Clyde on Deadwood/Shaft Log and Transom Area Construction

[bob mitchell]

         I am getting ready to rebuild the transom area of hull # 113, so Clyde is providing much needed information on the original structure. At a later date I will post discussion and photos of the actual reconstruction, but in the mean time I want to make sure that this important information gets posted.  (all below is from Clyde Phillips)

 

The attachment is a discussion of the keel and deadwood that may help in your rebuilding of the upper area, including the shaft log.  Take out the rotten area and (of course) replace with good wood.  I’d say that the only critical thing is how the shaft log is built.  It is made up of two pieces that mate on the plane of the center of the shaft.  If at all possible do your reconstruction without removing (or moving) the shaft tube (fiberglass covered grey plastic)

 

        This drawing (above) is of the west coast boats (note depth of keel). But the following is typical of all boats: The actual keel, the single piece of wood that is the keel, lies between the apron and ballast keel. Its forward end is the dotted line marked above by the second arrow up from the bottom (curved line with small arrow head originating at the right edge and sweeping up and to the left to the end of the keel). Note the forward keel (ballast) bolt passes through the forward end of the keel. The bottom of the keel sits right on the ballast and extends to the after end of the "deadwood." This is a straight line. The top of the piece that makes up the keel (as the keel "leaves" the apron) is parallel to this line. The height of this keel member is not known to me; it may have been cut from an 8X8, 8X10 or 8X12. The point is that the rest of the deadwood pieces are all parallel top to bottom except the bottom half of the shaft log (the log is of two pieces, one above and one below the shaft). The top of the lower log is parallel to the shaft and is at the line of the center of the shaft.

The actual deadwood is made of those pieces above and below the keel member that fills in the area needed to produce the required lateral resistance, hence the term "dead." Think of the "deadeyes" on the shrouds of old sailing vessels and compare that with the "live eyes" (with sheaves) of the blocks in a tackle (pronounced "TAY-kle"). But the whole of the area, including the keel piece, is commonly, and correctly, called the "deadwood." On some boats, like our centerboard Delaware Bay oyster boats, the keel is the lowest piece and the entire deadwood is above it. On other boats, like the Newporter, deadwood is placed above and below the keel. The keel is a working, or a "live," piece of the whole.

         

The drawing shows the transom, transom knee, and transom frame.  Note that the three layers of 3/8 plywood that makes up the “planking” of the transom extends beyond the transom frame across the bottom and up each side to catch the end of the bottom and side planking.  OR it doesn’t.  Hopefully you can discover which covers what when you take out the old.  It could be that the frame extends beyond the plywood (so the inside surface of the frame comes out to the inside surface of the planks if the planks overlap the transom).  Ask for other drawings if they are needed.  I don’t really remember and am looking at it both ways.  It’s always good to have plywood end grain covered but some end grain will show regardless at this point.

 

I only show the transom frame following the edges of the transom.  There may be some vertical pieces, and a crowned piece of the frame that hold up the end of the deck.  The frame piece I show at the inside top of the transom may not be there (it may be at the deck level).  There is no need for it at the top.  The cap rail sits on top of the transom and the transom may have at least one layer of 3/4” ply sitting on top of the deck, a la bulwarks.

 

The three layers of 3/8th were marine grade Douglas Fir (inside two layers) and the outside layer had an outside veneer of ribbon grain mahogany.  That made for a beautiful varnished transom for those who wanted the wood to show.  The frame could have been white oak to match the other frames and have much the same nail holding power.

 

The transom was built on a mold that had recesses to receive the frame sections and a place to hold the knee.  The three layers were tacked down (just at the top and bottom on the vertical center line) to hold them in place (gluing as you go) and the mold top was lowered over it all and clamped down for gluing pressure.  It’s possible, I suppose, to first build the mold, but for a “one off” transom you should be able to build it on the boat.  But that will require some well thought-out clamps in order to hold the inside of the plywood where it belongs and apply sufficient pressure from the outside.  No big deal!!!???

 

 

[bob mitchell]

Just wanted to add this photo of Dennis Gaffney's San Souci.