Before we started
WIth the vision of restoring SV Mercury to her former glory, detailed consultation with the original design diagrams of sister ship Albatross II sourced from the Thesen Family archives in Knysna, as well as with Dave Cox in Durban, skipper of Mercury (aka Mainstay) in Rio '73.
Stripping & exposing
The initial team comprised timber craftsmen with wooden boatbuilding experience; including Keith Barnes, Edward Walker and Dries Moolman.
Replacing & improving
By the mid 80’s rainwater penetration down Mercury's mast caused wood rot to the keelson and in 1986 a maritime services team in Durban, under Rob Sherlwood designed and installed a lightweight reinforced aluminium frame that would keep the keel in position and replaced the original I-beam holding everything together. Eventually after 25 years, electrolysis set in and wood rot was discovered right through the hull sections covered by the chain plates. Rebuilding these cold-moulded hull sections, skeleton and cockpit floor to original timber laminated specifications became the most sustainable solution going forward; but the task would be most demanding for appointed master carpenters Dries Moolman and Keith Barnes.
A high quality timber; grown in West and East Africa, Iroco with its natural oils, colour, texture and hardness so similar to teak it even smells like teak, was the wood of choice. Iroco has medium bending and crushing strength, very low stiffness and resistance to shock loads. The material would works satisfactorily with hand and power tools but with a moderate blunting effect on cutting edges. Iroco nails, screws and glues well, and would provide an excellent finish.
The high load of Mercury’s cold-moulded mahogany hull including the 3.6 ton keel needed to be resisted by robust stiffeners including boxed beams bonded to the bolted centreline I-beam and the new transverse (sheer to sheer) laminated wood ribs and stringers also bonded to the hull. Two of the ribs were extended all the way up to the deck, level with chain plates to secure this structureso as to share the load between deck and hull skin and to stand up well in hard weather. This reconstruction effectively shifted the diagonal leverage of the keel bolts to the laminated frames dispersing the load to the hull skin. Whilst great care wastaken to bond wood laminates with epoxy adhesive, Mercury would still rely on the stainless steel bolt fasteners (well bedded with epoxy to avoid water ingress) to increase strength and improve load carrying capacity of the I-beam.
The polyester resins in the 70’s were not good compared to the more expensive, durable epoxy resins of today that just last forever. Dave Cox, Mercury's skipper for Rio '73 was staggered that Mercury is still alive in 2012.
The increased adhesive properties and resistance to water degradation of Ampreg 21 made it ideal as a laminating epoxy resin for restoration of Mercury. Epoxies differ from polyester resins in that they are cured by a 'hardener' rather than a catalyst.
Engine power to weight ratio, performance and reliability cannot be emphasised enough when navigating the many precarious sea ports and harbours of the world; especially The Knysna Heads. Three engine models were identified and carefully evaluated, with a Nanni Diesel being selected as most suitable for Mercury’s intended use. The cost of the new engine alone exceeded the full cost to produce the original Mercury in 1970.
The Nanni Diesel 4 cylinder marine engine incorporated the the latest Kubota innovation which was particularly well suited for a displacement drive sailing yacht. The new engine was equipped with an E-TVCS combustion and injection system, considerably reducing particulate emission and smoke while dramatically improving fuel efficiency. Furthermore, this engine also complied with the most stringent emission regulations in the world: EU-RCD, US-EPA and BSO. A special coating of the pistons with molybdenum also lowered friction and reduced engine vibrations resulting in supplementary comfort concerning the sound levels.
The new engine was installed under the advice of Dorrien Keown and Roger Clancey of the Knysna Yacht Club.
Preparation to rebuild Mercury’s engine mountings, sound proof the engine room, reposition batteries and power cables, redesign electrical and lighting layouts has kept the restoration team bustling about with both tensions and enjoyment amongst artists, craftsmen, engineers, suppliers, contractors and project team members. An advanced Quash sound deadening fireproof and waterproof polymer material was sourced to line the engine room bulkheads to significantly
further reduce vibrations and noise.
LED lighting throughout will all new light fittings as the 42yr old fittings had perished for the most. A new miltary spec VHF cable, with fittings new aerial and installed to an Icon Mobile VHF Radio.
Mercury was blessed by the volunteer professional guidance and assistance from former skippers, boat building specialists and yachting experts, including Jannie Thompson former factory manager of Thesen Boatbuilders who built Albatross II in '70, Graham Barry former electrician at Thesen Boatbuildres who wired Albatross II in '71, Bruce McCurroch who skippered and crewed extensively on Mercury including Cowes Week '71 and Dave Cox who skippered Mercury from cape to Rio in '73.
Repairing & maintaining
Mercury’s aluminium mast revealed erosion of the anodising combined with small spots of corrosion due to electrolysis in various places including the base. With one inch then cut off the base to remove the corrosion and strengthen, followed by an oxalic acid wash and rinse, dutiful roller application of Plascon EpiWash two part epoxy primer ensued and the mast was now ready for a roller coat application of Awlgrip’s high quality (high priced) durable two-part polyurethane top-coat, slightly tinted to reduce glare and gloss.
Paint stripper, sanding and reworking sections where previously repaired mahogany deck area required new resin fill and matching of surface levels, followed by applying a 2k filler primer coat, further sanding and levelling to create the new deck surface. Sealing and effectively coating teak toerails and trim was completed before marking out and recoating the deck with a two-part resin flowcoat system.
The hull repainting and antifouling phase required careful and significant coordination as two teams had to execute repairs and maintenance at the same time; viz. Sea Services (Roger Clancey & team) working below the water line and Bentwood designs (Roger Hart & team) coating above the water line.
Assembling, setting sails & engine trials
A new set of sails; genoa, main & spinakker.
Operating from Knysna