Both engines are short shaft, 30hp being about 12mm longer and the cavitation plate about 20mm lower. Engine is also about 17kg heavier than the mercury
Having only done a trial run with the 30hp (which is pretty quick
) with the same lose 25mm block of wood I use with the 15hp I knew it needed to be higher and more substantial. 50mm being the highest I am willing to lift the engine up.
Having looked at other peoples examples of how they have extended the transom for the same reason of the water fall effect over the top I think this should work just as well.
I'm very aware of the problems of extending the transom and have no intentions of losing an engine or damaging the transom. As there were no off the shelf thumb screw plates big enough I've made one up out of 10mm marine grade alloy, this should spread the load.
Main test will be Easter holidays up Windermere, all being well will report back with the results.