Many thanks for all the comments, really appreciated. As yesterday was a lovely sunny day I cut the frames for my new ship which will be a P & O Freight Only Ro-Ro, scale 1/124. The tug has a home made sound system which is very effective and cut the cost of a commercial bought system by 75%. It incorporates twin speakers, micro amp and MP3 player. Very easy to link them together plus spending15 minutes on the Web.