702
    Location: Australia

    Mr Efficiency Senior Member

    No one wants to talk to you ? Never mind, I would prefer timber stringers to ply, I can't comment on species that may be available there. "Foam" is a very broad term, but selecting a PVC foam with good compressive characteristics would be suitable, imo, and you don't need epoxy for any of this stuff.
     
  4. enecolt
    Joined: May 2015
    Posts: 5
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Fort Lauderdale

    enecolt Junior Member

    Thank Mr Efficiency, at least I know wood is good and Polyester is ok, when I will be closer to start working with the floor will ask more questions!! I have attached a picture
     

    Attached Files:

  5. enecolt
    Joined: May 2015
    Posts: 5
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Fort Lauderdale

    enecolt Junior Member

    How do I differentiate if a previous repair was done with Polyester or Epoxy, the hull construction most probably is all polyester, am I right?
     
  6. Mr Efficiency
    Joined: Oct 2010
    Posts: 8,820
    Likes: 574, Points: 113, Legacy Rep: 702
    Location: Australia

    Mr Efficiency Senior Member

    Not likely to be any epoxy in there, the distinctive smell of polyester when sanded is unmistakeable, so that is your best guide.
     
  7. SamSam
    Joined: Feb 2005
    Posts: 3,900
    Likes: 196, Points: 63, Legacy Rep: 971
    Location: Coastal Georgia

    SamSam Senior Member

    Make sure the hull is supported correctly. You don't want to lose the shape or build in humps and bumps where badly supported. Check for twist also. Once you put the stringers back in the shape is set and locked in forever.
     
  8. CFMarine
    Joined: Jun 2015
    Posts: 8
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: New Orleans

    CFMarine Junior Member

    When choosing materials, consider life expectancy of project, purpose, and budget. There is often a clear solution considering foam and epoxy may cost 5x as much but outlast wood cores. The type of core used in the stringers will effect the amount of glass needed to obtain desired rigidity.

    If it were my project, i would use platinum grade plywood properly sealed and isophthalic polyester resin for everything. Considering the boat, there is no reason to spend all the extra money and only add minimal value, especially if it will be kept on a trailer. If constructed and maintained properly, wood cores can last 20+ years
     
  9. enecolt
    Joined: May 2015
    Posts: 5
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Fort Lauderdale

    enecolt Junior Member

    Thank you for the advise and comments, yes it is polyester we started cutting and the smell is very characteristic.

    Regarding supporting the hull, I read about that before, we are working over the trailer, the boat looks well supporter and aligned and we have not seen any deformation so far, we've been keeping some measurement to double check, we are trying to be careful, it is a project we are building in the backyard.

    we wanted to keep the two main stringers in one solid piece of wood, so we found spruce we very few knots is not that heavy, we will seal with polyester and then glue them with putty to the hull, check the shape, to start applying fiberglass.

    Definitely we will keep the project at a good material/quality ratio spending reasonable money for a 1984 GW.

    Any comment about the transom filling material? Seacast or Arjay are both polyester based and I have seen very good reviews of both, someone could say you have wood on the stringers why changing transom core, based on what we have read wood stringer will behave better.

    Thank you again I feel we are in the good direction, weill keep posting the progress ans some pictures, slow process ......the kids want their dad back for the weekends and the wife is not happy but that's life!!!!
     
  10. PAR
    Joined: Nov 2003
    Posts: 19,133
    Likes: 475, Points: 93, Legacy Rep: 3967
    Location: Eustis, FL

    PAR Yacht Designer/Builder

    Spruce is a lousy stringer material, simply because it's too light, which means it doesn't hold fasteners well and isn't especially stiff. It also tends to rot easily. Douglas fir would be a much better choice.

    Polyester bonds on wood are marginal at best, down right lousy if poorly done or something a novice is just trying to figure out. Epoxy is the hands down choice for the back yard repair with wood and wood to 'glass bonds.

    If you're using a pour in transom core, the surfaces must be impeccably clean or a poor bond will result.

    The reason they told you epoxy wasn't necessary is because they don't know epoxy, just polyester. Yes, you can gel coat epoxy, yes, it's far superior to polyester and yep, it also costs a little more, unless you're willing to shop around and get a good quality discount brand, instead of the major formulations.

    Lastly, be very careful about the foam you select for the sole. 5 pound density or better is the minimum, anything less and you'll probably have a delaminating issue pretty quickly. Once you price up the good foams, you'll quickly see why plywood is still so common in soles and transoms.
     

  11. JR-Shine
    Joined: May 2004
    Posts: 341
    Likes: 4, Points: 18, Legacy Rep: 54
    Location: Vero Beach, FL

    JR-Shine SHINE

    Exactly my advice.

    Nothing wrong with plywood at all. So long as your using epoxy, its pretty much a guaranteed success (in terms of bonding).

    Pour in place polyester cores might work so long as you can "know" the inside skins are prepped right - which you cant really know. That's why i would never use them myself.

    A foam core deck is great, will save weight, but I would probably take the $ and use it for epoxy. Plywood cored deck with epoxy laminate will not be too heavy, it will be lighter than one made with polyester because you do not need all the mat. For a plywood deck, i would use just 10 oz woven cloth, maybe 2 layers topside and one on the bottom - depends on the type of use it will get.
     
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.