eavega
Lieutenant
- Joined
- Apr 29, 2008
- Messages
- 1,377
I have a 1976 15' Yarcraft tri-hull with a like-year 70 HP Johnson. Right now its propped with a 17" p Johnson aluminum prop. I don't believe its original to the motor because it is in practically brand-new shape, with only some paint missing on the edge of the blades. The boat runs at about 33 MPH (by GPS) @ 5300 RPM WOT, cruises at 5K RPM at about 30 MPH. I've run the boat with two adults in it (Lets say 650 Lbs), and 3 adults in it (closer to 900 Lbs, the last guy was about 250 or so). with very little change in the speed (RPMs were 5500 with only the two adults). I have factored out accessory gear such as an anchor with chain, 6 gallons of fuel, battery, fishing gear, cooler, etc. because on either trip those variables were the same. The boat has Smart Tabs, and its a manual trim.
I think I am propped about as well as this boat is going to get, and am pretty satisfied with its speed on the water. The hole shot is pretty decent, as the boat gets on plane quickly. I was hoping that with this same prop I was going to be able to pull a tube or possibly a kneeboard for the kids, but those tests are going to have to wait until after winter.
My dilemma is this; I got a great price on an OEM 3-blade stainless steel prop. It was a 19" Pitch, but at the time I wasn't sure whether the motor would need or even be able to step up in pitch. The price was so good, though, that I couldn't pass it up.
Looking at the performance I am getting from the 17p prop, is it even worth running it with the 19p SS? I can feel that the SS prop is much heavier than the aluminum, so given the increase in pitch plus the added weight the motor is gonna try to spin around, I don't think its gonna be able to get up to speed trying to turn it, so there may be no advantage in putting this SS prop on. Am I better off just selling it or trying to trade for a smaller pitch? Any suggestions would be appreciated.
Rgds
I think I am propped about as well as this boat is going to get, and am pretty satisfied with its speed on the water. The hole shot is pretty decent, as the boat gets on plane quickly. I was hoping that with this same prop I was going to be able to pull a tube or possibly a kneeboard for the kids, but those tests are going to have to wait until after winter.
My dilemma is this; I got a great price on an OEM 3-blade stainless steel prop. It was a 19" Pitch, but at the time I wasn't sure whether the motor would need or even be able to step up in pitch. The price was so good, though, that I couldn't pass it up.
Looking at the performance I am getting from the 17p prop, is it even worth running it with the 19p SS? I can feel that the SS prop is much heavier than the aluminum, so given the increase in pitch plus the added weight the motor is gonna try to spin around, I don't think its gonna be able to get up to speed trying to turn it, so there may be no advantage in putting this SS prop on. Am I better off just selling it or trying to trade for a smaller pitch? Any suggestions would be appreciated.
Rgds
