Mark has indeed been watching too much "Monster Garage". The hot rods, houses etc are sitting on a solid substrate whereas a boat is floating on the interface between two fluids. A boat is a dynamic system. If you change one thing then every thing else changes/shifts to compensate. If you move the LCG by , say adding a cabin, then the LCB and the LCF have to shift to compensate [ unless you put it in exactly the right place]. This may result in a bow down, or stern down, trim. If you have increased the displacement [weight] then the bridgedeck will now be closer to the water and the power requirements will also have changed. You can make the changes you want but you do need to be careful. You can't just "chop & channel". Regards, Malcolm Tennant. Malcolm Tennant Multihull Design Ltd PO Box 60513 Titirangi, Auckland 1007 NEW ZEALAND ph +64 9 817 1988 fax +64 9 817 6080 e-mail malcolm@tennantdesign.co.nz www.tennantdesign.co.nz www.catdesigners.com