Prop Specs ONLY

[Larrys21V]

Hi all, recently purchased a 1990 20' Supra Sunsport with PCM Ford 351 factory 230 HP. 475 hrs on engine. I have the 1:1 tranny. This is the first boat I've owned, although been around boats most of my life. Still, learning a ton of new info. This is exactly the post I was looking for so thanks to SquamInboards for initiating it. I will be using the boat mostly for skiing and wake boarding and just all around cruising. I know I have a three blade prop and I believe it's OEM, but sorry I don't have other details. I'd really like to know what others would recommend for my boat and usage. Thanks!

Hi Rob

I hope all is going well with the SunSport! Every time I cross the wake of my 21V I miss your boat! The two props I gave with are both stock. you are correct. My understanding is that you wont find a prop that makes the boat go faster (due to Hull design). There may be a power prop available for wakeboarding, but I don't think you would need it unless you've added ballast bags to the boat. Not sure what you are looking to do. But I had 10 people in the boat and pull 3 skiers out.

Unfortunately, I don,t think you'll find a prop to make it go faster than 43 MPH due to hull design. Also I'd not mess with the RPMs if someone recommends that. I hope your enjoying the boat, I'm getting my out a lot this summer!

[korey]

Wanted to add my experience here

Boat Info: 1986 Supra Saltare, 22' open bow

Drivetrain Info: 454ci/330hp PCM 1:1 direct drive 1200+ hours

Prop Specs: ACME 209 4 Blade 13" x 12.5" 0.080 cup

Performance / Usage:
WOT unloaded: 4500RPM at 37.5MPH (ridesteady digital readout, GPS)
11.2MPH at ~2600RPM with ~1900lb ballast and wake sharper for surfing. Seems like it's working pretty hard, nearly not doable with more than 3 extra bodies onboard. No chance in the world of getting on plane with that weight.

Seems to cruise pretty happily unloaded at 2600RPM at 25-26MPH. Fuel consumption makes it seem like it's not in the secondaries of the carb, therefore fairly economical.

Switching to Acme 1229 (13x11 80 cup) this week to help ease load on the aging old girl while surfing. Hopefully I can avoid letting her spin too many R's when unloaded.

[korey]

Tried the 1229 out this weekend, and LOVE it! It's 13x11" 0.080" cup 3 blade.

WOT Unloaded: 4600RPM at 41.0MPH. Yes, it sped up and only turns 100 more R's than my old 209. I don't quite understand it, but it's true! The boat is "throw you out of the observer's seat" fast out of the hole now.

Surfed great with 1900lbs + 4 dudes all day. Decided to throw the long rope in with surf weight at the end of the day, and had NO PROBLEM getting on plane with 1900lbs of ballast and 4 dudes. I was blown away!

I don't love turning this old engine more RPMs all the time, but it sure does feel good...

[Zkdk3000]

Tried the 1229 out this weekend, and LOVE it! It's 13x11" 0.080" cup 3 blade.

WOT Unloaded: 4600RPM at 41.0MPH. Yes, it sped up and only turns 100 more R's than my old 209. I don't quite understand it, but it's true! The boat is "throw you out of the observer's seat" fast out of the hole now.

Surfed great with 1900lbs + 4 dudes all day. Decided to throw the long rope in with surf weight at the end of the day, and had NO PROBLEM getting on plane with 1900lbs of ballast and 4 dudes. I was blown away!

I don't love turning this old engine more RPMs all the time, but it sure does feel good...

It appears everyone is going to a 3 blade - even those that have always sworn by a 4 blade. Would you still say there is a considerably large positive difference between old 4 and new 3 for all around performance?

[SquamInboards]

It appears everyone is going to a 3 blade - even those that have always sworn by a 4 blade. Would you still say there is a considerably large positive difference between old 4 and new 3 for all around performance?

You'll feel a big difference going from ANY older-style prop to a new CNC prop, so long as it's a good match for your drivetrain. I think the old 4-blades were known for having better hole shot than the equivalent 3-blade, but now the difference is less between the two, so long as you're comparing CNC to CNC. It's like, different brands of snow tires perform differently on snow, but they're ALL better than any all-season tire.

[korey]

One of the many factors that I've been told (and backed up by my machining experience) is that in the beginning of CNC machined props, the fixturing and wild 6 axis toolpaths to required create a 3 blade prop (where the leading edge of one blade overlapped the trailing edge of the next) was not feasible to machine in one setup and harder to keep balanced. 4 blade props were easier to machine at the time because the blades did not overlap as severely. Since that time, advances in CNC machining techniques have made machining the wild features required to have overlapping blades on a 3 blade prop more economical and less risky. A three blade has a little more surface area than the equivalent four, as well as a little more cross section in the weaker areas that will make the prop more rigid (performance wise) as well as more resistant to major damage. The "myth" that a 4 blade is more balanced still floats around out there from the "old days" (we're talking the late 90's here) of CNC props. I'd bet my beer money that I couldn't tell the difference of equivalently sized 3 vs 4 blade props on my boat though.

Either of these are light years ahead of cast props from the 80's like many of our boats came equipped with from the factory.

[mbraun55]

purchased in fall - only ran to test drive... picking up in a week - concerned!!!

1990 comp ts6m
351w
1:1 I think
prop unknown - has spare

problem I have is during the test drive - 3800 rpm WOT and 38 mph was the max!!! I need more... hole shot was strong so i'm hoping I can change prop and gain a little top end but my concern is the wot at 3800 rpm seems low for a 351w...

I understand there are A LOT of factors that could effect this including but not limited to - bad fuel, dirty carb, bent prop (was so excited I was buying I never even looked - my bad) low compression (ran smooth) - what else could it be??? wrong prop size? best stock prop suggestion (what should the prop be???)

[Jetlink]

Could be a calibration issue with both as well. Just throwing that out there.

[scbowles]

91 Pirata
new reman 454 gen V with Edelbrock Performer Intake Manifolds 2561. Tbi Marine conversion. Ports matched. fresh air exhaust.
72c velvet drive 1,1
Acme 4 blade 14 x 12 #3033 .60 cup.
2000 rpm 17 mph
2200 rpm 24 mph
2800 rpm 30 mph
3000 rpm 32 mph
3400 rpm 34 mph
3600 rpm 37 mph
4200 rpm 41 mph
Using dual GPS speedometers.

[nboardskier]

1986 Sunsport Skier - 19'

351W / 230hp?
1:1 Velvet Drive
Acme 543 - 13x11.5 - .080" cup

WOT 4200rpm - 42mph. 2 adults aboard.

Use = wakeboarding and slalom
No Ballast