hi there
as me mother used to say 'hold the horse I want to get off' cos - we have crossed too many bridges and we aren't at the river yet
First question is - what materials are you building from/how are you intending to build it?
The model of the RTTL that Howway Son built - is built the same way as Vic Smeed plans tell you too - e.g. for an I.C. engine and therefore 90% of the bulkheads that the model is made from - is 6mm thick ply and sold - without the middles removed in other words. As Howway Son says it weighs in the region of about 3.4kilos.
The model I built which is the RTTL 2751 and its built in a completely different style. The framework or bulkheads is only 3mm ply and is also double diagonally planked with 1.5 thick planks and then layered over the top with 0.5 mahogany planks. The total weight of the hull is in the region of 1.5 lbs, which is extremely light.
She is powered by 2 Mtroniks vision motors which push her along at a good lick. I dare say if I stripped out all the sound modules, speakers amplifiers etc., to lighten the weight yet again, I would give any brushless boat of the same size a good run for its money. The only drawback is that both props rotate in the same direction as in the real lifesized boats - so she has a tendency to dive to one side and she has a lot of tail torque.
Think about this before we go on to what size motors we need. i.e. think about the hull and how we are going to build and how light it is ?
http://www.modelboatmayhem.co.uk/forum/index.php/topic,20758.50.htmlaye
John