Saturday, March 8, 2014

Ruddery Goodness

I've finally managed to free myself from the grips of winter and got back to work on some of the projects that need to be done.  There's still a lot of snow on the ground and it's too cold to work in the boatshed so I'm confined to the shop, but at least it's warm.

I stopped in at Goosebay sawmill last week and bought a sheet of 18mm Meranti marine plywood for the new rudder build ($155.00).  I went back and forth on whether or not to go traditional with solid mahogany planks or encapsulated plywood.  Ultimately, I chose plywood because I didn't feel comfortable enough with the movements of swollen planks and how to deal with it.  I've tangled with the properties of wet/humid wood on a number of occasions with tables and cabinets I've built, and it is really tricky to get it right.  I figured I didn't want to mess around with something as important as the rudder so I went with plywood which will be dimensionally more stable (especially once encapsulated).  The design will use two pieces of 18mm Meranti epoxied together to make a thickness of just under 1.5".

I had picked up my newly fabricated rudder post back in December and it had been sitting in my shop waiting for action.  Once I had the plywood I ripped it in half (lengthwise) and used the old rudder to trace the shape onto it.  Fortunately the maximum witdth of the old rudder is only 23" or I would have needed two sheets of plywood instead of one.

Using a saber saw, I cut proud of the traced line and then screwed on a piece of plastic laminate to create a fair arc.  I mounted a flush cut bit to the router and used the laminate as a guide to make a perfectly smooth arc along the trailing edge of the first piece of plywood.

On the front edge of the rudder where the propeller aperture is located and the post attaches, I carefully cut along the line and cleaned it up with a rasp to make sure the new rudder post would attach with the proper angle.

When I was satisfied with the shape and fit of the first piece of plywood I screwed it down to the second piece and rough cut it to the basic shape of the first using the saber saw.   I broke out the router and flush cut bit again and cut out a copy of the first.

Now that I had 2 identical copies of the rudder I could focus on setting a cove into leading edge of both pieces so the rudder post can nest into the cove once the 2 pieces are epoxied together.  The router saved the day again; using a 3/4" radius cove bit I cut a cove on each half of the rudder.  I had to shape a guide board for the aperture area for the bit that took a bit of time, but overall the process went smoothly.  I temporarily screwed the pieces together to make sure both the new and the old bottom shaft fit.  It was just about perfect.  Tomorrow, I'll make a test fit on the boat just to make sure the shafts line up properly before I cut the channels for the drift pins that will be sandwiched in the rudder.

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