Capt. Reynolds is right as to space available under a vessel on drydock. I've spent way too many hours crawling on my belly to hull gage a vessel. Now a marine ways set up might be the way to go, on the ways there is usually 5-6 ft. of clearance. It might be possible to excavate an area to get that boiler length out. However I'd go with Capt. Bob, cut them up.