Skin on Frame: Glue and Wood Question

Discussion in 'Boat Design' started by bjdbowman, Feb 12, 2019.

  1. bjdbowman
    Joined: Apr 2017
    Posts: 68
    Likes: 2, Points: 8, Legacy Rep: 10
    Location: Florida

    bjdbowman Junior Member


    Working on my Pa-Pram-meters for my Pram build, and I have tons of clear straight maple on popular composite wood 3"-5" wide 5/8" thick with 3/16" maple with 7/16" popular bonded to the bottom. This is a natural wood flooring material. The wood runs in lengths from 24" long to 80" long. I was thinking that; "hey this here is free wood!... Why not use it?" Plenty to choose from.

    I was thinking why not use this wood for the skin on frame build.

    Question One:
    Should I trust the existing bond and use as is, just cutting to width for use on the build?

    Question Two:
    Should I try to remove the popular from the maple?
    If so maybe I could laminate two smaller layers of maple on top of one another to make a 3/8"x3/4" stock. With this method, I could stagger the longitudinal joints making the required longer stock material.

    Question Three:
    If I want to steam bend this stock, which wood will work better for bent frames? The maple or the popular?

    Question Four:
    If I want to laminate the frames in a jig or directly on the male mold (stations) in place, what kind of bonding agent would work best to hold the layers while it cures? Should a quick setting epoxy be used, or is there a better solution?

    Here are some silly thoughts:
    I was thinking that I like the idea of a type of contact cement. I was thinking I could attached the first layer of strips directly to the mold station with brads, and then layup the glue on the outside surface and the inside surface of the second layer at the same time. Doing all of the frames for the entire boat. Once the contact cement is ready I could starting at the center line attached the second layer of strip on to the first, bending the wood to the mold with clamps from the keel to the sheer.
    I could simply just bond each layer in place with a few clamps and off to the next frame doing one layer across the complete boat at one session.

    After a short break I could go back and add another layer using the same method.
    Once the frame is complete I would have to cut away the molds and pull out the brads from the original first layer of strips.

    Next question: How could I make long thicker stock for the stringers? Would I have to lay them up on the molds or frames in the exact (final) shape making a composite stringer the same way I just described above with making laminated frames? Any ideas on how I can make this easy and quick without too much fussing about? Could I layup the long stringers and then attach them after they are cured, or is it better to attach them wet?

    So the idea is to keep it light but strong. I will use Kevlar twine and 500 lb braided Kevlar Line
    to make a geodesic frame, but I wanted to add a few strips of Kevlar or carbon to in the mix to assist in making the frame rock solid.

    Any help on this construction method? I have other ideas, but this first build will be using what I have on hand. This is not going to resemble a Steinway piano or a highly finished piece of craftsmanship, but a work boat, tender.

    Please feel free to tell me that I'm an idiot... I've been on this site before, so I can take it.

    This is an example of what I'm trying to build, but not exactly.


  2. messabout
    Joined: Jan 2006
    Posts: 3,065
    Likes: 242, Points: 63, Legacy Rep: 1279
    Location: Lakeland Fl USA

    messabout Senior Member

    Maple is pretty heavy stuff, It does not bend that readily either. The general idea for a SOF boat is to keep it ultra light. That is reason enough not to use maple. Poplar is a different deal. It has a reasonable weight density.

    I would urge you to forget free wood and get the most nearly appropriate wood that you can either find or afford. Top of the list might include Sitka spruce, Atlantic white cedar and so on in declining preference. Ordinary (knot free) white pine will work well enough but it will need some preliminary treatment to preserve it.

    If you build such a boat you re going to put plenty of labor and a good measure of passion into the job. It makes little or no sense to use inferior materials.........
    rwatson likes this.
  3. Blueknarr
    Joined: Aug 2017
    Posts: 887
    Likes: 171, Points: 43
    Location: Colorado

    Blueknarr Senior Member

    Ditto to what Messabout said.

    I wouldn't trust the existing bond between the maple and popular. The flooring stock was originally designed for interior use, so won't have water proof gluing. Those woods have vastly different expansion and flex properties.

    It probably will take more time effort and cost more to separate them than would be saved. Sell that stock to someone who is remodeling a bathroom and use the proceeds to buy better material for your project.
  4. bjdbowman
    Joined: Apr 2017
    Posts: 68
    Likes: 2, Points: 8, Legacy Rep: 10
    Location: Florida

    bjdbowman Junior Member

    Okay I see your point, however I have seen many make canoe and kayak frames out of steam bent oak. Oak and Maple are about the same density, no? What if I cut the maple to make the frames and use the popular for the stringers? How are these inferior materials? Is it because I want to jigsaw puzzle the smaller runs into longer stock? I don't think that joined maple is inferior to pine. I do want the puppy to be light, but not balsa light. If I use two or three layers of 3/32" maple steam bent how is this not a good thing compared to using pine or spruce?

    If needed I don't mind spending money, it's just that I have all of this wood on hand that needs a place to go. And I also have 1,000 sf of pre-finished maple engineered flooring left over as well. I have ton's of great wood, why should I have to go out and buy pine or spruce to save a bit on the weight. With the maple, could I not make the members smaller since the strength is that much greater than spruce or pine?

    Just a thought... I've advertised the wood for sale, but no takers...

    I know that many have built with pine and spruce, but I would assume that stronger smaller material would be better for the build. Just a thought.

    Thanks for the input. I'll try to make a simple test frame to see how the weight and strength is...
    Project for another weekend.

  5. bjdbowman
    Joined: Apr 2017
    Posts: 68
    Likes: 2, Points: 8, Legacy Rep: 10
    Location: Florida

    bjdbowman Junior Member

    Yes... you are correct. I just ran the numbers and the frames being 3/4" X 3/8" @ 12" o.c. out of maple would be 60 pounds alone... which exceeds the total budget for this build.

    [EDIT] had the wrong decimal place... the above is only 6.2 pounds for the desired frames... So the weight is not the issue then... I could triple the amount of frames and double the thickness and still be within the weight budget. I also can create all of the frames (first layer) of full length stock of maple or popular if needed.... I found enough 8 footers to do what I need to do.

    So now it's all about why not to use maple or popular? And what glue to use... if any.
    I was trying to figure out why the boat was so heavy... my maths were just off a schoach.

    Thanks again, for the input!
    Last edited: Feb 13, 2019
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.