4 blade turning point hustler

[rock doc]

Looking for some advice. Here is the info I have:
1990 Larson All American 21' cuddy
Approx 3000 Ibs 4.3l mercruiser 175 hp
1.84 ratio alpha 1 gen 1 19 pitch 4 blade 14" dia
light chop and 3 people on board produced the following results 37 mph at 4200 rpm wot
25mph at 3000 rpm
30mph at 3500 rpm
I am considering dropping to a 17 pitch 4 blade hustler. Is this too big a change for this prop? I believe the stock prop was a 3 blade 19 pitch 14 1/2".

 

[rock doc]

Very sorry that the info got jumbled...I had it formatted into a list but it ended up posting all in 1 sentence.

 

[rock doc]

Very sorry that the info got jumbled...I had it formatted into a list but it ended up posting all in 1 sentence.

 

[jestor68]

4200 rpm at WOT is out of the recommended operating range(too low).

So the 17 pitch is a move in the right direction if you desire a TP prop.

 

[Starcraft5834]

Get a Solas in those dimensions. . MHO..

 

[Starcraft5834]

Yup. 17 should be in right direction. .look at Solas 4 blades

 

[rock doc]

I ordered a 17 pitch and will try it this weekend. Will provide an update once I get a chance to test it. Going to a 4 blade was a big improvement. I was a little hesitant to drop down to a 17 because it looks like the motor will be revving somewhere around 3500 rpm at 28 mph, which seems to where the hull is most happy. It was very smooth at 26-28 mph with the 19 pitch.

 

[rock doc]

Tried the 17 pitch today. The 19 pitch was a 14" diameter and the 1 pitch is a 14 1/2". I am a little disappointed with the 17 pitch. I am forced to run the motor at 3500rpm to be efficient in the water. The stern seems to want to sit down deep in the water and generates a fairly big wake. Speed falls off quickly below 3500 rpm. Is it ok t run a 4.3 L this hard for extended periods? At WOT the trim pump will complain at times when trimming out. The up side is the prop definitely pulls hard and pulls skiers up easily.

I'm thinking I need both props as long as running the 19 pitch is not over loading the motor. It is a vented prop so it seems to get on plane ok. The motor also seemed content pulling my wife up on a slalom with 2 adults and 120 litres of fuel on board. Just won't rev past 4200 rpm.

Thoughts?

 

[steelespike]

Just to avoid confusion list your prop sizes simply diameter X pitch.
You may notice that as pitch goes down usually diameter goes up.
Diameter is a secondary consideration.
I wonder if your tach might be off a ltitle on the low side. Your slip at 4200 and 37 mph is 9% that is good but a little unusual.
A little more actual rpm would raise your slip closer to more typical double digits.It would also get you into your rpm range 4400-4800.
Being 24 years old your tach iOS suspect. Perhaps you can borrow a shop tach.
It does appear your setup is happy with the 19" pitch; holding plane better making more speed with a given throttle setting.
It appears the 17 is not happy at the rpm your required to run it at for your activities.
It probably would respond well with a boat load with water sports.

 

[rock doc]

Thanks steelspike - I wondered the same thing when I same the efficiency. I have read conflicting information on the effect of cupping. Can cupping create a similar effect to adding a little pitch to the prop?

The boat came with a 14 1/2 x 19 3 blade aluminum. I assumed the 14x19 4 blade would drop it down at least 200rpm. The Hustler appears to have a lot of rake and cupping compared to the prop I took off.