Monday, 17 October 2011

Cutting holes in the hull.

So, having more or less finalised the interior planning, bulkheads (walls), wiring runs, pipe runs etc., we were able to start cutting the holes.  Windows, portholes, hatches, vent pipes and skin fittings.  Skin fittings are pipes through the hull to let out/in water, gas/air.  I was keen to have as few holes below the waterline as possible.  The engine is cooled by a heat exchanger welded into the hull side so no holes for the engine cooling.  All sinks and showers are above the waterline and only the propeller shaft is left below.  This has an old fashioned stuffing seal, yes they can dribble but are far less prone to catastrophic failure, in my opinion of course.

Having marked the position of the windows and designed them I had to then make them.  I used 5mm mild steel angle and had the curved top rolled by a local firm.  They did this two long lengths and I cut off the section needed.  These were then welded up and painted with a holding primer, ready for fitting.

 That was the windows out the way, next the ports.  In order to make the ports I had to get some steel to fabricate the angle as it was not possible to roll the radius I needed locally, if at all without too much distortion.  I used the steel cut from the cabin sides when fitting the main windows.

There were 11 of these so steel was plentiful.  The rings were cut using a 41/2" grinder (115mm) using a thin cutting disk.  Thin disks my be more expensive but I reckon I used less.  I prefer the small grinder as the 9" is not as handy and can kill you rather badly.  So once the rings were cut, strips of steel were welded round the outside. The heat from welding enable me to just use hand pressure to bend the strip to the ring after a rough circle had been fashioned.

The final fabricated angle was ready for cleaning and priming.

There are 11 windows and 5 portholes and the making and fitting of the frames to the cabin took some time but I got there in the end.  Most barges seem to have much wider windows that the ones I made.  I chose ones that would fit between the frames of the boat.  Wider windows would have meant cutting (weakening) the structure of the boat and I was not keen on this idea.  You can see what I mean in the picture below.

 I ended up spacing the windows every other frame and not one frame was harmed in the making of this barge.

I guess it is a matter of taste but I rather like this style over the wider types.  Note that none of the windows open.  Research has shown that opening windows leak, especially the narrowboat hopper types.  This barge is on the salty side and waves and wind will make water go were it doesn't normally go on the inland waterways.  The glass units I had made up by a local firm and I what I should have specified was 6mm toughened with a 12mm air gap and a 4mm toughened pane on the inside.  It is important to specify this 4mm for the inside and I made a mistake initially and had 6-12-6.  The unit was so stiff the seals blew and the panes filled with water.  The 4mm inside pane allows the pressure to alter by bending the thinner pane.  The units are simply stuck into the frames using a proprietary adhesive sealant with suitable primers for paint and glass.  Window technology has come on in leaps and bounds recently.  The marine sector is lagging behind a bit except for the very high end of the market.  Today one can get thermally broken frames and coated glass that make them so much more efficient.  The idea of bolting aluminium to the outside and having it connected to the inside frame thus creating a cold bridge just didn't seem right to me and everyone who has them complains about copious condensation and the cold frames.  But not everyone can afford aircraft grade honeycomb composite structures that are very light and very strong to make their window frames out of.  Because of my mistake in the glass thickness all of the lower units are due to be replaced with 6-12-4 using thermal spacers and low e glass.  This will significantly improve the windows thermally and hopefully get rid of the slight condensation I get at the very edges of the window where the present metal spacers act as a cold bridge.

The other thing that is perhaps wrong with the picture above is the stepped bottom line of the frames.  With wider windows it is possible to follow the curve of the deck (sheer line) which looks rather nice.  My narrow windows only just fit between the frames so this was not possible.  This step line can be disguised by taking the black deck paint up the cabin sides to cover the bottom of the windows.

Next were the hatches and these were fairly simple rectangular steel surrounds fitted between the framing of the cabin top.


  Sections of heavy gauge pipe were welded through the cabin top in seven places to provide ventilation and extraction.  The pipe was sized so that 110mm pvc drainage pipe could be used as a liner.  Temporary hatch covers were made out of pine and ply and given a quick coat of paint.

This is the main hatch and is 3' x 5' and is covered by the rather handy Land Rover short wheel base roof.  Being aluminium it is nice and light and has done sterling service until the dome arrived.  The hole is big enough to get 8x4 sheets below and the huge sofa.

It would be lovely to have a traditional wooden varnished skylight.  But even when new and built correctly they leak.  Even the local shipwright said he couldn't make one that wouldn't leak.  Everyone that has them covers them up in canvas.  1 - to stop the leaks and 2 - to protect the lovely varnish.  To me this was pointless and I went for something completely different and unheard of.  A triple skinned plastic roof dome with remarkable insulation properties and it doesn't leak!

Here it is at Christmas time with snow on the decks.  It took a couple of days before the snow melted on the dome but this is as far as it got.

The dome opens on a double brass screw jack from Black Country Metalworks.  It has a spring loaded quick release so that it can be opened fully for access or serious air.  This together with the front and rear escape hatches and the pipe vents are enough to keep us nice and cool in the northern European summer.

We did consider electric openers and even ones that opened when it got to a certain temperature and shut when it rained.  Perhaps simple is best in the end and it certainly looks nice in a Fred Dibnah sort of way.

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