News

27th December 2010


CAP RAILS

Traditionally, enhancing a vessel to a “yacht like” standard required fitting lots of timber to the exterior, teak decks, highly varnished cap rails and hand holds for example. This was true for steel, GRP and Aluminum boats; there was a need to imitate wood. However these require work to keep looking good, varnish or oil. Today’s preference is for a vessel that requires little external maintenance, preferably restricted to fresh water wash down.



To this end we have experimented with various options that would eliminate work yet remain “yacht like” while also serving to protect the steel and paint system.

One of the advantages of steel is the number of “allies” or companion materials that are happy working alongside it to contribute towards the finished product.

Stainless steel is one of these companions. Not only can it enhance the vessel but it is also the perfect material to use in areas that may be subject to abrasion.



A decade ago we looked for an option to use as a cap rail for the bulwarks on our vessels. Until then we had typically used rolled hollow section – box section – mild steel, painted. This has limitations being in an area were the paint is vulnerable to damage. Also box section is not very “yacht like”. Where wood – teak – be used traditionally it would be shaped into a profile that would be pleasant visually and to touch. We wanted to duplicate this.

There were some stainless steel profiles available including an oval section from a manufacturer in Korea. However none met 100% of our requirements. The solution was to design the sections we wanted and have a set of rolls made that would flatten schedule pipe into an oval profile.

This was not an inexpensive exercise. Anything in the marine industry that is non standard or not “off the shelf” never comes cheaply. Yet it is this extra effort that lifts the vessel up out of the morass of ordinariness; detail being what good design is all about.



The rolls we manufactured are used in a machine at a factory that specializes in the manufacture of stainless tubing, mainly for the food industry. The photo above shows the rolling machine in action.



And here is the finished shape emerging after being extruded through five sets of rolls.

Of course a boat has, or should have, shape. For cap rails this means shear, deck camber and deck line shape.

The shear and camber we can deal with on the vessel. But for deck line we need to edge set the profile before we can begin.



To edge set the profile we go to a jobbing shop that specializes in rolling steel sections for architectural and industry use. A set of pipe rolls perform this function, working from full size patterns taken off the vessel under construction. In the photo above the transom shape is being wheeled into the profile.



A shop like this is always interesting to visit for the variation of work they perform.



Like this heat exchanger coil that is being rolled from 3 inch schedule steel pipe. Each new 20ft length of pipe is TIG welded to make a continuous length.

The welder in the photo is running three runs of weld in each join which is required to withstand the compressive and tensile strain the pipe is subjected to as it is cold formed. A TIG weld is the Rolls Royce of weldments and a trade in itself.



The shaped lengths are then fitted to the vessel and polished up.



The deck access door is cut out with the cap rail nicely capped on the ends.





Incorporated into the cap rails are our tie up posts. We prefer not to use deck level bollards or sailboat type cleats. This avoids being on hands and knees when tying up. Also these posts are strong enough that they can be used for towing. And of course they are a traditional motor boat feature.



Once all the stainless steel fittings are completed and every weld required has been run the structure is then readied for abrasive blasting and paint system application; something that we will look at later.

Regards,
Pete

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Last Updated (Friday, 04 March 2011 00:41)

 
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