Thanks to some of you on here I now have the correct prop on my Cruisers Rally with a merc 470. When I bought the boat it had a 14x25 alum prop on it. This gave me about 45 MPH (GPS) at 3800 RPM WOT and struggled to get on plane with 4 or more people in the boat. After some research, I decided on a 13 7/8 x 23. I got a used stainless mercury prop in this size on Ebay for $65. (48-75724-23) The prop came last week and I ran it.
The boat has an improved hole shot, better mid-range, and with just me in it now runs 47 MPH (GPS) at a dead on 4200 RPM. The prop gives more bow lift and also lets me trim higher without cavitation. I never did find max trim for the new prop the other night because there was a good chop on the water.
I am extremely pleased with the outcome. I expected to loose a little top end but this was not the case. The new prop has thinner blades, a slight cup, and is vented. Those things coupled with running at the top end of WOT RPM seem to work well on my boat. (it is a little louder with a vented prop though)
-Eli
1978 Restored Cruiser Rally 174
The boat has an improved hole shot, better mid-range, and with just me in it now runs 47 MPH (GPS) at a dead on 4200 RPM. The prop gives more bow lift and also lets me trim higher without cavitation. I never did find max trim for the new prop the other night because there was a good chop on the water.
I am extremely pleased with the outcome. I expected to loose a little top end but this was not the case. The new prop has thinner blades, a slight cup, and is vented. Those things coupled with running at the top end of WOT RPM seem to work well on my boat. (it is a little louder with a vented prop though)
-Eli
1978 Restored Cruiser Rally 174
