The Strongback

Still coming up to the present in my posting so here we are at the building of the strongback and frames...

Building Basics:

For everyone reading who is not familar with the method of construction I've chosen or boatbuilding in general, I'll briefly cover the basics of what this construction method consists of and why you need a Strongback (not a strong back, although it probably wouldn't hurt to have one of those too). Screw and Glue is basically building a rigid skeleton of frames spaced at pretermined distances (Stations). The Frames are also mounted at specific heights off of a base line to create a curve or Rocker to the hull if you view it from the side.
The frames are then covered with a layer of plywood and attached by screws and glue.  The hull is then covered with either a fiberglass or polyester cloth embedded in epoxy resin.  The purpose is to create an abrasion resistant layer. For this purpose I will use xynol, an abrasion resistant fabric that conforms to the curves well and is sort of a poor man's kevlar in its performance.  The hull is constructed upside down, finished out as far as possible, then flipped to be finished right side up.  That's about it for the basics.

Strongback:

 The Strongback (SB) is the framework of lumber that provides a flat, sturdy surface on which the frames are mounted upside down temporarily as the hull is constructed.  Here is a drawing of it with a figure added to create a sense of scale in the drawing.

You'll notice the Station numbers in 2' increments and the rocker I spoke of from front to back.  the figure is looking toward the back (Aft) or at the Transom.  The front (Fore) has a stem that creates the sharp front of the boat.


View Looking from the Transom - note yellow centerline string

The Strongback is built out of standard 2"X4" SPF lumber, nothing special but I did take care to pick out the straightest ones that HD had to offer.  I also used a combination of 2-1/2" and 1-5/8" pocket hole screws as they drive easy due to the square drive and cut tip.  I used scrap 1x material for bracing the upright ladders both fore and aft as well as athwart ships (side to side) once they were leveled.  I also used a Bosch laser level mounted on the wall at the end of the photo.  This I used to level the horizontal deck of the Strongback, the most important part of the assembly.  The bottom cleats are screwed to the floor. Note diagonal bracing as well.

Another view from the Stem. Strongback at Stations 4 and 2 are not assembled because the have a closed deck beam and have to be threaded on.