Prop Pitch

[atxlakerat]

Hey, I am putting my Suzuki 90 on a 1980 Ranger bass boat. What would be a good prop pitch and size?

Austin Lake Rat

 

[limitout]

Re: Prop Pitch

what size is the boat and do you know the weight? I heard rangers are heavy and sit low in the water

 

[steelespike]

Re: Prop Pitch

Check "read this first" at the top of the prop forum.
What year motor?2 stroke/4 stroke? Size and model of the Ranger?What is the hp rating?
If the motor has a prop do some test runs and get us the prop size, lightly loaded wot rpm and GPS speed.
Prop size is usually near the base of the blades or under the prop nut.

 

[hwsiii]

Re: Prop Pitch

Spike , it is great to see that you are still here, helping everyone you can as always. I can see by the number of posts you have that you have been hard at work.

H

 

[steelespike]

Re: Prop Pitch

Spike , it is great to see that you are still here, helping everyone you can as always. I can see by the number of posts you have that you have been hard at work.

H

Great to see you too!When it comes to hitting it right on the nose your the one.

 

[atxlakerat]

Re: Prop Pitch

I have a 1980 ranger 1780 V. It is a 17 foot boat. It weighs about 950 lbs. It is rated for 115 HP. The motor is a 2007 Suzuki four stroke fuel injected 90 HP. The prop I have on it now is a 14 inch 18 degree pitch prop. I'm going to get it out on the lake tomorrow to see how it runs at WOT and speed.

 

[steelespike]

Re: Prop Pitch

Prop numbers are in inches. 14" X 18" 18 is the theoretical distance (18") the prop moves forward in one revolution.
The actual distance is graded in percent of slip. Typical slip is around 8 to 12%.Pontoons and heavy boats have higher slip
numbers.Any number of other variables can affect slip as well.

 

[Texasmark]

Re: Prop Pitch

Other thing that is important is your lower unit gear ratio. Merc 115 uses 2:1....prop turns half as fast as the powerhead. 90 hp like mine use 2.33; prop turns slower. With the gear change, you might be able to run the same boat with either engine using the same prop. I ran a 21 ported and cupped, high rake (bow lifter) SS on my 115 on my similar Ranger, pad hull, and it was just right. The ports made the hole shot and the pitch made the WOT.

Mark

 

[hwsiii]

Re: Prop Pitch

Mark, it is great to see you here as well, and I can tell by your postings you must be " living " here. LOL

H

 

[atxlakerat]

Re: Prop Pitch

Well, I got the boat out today and had 35 mph at 5500 rpm. I could not go to WOT because I would be over 5500 rpm which is per the manual the top end of the RPM range. I know I need to get another prop. I would like to get good mph at 5000. I intend on making 5000 rpm my own limit to try to extend the engine life. Thoughts?

 

[steelespike]

Re: Prop Pitch

If you force the motor to operate at a lower rpm you may actually make it harder for the motor perform.
Hole shot may be slower and harder to gain.Adding weight it may fade faster.Cruising speed may be harder to maintain evenly.
Prop it for the best performance and operate at whatever rpm you prefer with the throttle.
I believe the motor is rated for 5300-6300 rpm.
My info indicates 2.59 gear ratio.

 

[Texasmark]

Re: Prop Pitch

Mark, it is great to see you here as well, and I can tell by your postings you must be " living " here. LOL

H

Thanks HW. I am retired and in the mornings before breakfast I frequent the online "coffee shops". Really neat; great coffee, don't have to get dressed, don't have to fight any weather, no gasoline burned, talk with intelligent people with different faces every day, learn something every time I log on and on and on.

I spent 4 years down there compliments of uncle sugar and thoroughly enjoyed the fishing; Back bay brackish reds and "green trout", front of Pine island specs, North side of Cat Island specs, channel between Ship and Cat islands Spanish Mackrel.

Mark

 

[PapaBB]

Re: Prop Pitch

If I may drop in on this discussion please, I have a question/need help??

See photos of a prop I have and considering on putting back on my 150HP Johnson Oceanpro 2 stroke motor that powers my 1986 22CC Hydra Sport....

I was having some issues with what I though was prop slip and was told last year that I could replace prop (shown in photos) which I did but used an aluminum replacement,,,,,,,, which resulted in about a 15MPH decrease in my speed, went from 50MPG top down to about 35MPG???

Now I am wondering if replacement was a good thing, so an considering putting old prop back on,,,, after I get it checked out???

What can you tell me from numbering on the prop???? (looks like there's a lot of numbers/letters stamped(x'd) out???

 

[steelespike]

Re: Prop Pitch

While we are eager to help you out.It's against the rules and confusing to hijack a thread.
If you use the big red "New Thread" tab at the top of the prop forum it will be less confusing.
Also if you read "read this first" And try to get us the info needed.It will make it easier.
Some test runs with your stainless prop.Do you know the gear ratio of your motor?