Replacing the flue collar on a Morsø Squirrel

The Morsø Squirrel range of solid fuel stoves is probably the most popular for narrow boaters. It's compact, gives off the right amount of heat for a cold metal boat of 40-50 feet long and has few things that can go wrong.
Ours, however is 20 years old and starting to show its age. This picture shows the stove in situ ...

... and closer inspection shows the collar that joins the flue to the stove is in bad shape.

I had filled the gap with fire cement but this may have made it worse by restricting natural expansion and now the collar has broken into three parts.
As a stove potentially gives off poisonous carbon monoxide this is Not A Good Thing, so we planned to fix it.
The first thing needed was a flue collar

and the lugs and screws for fitting it. I bought ours from Bowland Stoves which is the parent group for Morsø.
First we examined the top of the flue because we were unsure how that was fitted and it would be necessary to raise the flue a few inches to insert the new collar. As it turned out we need not have worried, as it was held in place by packing, insulation and mastic rather than troublesome bolts. It should be able to simply slide up if the packing is loosened so there was no need to unscrew the circular panel around the flue, which appears to be there to tidy up the edges of the ceiling panels.

You can see how the flue disappears into the cast iron chimney collar (that's the one that emerges outside the roof of the boat) and the fire rope packs it in place.
We were now able to knock away the broken old flue collar and its fire cement, revealing the bottom of the flue where it joins the stove.

Now it becomes clear that there is a simple hole in the top of the stove, which we cleaned up with a wire brush. We also found that there was a baffle inside the stove - created to direct the hot gases - but which had accumulated 20 years of non-combustible material on its top surface. This was cleared out from inside the stove before going any further.
The collar has two tabs and by inserting the two screws and screwing loosely to the two lugs we were then able to lift up the flue a couple of inches and slide in the collar with its screws and lugs in place. This took two of us - one to lift the flue and the other to slide in the collar.

This closer view shows the collar in place with the screws visible. Before the flue was put back into place the lugs were placed under the top surface of the stove and the screws tightened to hold the collar firmly in place. Note that there is a long end and a short end to the lugs and it's the long end that should be placed under the edge of the hole. So the screws hold a sandwich with the lugs at the bottom, the stove top next and the collar tabs at the top. A clean surface to the edge of the hole in the top of the stove ensures a good seal.
Finally, the bottom of the flue was placed firmly back in the centre of the collar, the small gap between flue and collar packed with fire rope and we ensured the top of the flue was seated neatly into the chimney collar, packed firmly and made waterproof from the outside with mastic.
All in all this took us a bit over an hour and the biggest problem was washing our hands and arms of soot! We will, however, monitor the gases from the stove with our CO sensor as no risks should be taken with gas and stoves.

I strongly recommend the pdf file "Installing Stoves in Boats" by SOLIFTEC.
See also the Boat Safety Scheme Advice.
And Morsø's own installation guide.
See also our blog entry on re-seating the blanking plate on a Morsø stove.