Bad Fasteners....

From a recent survey where stray current in the bilge wasted a bunch of bronze fastenings -

NON STANDARD CONDITIONS AND OBSERVATIONS:
The following Observations and or Non-Standard Conditions were noted at the time of survey:
NVIC 8-95 was used as guidance in the inspection of the vessel described herein.
The vessel has been open moored in fresh water with the machinery, bilge, and cabin spaces generally accessible but materially limited in the forecastle, beneath machinery space, in after cabin, and at the transom.
Vessel’s hull and underbody was found to be in generally good condition. Hull top-sides, foredeck, and interior appear to be good condition and structurally sound (given the survey limitations as mentioned herein) with no signs of grounding or other damage and or structural failure except as follows.
The vessel described herein is a manufactured model therefore the undersigned has made no opinion herein as to the design, scantlings, workmanship, and or materials except as to modifications and or repairs.
Bronze hull fasteners (#12 – 1-3/8” wood screws) were drawn from various locations at the vessel’s underbody and examined (visually under optical magnification) and found to be in serviceable condition with the threads sharp with marginal visible alloy breakdown with the exception of the underbody hull fasteners at the garboard seam which generally showed serious wastage due to stray current corrosion. The cause of which was traced to 12-volt DC wiring in contact with bilge water. The undersigned strongly advises that all electrical wiring be inspected and repaired – replaced as required to prevent stray current. New #12 – 1-1/2” bronze fasteners were installed where a (wasted) fastener was removed. When installed - new fasteners properly tighten up in the keel timber. The undersigned strongly advises that the garboard fasteners be thoroughly inspected for wastage should be replaced where required within the foreseeable future to ensure the seaworthiness of the vessel. Refastening should begin at garboard plank at the keel on both beams. Open up, examine, and replace existing original and or wasted hull fasteners with same size (approximately #12 – 1-1/2’) and correct length marine-grade bronze wood screws. Over-size fasteners should only be used those instances when a new fastener will not properly tighten up. Sister fastening should only be used when an existing fastener cannot be removed without causing damage to the wood hull – frame structure. A sister fastener should only be fitted when it does not compromise the adjacent wood structure, (that is – to cause cracking, splitting, or create a weak spot). In the event that good serviceable fasteners are found and documented (for example, working from an area of non-serviceable fasteners into an adjoining area where the vast majority of existing fasteners are visually free of wastage and alloy break down), then scheduled refastening may be dispensed with in that specific area only. In the event that damaged, soft, weakened, or decayed (rot fungi) wood is discovered, the nature and extent of which must be determined. Any replacement or repair to existing wood structure(s) should be reviewed by a competent shipwright.
The vessel has been re-fastened in localized areas (the extent of which is unknown) of the hull with marine-grade silicon bronze wood screws.
The vessel’s keel bolts, where accessible, were visually inspected and hammer punched – filed to observe the condition of the underlying material. They were found to be serviceable with the following observation. Areas of rust deposits were observed at the keel. The undersigned believes that these rust deposits are from the vessel’s steel keel bolts. The condition of the vessel’s fasteners should be re-examined during the vessel’s next scheduled haul out. As with any wood yacht – the condition of the hull and structural fasteners should be regularly examined and replaced as required by a competent shipwright.
The entire vessel, all planking was fair-to-the-eye with no apparent rattling or loose planking. Underbody should be re-coated with a marine grade anti-fouling paint.
Portside underbody amidships – the hammer tone changed slightly in the area of the 1st and 3rd broad planks in the area of a bronze thru-hull fitting. No soft or decayed wood was visually observed. The undersigned recommends that this area be examined during the vessel’s next scheduled haulout.
Starboard underbody amidships – the hammer tone changed slightly in the area of the 3rd and 4th broad planks. No soft or decayed wood was visually observed. The undersigned recommends that this area be examined during the vessel’s next scheduled haulout.
An area of weather deck (wood) at the starboard quarter was found to be weak (allowing the ingress of water into the cabin’s interior) and should be repaired with marine grade materials in accordance with marine industry repair practices.
At the transom, upper most outboard areas – soft and decayed wood planking was observed which should be repaired with marine grade materials in accordance with marine industry repair practices.
When hauled, the vessel’s sacrificial zincs were found to be wasted. New zincs were fitted on the prop shafts, trim tabs, and rudders prior to re-launching
Water was found in the bilge.
The undersigned had a limited - restricted view of the stuffing boxes for both the propeller and rudder shafts due to limited access. In addition, various areas of the vessel’s structure could not be view due to limited access caused by interior fixtures, ceiling, and decks – soles, forecastle, stern, machinery, and stowed items which precluded a more complete or even partial inspection process.