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A Widebeam Called Cettia
This webpage describes the building a a widebeam narrow boat, called Cettia, for a London mooring. The boat was built at
Sharpness Shipyard and Drydock. All the steelwork was done by the Shipyard itself, as was
internal battening, plywood flooring and external painting. The fitting out was done mainly by the Swing Cat team.
The pictures below, and the text alongside, give an overview of the build. There are also plans and construction details. |
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The beginnings of a new kind of widebeam narrowboat. It sounds a contradiction in terms - "widebeam" and "narrowboat" - but these are the terms used to describe a narrowboat which is wider than normal. A narrowboat built for the British canals is normally 6' 10" wide. Widebeams, like Cettia, are 12' wide. It is a "new kind" of widebeam because most widebeams are cruising boats that can be lived on; Cettia is designed primarily for living on, but can be cruised. It is essentially a houseboat that can move using its own engine. The picture shows the bottom plate being constructed from 10mm thick mild steel sheets. Top of Page 
It looks like we are building a big steel box! The straight sides are all part of the plans. Most canal boats have side decks and tumblehome topsides - i.e. sloping cabin walls above the sidedecks. This looks nice and makes the canal boat easy to cruise but complicates the fitting out; we wanted to make the fitting out as easy as possible. Top of Page 
The bow showing the 75mm angle iron being used as bracing everywhere. You can also make out the raised companion way on the aft end of the coach roof. Note, the edge of the angle iron, rather than the flat, is welded to the hull, to avoid water getting wicked into small spaces between the steel plate causing rust. Top of Page 
The bottom plate being welded by Dave. The shape of the companionway is more obvious here; it posed a considerable engineering challenge for the engineering manager, Steve; i.e. how to cut a curved steel sheet to neatly join another, differently curved steel sheet - at an angle! Top of Page 
The raised companionway allows for nice big, tall doors, so people do not need to stoop going into the main cabin. Raising the coachroof is not required at the bow since the foredeck is much lower than the aft deck. Top of Page 
Cettia is craned into the water to check for leaks and for trim. Top of Page 
The insides have been shot-blasted, primed and battening has started. Double-glazed windows have been added from Caldwells Windows. Top of Page 
The rails around the aft deck have two gates in them. The scuppers in the gunwale, going around the aftdeck, allow for drainage of rain water. Top of Page 
Plywood flooring has been installed and the boat is almost fully-battened. Sixty-five mm of Polyisocyanurate (PIR) foam insulation is being added to the walls. The pipework is for the Mechanical Heating and Heat Recovery (MVHR) system. Top of Page 
The walls are now clad with "Weather & Boil Proof" (WPB) 6mm plywood and the curved ceiling with tongue and groove to give a boaty look. The original idea was to simplify the electrics by using 240V throughout, as Cettia will be connected to shore power. However, there was not enough room between the ceiling and the deck to fit 240V LED light fittings. Also 240V pumps are too big for a boat. So, a mixture of 12V and 240V systems were forced on us. For further information see the construction details. Note the solid Iroko doors now fitted. These lead from the bedroom onto the foredeck. A better view will be seen later. Top of Page 
Cettia's mooring dries out; about half of the time the boat is resting on its gravel campshed. The bottom plate is 10mm thick but, nevertheless, it was decided to protect it further against physical corrosion by using grounding bars. To protect against electrolytic corrosion, specifically stray current corrosion, Cettia also has an isolation transformer. Top of Page 
A view of the shower room showing tiling in progress. There is also a separate lavatory. Above the shower is an MVHR vent to extract the warm, moist air and vent it to the outside via the system's heat exchanger. There are also extraction vents above the cooker and in the lavatory; supply vents are in the two cabins. Top of Page 
A side view of Cettia on the transport. She weighs 15.2 tonnes. Top of Page 
Stately progress through Kingston. The Yamaha, at 2/3rds full throttle, gave us a cruising speed of 3 mph! At this point the Thames is non-tidal but, after Richmond lock it is fully tidal. Since the tidal flows can be strong, careful planning was required: we needed an ebb from Richmond and the end of the flood for the final approach to the mooring! Top of Page 
The view from Cettia looking East, towards London, with a fine view of Kew Bridge. Top of Page 
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Some important things have to be decided early - like the curvature of the roof. Top of Page 
That big steel plate is going to be the aft deck. Most narrowboats have self-draining decks, which inevitably get clogged up and leak rain water into the engine compartment. Cettia has no engine compartment; underneath the aft deck are electrics, a water tank, a Mechanical Ventilation & Heat Recovery unit and general storage - basically stuff that can't get wet. A one-piece aft deck ensures a watertight space underneath. Top of Page 
The boat is built by "chalk and talk", plus a few plans. Top of Page 
Cettia is now out in the rain and cold, with the steelwork almost finished. The combination of a raised bottom plate at the bow, curved gunwales leading up to the coachroof, grab rails and coachroof overhang contribute to a definite "boaty" look, despite its intended use as a houseboat. Top of Page 
The inside of Cettia before shot-blasing, priming and putting in windows. The shot blasting is required to remove mill scale and rust. Mill scale is the flaky surface left over from the manufacturing of hot rolled steel. The view is looking forward with port holes to port and rectangular windows to starboard. Top of Page 
Cettia is now coming out of the water. From the visible waterline, one can see that, despite weighing 12.5 tonnes, at this stage, the draught was only 12 inches. Top of Page 
Both coloured paints are primers. The rectangular windows are bigger than the portholes on the port side and will be facing south over the river. Top of Page 
One key feature of this design is the atrium over the main cabin. Here the frame is in place. It will be filled with high-specification double-glazed units: low emissivity, argon filled & self-cleaning. The idea is to create lots of light inside the main cabin and to make the most of the mooring's south-facing position to maximise solar gain whilst minimising heat loss. Top of Page 
The MVHR system has a number of benefits:
Top of Page 
The Yamaha 9.9HP outboard motor is fitted and tested. It is designed to drive heavy craft slowly rather than light craft quickly; it has a extra long shaft and high thrust gearing. Top of Page 
The main cabin, almost finished. Top of Page 
Stern view of Cettia on the transport which took her from Sharpness, up the M4 and around the M25 to Shepperton Marina. An escort was needed for the last bit of this journey, on minor roads approaching the river. The Yamaha 9.9HP outboard motor looks far too small to drive such a big vessel. Notice the rudder strapped to the back of the outboard to help with the steering - this is the only rudder! Top of Page 
Just after craning her in at Sheperton Marina on the Thames. The journey to the mooring at Kew Bridge is about 16 miles and we have to go through 4 locks: at Sunbury, Molesy, Teddington and Richmond. Top of Page 
Made it! The mooring, Ciconia, at low tide. The tidal range at Springs, at this point in the Thames, is over 5m and was so on the day of travel (11th September). The journey from Shepperton took us about 6 hours and we needed a temporary mooring overnight before we had enough water to get onto Ciconia. Outside Cettia is Kamelya; both sit on brand new, and very expensive, campsheds - necessary so they dry out level. Top of Page 
Here is one interior view of Cettia. For more views please visit our Airbnb listing. Top of Page |
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