Hi KBIO AND Rhavane,
1st Rhavane, for the trim I will use the principals of ship stability.
I take note of the weight of the hull, w, and find it’s longitudinal Centre of gravity, gl, by simple balance method. I measure the distance of gl from the stem post. Multiply hull weight w by gl distance gives you a moment around stem post. Each item added to the hull has a weight, w1——— n and a c of g measured also from stem post. W1——-n multiplied by distance from stem post equals it’s moment about stem post. Take the sum of every moment and divide the answer by the sum of all weights(displacement) will give you the distance of the final centre of gravity Gl from the stem. This is theory only. In practice and using my eyes I can place each major, heavy item in the hull to keep c of g where I want it. When all parts are fitted to or in the hull I can adjust Gl by sliding the steam plant metal tray either forward or aft to achieve the required trim (by the stern). Ballast will only be required to achieve the required draft which is largely determined by the size of the propeller and visual aesthetics. The major problem is that the makers of the propeller I want had a major fire and is not taking any orders at the moment.
2nd KBIO, here is a link to my first launch built from scratch using original plans.
http://www.modelboatmayhem.co.uk/forum/index.php/topic,33737.0.htmlThank you very much for your picture. I am ok with building from plans, even ok with building from pictures but am not very good at designing myself. If you are happy for me to borrow (steal) some of your ideas, methods and solutions I would be eternally grateful to you. If you are willing then please put some more pictures up and with your help I can move along with this build. Thanks in advance,
Jerry.