Prop to be replaced or upgraded, please advice.

[magjistari]

Hi, I have a 2003 Blue Water Monte Carlo Cuddy, Volvo penta SX, Volvo penta 5.0GL v8 engine 220 HP, 20 feet. As its my first boat with no prior any sort of boating experience I did hit gravel a couple of times in lake Travis here in Austin. I was wondering if I needed to change the propeller and what would be my best upgrade. Stainless or Aluminum? 3 or 4 blades? Does it even need to be upgraded. Please see the pictures. I went through an automated process of selecting a prop at westmarine website and it yielded results of 14 to 15.25 x 15 to 17 with 3 or 4 blades. Normal load is about 4 people. Please advice. As of now i use the boat for riding around. No fishing, in the future add a towing tube.

 

[jimmbo]

Well your engine has a WOT range of 4400 - 4800 rpm. What rpm were you getting at full power with the prop (14 1/4 X 23) you currently have? It looks like a Volvo prop.

 

[magjistari]

With two people on board maybe with a 150 pounds of other things with a full 30 gallon tank i took it to a max of 52 mph and as far as i remember i think it was about 4500-5000 rpm. The existing prop is from turning point, the boat came from California, but i dont plan on taking it anywhere but lake water.

 

[Maclin]

That prop seems right on target to me.

 

[magjistari]

Do you think it needs to be replaced? Is it in bad condition after I went through gravel a couple of times? Im suprised that other site was giving me quite different prop dimensions.

 

[Rick Stephens]

That's impressive with a 5.0L and a 20' boat. I'd get the exact same 23 pitch prop and have that rebuilt and keep as a spare.

 

[magjistari]

Same exact aluminium prop on ebay is not even 85 bucks. Not an issue at replacing it if its needed to.

 

[jimmbo]

With two people on board maybe with a 150 pounds of other things with a full 30 gallon tank i took it to a max of 52 mph and as far as i remember i think it was about 4500-5000 rpm. The existing prop is from turning point, the boat came from California, but i dont plan on taking it anywhere but lake water.

Well 4500 - 5000 is pretty vague. 4500 is within the range, but in the bottom half, while 5000 is 200 above that range. So based on that info no good recommendation can come from that, at least from me

 

[Scott Danforth]

I wouldnt replace the prop yet. wait until you really ding it up.

 

[Sea Rider]

There's a great performance difference running 5 or 5.5K wot revs. Need to tach engine right as loaded and check how much rpm is needed for engine to rev at near or max wot rpm range which is ? After a prop maximization if needed, hole shot will ibe mproved much better with slight top end speed lose.

Just for the record,.perform a new wot test on calm flat water cond and report max wot rpm engine achieved..

Happy Boating

 

[Maclin]

If you can live without it for a couple of weeks, just have that prop refurbished. Then see what the numbers are and report back. While I replied that it was on target, the arrow did hit the hay at least in archery terms. I suspect you may be at the low end of the RPM range when loaded, depends on how accurate the MPH is and what the drive ratio is.

 

[magjistari]

As we are expecting temps as low as 10 degrees in central Texas, i have drained the water of the boat and sort of winterized it. First chance i get to take it back on the lake i will keep note or make a video, march or april . Sorry, im still a noob to the boating world. Speed was measured with the lawrence navigation gps and also with the cluster instrument odometer.

 

[Maclin]

Very good, I am in Denton so I have mine bunkered in for the winter. I was judging by your speed on how close your prop is to ideal. Accurate RPM's is next thing to verify. If (when you can test again) you can get to 4400 I think you are good, below that and you need to think about going to a 21 pitch. Top speed would be about the same with a 21 with higher top RPM's.

 

[QBhoy]

Hi
As mentioned, you need an accurate RPM reading with current prop, as well as a GPS speed reading. It’s unlikely the speed stated is accurate with that set up
all the best.

 

[magjistari]

Thank you all very much, will definitely make a video or take exact notes of odometers and rpm next chance i get. Aftermarket Lawrence gps/navigation/fishfinder and odometer from cluster instrument have the same speed reading. Im very sure ive taken it to 45/50 and a max of 52mph on placid water. Ive had a total of 10 adults on labor day and i couldnt make past 9mph. We actually did get pulled over for being overloaded.

 

[Maclin]

Ok, well, you need a lower pitch prop methinks.

 

[Sea Rider]

It's a very bad idea to prop right that engine for say 2-3 up if that's the amount of souls that will be having fun with that combo on a regular basis and then overloading it severely. When that happens is like going up hill on third gear from a dead stop. Too much stress on pistons and crankshaft, engine could develop overheat issues without operator knowing anything about it.

Good idea is to maximize a prop that makes engine to rev at its full wot range with say 2 souls, add more souls accordingly till wot revs dials middle wot range.That's you max souls allowed for engine to run nicely. Don't go towards min lugging side adding more souls.. That way engine will run safely between middle and max wot rpm range. Will achieve good hole shot, good fuel consumption and good speed.

Happy Boating