Saturday, September 13, 2008

Wood Yacht Underbody and Fastener Report....

When I survey any vessel - I have a section in my report which deals with the hull structure and's framed as a narrative (good and bad)...which sometimes sets the stage for any recommendations. Here's what I said about a wood Grand Banks from early this summer -

The following Observations and or Non-Standard Conditions were noted at the time of survey:

The vessel has been very well maintained and very presentable with the machinery space generally accessible and very clean. It has been reported by the vessel’s owner (list provided – see attached) that the vessel has recently undergone extensive maintenance and refit. Upon examination, the undersigned found evidence of such activity. The quality of workmanship and materials is evident.

Vessel’s hull and underbody was found to be in very good condition. Hull top-sides, foredeck, and interior appear to be very good condition and structurally sound (given the survey limitations as mentioned herein) with no signs of grounding, rot fungi, 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 wood screw hull fasteners (#14 - 2”) were removed by Mr. Smith and visually examined at various locations from the vessel’s underbody (waterline and garboard). The fasteners were found to be in serviceable condition with the heads - threads materially substantial with marginal (visible) alloy breakdown. The fasteners at the garboard were judged (by Mr Smith and the undersigned) to be in about 90% of new condition while the waterline fasteners in about 70 – 80% of new condition. The condition of the vessel’s fasteners should be re-examined during the vessel’s next scheduled haul out. New bronze fasteners were installed and bunged. Ownership retained removed fasteners for future reference and has been made aware of these findings.

A bronze through bolt at the starboard chine timber, amidships, was examined and found to be in serviceable condition.

The underbody was extensively sounded. An area of planking ahead of the most forward bronze through-hull fitting, portside was found to be slightly different relative to the rest of the underbody. No soft or structural weak wood was discovered, only a slight change in the hammer report. No interior structure or fitting was discovered which could create this condition. The undersigned determined that no immediate action was required and this area should be re-examined during the vessel’s next scheduled haul out. Ownership has been made aware of this finding.

At the portside underbody, near the stern, a small lead patch (approximately 4” X 4”) was discovered which covers a removed through hull fitting. Patch - plug appears tight and stable.

Small patches of a black oil-like substance was found on the portside underbody near the garboard seam forward of amidships. Its nature, source and or cause could not be determined and presents no immediate concern or action.

When hauled, the vessel’s sacrificial stern plate zinc was found to be wasted. A new plate zinc was fitted. Prop shaft fitted with brush. No visible evidence of alloy breakdown was observed.
The vessel’s keel bolts, where accessible, were visually inspected and hammer punched – filed to observe the condition of the underlying material. Keel bolts were visually inspected and determined to be in serviceable condition. Ownership has been made aware of these findings.

The vessel has steel structural fittings in machinery space – bilge area. Some slight surface rust was observed and should be monitored, cleared, and painted.

Interior areas of bilge, machinery space, and lazarette have been well maintained and found to be clean and uncluttered with fresh paint.

It was observed by the undersigned that the underwater hardware bonding was perhaps causing localized current activity in the vessel’s interior wood structure(s) (evidenced by the production of sodium hydroxide) at the propeller shaft tube - log and most forward starboard along the keel just aft of the stem (under and near an existing bare metal bonding strap). The undersigned advised ownership to clean affected areas with a wire brush - vacuum clean and treat with white vinegar. In addition, penetrating epoxy could be applied as well to stabilize affected area(s). An interesting observation was made by the undersigned as it relates to the production of sodium hydroxide in the forward area of the keel. This activity was indicated with a moderate but material reading on a digital volt meter at or about 30mv DC (the potential between a bronze keel bolt and affected metal fitting, fastener, or fixture), relative to a much lower reading (<3.0mv DC) in areas of no observed sodium hydroxide production activity. In the opinion of the undersigned, the bonding system - strap should be removed and area(s) of wood structure to be monitored. Ownership has been made aware of these findings.

The teak weather deck has been materially sanded to a reduced thickness thus exposing bronze screw fasteners on the port bow. Otherwise, teak deck is in good condition with tight seams.

The vessel’s house is in very good condition with tight windows, hatches, and fittings. No water leakage was observed. The finger hole for the sliding door latch at the aft cabin bulkhead is fractured and should be repaired. The fly-bridge weather deck surface appears to be new with a non-skid composite surface.

At the upper helm, the plywood beneath the forward portside seat was found to be decaying and should be renewed to ensure proper structural support for seat base.

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