SHAFT COUPLING TO PROP DETAILS

[bob mitchell]

        While rebuilding the apron and upper layers of deadwood at the aft end of the boat I had the opportunity to disassemble the propeller/shaft system. Captain Clyde answered numerous questions I had, so he deserves credit beyond just the specific quotes of his that are included. The first two photos show the shaft coupling which connects to the transmission coupling, and next the stuffing box (aka. packing gland) with the heavy, but flexible, hose making it a "flexible stuffing box" (as opposed to a "rigid" stuffing box with no hose). The shaft itself (on my boat) is stainless steel,

1 1/4"x 68 9/16". 

           At the aft end is the cutlass bearing which is a bronze sleeve that has a splined rubber insert. The piece on top of the cutlass bearing is what I call the cutlass bearing set screw (backward in photo) fitting. It is an abbreviated form of what is known as the stern tube bearing housing. This fitting is actually fastened to the back of the deadwood, and surrounds the shaft tube (shaft alley), and is used to keep the cutlass bearing from spinning in the shaft tube (as opposed to the shaft spinning in the cutlass bearing, which is correct. Because my cutlass bearing set screws had been fiberglassed over they could not be tightened, or the last guy with the boat did not know what they were for, and my cutlass bearing had actually spun in my shaft tube). Next( on my boat) is the sacrificial zinc anode, then the prop on the tapered, keyed shaft, and finally a couple of nuts with a cotter pin.

       The shaft is surrounded by the shaft tube (shaft alley), which is a plastic tube wrapped in fiberglass going through the shaft log in the deadwood (see the blog "Deadwood Structure" for a more information) .

The above photo shows the new deadwood and the shaft tube. Where the plastic tube is encased is where the 6 layers

of plywood that form the apron go (which sits, obviously, on top of the deadwood - till the end of this piece. Then the apron extends out into space, over and beyond the rudder, forming the horn timber which supports the transom knee. The grooves in the side of the deadwood are for the threaded rods that hold the aft (beyond the lead keel bolts) deadwood stack together and connect it to the apron. The grove is not visible in the new deadwood because I was able to drill it from the bottom while it was unattached to the main deadwood body. (actually, in this picture, they had not been drilled yet)

     A very important detail (that Clyde pointed out and explained to me) is shown in the next photo. WELL I SEE I AM LIMITED TO 3 PHOTOS IN THE BLOG AS WELL, SO MOVE TO "SHAFT COUPLING TO PROP DETAILS, PART 2, FOR THIS VERY IMPORTANT INFORMATION."