FYI, was running from Ilwaco in the mouth of the Columbia River when smelled exhaust in cabin. Within moments there was smoke coming out of the engine compartment. Shut down both engines, and took a look. Smoke was coming from the rear of the starboard engine and the soundproofing insulation (the fiberglass covered by the foil) was smoldering and smoking. Grabbed a fire extinguisher and sprayed the area down. Was able to limp into Astoria on the single port engine. What had happened was the bolt securing the clamp that attached the exhaust elbow to the riser had broken. Consequently the clamp failed and the elbow had detached. Super heated exhaust was coming out and just cooked the sound proofing insulation. According to the mechanic I spoke with the exhaust is around 400 degrees and we were lucky we had no fire. Was able to get a new clamp from Yanmar Seattle within 1 day and reattached the elbow, cleaned up the mess, wrapped heat insulation around the elbow to be extra safe (probably overkill) and replaced the foam col

lar over the air intake for the turbocharger. Ran the boat up the Columbia to portland (90 miles) without problems where she will stay for the winter. Now need to see if I can find a wy to repair the sound proofing insulation as it charred about a 2x2 ft area out of this. Also will probably need to repalce a few hoses in the vicinity as don't want failures down the line. Any ideas on how to replace the soundproofing.
Scary though that a single bolt can fail and potentially cause devistating problems. This is a clamp that even if I checked I would not recognize any impending problems until after they occured.
Jeff S