by
Stuart M Roy
Naval Architect and Surveyor
Stuart M Roy
Naval Architect and Surveyor
YACHT & POWERCRAFT DESIGN SERVICES
Yacht & Powercraft Design Services Ltd
Email: info@yacht-designer.co.uk
Tel. 44 (0) 1489-583346 Fax. 44 (0) 1489-583346 Mobile 07803-724317
Email: info@yacht-
Tel. 44 (0) 1489-
An almost invisible crack (1) below the port tube on this RIB indicates a potentially serious structural problem. The tube support structure is beginning to break away from the main floor structure. An aluminium stanchion base (2) with a brittle fracture probably caused by snagging the lifelines when coming alongside.
It is inadvisable to have a large gap between the rudder top and the underside of the hull (3) as it reduces the rudder efficiency, allows ropes to become jammed in the gap and increases the bending moment on the rudder stock. The brass sleeve on this fluted rubber stern tube bearing (4) has crumbled away due to galvanic action between the brass and other parts of the sterngear, which were inadequately bonded by cables to the anode.
Although the varnish sealing layer on this gunwale capping has failed (5), the wood underneath is perfectly sound and should come back to its former appearance after stripping and treatment. A surveyor’s work is not all about defects. When assessing the value of a Ray Hunt designed powerboat from 1970, it was noted that the spray rails (6) are still sharp, undamaged and in excellent order.
Crevice corrosion on a propeller shaft (7) can account for vibration problems and leaking at the stern gland. The wiring (8) on this yacht is installed in a random and haphazard manner. Also damp has been able to reach the connectors. Following the survey a number of recommendations were made to the new owner.
Some catastrophic failures. A rudder stock from a motor boat after its blade was lost at sea (9) and a fractured fin from a windsurfer (10) - what do they get up to?
The GRP sides from this rudder (11) have broken away leaving a bare stainless steel stock and the foam filling. The crew were fortunate to be able to get home safely.
It is inadvisable to have a large gap between the rudder top and the underside of the hull (3) as it reduces the rudder efficiency, allows ropes to become jammed in the gap and increases the bending moment on the rudder stock. The brass sleeve on this fluted rubber stern tube bearing (4) has crumbled away due to galvanic action between the brass and other parts of the sterngear, which were inadequately bonded by cables to the anode.
Although the varnish sealing layer on this gunwale capping has failed (5), the wood underneath is perfectly sound and should come back to its former appearance after stripping and treatment. A surveyor’s work is not all about defects. When assessing the value of a Ray Hunt designed powerboat from 1970, it was noted that the spray rails (6) are still sharp, undamaged and in excellent order.
Crevice corrosion on a propeller shaft (7) can account for vibration problems and leaking at the stern gland. The wiring (8) on this yacht is installed in a random and haphazard manner. Also damp has been able to reach the connectors. Following the survey a number of recommendations were made to the new owner.
Some catastrophic failures. A rudder stock from a motor boat after its blade was lost at sea (9) and a fractured fin from a windsurfer (10) -
The GRP sides from this rudder (11) have broken away leaving a bare stainless steel stock and the foam filling. The crew were fortunate to be able to get home safely.
Examples from Yacht & Boat Surveying 1
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