Saturday, July 30, 2016

Done Whining For A While And Back To Boat Building


The forward roof will be three layers of fir plywood 1/4 inch G1S.  The first layer went down lengthwise between the stringers and bulkheads so no seams were exposed.  I put the good side on the inside and used Titebond 3 along with 1 inch galvanized ring nails every 6 inches.  After the glue cured I put a second layer down athwartships in strips about 5 inches wide, with Titebond 3 and lots of temporary screws.  In this pic I'm almost done with the second layer.


Here the second layer is complete and trimmed to the cabin sides.  I then put on eave boards.  The third layer will go on lengthwise over the eave boards.  The temp screws will have to come out first.  I'll put the third layer on with Titebond 3 and nail through all three layers with 1-1/2 inch galvanized ring nails into the stringers and the bulkheads.  It will all get covered with fiberglass cloth set in Titebond 3.


12 comments:

  1. Wow, maybe you should whine some more -- that's a lot of progress in a short time! ;-)

    For a couple of reasons, I've been leaning toward a flat roof in my own sketches. The benefit of better drainage with curved roofs, like yours, wasn't lost on me, but I wasn't sure that that perceived sole benefit was enough to overcome the other benefits of a flat roof (for me). However, as I watch your roof come together, in addition to beauty, it exudes an air of strength as well. It is the strength that I had not previously given due weight to in my design thoughts.

    Overall, very nice roof and a good way to work out frustration and lower your BP to boot.

    By the way, before putting on the third layer, will you have 20,843 temp screw holes to putty in that second layer? I hope not, but I fear the answer is yes.

    ReplyDelete
    Replies
    1. I counted 20,941 screws. You're certainly screwed.
      I'm sure there is a reason for the narrow strips instead of full width plywood. I wonder what it is?

      By the way. It looks great.

      Delete
    2. Hi guys! The roof is very strong. I don't even have the third layer on and it is quite solid. The first layer by itself though is very weak. I would not put any weight on it while working on it lest my knee crack it. But the second layer, once the glue cured made it quite stiff. I'm sure the third layer will make it bullet proof - not that I want you to test it Everitt :-). The transverse plywood was cut into strips because it bends more easily since it is using the plywood on its lengthwise axis which is quite stiffer than cross-ways. Also I'm sure I'm getting it down without any voids. The other thing is it is very hot here now - over 32 celsius - and the glue is skimming over quite quickly so it's easier to get the smaller pieces down while the glue is still wet. To settle the score 19.5 x 10 to the power of 16 screws, or at least it seemed so...

      Delete
    3. And thanks for the compliments!

      Delete
  2. And the not-so-tongue-in-cheek question about the putty?

    ReplyDelete
    Replies
    1. I'm not bothering to fill the holes topside. The glue and plywood will cover the holes ok. Inside the screw holes - when you back them out - are quite small. A little bit of DAP on the finger to go over each one before the paint should do.

      Delete
    2. They stick down through the ceiling.

      The only reason they were there in the first place was to hold both layers of plywood together tightly while the glue cured. Once the third layer goes on, I will fasten with either nails or screws through all three layers into the stringers and bulkheads only. The glue does most of the work holding things together. The nails or screws are just for backup.

      Delete
    3. Hey Al, to continue Everitt's topic ... assuming conditions are such that glue drying time isn't a problem, if a person wanted to minimize the seams in that middle layer (where you did 5" strips), but also wanted to avoid serious bending problems with 1/4" plywood, what would you guess the maximum feasible strip width to be, now that you've done it?

      Delete
    4. Only a guess but at this radius and with 1/4 inch fir I'd say maybe 6 inches. The problem is ensuring there is full contact without voids. I tried the first two pieces near the aft cabin at a foot wide and I had trouble getting the edges together as well.

      Delete
    5. Starting to see better. In the case of your 12" plank experiment, can you say exactly what it was that made those planks more difficult, or why you felt you could not get their edges together sufficiently?

      Delete
    6. Probably some inaccuracy in the curve or camber made the larger widths harder to wrestle the seams together. Going narrower (and more flexible) made it easier.

      Delete