|
|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|
|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|
|
|
|
|
|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Back in 2003 my
wife and I were sailing our Dockrell 22 when the rudder snapped off at the
point where the lower pintle is bolted on. We were very
fortunate because, although it was a bit embarrassing, several boats
including a pleasure boat full of passengers came to our aid, the RNLI rescue
team towed us
back to our mooring with their inflatable boat which was very kind of them.
As you will see
in the photos, I first epoxied several layers of marine ply together and then
using the broken rudder as a template I cut them to the basic shape. What the
photos don't show though, because I forget to take them,is inside the rudder
I sandwiched two stainless steel bars approx 40mm x 5mm x 450mm between the
middle two layers. The bars were positioned inside along the length of the
rudder near the pintle brackets to reinforce which is the weakest part of the
rudder. Next came the hard work, shaping of the rudder. I used NACA 0012 foil
tables to make a template of the rudder blade profile and I modified the blade
shape. After a lot of
planning, filling with epoxy mixing with microfibres as thickening additive
which is good for bonding to wood, I gave the rudder several coats of epoxy. Finally I painted
the whole thing with white topcoat and then drilled the holes for the pintle
brackets and bolted them on. Click here
once to download the excel spreadsheet showing the values and profile that I
used for the rudder blade. You can then open the excel file in your downloads
(top right of Firefox or Opera browsers).
|