Stainless Rudder Stock Needs Replacing In Foam Core Rudder?

[dennisail]

Originally Posted by drewke07

If it were me I'd use a Fein tool to split the fiberglass shells apart, and then a sawzall to work the foam inside. Much more control with the Fein tool. I'd use schedule 80 316 stainless pipe for the shaft, it has a thicker wall. The Aquamet 22 is a great choice if you do not have to weld to it. Be sure to use only epoxy to put it back together, and be sure to glass at least the leading edge with 17oz biax or similar. Be good to go!

We will have to weld to it. What are the problems with welding to A22 and 2205?

[Weyalan]

Originally Posted by dennisail

What are the dimensions of your rudder and rudder stock? Was the old stock tube or solid.

From memory, the old stock was, at the widest section, about 72 mm diameter.

The old stock was tube but, as I mentioned, the naval architect insisted that the new stock be solid (same diameter as the old).

[dennisail]

I assume you have a high aspect rudder? Mine is low aspect (less leverage) plus it has a fair bit bigger shaft, hence the naval architect who designed my boat to a CE A rating stipulated the use of tube. Was your boat designed to a CE A rating? Possibly your NA ran the figures and it would have never passed a CE rating, but that does not mean mine has not.

Think of all the other boats out there whos rudders are about ready to break on old boats? The fact is I sailed this boat from the USA to Brisbane last year with this rudder shaft (passed survey but how much can you really tell without pulling the rudder). And even with this corrosion it did not break. So going by that an exact replica will last another 20 years. This one has NOT failed. It may last another 20 years for all we know, but I am not going to try and prove a point as to how much structural integrity it has left. I will be miles ahead of all the other boats out there with 20 year old corroded shafts whose owners are oblivious to the damage as you were. Many people would probably just put the old one back in then sell the boat!

Do you think yours would have broken if you replaced it with the same size tube prior to the disaster? How old was it when it broke? Clearly stainless rudder shafts are a consumable item and they need to be replaced. The material degrades over time and as you found out and you can not tell if there are probs. We replace our rigging every 10 years and it is the same material only its not immersed in stagnant sea water! This whole thing would make me very hesitant to own an old boat with an old SS spade rudder of any design.

[Weyalan]

The old rudder (that broke) was almost certainly original (i.e. 1985) and it was the typical "barn-door" shape of that era. The new one is a more modern high-aspect design. The NA did indeed run the figures and tell us that the old stock wouldn't have passed a CE rating.

I'm not sure that pulling the rudder is necessarily going to tell you much. Like I said - our rudder stock broke inside the blade, whereas all the exposed shaft looked A-Ok. Short of getting the thing X-rayed (and how do you even do that), there wasn't really any way we could have known.

I'm not sure that I'd be considering a rudder as "consumable" as such... if our rubber had been built to a standard we probably would still be using it quite happily. Should we be considering replacing the keel because the keel bolts are old? Maybe we should - 'tis food for thought anyway.

[dennisail]

I know of people who have changed their keel bolts and/or added extra new ones.

[robwilk37]

old thread i know, but never got an answer to the weldability issue with A22. soon to be building my new rudder and chose A22 for the rudder stock to match the prop shafting - the only two underwater metals i have. will need to weld an armature to the rudder stock so...