Wednesday, 6 November 2013

Rudder Maintenance

The part of the Drascombe design that does not quite live up to the standard of the rest of the boat, is the rudder. I'm surprised that is not possible to buy a replacement made out of a lighter material. I'm sure it is not beyond the capability of a small manufacturing company to produce a copy made from anodised aluminium or even use stainless steel.

The aim is to take the rudder apart, clean it and re-paint using Galvafroid. When re-assembling the rudder the plan is to use two large washers, which will be glued to either side of the rudder blade. Drilling the pivot pin out revealed a bush in the blade. This was loose and the hole in the blade slightly elongated. The decision has been made to make a new bush, which will be an interference fit into the blade. A new pin will also have to be made.



The washers have been made from 0.5 mm thick Polypropylene sheet and these will be glued to the blade using an impact adhesive. A nylon washer will also be added to shaft to help prevent wear on the top bearing.

Galvafroid is a zinc rich paint that is ideal for protecting steel. It can be painted over if a different colour or finish is required. It's easy to obtain on-line or at a good builder's supplies.


The hole in the rudder had become oval in shape, so this was reamed to 5/8 inch, before a new bush was machined out of stainless steel and press fitted into the hole. A new pin was also turned with a small shoulder one end. Once the rudder and stock have been painted, the washers glued in place, the plain end of the new pin will be riveted over. This should then provide a long lasting solution.


Galvafroid paint does need stirring well and can be applied quite liberally. I used a thin piece of wood wrapped in kitchen paper to paint the inside faces of the stock. Three coats later it seemed to be finished and I then added two coats of smooth Hammerite onto the rudder blade. Once the blade and stock were painted, it became very clear that the plan to add the two washers was not going to work and in fact the blade was now a very tight fit into the stock.


There was need to use some force to get the blade into place, which did remove some paint and when a new layer of Galvafroid was added, it soon became clear that this would cause the Hammerite to soften and bubble. The only solution was much rubbing down and repainting in some areas. Waterproof grease was packed with the blade and stock and although I'm sure it will wash out in time, it did help with the final assembly and will keep it lubricated for a while. The pivot pin was riveted over and another coat Galvafroid added to outside of the stock.


A washer was added to help prevent wear on the upper bearing. This was made from some 40 mm dia. nylon and hopefully will also make the rudder smoother in use.



 
 

No comments:

Post a Comment