Originally Posted by Orange2900
So, here it starts. I have -05 2900se with twin 4.3 carb, 190hp engines. I think props are not correct, due WOT is 5200rpm, but top speed is only 31kn. Getting plane takes only 3-5 seconds.
I don't know specs for props, so can you recommendate good setup. Boat is equipped with generator and lead piece, so it got quite heavy rear end.
Todays setup in pic.
1) Max RPM is 4400- 4800, so you're under-propped and over-revving the engines.
2) I'm unclear what you're referring to regarding the 'boat is equipped with 'lead piece'. This sounds like ballast. Ballast in the stern doesn't make sense. Ballast is typically used for lateral trim, so is placed toward the the gunnel to correct for a list.
3) You're missing the zinc's in the anti-ventilation plate.
With lead at the stern and under-pitched props, it sounds like someone tried to set-up the boat to be a wakeboard boat. The under pitched prop would get them on plane faster while towing and the weight could add to the size of the wake.
1) Measure how much space between the tip of the prop blade and the bottom of the anti-ventilation plate.
For Prop diameter sizing you want the space between the anti-ventilation plate and the tip of the prop blade to be 15% -20% of the prop diameter (20% being ideal). I'd start with how much you have now and calculate what that value with be with a different diameter prop.
2) Record the pitch of the prop (it should be written on the hub).
As prop diameter increases OR Prop Pitch increases, max RPM decreases and Max Speed increases. However, Time to plane (hole shot) also decreases.
Ideally your target is to be able to reach (but not exceed) 4800 RPM regardless of what your top speed is.