Eric Perez
Well-Known Member
- Joined
- May 13, 2002
- Messages
- 410
Well I finally bit the bullet and got some lifting props sized for .12 (Small Block) Rigger applications. All the props tested fit a 3/16 shaft.
The first prop on the picture is the infamous V937 This prop is very popular with the fast-electric boat crowd and it is very compatible with even sport small-block nitro power.
After I had baseline setup on my boat with a Prather S220 heavily back-cut and with reduced diameter by moderate rounding of the tips I decided to try some lifting props.
I put in the V937 and it was pushing very hard on the front, Talk about lift! I continued to move the strut up until I ran out if adjustment with my strut. The prop was very high, still the rear end would fight the front and the boat would pitch back and forth, Seemed that for my hull with a forward CG and with light tail loading the V937 was not going to be my meal ticket for a fast stable hull. Note: The V937 cavitates badly on launch until it hooks up, the good news is that it's easy on the engine because it will not bog down the engine.
I then changed the prop to the 1740 and the lift was more manageable and controlled. Launches where not a problem. The prop would lift the tail and it would just stay there. I did not notice the wild front to back pitching that I saw with the V937. I could tell that the engine was a bit more loaded than with the free-spinning V937 -but RPM seemed to be in the ball-park for proper engine/pipe interaction. Speed/ Acceleration seemed good and was able to run the strut very level and still keep the front down when going over the nervous sections of the pond.
The last prop that I tried was the 1640. This is basically a miniature version of the props commonly used on 21 Eagle SG owners in my club, so I was expecting good things from this prop. I started with the prop as high as my strut allowed to get a feel for the lift-characteristics of the 16 series propeller (This was my first foray into this very serious looking profile). The prop cavitates very badly at launch, unlike the V-937 this prop has a-lot of face area so it really loads up the engine at launch. My engine liked to launch the 1640 with plenty of throttle to keep cavitation high, and lower the demand on the monster inside! The back end of the boat picked up and it was soon screaming WOT. Speed and handling was good the engine was very responsive to throttle input allowing low speed cruising or fast accelerations. Ended up lowering the strut a bit to put just a little more weight on the front so I could hammer the throttle with little worries of blowing over. I really liked the way this prop eats its way through the rough spots on the pond.
I will have to test this prop again in smoother water to make sure it will not overload the engine.
The props on the pictures are V937-3, 1740 and 1640
The first prop on the picture is the infamous V937 This prop is very popular with the fast-electric boat crowd and it is very compatible with even sport small-block nitro power.
After I had baseline setup on my boat with a Prather S220 heavily back-cut and with reduced diameter by moderate rounding of the tips I decided to try some lifting props.
I put in the V937 and it was pushing very hard on the front, Talk about lift! I continued to move the strut up until I ran out if adjustment with my strut. The prop was very high, still the rear end would fight the front and the boat would pitch back and forth, Seemed that for my hull with a forward CG and with light tail loading the V937 was not going to be my meal ticket for a fast stable hull. Note: The V937 cavitates badly on launch until it hooks up, the good news is that it's easy on the engine because it will not bog down the engine.
I then changed the prop to the 1740 and the lift was more manageable and controlled. Launches where not a problem. The prop would lift the tail and it would just stay there. I did not notice the wild front to back pitching that I saw with the V937. I could tell that the engine was a bit more loaded than with the free-spinning V937 -but RPM seemed to be in the ball-park for proper engine/pipe interaction. Speed/ Acceleration seemed good and was able to run the strut very level and still keep the front down when going over the nervous sections of the pond.
The last prop that I tried was the 1640. This is basically a miniature version of the props commonly used on 21 Eagle SG owners in my club, so I was expecting good things from this prop. I started with the prop as high as my strut allowed to get a feel for the lift-characteristics of the 16 series propeller (This was my first foray into this very serious looking profile). The prop cavitates very badly at launch, unlike the V-937 this prop has a-lot of face area so it really loads up the engine at launch. My engine liked to launch the 1640 with plenty of throttle to keep cavitation high, and lower the demand on the monster inside! The back end of the boat picked up and it was soon screaming WOT. Speed and handling was good the engine was very responsive to throttle input allowing low speed cruising or fast accelerations. Ended up lowering the strut a bit to put just a little more weight on the front so I could hammer the throttle with little worries of blowing over. I really liked the way this prop eats its way through the rough spots on the pond.
I will have to test this prop again in smoother water to make sure it will not overload the engine.
The props on the pictures are V937-3, 1740 and 1640
