Is the boat still useable now or have you finished for winter ? If still in use, I’d go out again with the 19” and get some numbers for sure. See how easy it’s on the limiter and how quick. Record the exact speed in gps as it’s approaching and on the limiter. You should be a little quicker than 30 something mph for sure, I’d say. Just going by the likely mathematics around it maybe. I wouldn’t pay too much attention to the other 22” prop. Just because it’s maybe of an unusual dimension, in terms of diameter (for comparing at least). If you can get a 21” 3 blade prop of the usual generic dimensions, then take that too.
Something like a 14x21” or just around or under the 14” diameter might be the norm and great for a benchmark and data.
Just to explain why..
If you are only getting 34 mph on the limiter with a 19”, your prop slip is crazy high. To the point of ridiculous even. Way over 30% for sure, without checking the maths. Likely more even. You should be into the 40’s for sure really.
So..if you can get a 21” prop to run close to the 6000 rpm mark, and even with a very average and realistic slip of about 15% (to make it easy on my in head maths
)…you should be able to see a realistic mid to late 40’s gps I’d think.
Anyway. See if you can borrow a normal sized 21” 3 blade to try out. Or even if you can’t. Try that 19” out again and gather exact numbers. Also have it in mind that you are trying to gather how much the rpm limiter is taking from you. How much is left to go if you like. Is she easily hitting the limiter ? Or only just on occasion perhaps ? Is there enough left over to run a 21” up near 6k ? That’s what you’re trying to find out from what the 19” can tell you as she is.
Forget the other 22” I’d say. Too obscure and a weird diameter size for data collection, I think.
What were the actual type of 19” and 22” props you tried ? Make and model ?
