I have a 1987 Hunter 34, with a 27hp Yanmar 3GM-30F , turning a two-blade prop. The boat is very slow, when under power. Can anyone advise as to whether I can put a three-blade prop on the shaft ? If so, what is the correct pitch and diameter ? The shaft is either 1 1/8" or 1 1/4" in diam. I need to measure it.
The boat motors at 4 mph when running the engine at 2,000rpm's. I don't like to push the engine much harder than that; she's 33 years old. But even at 2,500 rpm, the boat is still only doing about 5 mph. When the wind is good, I can sail her at 6+ mph. I check my hull and prop once a month for any growth and fouling. That has not been an issue over the years. The engine has always run very well and smooth. It's just that I have noticed that other sailboats while under power, are always cruising past me at a higher speed. Also, while on the hard this time of year, I have seen that other sailboats, even the smaller ones, have three blade props. It's rare to see another boat with a two blade prop like mine has. So, I was just wondering if it's worth the trouble to replace it.
The boat motors at 4 mph when running the engine at 2,000rpm's. I don't like to push the engine much harder than that; she's 33 years old. But even at 2,500 rpm, the boat is still only doing about 5 mph. When the wind is good, I can sail her at 6+ mph. I check my hull and prop once a month for any growth and fouling. That has not been an issue over the years. The engine has always run very well and smooth. It's just that I have noticed that other sailboats while under power, are always cruising past me at a higher speed. Also, while on the hard this time of year, I have seen that other sailboats, even the smaller ones, have three blade props. It's rare to see another boat with a two blade prop like mine has. So, I was just wondering if it's worth the trouble to replace it.