Chimaera Built by Brian Caesar

Boat of the month January 2023

Chimaera by Brian Caesar

Chimaera was a steam powered pilot boat working out of Barry, South Wales in circa 1913. My model is a representation of that boat built using a plank on frame construction and powered by a Libra double acting oscillating steam engine coupled with a horizontal boiler. The overall build time was in the region of 2,000 hours.

The hull was built in two halves, split along the hog. A jig was used to keep each rib or frame correctly spaced and in the right orientation then clad using individual planks. The hull was first planked in beech as this is a stable hardwood. Then a second skin of planking was applied consisting of mahogany from the hog to water line, a single plank of beech to denote the water line and then walnut from the water line to gunnel. Then both halves brought together and glued along the hog. At this point a non-lube prop shaft was also installed. Followed by many coats of varnish. The deck was again constructed from individual planks of beech with walnut planks on edge between the horizontal planks to produce the effect of caulking. The superstructure is also walnut.

The main challenges faced were:

Maintaining contact between the planking and ribs while glue dried without damaging or pinning the planks. To overcome this, I made some temporary horseshoe shaped frames which closely followed the shape of the hull and placed wedges between these frames and the individual planks at each intersection of plank and rib. This made planking a slow process but worked very effectively. The rudder. Due to the "swept" stern and finished Well Deck level, there was very little room to house a robust rudder arrangement and servo linkage. A 4mm brass tube was inserted vertically through the hog and epoxied in. A small block of hardwood was then fashioned to straddle the hog and encase the brass tube, again epoxied in and adding strength to a potential weak area of the hull. The rudder stock was then passed up through the brass tube and a tiller and servo linkage attached.

The electrics. Due to the engine and boiler being enclosed below decks there was the potential for the electrics to be affected by the steam. I have therefore used waterproof Etronix servos, enclosed the batteries and receiver in plastic cases, shrink wrapped exposed connections and created as much ventilation as possible by opening hatches and adding a hatch to the saloon roof.

The funnel. Whilst the white funnel is really just for show, it must be capable of withstanding the high temperatures created by the working funnel and steam whistle housed within it without discolouring or deforming. In addition, it must be capable of being removed with the superstructure to enable maintenance of the steam plant. This was made from a copper tube which I had powder coated locally which gave a consistent and heat resistant finish. The brass capping ring was made for me by Alderson Engineering, another local and very accommodating company.

And finally, the ongoing challenge of getting the burner lit, maintaining boiler pressure, keeping gas jets clean and fixing steam leaks which I'm sure many of you will have seen me struggling with each weekend!