Did I buy the right prop?

[tollus]

I bought a new to me boat this season. It's a Larson 1997 226 SEi with a 5.7L Mercruiser I/O.

I replaced the beat up 3 blade aluminum prop with a 19 pitch to an 18 pitch 14.5" 4 blade aluminum prop. Between the boat and the stuff we added, I figured a SS prop needed to wait until next year.

The WOT is 4600, running roughly 44 to 45 MPH (fish finder speedometer). I got the 4 blade to pull boarders and tubes. I'm about 225, so I wanted a better hole shot to get me out of the water (which it does by the way, I'm up on the board prior to hitting the prop wash from the initial spin up of the prop).

I posted a question about speed in the wakeboard forum and figured I would investigate further here. The boat planes right around wakeboard speed and suddenly, you're up on plane and going 5mph faster. It takes constant input from the throttle to keep the boat at a good boarding speed and even then it's not a constant speed. Could it be that a different prop would have been better?

 

[Tail_Gunner]

Re: Did I buy the right prop?

I bought a new to me boat this season. It's a Larson 1997 226 SEi with a 5.7L Mercruiser I/O.

I replaced the beat up 3 blade aluminum prop with a 19 pitch to an 18 pitch 14.5" 4 blade aluminum prop. Between the boat and the stuff we added, I figured a SS prop needed to wait until next year.

The WOT is 4600, running roughly 44 to 45 MPH (fish finder speedometer). I got the 4 blade to pull boarders and tubes. I'm about 225, so I wanted a better hole shot to get me out of the water (which it does by the way, I'm up on the board prior to hitting the prop wash from the initial spin up of the prop).

I posted a question about speed in the wakeboard forum and figured I would investigate further here. The boat planes right around wakeboard speed and suddenly, you're up on plane and going 5mph faster. It takes constant input from the throttle to keep the boat at a good boarding speed and even then it's not a constant speed. Could it be that a different prop would have been better?

4blades do just what you are experiencing...increase stern lift and getting up on plane faster than a 3 blade. Believe it or not you need a 3 blades that digs and cannot get out of the hole...Or get flood pumps for your bilge and ski locker......

 

[sschefer]

Re: Did I buy the right prop?

Tail Gunner, that's the best way I've heard it put yet. Getting up on plane is the last thing you want for a good wake. Lot's of HP and and nose high push. You should see my brothers Natique with the flood tanks and the big block.

 

[tollus]

Re: Did I buy the right prop?

Hmmmm....and here I thought I'd need the 4 blade to pull my girth out better. Which it certainly does, but I didn't expect the planning issue right at the speed I want to board at.

I tried trimming the motor up so that it would increase bow lift and make it tougher to get on plane, that seemed to help, but I needed to stand to see over the bow.

Perhaps I'll try that again.

 

[junior1113]

Re: Did I buy the right prop?

high five

 

[tollus]

Re: Did I buy the right prop?

high five

That's what I wanted, but just bought the boat and added an $1800 extended swim platform that added 3 feet of swim deck space (invaluable by the way).....had to settle for a 4 blade aluminum for this season.

High Five for sure next summer

 

[Varago]

Re: Did I buy the right prop?

I have to disagree on this I dont think that your bow in the sky is the what you want. There are other ways to go slow and stay on plane, with a level boat.

As a general rule of thumb the more blades on your prop the slower you can stay on plane, more blades gives more stern lift which lets the boat stay on plane at a slower speed. The very best way to stay on plane at a slow speed is with trim tabs (SmartTabs work awsome for this).

With a HighFive and SmartTabs I can stay on plane at 15-16mph, makes all the difference in the world, plus the boat is level all the time, you can see where you are going.

Some will say the SmartTabs kill your wake, I did not find this to be the case and with your size boat you have the weight to make a nice wake.

Just my two cents

Dave