Can I draw your attention to the photo that you posted of the idro and point out a few differences to the IDRO that I originally posted. The Idro in your photo has a platform stretched between the floats ,however this may be merely cosmetic. The idro in my posting has at various times a spinner and a Townsend ring ,it is also fitted with a 2 bladed prop. Probably the most important difference is what is written on the back of your photo , it states that the Idro is fitted with an AR Lynx engine which when you check the photo it clearly is ,as the Lynx is a 7 cylinder engine, however the engine on my orignal posting ,is, as I stated in the posting a 9 cylinder engine . This leaves us with a number of possibilities , either this is the same Idro upgraded from a 7 to a 9 cylinder Alfa motor , or it is a completely differrent boat .
There were in fact more than one of these boats that took part in the Pavia -Venezia race , That would explain the lettering on the side of your boat, so could this be another boat.? They were banned from the race post WW11.