I regret that I am rather late with this entry, but some of you may wish to see the flickr pics from shipyard and know what they are about.
In the last drydocking in 2004, we replaced two planks (one of which can be seen at right.) This year we left Erie on September 22nd for the Great Lakes Towing Shipyard in Cleveland, OH. After haul-out on Sept. 25th and surveying the hull for the first few days of the drydocking, we were please to find no rot in the hull.
The drydocking this time involved a substantial re-corking job. NIAGARA is carvel planked, which means each plank is layed alongside the next as they are fastened to the frames. The seam between the planks is “corked” by driving relatively thick cotton yarn into the seam, then several layers of oakum. Oakum is a thick hemp yarn, which is treated with a tar/ linseed/ terpentine or similar chemical mixture to protect it from water intrusion and rot. After the cotton and oakum are driven into the seams, the remaining 3/8″ or so of the seam’s depth is filled with a seam compound (putty).
We hired a team of four corkers from the Haven Boatworks shipyard in Port Townsend, WA to work for three weeks at the yard in Cleveland, OH where we hauled out.
Together, their team and our crew reefed and re-corked the hull from about one foot above the waterline to about 3-4 feet below the waterline. This area is the wind-water line. Last spring the same company came to Erie to reef and recork most of the topsides of the ship (one foot above the waterline to the waterway plank at the deck edge).
The corkers were quite impressive workers. While our crew stayed ahead of the corkers reefing out the old oakum in the shipyard, they followed behind with oakum, irons, and mallets ten hours a day for twenty days. Ibuprofen was the drug of choice to keep their elbows and wrists on task.
As we finished reefing, we followed behind the corkers painting the finished oakum with bottom paint, then filling the seams with underwater seam compound. Now the ship’s hull is re-corked from the deck-edge to well below the waterline. Our survey indicated no rot in the planking and no rotten oakum below the waterline (or anywhere else in the hull).
The oakum we removed from the wind-water line was not rotten, but was wet and moving towards rot. After 18 years of service, we were fortunate to have the funding to replace the oakum in time to prevent rot from occuring. I have hopes that we won’t have significant rot problems in the wind-water or topsides areas of the hull for many years to come.
The yard period also consisted of all of the usual routine maintenance. We lifted the rudder to inspect the pintles and gudgeons (rudder hinges). We withdrew the tail shafts to inspect bearing tolerances. We sent the propellers to their dealership on the west coast for inspection and maintenance. We pulled six plank fastenings for USCG inspection, and we received and passed our bi-annual US Coast Guard drydocking inspection.
We also installed a new speed and depth transducer to help keep our navigation electronics up to date. We launched on October 14th and returned to Erie that weekend.