New prop for 1989 Sunbird Corsica 195, 19', 3.0 OMC

[david_tye]

hello all, this is my first post although i've been reading from the sidelines for quite a while...

i have a 19', 1990 Sunbird Corsica 195 with an OMC 3.0. My problem is the top speed is 30 MPH(using a gps), at WOT on smooth water and two people. I'd just like to get where i'm going a little faster without running WOT all the way there. The hole shot seems decent... i get up pretty easily on the wakeboard

Unsure about the prop manufacturer, but it is aluminum with some significant wear on the ends of the blades

Current diameter and pitch is 13x19

WOT RPM is 4700rpm at 30mph

Engine is a 1989 OMC 3.0 140hp. it has some serious blowby, timing is correct, rebuilt carb, runs well overall...havent checked the compression.

Any suggestion are very appreciated. Thanks!

 

[steelespike]

Re: New prop for 1989 Sunbird Corsica 195, 19', 3.0 OMC

The prop calculator says at 4700 19" prop with 10% slip,1.86 gear ratio would do about 40 mph.
At 30 mph you have about 34% slip, very high. Could be your badly worn prop
and a good place to start would be a new 19" prop. Solas Amita have a good reputation.
Are you sure you have a 19"?
If you look up props for your OMC 3.0 The diameter should be right.

 

[david_tye]

Re: New prop for 1989 Sunbird Corsica 195, 19', 3.0 OMC

The prop calculator says at 4700 19" prop with 10% slip,1.86 gear ratio would do about 40 mph.
At 30 mph you have about 34% slip, very high. Could be your badly worn prop
and a good place to start would be a new 19" prop. Solas Amita have a good reputation.
Are you sure you have a 19"?
If you look up props for your OMC 3.0 The diameter should be right.

Holy cow...let's hope it is indeed the prop then. I'll go ahead and get a new 13x19 on the way...i'll post the results. Thanks!

 

[david_tye]

Re: New prop for 1989 Sunbird Corsica 195, 19', 3.0 OMC

The prop calculator says at 4700 19" prop with 10% slip,1.86 gear ratio would do about 40 mph.
At 30 mph you have about 34% slip, very high. Could be your badly worn prop
and a good place to start would be a new 19" prop. Solas Amita have a good reputation.
Are you sure you have a 19"?
If you look up props for your OMC 3.0 The diameter should be right.

Got the new Solas Amita 13x19 on this weekend and i'm pretty pleased with the results. New top speed is 36 mph and the hole shot is dramatically better, but WOT is now only at 3800. Thanks for the help!

 

[david_tye]

Re: New prop for 1989 Sunbird Corsica 195, 19', 3.0 OMC

Got the new Solas Amita 13x19 on this weekend and i'm pretty pleased with the results. New top speed is 36 mph and the hole shot is dramatically better, but WOT is now only at 3800. Thanks for the help!

any thoughts on the drop in RPM? If i went with a 21P would my rpms go up or down?

 

[david_tye]

Re: New prop for 1989 Sunbird Corsica 195, 19', 3.0 OMC

any thoughts on the drop in RPM? If i went with a 21P would my rpms go up or down?

bump...plus one more thing to note. i'm currently running a hydrofoil. after some reading i'm thinking the drag it creates may be contributing to the drop in wot rpm. any thoughts?

 

[Maclin]

Re: New prop for 1989 Sunbird Corsica 195, 19', 3.0 OMC

Going to a 21p from a 19p will drop rpms.

As for the foil, I am very opinionated on the subject, and this saying sums it up for me... "Friends don't let friends use hydrofoils".

Again, this is my opinion. If you read back a ways in this topic you can find at least 2 recent testimonials about top speed coming back after a foil is removed. Trim tabs make better bedfellows so to speak. Tabs work from the edges of the hull. Foils are like holding a 1 foot wide 3 foot long board by the middle of the 1 foot edge and trying to get it do do what you want it to do. Compare that to holding an edge with each hand.

 

[david_tye]

Re: New prop for 1989 Sunbird Corsica 195, 19', 3.0 OMC

Going to a 21p from a 19p will drop rpms.

As for the foil, I am very opinionated on the subject, and this saying sums it up for me... "Friends don't let friends use hydrofoils".

Again, this is my opinion. If you read back a ways in this topic you can find at least 2 recent testimonials about top speed coming back after a foil is removed. Trim tabs make better bedfellows so to speak. Tabs work from the edges of the hull. Foils are like holding a 1 foot wide 3 foot long board by the middle of the 1 foot edge and trying to get it do do what you want it to do. Compare that to holding an edge with each hand.

I'm going to pull the foil off tonight and hopefully ill get to test it Monday...ill post the results

 

[steelespike]

Re: New prop for 1989 Sunbird Corsica 195, 19', 3.0 OMC

The drop in rpm is from the new prop being more efficient and loading the motor more.
If you have blow by issues your motor is tired.you may want to go with a 17" pitch to get your rpm within range.
It might lose a little top end but should have better hole shot and load ability.
Also your tired motor should be happier being able to reach proper rpm with less strain.

 

[david_tye]

Re: New prop for 1989 Sunbird Corsica 195, 19', 3.0 OMC

update...

had the boat out this weekend without the foil...there was zero change in max speed or rpms and maybe just a little less hole- shot. overall i'm still happy with the prop change, but it's definitely time for an overhaul.

 

[jestor68]

Re: New prop for 1989 Sunbird Corsica 195, 19', 3.0 OMC

While you're waiting to get your motor rebuilt, you need to run a Solas 17" on there to get those rpm's up near the recommended range.

4200 rpm will do a lot less damage than 3800 rpm.