Cracked rudder head
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menace53243
- Posts: 2
- Joined: Sun Feb 18, 2007 10:41 pm
Cracked rudder head
I have got into trying to repair the head of my rudder where the resin has cracked from the surface to the rudder shaft. I have started grinding away leaving the skin. has anyone gone about a repair this way ? I dont really want to buy a new rudder but, want to keep my 7.9 going and safe. I have some pics that I can emial. I have read on this website of how to insert the aluminum in the rudder as well. Want to do that after this repair is complete. Great forum and what a fun class to race in. Mike D.
same
Mike, It's sometimes not necessary to grind very deep into the laminate IF you come back with a heavy grade of carbon fiber and vinyl ester or epoxy resin. Plain old polyester will work too, but if your going to do it you might as well do it as good as possible. Having said that, it IS necessary to grind until you reach the ultimate depth of the crack, if you really want to do it right. Carbon fiber is so strong and stiff even in thin layers that there is some fudge factor that you can get away with, but grinding out ALL of the fractured laminate is the strongest way to go. Fiberglass flexes a good bit without cracking, gelcoat doesn't. Fortunately, the dust coming off of the grinder tells you when you've gotten to the bottom of the crack. As you grind through the gelcoat and into the glass you should be able to see fine white lines of glass dust that build up on the surface. I have no idea of why fiberglass does this but I don't need to, as long as I know it's still showing me the crack[s]. I personally would keep grinding until you can't see this anymore. That means that you have found/passed the bottom of the crack.
As to inserting aluminum into the rudder and soforth. Think of an airplane. The wings are just ribs and struts that are all tied together by the skin. Sure, you could make a wing out of solid steel if you wanted to but that defeats the purpose, getting off the ground! A rudder is no different. The class minimum weight of the 7.9 rudder is so high anyway, why would you want to add anymore weight than necessary to achieve the goal of a strong, stiff rudder? Adding carbon fiber to the skin where needed AND tieing both sides of the skin together [around the leading and trailng edges] is a much stronger, lighter, stiffer alternative to adding metal inserts to [try to] do the same thing.
Dave
As to inserting aluminum into the rudder and soforth. Think of an airplane. The wings are just ribs and struts that are all tied together by the skin. Sure, you could make a wing out of solid steel if you wanted to but that defeats the purpose, getting off the ground! A rudder is no different. The class minimum weight of the 7.9 rudder is so high anyway, why would you want to add anymore weight than necessary to achieve the goal of a strong, stiff rudder? Adding carbon fiber to the skin where needed AND tieing both sides of the skin together [around the leading and trailng edges] is a much stronger, lighter, stiffer alternative to adding metal inserts to [try to] do the same thing.
Dave
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menace53243
- Posts: 2
- Joined: Sun Feb 18, 2007 10:41 pm