Hi, Patrick!
Last year I visited Drogheda, my vessel was 88 m in length, and 12 m in breadth, with maximum draft 4.6 m for aft (the summer draft on midship is 4.33 m). For the first it was not so nice to make turn in river. Also we needed some shifting along the birth for proper loading of cargo. Due to the weather conditions we were loading magnesite for 3 days and on departure we were unable to float because we stick to the bottom under the weight of the cargo. Finally we successfully departured when the time of high water came, also we assisted by main engine to float.
In case of Rusich-1really I can't imaging how they 'll make turn in river. But they have small advantage: on Rusich type vessels there are 2 engines with 2 propellers that's why the manoeuvrability is better and vessel need less area for turning. Vessel has maximum draft 4.2 m and I think there '' no problems.
According to Sailing Directions (NP 40) limiting conditions for Drogheda are MAXIMUM SIZE OF VESSELS HANDLED: At Tom Roe's Point maximum lenght 120 m, beam 10 m; on the town quays ay Drogheda maximum length 100 m, beam 20 m.
May be you know the maximum safe turning circle in the river? May be there are some exceptions? In any case time 'll show what's happen. :-)
As for me, Drogheda is nice town.
Regards, Yevgeniy.