Prop questions

[biggerseagar]

I am looking to get new aluminum props for next season. I have 18 3/4 by 21 props on there now on my 01 3000 scr 5.0L carbs bravo 2 outdrives. They work very well but I think that they are worn out. Original equipment.

My first question is: how close to the original diameter (18 3/4) do I need to get to. It seems like I see 17 3/4 alot or even 18 1/4. I am happy with the 21 pitch.

I have found a store on line, The Delta Prop shop in Cleves Ohio that is close and prices are reasonable as a possible store to buy from.. Any suggestions in a make or manufacturer or prop shop that you know of or recommend?

Thanks
Roger

[mmwjr]

IMO if you go with the 18 1/4 and 21” pitch you shouldn’t see much change in performance. I would go this way instead of the 17 3/4.

[shrew]

For Prop diameter sizing you want the space between the anti-ventilation plate and the tip of the prop blade to be 15% -20% of the prop diameter (20% being ideal). I'd start with how much you have now and calculate what that value with be with a different diameter prop.

18.75 x .15 = 2.8125"
18.75 x .20 = 3.75"

17.75 x .15 = 2.6625"
17.75 x .20 = 3.55"

Decreasing diameter may impact performance similarly to decreasing pitch. 1" of diameter is not insignificant.

[Kendussome1966]

I would stay with factory pitch and diameter and go with stainless steel props .there's less flex in the stainless steel there for better performance. That's my opinion anyways

[mmwjr]

Originally Posted by Kendussome1966

I would stay with factory pitch and diameter and go with stainless steel props .there's less flex in the stainless steel there for better performance. That's my opinion anyways

SS doesn’t flex and is heavier than aluminum so to achieve the same performance one typically has to decrease one pitch size. A down side to SS is if you hit something the energy is transferred into the drive which can cause damage instead of the aluminum prop absorbing it.