Prop question and RPM @ WOT

[87rocket455]

Hello i am relatively new the I/O motors. I recently bought a boat 1991 Centra trade winds 19' cuddy cabin weight is about 2400lbs. It has a 135hp 3.0L merc with an alpha 1 drive. At WOT the boat runs about 34MPH and @ 3800RPM's. The prop has this # stamped on it: 18 7812 A40 19P. My question is what can you decipher from this prop# and what would your guys suggestions be for increasing the RPMs up to the recommended 4200-4600 rpm operating range for that motor. Also the prop measures 14" Dia.

thanks

 

[rndn]

Re: Prop question and RPM @ WOT

Hello i am relatively new the I/O motors. I recently bought a boat 1991 Centra trade winds 19' cuddy cabin weight is about 2400lbs. It has a 135hp 3.0L merc with an alpha 1 drive. At WOT the boat runs about 34MPH and @ 3800RPM's. The prop has this # stamped on it: 18 7812 A40 19P. My question is what can you decipher from this prop# and what would your guys suggestions be for increasing the RPMs up to the recommended 4200-4600 rpm operating range for that motor. Also the prop measures 14" Dia.

thanks

If you drop 1 inch of pitch you should see an increase of 200 rpm's assuming you are using the same prop mfg. The number on your prop tells me it is a 19 inch pitch so you should look at either a 15 or 17 inch pitch prop. The 17 should get you to 4200 and the 15 would get you to 4600. I would try the 17 if it were my boat. This link is to the iboats.com page for your setup in the 17 inch range.
I hope this helps.
http://boatpropellers.iboats.com/Me...andard&**********=223294401&*******=883942648

 

[87rocket455]

Re: Prop question and RPM @ WOT

Thanks i will give the 17P prop a try. I also verified that the throttle is opening all the way and the motors is in time and carb seems to be adjusted corrrectly.

 

[Prop MD]

Re: Prop question and RPM @ WOT

Be certaint to stay with the quicksilver line. Other wise you are changing brands and then there is no telling what you RPM's will do.

I think you can find a better deal on that as well.

 

[Silvertip]

Re: Prop question and RPM @ WOT

Before spending money on props, I suggest you check the accuracy of the tachometer and use a gps for speed. You should not have to drop to a 15 or 17P prop to get to the upper end of the rpm band on that relatively light boat.

 

[87rocket455]

Re: Prop question and RPM @ WOT

Good idea i will try and get another tach and verify RPMs

 

[87rocket455]

Re: Prop question and RPM @ WOT

Be certaint to stay with the quicksilver line. Other wise you are changing brands and then there is no telling what you RPM's will do.

I think you can find a better deal on that as well.

Prop MD How do you know that i have a quicksilver prop?

 

[Tail_Gunner]

Re: Prop question and RPM @ WOT

Prop MD How do you know that i have a quicksilver prop?

He's more than probably a vendor...

 

[walleyehed]

Re: Prop question and RPM @ WOT

Be certaint to stay with the quicksilver line. Other wise you are changing brands and then there is no telling what you RPM's will do.

Unless.....you have the data to show how one runs against the other.
Staying with quicksilver is an opinion that tells me you need to run a few more props of different brands before asking someone to spend the money on the quicksilver that may have less performance than what we have actual data on.
Silvertip and TG...you're on the money guys

 

[Prop MD]

Re: Prop question and RPM @ WOT

The part number you gave, It is close to a mercry #, you may have got the 1st number wrong, Then the link to the Iboats page, the ones they sell are all different brands, but the quicksilver prop is made by mercury so it should run the same. There for once you figurfe out everything else you can be assured that the prop will preform as you hope.

 

[walleyehed]

Re: Prop question and RPM @ WOT

The first digit is a 4, indicating Merc OEM.
How is the over-all lift with the first prop? do you have to trim quite a bit to get the desired ride?

 

[Tail_Gunner]

Re: Prop question and RPM @ WOT

The first digit is a 4, indicating Merc OEM.
How is the over-all lift with the first prop? do you have to trim quite a bit to get the desired ride?

About time.......

 

[87rocket455]

Re: Prop question and RPM @ WOT

Thanks for all your help.
I did buy a 17P prop and it took my WOT rpm's to 4400 (right in the middle of my operating spec) and i gained a few mph It also seems to get on plane a little faster to.