20 or 25 inch shaft?

[Tobb1]

I have a Gilbert 21 , which is a 21 foot V hull. It has an approximately 25 inch transom. I was told that a 20 inch shaft would be the right setup for this boat. Because the engine would need to be lifted anyway. I know very little about rigging and engine heights as this is my first high performance boat. But too me five inch seems like a lot of lift to start with. Should i god for a 20 or a 25 inch engine ? Pros and cons?

20 inch engines are few and far between in Norway, bit a 25 inch engine is easier to find.

[Motv18]

Standard set up is 0” over transom if transom is 25” and no setback is involved be it added or built in setback.

When end you start looking at negative angle transom, dead rise, notched, and other things can have you at 20” fairly quick.

[Tobb1]

Thanks! Already bought a 20 inch engine