Stainless and aluminum prop comparison

[ryanb]

I'm looking at getting a couple of spare aluminum props for my boat for remote trips. Currently the boat has eco enertia 13.6x21p stainless props and if anything the boat is slightly over-propped. When purchasing an aluminum prop, what would be a good comparable? Any recommendations on what's a good affordable spare that won't get used except in emergencies?

Thanks

 

[trophywife]

look on ebay, lots of cheap brands.. just for emergencies any ways.. literally they are 100.00 backups.

 

[Squire]

Yamaha Counter-rotating Stainless Propellers - boat parts - by owner

2 sets of Yamaha outboard counter-rotating painted Stainless Propellers 13 3/4 x 19 Excellent condition - no damage. Used as spares only - 1" shaft - 15 spline. Selling by pair only. $100.00 ea. or...

vancouver.craigslist.org

If you are currently overpropped this may be an economical option?

 

[brutus]

I run the same pitch same size prop in stainless, my back up is alluminum, I loose 5 mph when I use the aluminum, and burn more fuel, slower getting out of the hole too. My boat is underpowered a bit, but played with props and now am happy with it. Definitely see a difference in stainless versus aluminum, just keep that in mind

 

[brutus]

I'm looking at getting a couple of spare aluminum props for my boat for remote trips. Currently the boat has eco enertia 13.6x21p stainless props and if anything the boat is slightly over-propped. When purchasing an aluminum prop, what would be a good comparable? Any recommendations on what's a good affordable spare that won't get used except in emergencies?

Thanks

When you say overprop, you mean it take a while to get on plane but once you are it goes like stink ????

 

[Foxsea]

When you say overprop, you mean it take a while to get on plane but once you are it goes like stink ????

Overpropped means the engine cannot get up to spec'd RPM's at WOT.

 

[brutus]

Overpropped means the engine cannot get up to spec'd RPM's at

Overpropped means the engine cannot get up to spec'd RPM's at WOT.

To most yes, it leaves a big gap in Rpm range5000- 6000 at wot. I would say if he is not in those range he should worry more about his main prop lol. 21 pitch he is running should have a lower pitch. Example I was running a 3 blade 14-3/4 x18 pitch, still in Rpm range and was way overprop for my boat, would take forever to get on plane4200 Rpm 20mph, top out at 5800rpm at 36 mph. Now running 4 blade 15-15 pitch get up in no time3600rpm at 16mph, wot at 6000rpm at 38 mph, boat can plane at way lower speed like 13-14 mph and stay up without having to run 4200 Rpm. Now cruise at 25 mph at 4200 Rpm. So all I am saying here is we need numbers to know. If he is not running at least 5000rpm with the prop he has now he is wayyyyy overprop IMO

 

[ryanb]

The engines turn 5600rpm at WOT, so it's not really a problem. Ideally, IMO, top rpm would be maybe another couple hundred rpm. The question was more do I need to change the pitch or diameter once I go to aluminum backups or should I just buy aluminum props with the same specs?

 

[noluck]

I'm looking at getting a couple of spare aluminum props for my boat for remote trips. Currently the boat has eco enertia 13.6x21p stainless props and if anything the boat is slightly over-propped. When purchasing an aluminum prop, what would be a good comparable? Any recommendations on what's a good affordable spare that won't get used except in emergencies?

Thanks

if it is slightly overpropped in ss a aluminum prop same spec will be perfect, as there is enough flex in the aluminium prop to help meet top rpm

 

[BC Coast Pilot]

I'm looking at getting a couple of spare aluminum props for my boat for remote trips. Currently the boat has eco enertia 13.6x21p stainless props and if anything the boat is slightly over-propped. When purchasing an aluminum prop, what would be a good comparable? Any recommendations on what's a good affordable spare that won't get used except in emergencies?

Thanks

If it's 13.6 dia you have an Enertia not Enertia Eco

The Enertia Eco is 16 inch dia and a totally different wheel. Just something to be aware of.

 

[ryanb]

If it's 13.6 dia you have an Enertia not Enertia Eco

The Enertia Eco is 16 inch dia and a totally different wheel. Just something to be aware of.

Thanks, had no idea there was a difference.

 

[BC Coast Pilot]

Thanks, had no idea there was a difference.

Noluck is exactly right about the aluminum "flattening" per say at speed resulting in more rpm but less efficiency. It's typical if you switch from aluminum to stainless to drop a pitch with no change in diameter to keep similar rpm.

 

[ryanb]

Thanks, sort of....now that I know about the enertia eco I want to try them to see if it's much more efficient (seems like it should be).

 

[BC Coast Pilot]

Thanks, sort of....now that I know about the enertia eco I want to try them to see if it's much more efficient (seems like it should be).

They worked for me. I went from 4400 rpm 95 litres hr (combined) cruise at 24kts to 3800 rpm 75 litres hr. 24 knots. However I was also underpitched. From what I understand They were specifically engineered for the Verados due to the complaints of high burn rates. Bringing the revs under 4k also got them out of the supercharger higher boost range.
Try this prop selector:

Mercury Marine - A Worldwide Leader in Marine Propulsion | Mercury Marine

Manufacturers of outboard motors and MerCruiser inboard engines, with over 4000 dealers in the United States.

www.mercurymarine.com