36cc Engine exhaust water leak

Bear with me here...and I'll try to explain! 

I have a B36cc 2002 with a very small leak of sea water from the aft end of the black rubber...silencer??.. in the engine room.  It appears to leak at the union between the rubber and the stainless steel aft section.  The union has two hose clips on it - both of which I've tightened - but the water still leaks.  Only a very small drip, mind you.  But it's rusty water and is annoying.  The rubber seems in very good condition - no disintegration - as does the stainless steel bit.  Any ideas anyone?

Cheers

Cliff