I have just built up a new engine for my boat, a ruston 2ywa with prm 402 box 2:1 reduction (which I'm aware is excessive, it just came at the right price) my question is; my current prop matched to the old engine is massively too small (16x10) however I have a old prop made by crowther which came off from another previous set up, that prop is 21x20. I have used the standard vic prop calculator which is suggesting something around 19x(can't remover pitch maybe something around 11) anyway, I called crowther about this issue, they said they could adjust my 21x20 to suit. And also asked if I had enough space to swing a 22, which I do, as that would be the ideal. Now the problem is obviously they don't let on the pitch they recommend. And I'm wondering if the pitch I have is usable with out shelling out on getting it adjusted. I know of that other downloadable prop calc program which I can't remember the name of, but it only works on PC, and I don't have that.
Any input much appreciated,
Laurie.