So what does the word monitor mean here, I mean why is it used? I associate the word with a broad floating platform for one or more heavy guns with next to no freeboard.

Difficult to say. Doesn't apparently signify anything. It seems this design was the brainchild of Arthur Haver, naval architect, who previously worked for Doxfords and developed the 'turret deck' steamer (which didn't have any turrets!). This was promoted by and subsidised by Doxfords to attract orders. All sorts of advantages were claimed for the 'turret' ship but it was a potentially dangerous design which resulted in ship losses. After leaving Doxfords Haver developed the 'monitor corrugated' hull design which got rid of the problem of low freeboard but was also subject to criticisms. The corrugations were claimed to improve water flow to the propellor and save running costs (doubtful); also to improve structural strength but using less steelwork, though the resulting rigidity produced stresses which gave rise to hull cracking. Owners of the corrugated ships are referred as the 'Monitor Corporation' and the 'Ericsson Steamship Company'. It may be just a coincidence that the USS Monitor was designed by the Swedish engineer John Ericsson.

I understand, it was just the "name of the patent" - whether it was patented or not.

Stein,
Just look at the draft, no freeboard! Maybe an anti torpedo design.
Rgds.
Dave

I just read the text - no stringers, substantial increase in speed etc.

A "faster" monitor design.


Rgds.
Dave

Reminds me of the Spanner "Swirlyflo" and "Sinuflo" boiler tubes