On most boats the rudder should be light with neutral buoyancy - it should neither float, nor sink, so letting water into it seems like a bad idea? When it is completely enclosed, there's also the risks of corrosion.
Not trying to slam your product, just sayin'
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Originally Posted by stainlessoutfitter
Stainless outfitters up in barrie Ontario have had quite a bit of success fabricating new rudders in stainless steel.They are the exact shape as the original and fully welded where the shaft enters the rudder.Completely sealed it is very light or ballast it with water which you just drain out at the end of the season. Built like an aircraft wing and skinned with 14 gauge stainless plate, they cost no more than a new fiberglass rudder.