New Prop Newbie

[fbozek]

I just bought a used boat and noticed the prop was pretty dinged up. As I do my research on what prop to buy as a replacement many questions pop up:

1. - why would a buy a stainless steel over an aluminum prop or vice versa
2. - how can I determine to what degree I can change the stle (pitch?) of prop i have on my boat.
3. - Is there a pricepoint where you are just spending money without much return on the investment?
4. - along the same lines, is there a low pricepoint where you want to exceed otherwise you are buying junk?

thank you.

 

[usskydvr]

Re: New Prop Newbie

1. Stainless Steel flexes less than Aluminum so is more efficient and is also more durable if you happen to hit something.

2.
ESSENTIAL DATA REQUIRED
When posting a question about propellers, you cannot get a reasonable answer unless you provide the following information in your post: Items 1-4 are essential for meaningful response to most questions.
1) Performance issue you are trying to correct.
2) Current prop manufacturer, model, aluminum or stainless and as a minimum.
3) Current prop diameter and pitch (required).
4) Wide open throttle RPM and speed with an average load (very helpful)
5) Engine/drive make, model, year, and HP
6) Boat make model, year, length and weight

3. Personal choice. Some folks will spend the bucks for a 'lab finish' prop just to get a few extra MPH.

4. All the major prop Mfg make a decent base product. As you get more specialized applications the price goes up.

 

[jeffnick]

Re: New Prop Newbie

I've tried 15 different props. For general use a factory 3 blade aluminum that puts my RPM's at the low end of the WOT range works best for me.

 

[steelespike]

Re: New Prop Newbie

Actually its is generally considered best to prop to the high end of rpm range.
The motor will do better over the long run on todays doctored fuels and feel peppier.

 

[jeffnick]

Re: New Prop Newbie

Actually its is generally considered best to prop to the high end of rpm range.
The motor will do better over the long run on todays doctored fuels and feel peppier.

True, but my motor is seldom wide open. My interest is cruising mpg.

 

[steelespike]

Re: New Prop Newbie

A marine motor is working like that in a car going up a hill.imo you have it going up an even steeper hill in the wrong gear.
Do you have a flow meter?Most likely you require more throttle to reach the
cruising rpm than with a lower pitch prop.It may or may not be faster.Whether it makes up enough speed to overcome the throttle setting only a flow meter or extensive testing knows for sure.Ideal cruising speed can be anywhere from just on plane to about 1,000 rpm higher.
If your lugging the motor at the bottom of the rated rpm your lugging through the
whole throttle range.
Lower rpm doesn't work like on a car. Its kind of like going up a long hill in overdrive.

 

[jeffnick]

Re: New Prop Newbie

Observations are based on FloScan readings.