Sunday 2 December 2018

Coach Roof Coamings and Trims



The amount of timber consumed by the build continues to surprise me, pretty substantial rough sawn boards are regularly purchased, sawn and planned to size in my workshop before disappearing into the boat, leaving one wondering where it’s all gone. The coach roof and coaming trims are a case in point, requiring a number of seemingly minor lengths of timber which collectively forms a fair bit of material. The geometry of the cabin and coamings call for quite a bit of bending and twisting of materials to form the composite shapes and lines, you therefore need plenty of cramps available for use.

The cabin coamings are fitted with oval deadlights, specified are two flat bronze rings bolted either side of the coamings and glazed in Plexiglass sandwiched between. I have slightly modified this by substituting the inner ring for one made of sapele, this will be clear varnished along with the coamings. I manufactured these by machining a tongue and groove in two boards, when glued together they produced a single board of sufficient width to machine the rings from. To aesthetically harmonise with other components within the cabin, I machined an ovilo mould to the outer edge. The outer bronze ring is simply held in place by bronze wood screws passing through the plywood coaming into the inner hardwood ring.






On the forward end of the cabin coamings is an angled projection which, to my eye appeared too steep. I therefore requested when ordering the plywood for CNC cutting that this be extended further forward, thus decreasing the angle. I softened it further still by fitting a sapele cap tongued and grooved into the edge of the plywood.




Rubbing strakes and gunwales have also been fitted which, beautifully accentuates the sheer. As a decorative feature I machined a half round recessed mould into the centre line of the rubbing strakes before fading it out to a point around half a metre from the transom and stem respectively. I also carved a small scroll in the fore end between the fairlead and the stem, both of these features will be picked out in black paint before being clear varnished along with the gunwales and toe rails, all of which have been manufactured in sapele. 





I have begun screwing and bolting on the fittings for a dry run. They will all be removed before painting and varnishing then re-fitted with a sealant bed to prevent water ingress between the metal and the wood.



There are two hardwood blocks fixed to the outer face of the cockpit coamings, these provide a firm platform and fixing point for the jib sheet cam cleats. I have also fitted additional smaller blocks further aft to carry rowlocks. The boats transom is designed with a notch to accommodate a sculling oar, however I considered it might be useful to manufacture an additional oar and build in provision for rowlocks, this is a relatively light boat and oars could prove a useful addition. I wanted to minimise the visual impact of both of these blocks and chose to manufacture them with a radius at either end, this created an aesthetically pleasing shape inspired by the design of a capstan which, will hopefully provide additional interest to the build. I achieved this by building up either side of the block stock with sacrificial timbers glued and screwed to a plywood base; they were then worked in my wood turning lathe to achieve a cylindrical design of the appropriate diameter and thickness. When finished I simply cut away the sacrificial timber to reveal the profiled blocks within. 


The starboard blocks fitted to the cockpit coaming. 
Forward the jib sheet cam cleat and aft the rowlock. I have propped the jib sheet block to give an idea of its position.


Port side rowlock support block. The deck has been reinforced below both blocks either side.