I was not overly happy at the arrangements for the cooling water intake. Its done through what's known as a Mud Box.
The primary strainers on the hull had no way of being unblocked without getting wet.
Original strainer inlet
I asked on a Canal Forum and it emerged there's a better way which enables the primary strainer to be cleared from inside the mud box.
This meant cutting out a larger single hole in the hull.
Hole cut, viewed form inside the mud box
Then to make the internal strainer.
First a template
Then a 4mm plate cut to the template
Then several hundred 5mm holes
This strainer fits where its shown above. There will be some guides to locate it ans it will be removable for easy clearing.
So thanks for the discussion on The Canal World Forum for this modification.