Thanks for all the comments, they have been helpful, and I would not disagree that one should be proficient in steering without the aid of a bow thruster, but that was not my 1st or 100th consideration in the possible purchase of the boat. BUT that is how the boat is being sold, and the owner being well aware of the issue of the bow thruster tube without a reflection in his opinion of the value of the boat, without that feature (ie removed) the boat would be devalued, especially on resale should that ever occur. So my conclusion is that serious renegotiation of the price will occur once the survey has been done.
Thanks again for all your comments