MAY 2015 TOOLBOX VISIT

‘BLUE RIBAND’ and a WHOLE LOT MORE

Our May Toolbox visit was to the premises of AJW Shipwrights in Lerista Court, Bibra Lake. It was very apparent from the start that our host, professional shipwright and director of the company, Aaron Woodall, had put a lot of thought into providing us with a structured visit to his premises with not only the opportunity to inspect a range of works in progress but a very informative commentary/technical talk throughout the afternoon.  Aaron also kindly put on a very much appreciated afternoon tea during a break in proceedings.

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Aaron commenced by describing his business as a timber/composites boat specialist and he certainly has the facilities to go with that function.  The premises themselves – only two years old – are palatial. Designed to accommodate up to a 70’ vessel, the sliding access doors measure 8 metres by 8 metres. Apart from substantial storage for materials which Aaron purchases by the container load there is also a separate permanent machining shop.

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The afternoon commenced outdoors with inspection of a lap strake or clinker construction dinghy which had been purchased second hand with the intention of it being used as a tender for Pollyanna, a 60 foot Halvorsen classic cruiser which Aaron had completed a major restoration on in 2006.  However, the dinghy’s condition has now been assessed as not worthy of restoration and the full lines and details have been taken off so that construction of a new dinghy along similar lines can proceed.

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The other outdoors project we inspected was a 24ft Scruffie design (see www.scruffie.com ) which was completed as a bare hull upside down awaiting fit out. This boat had been completed to a basic timber hull stage by the owner who has now enlisted Aaron to assist with further progress.

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We then moved inside to inspect the current major project. This boat – Blue Riband – is a 35 ft Raymond Hunt designed sports fisherman type built in 1968. She has a deep V design typical of these boats primarily designed for game fishing when it was a relatively new sport. The work being carried out on Blue Riband comprised a complete replacement of the bottom and reinstallation of engines, rudders stern gear and associated engineering. This had become necessary because the original laminated bottom had begun to leak and on investigation was found to be substantially water logged due to age and the onset of delamination.

The technique was to remove all but the inner most original plywood lamination and commence a rebuild from there. This involved cold moulding multiple layers of ply diagonally and continuous across the bottom of the vessel from chine to chine. The resultant hull is 28mm thick on the sides and 34 mm thick on the bottom with some thickening around the bottom below the engine beds. The design uses the ply curvature to reinforce the structure of the hull and the substantial jarrah keel was internal.

At the time of our visit, the vessel owner and friends were applying the first colour coating to the bottom. This will be followed by reboring of stern tubes for the two diesel engines and installation of all the engineering systems including the rudders, all of which had to be removed to accommodate this major rebuild process.

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Aaron’s description of the works being done on Blue Riband and our inspection of the project led nicely into the next segment of our visit in which Aaron stepped us through some of the techniques that are regularly used in a specialist and  traditional boat building business such as his.  He commenced with an explanation and display of the tools used for drilling out a deadwood or the like prior to fitting a stern tube for a propeller shaft.

This process commences with the drilling of a pilot hole to accommodate the boring bar using an auger or spade/shell drill bit. The boring bar – in this case a round steel bar of about 25mm diameter – is fitted along its length with radiating square cross section cutting tools retained with small set screws which facilitate adjustment of the diameter that each cutter will generate. The projection of these cutters is adjusted along the length of the boring bar so that there will be a pre-determined increase in the diameter of cut from one end of the bar to the other. Each end of the boring bar is mounted in bearing blocks and the cutter arrangement results in the diameter of the stern tube hole be increased as the boring bar progresses into the deadwood being machined.

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When this main stage of the process is complete, a faceplate cutter is fitted to the boring bar and similar cutters mounted thereon are used to face off the area around each end of the stern tube hole so that it is square to the hole ready for accurate mounting of the stern tube flanges. The boring bar is powered during this process by a slow speed, high torque power tool. A similar process is adopted when required to accurately drill a tube for a rudder post.

In the next segment of this most informative Toolbox afternoon, Aaron set the scene for a demonstration of lap strake construction later in the afternoon. This was centred on his collection of different planes and chisels, their specific uses, blade materials and sharpening techniques. The specific tools used to create lands and gains for lap strake construction are the rebate plane and carriage maker’s plane. Aaron uses both English and Japanese tools, the latter requiring the artisan to work towards rather than away from him/herself. One needs to use a plane that is no wider than necessary for the job as these get very heavy when working professionally over a longer period of time – No 2 and No 4 planes are used most regularly in the trade. Other tools mentioned that are used along the way are low angle planes and short butt chisels.

There are three alternative materials that can be used to sharpen the blades for all these tools – diamond, natural water stone or manufactured stone. In the trade it is important to use blades made from the best tool steels available. Aaron indicated a preference for Sheffield (English) tool steels with superior hardness, which is measured on a Rockwell scale. A good number to look for is a blade with tool steel Rockwell Hardness 64.  Aaron mentioned Veritas & Lee Valley as a brand to look at (see www.leevalley.com and click on the ‘woodworking’ tab).

An important point to note for amateurs was that cheaper, general purpose blades should not be sharpened on a stone with too fine a grit as this forms a burr on the cutting edge that subsequently breaks off leaving a less than desirable edge on the blade.

Following a break for afternoon tea and eats which Aaron kindly provided, he commenced the demonstration of lap strake construction with specific relevance to the fairing in of the planks to fit flush at the bow and transom of the vessel.

The process commenced with the marking of the land and gain using a marking gauge so that the overlapping planks had an overall thickness that tapered from two plank thicknesses to one over a chosen distance from the stem or transom as the case might be. The rebate equal to half the plank thickness was then planed into the face of one plank and the reverse side of the other using a carriage maker’s plane.

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The joint then needs to be nailed together. This requires the use of copper nails and roves. Aaron recommended that for plywood, the drill size should be equal to the shank size of the nail – noting that our nails are generally square but in the US they use round copper nails. For hardwood timbers such as jarrah, the hole size should be one drill size bigger than the nail shank size.

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The nail needs to be driven with the minimum number of hammer strokes to avoid bending the nail. If the nails are to be a feature, then they can be set just to the timber surface. Otherwise, they should be punched into the first veneer. For hardwoods, this may require the hole to be countersunk prior to driving the nail.

The next part of the process requires a dolly (with a spring loaded counter weight) to be held up to the nail head and a copper rove driven over the nail from the inside with a rove punch. The nail is then cut off at a distance equal to the nail thickness clear of the top of the rove. With the dolly in place the cut off end is then hammered over and rounded off with a ball pein hammer.

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ABBA members ‘having a go’ at nailing, roving and holding up on the dolly

The final demonstration for the afternoon was the caulking of the planks in carvel construction – an alternative to the lap strake method. Aaron pointed out that we should use modern caulking cotton as this is compatible with modern sealants. The caulking line goes only half way through the plank thickness and is created on only one of the pair of planks to be caulked. For smaller boats – less than about 12 feet – the cotton can be rolled into the seam using a roller similar to that used to repair fly screens. However, for larger vessels there are specialist tools known as caulking irons which come in different configurations for different uses. There are ‘raking irons’ for cleaning out the seam prior to caulking, ‘making irons’ for driving the caulking into the seam and ‘finishing irons’ to smooth over the caulking and prepare it for the putty or sealant that follows.

Before commencing to caulk the seam, the cotton off the roll needs to be sized to the seam to be caulked. This involves selecting enough strands of the cotton so that when spun or twisted together, the size is just less than the seam width. The caulking can then begin by forming tufts and then driving them in with the iron using a caulking mallet. The caulking is driven in to about half plank thickness and it is important not to drive it too hard. This will depend on the seam width and the depth of the caulking line.

As the afternoon drew to a close, Aaron returned in some sense to where we had started. Laid out on a sheet of MDF on top of an adjacent workbench was the full size lofting of the clinker dinghy that we had inspected at the commencement of our visit. This was the starting point for the recreation of a new dinghy of similar lines. Aaron pointed out that the lofting allowed some movement in the old timber dinghy to be corrected to the original lines. It also allowed him to do full size design of some of the detail for the construction phase. This was a very pretty traditional shaped dinghy and it will be very interesting to see the new version which will no doubt be built to the highest standard which is apparent in all of Aaron’s projects.

This was a most interesting Toolbox afternoon. I’m sure all those present learnt a great deal from Aaron’s most informative commentary on such a great range of subject material. ABBA thanks Aaron for contributing his valuable time and so willingly passing on his knowledge of his trade for the benefit of our members.

Very Important Footnote!

As well as the projects undertaken by his two businesses – AJW Shipwrights (www.ajwshipwright.com.au) and Legacy Nautical Boat Builders (www.legacynautical.com.au), Aaron is a supplier of a number of quality products which all of us building boats will need at some time. This includes boat kits as well as certified marine plywood, silicon bronze and stainless steel fastenings. All these products and more are detailed on the above websites so please support Aaron if you need any of these items.

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