1992 115 mercury on a 1992 alumacraft 170 trophy

[dcf]

Hit some rocks last year and had the local fix-it shop order me a replacement with the same specs. and what I got I have no idea, theres no markings on it, but now the rpms will hit 5600 which is way to high and the boat is slower, I believe 5200 is max, so it states in the books, its a 60 40 boat 60 percent fishing, 40 tuben, all I remember is it was a 19 pitch, 48 something.
what prop should I look for to get my rpms down. thanks

[steelespike]

5600 with slower speed indicates excessive slip.A prop shop may be able to add some cup.
This should lower rpm and improve slip numbers.

[dcf]

thanks steelpike but unfortunately I live 3 hours from any prop shop. I'll just replace it, what would u recomment if I may ask,

[steelespike]

Do you know what the rpm was with the 19" prop?
Prop selection is a bit of a gamble when we have all the info we need.
If I had to pick at this point I would suggest a 17" prop.If its wrong it is likely to be undersized which you could still use by watching the rpm. If we go with a 19 and its over sized you just plain shouldn't use it.If you feel your 19 had good hole shot and good overall performance get a 19.
You could mail your new prop off to a good prop shop and have them tell you the size.
Sometimes when you change brands you can end up with odd results. At least would know if the prop is the right size,and they could tell you if they can make it work.