Propping your engine/boat configuration

[Sea Rider]

Have asked this same question to different boaters and every one of them seems to have their own tech ideas, some says should prop a empty boat with just driver, 1/4 fuel tank, others says you should prop engine with "normal" weight you will boat with, that is more fuel, passengers, gear, wot both methods and play with prop pitch to achieve max rpm factory stated for that engine. Factory deliverd engines with attached props are medium pitched.

Is it just a personal matter to have best hole shot with less max speed or best top speed with less hole shot, as you cannot have both with same prop at same time. Is there a third near rocket science method to prop boat right ? Ideas, suggestion, technical views are welcome...

Happy Boating

 

[Chris1956]

Re: Propping your engine/boat configuration

you cannot max hole shot, max top speed and max fuel economy. Of the three, top speed and fuel economy are related, and most people go for this.

To choose those two, prop the boat to reach the middle of the max RPM range with a normal load. Now you will have enough reserve power if you get a few extra folks. Now run the boat at a speed just over a solid plane for the best fuel economy. If you want a bit more power for watersports, prop to make max RPM with normal load.

 

[Sea Rider]

Re: Propping your engine/boat configuration

Yes I understand the point, that's why it's good to keep the factory delivered prop if your engine was sent with one, will give near middle rpm, have good hole shot and nice speed. Or count with a spare prop for different boating applications like skiing, top speed, etc.

Happy Boating

 

[craze1cars]

Re: Propping your engine/boat configuration

I say there is no "right" way to do it. Boats must be propped for the intended application. The method of accomplishing this may be different from one another.

What is the point of propping perfectly for your empty/unloaded boat, when 90% of your time is going to be at full load capacity? It would obviously be smarter to prop that particular boat for near full capacity, and then just use caution to not over-rev and damage the engine/drive on those rare empty-load runs.

Take 3 identical brand new runabouts, delivered on the same day to 3 very different people, and each is savvy enough to shop for the "perfect" prop. The watersports guy will prioritize holeshot with a boatload of people. The long-distance cruising couple will prioritize fuel economy for cruising with an avg/light load. The speed-freak racer who wants bragging rights will prioritize absolute maximum top speed while riding alone with almost zero weight on board.

Each of these applications will require substantailly different props, and likely will have different WOT RPM targets, despite being on the same exact boat. And yet each of these people will undoubtedly settle on a different "right" prop for his/her application.

Anyone who advises you how to prop your boat, without first asking you details about how you are actually using your boat, stands a strong chance of giving poor advice and steering you to a poor prop for your application.

 

[BaileysBoat]

Re: Propping your engine/boat configuration

I say there is no "right" way to do it. Boats must be propped for the intended application. The method of accomplishing this may be different from one another.

What is the point of propping perfectly for your empty/unloaded boat, when 90% of your time is going to be at full load capacity? It would obviously be smarter to prop that particular boat for near full capacity, and then just use caution to not over-rev and damage the engine/drive on those rare empty-load runs.

Take 3 identical brand new runabouts, delivered on the same day to 3 very different people, and each is savvy enough to shop for the "perfect" prop. The watersports guy will prioritize holeshot with a boatload of people. The long-distance cruising couple will prioritize fuel economy for cruising with an avg/light load. The speed-freak racer who wants bragging rights will prioritize absolute maximum top speed while riding alone with almost zero weight on board.

Each of these applications will require substantailly different props, and likely will have different WOT RPM targets, despite being on the same exact boat. And yet each of these people will undoubtedly settle on a different "right" prop for his/her application.

Anyone who advises you how to prop your boat, without first asking you details about how you are actually using your boat, stands a strong chance of giving poor advice and steering you to a poor prop for your application.

Exactly.