Prop Size and pitch

[Helstrm]

I have a 1984 19' Sunbird CC with an AQ125A\270D<br />WOT is about 4100 rpm and currently I have a 14" 19 pitch LH prop I found a post saying that the stock prop was a 15" 15 pitch. Does this sound right to you guys. Max speed with 2 adults and 2 kids is around 28mph right now. If I change to the 15" 15 pitch prop what kind of speed and rpm would I be getting. The selco manual says my WOT should be 4800 rpms.<br /><br />Anyone know a good source for the right prop?

 

[TilliamWe]

Re: Prop Size and pitch

If your rpms on the tach are correct, and the Seloc manual is correct, you are WAY over propped! You need to have at the most a 17 pitch prop on there.

 

[Helstrm]

Re: Prop Size and pitch

I thought that she ran a bit slow. Seems tough to find a prop for het though. Any idea where to look. The PO put this prop on the boat.

 

[rbezdon]

Re: Prop Size and pitch

There is a good prop selector and most are available on this site. Go to iBoats home and look at the product tags toward the upper left of the window and click props. I think you'll find what you need right here. By the way, you pick up roughly 200 rpm for every inch of pitch you drop. You need to increase about 600 rpm so decrease the pitch by about 3 to 4 inches or to a 15"itch as suggsted. The speed will be what it is for your boat and load but the prop you have is definately over loading the engine if the WOT RPMs are that low. Not good for the engine. My guess is the PO was not satisfied with the speed and was trying to get more MPH and wound up over loading the engine.