Please help newbie to choose the RIGHT prop!!!

[seaturtle]

I moved from high altitude to sea level. I was using a 17" Mirage Plus stainless. Not knowing the new waterways, I thought an aluminum prop may be best to start with. Do you agree? I hit a rock with a stainless prop once. I had to replace the drive shaft and the entire lower unit. The dealer told me that I was 'lucky' that the engine wasn't damaged. Is stainless prop really that dangerous? Should I take a chance and stick with Stainless. Is there a quick change system between the 2?

The boat is a V hull fiberglass cuddy cabin with a 7.4L Meruiser Bravo 1. The WOT RPM range is 4400 to 4800. We usually have 3 to 4 people on board with a 80 gallon fuel tank and 10 gallon water tank. We do fishing and water sports. Absolute top speed is not as important to me as hole shot and handling. Of course, money matters too. What are my 'best bang for bucks' choices for Aluminum / stainless props?

I've read the prop basics but still don't quite understand hubs. Do I need to buy a hub for any new prop (such as Turning Point Stainless Express)? What’s wrong with the factory rubber hub?


Thanks in Advance!

ST

 

[WillyBWright]

Re: Please help newbie to choose the RIGHT prop!!!

Prop may not be the only difference. The gear ratio may have been changed and carburetion may have been changed as well. Address those before propping, at least the carb issue. If it's an EFI, then don't worry about that. Are you saying that you are getting 44-4800RPMS? Then I'd say that you already have the right prop. Otherwise what R's are you turning?

Stainless props add mass which is much harder on the drivetrain. They're also very unforgiving in a prop strike. I've seen aluminum props missing blades, yet the gears survived. I've also seen stainless props that had minimal damage, but the gear teeth stripped clean.

Many prop offferings have hub kits needed to mount it to whatever brand of shaft. There are also high performance hubs, but your rig wouldn't need one of those.

 

[Silvertip]

Re: Please help newbie to choose the RIGHT prop!!!

Although you indicated the wide open throttle RPM is 4400 to 4800 rpm, that range is the "recommended" range. We need to know what wide open throttle rpm actually is with your current setup because it's the prop pitch that ultimately determines how many RPM the engine turns. Along with that, we need to know what maximum speed is at WOT setting with what you consider an average load. Without those two numbers we can only guess what the best prop would be. In my view, unless you have a special circumstance or are looking for ultimate performance, the average boater should stick with a good performing aluminim prop.

 

[seaturtle]

Re: Please help newbie to choose the RIGHT prop!!!

Thanks for the response. The engine is carbureted with jets for 7,000ft high altitude with max speed at 47. It was running at about 4,700 RPM WOT. I have not tested this set up at sea level.

The carb will be adjusted to sea level, but I need to acquire a prop soon. I'm considering the 21" aluminum prop from Turning Point called the Express

ST

 

[WillyBWright]

Re: Please help newbie to choose the RIGHT prop!!!

Until you get a run with it in the water with the right carburetion, there's not enough info for us to pinpoint the right pitch. Your motor will be making substantially more horsepower at sea level than it did at well over a mile high. It's probably safe to assume that you will need to go up in pitch. How far is the question. That's about all I can offer right now, except that 21 would be the one I'd try first.