Which prop?

[MurphysLaw]

Ive got a 17' 86 chris craft with the 3.0l GM motor and first gen alpha 1, its got a beat up 13.75x21 iirc prop on it now. What should I buy for it now? I was told that a 14x21 or 23 would be good. Also, what should I expect for a top speed out of that setup? its a scorpion 178 boat that rides fairly high out of the water and only weighs about 1600 and I usually have maybe 600# of people and stuff on it. Thanks, Steve


Sorry, i didnt realize there was a prop thread, please move

 

[Don S]

Re: Which prop?

Moving to the Prop forum.

 

[walleyehed]

Re: Which prop?

The size and style of prop you need will be determined by hull design and balance...in other-words, do we need a bow-lifter or a stern-lifter.
The most important question would be; what is your WOT RPM now with a normal load?

 

[MurphysLaw]

Re: Which prop?

I have no idea if Id need a bow or sern lifting prop. Im taking the boat out tomorrow and hopefully will get to WOT to see what the rpms get to, but the boat had a huge carb on it and would flood out if I gave it gas over 2000rpm

 

[MurphysLaw]

Re: Which prop?

WOT is supposed to be 42-4600. Im not sure if the mixture is rite, but I was getting about 4000 on my current, beat to crap prop which is a 13.75x21. It feels like i need a stern lifter, the bow had no problem coming out of the water and it is fairly fast as it is, but I want to get it correct prop for it.

 

[walleyehed]

Re: Which prop?

sounds like a 19P would be better suited to your rig...likely the diameter may play a small role in this as well. maybe a std alum in 14 to 14-1/2"X19P might be a good choice for all-around use.