Our GRP-constructed Rudder is collecting water, no matter what I did to it.
The construction: a stainless steel rudder shaft, the rudder is out of fibreglass.
The rudder is held at the bottom (sitting behind a skeg), the point where the shaft leaves the rudder at the top end lies under the CWL.
I know that the connection between GRP and metal is always a critical point.
And this is what I did in the past:
The first time I took out the whole rudder, took it home, drilled holes in it, sat it on a central heating radiator for a whole winter to let it dry out, laminated a couple more layers to make the construction stronger (using the WEST-epoxit system), shaped a groove around the shaft on both ends and filled it with a sealing compound for underwater use (Pantera), closed this with a last fine layer of mats and hoped, that this should keep the rudder watertight...
Two years later: water in the rudder. This time cleaning the grooves, letting it dry out over the winter, sealing them again. With the same long term result: water in the rudder...
Now I start again!
For two reasons water in the rudder is not so good: we know that wet fibreglass over a long time is weakening the construction (delamination) and I have seen one rudder that split during winter storage at freezing temperatures (that due to global warming becomes less of a problem here...).
Do you have an idea what else I can do to keep the water out for more than just a year or two?