Need pitch answers..

[dswi]

I just bought a Glasstream Cuttlass 172 with Merc. Alpha 1 (3.0L), Merc. outdrive...Prop says 48-78120-19. I am told this is a 19 pitch...It goes about 40-45 with 4 adults and 3 kids on board...not really that fast at the start though. I would love to pull skiers (I know I don't need that many people in the boat when pulling a skier)...What pitch prop do I want to go to teaching my kids how to ski...and re-teaching me how to ski (haven't done it in about 20-25 years).
I have heard go to a 17 pitch...Correct or not??
How much speed will I sacrifice going to a 17 pitch??

Thanks for all of the help

 

[Maclin]

Re: Need pitch answers..

What is the RPM at WOT and top speed?

 

[dswi]

Re: Need pitch answers..

Newbie....still learning acronyms...
RPM at 40 or so is about (if I remember correctly) 4,000, I believe.
No idea what WOT is...would that be for the engine or what...(probably a stupid question)...how can I tell/know WOT?

 

[Robin30588]

Re: Need pitch answers..

WOT = wide open throttle

 

[jestor68]

Re: Need pitch answers..

WOT stands for wide open throttle.

If you're only getting 4000 rpm, you definitely need to change to a 17 pitch prop.

In aluminum, I recommend Solas and Mercury's as a close second.

 

[steelespike]

Re: Need pitch answers..

There are no stupid questions only those from boaters eager to learn.
What year is your setup?We need your carefully tested specs from a dedicated test lightly loaded.
Typically, depending on the year, your motor would be turning about 4900 to do 40
Probably slightly over the wot rpm recommended.
isn't likely to do 40 with 4 adults and 3 kids.
To answer your question yes a 17" pitch will help your water sports with a load.
You will need to watch your wot rpm especially lightly loaded.

 

[Maclin]

Re: Need pitch answers..

I think 4000rpm on that engine is about right, 3800-4200 I believe is the WOT range. Your setup sounds pretty good right now, but let us know the RPM at the 45mph top end..

You could drop down to a 17 for towing, but you may have to watch the tach to not over-rev when not loaded down.

Are you using the power trim effectively? Start with the drive all the way down, then begin to bump up slowly after you hit the throttle?

 

[dswi]

Re: Need pitch answers..

I will let you guys know the next time I am in the water...SOON hopefully!!
Is there any way to ensure that I am not over-revving the engine?

Oh yea, it's a 1989 Glasstream Cutlass 172.

Thanks for all of the info.
Darrin

 

[Maclin]

Re: Need pitch answers..

"Is there any way to ensure that I am not over-revving the engine?"

WATCH the tachometer...
and learn the engine sounds at the top rpms.

 

[Philster]

Re: Need pitch answers..

Get a tachometer on that rig.

 

[dswi]

Re: Need pitch answers..

Alright...I have some numbers for you guys...
WOT--4,200 RPM, 43 MPH, with 450 pounds of people on the boat. Prop pitch is 19
Do I want to go to a 17 to have more torque out of the hole (starting skiers)???
I am told that i can put a (I believe) whales tale on the outdrive to help the boat plain quicker (Wal Mart-about $40.00)...Good idea...bad idea...thoughts please.
Had great family time today though.

 

[oldman570]

Re: Need pitch answers..

Putting a whale tail on is not realy a good solution to your trouble. Dropping to a 17 pitch and trimming up at takeoff will get the skier up and the boat planed off . As soon as the skier gets up trimm the motor down some for a smooth ride. Best sking speed is between 20 and 25 MPH. Over that the skier cannot control their movement as good and hitting the water on a fall becomes more dangerous. Watching the water and tach is the only job the boat driver shoud have thier attn on while pulling a skier. One can carry both a 17 & 19 pitch in the boat and switch them as needed for the job to be done, and you will always have a spare prop incase one goes bad on the water. Just my thoughts.
Oldman570