Stainless Steel VS Aluminum Props

[sh4325]

I will be buying a 2005 Cobalt 220 with a 5.7 Gi 300HP with a Volvo Penta duo prop outdrive. The boat has a set of aluminum props, which I hate these kinds of props. Good fro a spare set only. I will be installing a new set of stainless steel props on the boat shortly after I get the boat home. I know the SS props should improve top speed but how much additional top speed can I expect with the stainless steel props?

Thanks!!

 

[steelespike]

Re: Stainless Steel VS Aluminum Props

A can't speak to the duo prop specifically but your ss results will vary widely based on what props you select. There is a vast array of ss props out there, I think ,even for the duo prop.As I understand it beyond certain speeds only ss props are suggested.
The simple move to ss props isn't a miracle cure.
There are some very good al props out there I think changing from a very good al to an entry level ss would have minimal results.

 

[tpenfield]

Re: Stainless Steel VS Aluminum Props

There is probably not a lot of experience in this regard, as most dual prop drives would have SS props to begin with. You should have less cavitation off the back side of the prop with stainless, as the blades are a lot thinner. So, maybe a couple more mph out of the deal.

you are better off with a SS prop on a big engine anyway. Have you priced out the prop set?

 

[sh4325]

Re: Stainless Steel VS Aluminum Props

I have priced out a set of props. Not cheap!

 

[sh4325]

Re: Stainless Steel VS Aluminum Props

I have not taken possession of the boat yet. The lower unit was stolen off the boat while stored at hos storage unit. Later on after that the engine had a problem and was replaced by Marine Max in Dallas TX. This is a condensed version of the situation. After the cost of the lower unit and the engine work he skimped on the props. Kinda sad actually. Aluminum props an a Cobalt is just not right. So the boat runs around 51MPH with 4 people in the boat. Another owner that I spoke with has the same exact boat with a 300HP 350 MAG Mercruiser with a single 19" prop that runs 60-62MPH. That's very respectable. I was hoping for maybe 3-5 MPH increase with the SS set of props. I am not out to set a speed record on water just getting an idea if this is adequate power for the boat. I like a boat that has enough reserve power so that the engine is not stressing out just cruising around the lake. What does the Admiral think? Thanks!

 

[sailingseven]

Re: Stainless Steel VS Aluminum Props

I picked up about 4 mph (on GPS) by switching from aluminum to ss with the same pitch and size. That was with a single prop boat though. The biggest difference for me was the boat planed faster and stayed on plane at lower speeds.

 

[doyall]

Re: Stainless Steel VS Aluminum Props

I will be buying a 2005 Cobalt 220 with a 5.7 Gi 300HP with a Volvo Penta duo prop outdrive. The boat has a set of aluminum props, which I hate these kinds of props. Good fro a spare set only. I will be installing a new set of stainless steel props on the boat shortly after I get the boat home. I know the SS props should improve top speed but how much additional top speed can I expect with the stainless steel props?

Thanks!!

You need to study the attached publication, in particular the 'D' (aluminum) and 'F' (SS) series.

I have experimented with the Quicksilver Thunderbolt DPS (4 x 3, 22.5 pitch) and while it may have some minor advantages in my application (4300#, 22' w/5.0 GXi), IMO the VP 'F' prop (3 x 3) is the better all round choice between the two considering price. You should be able to find a decent used set on that auction site at a reasonable cost. I have not tried the 4 x 4 Signature so I cannot comment on it in use. I also experimented with an 'X' series composite but it had a stress break on the first outing. Must be why they are discontinued. I also have the 'D' series aluminum (3 x 4) recommended by VP but as it is obviously not the same pitch (D3 ~ 19 pitch?) as the F5 (~ 23 pitch) recommended for my application it will not be a valid comparison.