Best prop Regal 2100

[Appollo]

2017 2100 regal. 240hp 4.3 wot 6000 rpm 52 mph
max trim 14.5x19 prop. 30 mph at 4000 rpm. I would
like to be 30mph at 3000 rpm. If this is possible.
It is a Volvo penta SX drive. And can I gain a couple mph

Thanks for any help

also I did try a 14x21 4 blade prop today, not impressed
didnt want to stay on plane. Rpm was 5500. At 47
mph. 3500 rpm at 27 mph

 

[QBhoy]

I’m not familiar with the 4.3 240hp to be honest. What is the max rpm rating and recommended rpm range ? If it a GM based engine...6000rpm sounds very high. I know there are Merc 4.5 mpi these days that run almost as high...but the 4.3 size suggests GM. I’d be careful.

 

[Appollo]

It’s the new gen 5 Volvo it’s designed to turn 5800

 

[porscheguy]

Are you using standard VP aluminum props? Do you happen to know your gear ratio?

if you were running 47mph you weren’t having too much trouble staying on plane. But you went up in pitch and lost both rpm and speed so 21 is not for you.

Anyway, depending on your ratio your slip could be anywhere from 13-23%. I’ll assume you’ve got an aluminum prop. But if you can fill in the blanks, it would help. Check your paperwork to see if it lists the gear ratio.

 

[tpenfield]

Simple math says that you would need a 25" pitch prop to be doing 30 MPH at 3K RPM, given the fact that you are having to go 4K RPM to do 30 mph currently.

Sanity check says that engine does not have the ponies to spin a 25" pitch prop, and as you can attest, the 21" pitch prop reduced the performance of the boat.

Most boats come from the factory with the best overall prop. We often see folks on the forum trying to play 'prop magic' and end up wasting time and money.

 

[Scott Danforth]

2017 2100 regal. 240hp 4.3 wot 6000 rpm
like to be 30mph at 3000 rpm. If this is possible.

Never going to happen, not possible. You dont have enough torque to turn that much prop efficiently. And if you put the prop on the boat, you will be severely over-propped and lug the motor and burn more fuel than you are now while killing the motor

 

[Appollo]

Thanks absolutely it lugs at 30 and I have any weight
tranfer it falls off plane. We are making long cruises 130 miles. My idea was to be able to have more distance on the
tank at 30

back filling in the blanks gear ratio 1.92
Scott I from my ride yesterday I believe that you hit the nail on the head 19 pitch prop is the ideal prop for the boat.
it pushes me with full tank 10 extra gallons and 3 average
size people 50 also it doesn’t lose much speed loaded with 5
of us it goes 45, so am I going to have luck with other props
or size etc.

thanks for all input
Kleve

 

[Scott Danforth]

use the trim tabs to adjust attitude for ability to plane at lower speed. however depending on your fuel tank size, you may have to stop for fuel.

internal combustion I/O motors burn 0.4# of fuel per HP per hour. so your fuel rate is directly tied to your commanded HP (hand on throttle).

most likely you wont get anywhere with props as VP does a good job initially.

your ideal cruise speed will be above 30mph, probably closer to 33-35mph. take a look at boattest.com

with any trip, use 1/3 your tank to your destination, 1/3rd to get back and 1/3 for the OS factor

 

[Appollo]

Thanks for the advice, Is there any one prop better at performance than another such as the stock Volvo Penta
vs turning point etc or any other prop out there. The boat
is really impressive I was only interested in tweaking it a little
volvo and regal evidently already have.

 

[porscheguy]

Most boats come from the factory with the best overall prop. We often see folks on the forum trying to play 'prop magic' and end up wasting time and money.

I hope you’re kidding here. That may be true on some brands that place high priority on performance. On most recreational open bow boats, they’re shipped with a cheapo aluminum that may or may not be the ideal size. It all depends on what the dealer had in stock and if the previous customer wanted a different prop. Your boat may have shipped with a 19 but if the previous customer wanted a 19 and the dealer had none on the shelf, they’ll swap yours with his 17 or 21, and just kick the can down the road.

Now that we have a gear ratio, it looks like the slip is around 7.5%. So it looks like whatever is on it is the best bet

 

[porscheguy]

Thanks for the advice, Is there any one prop better at performance than another such as the stock Volvo Penta
vs turning point etc or any other prop out there. The boat
is really impressive I was only interested in tweaking it a little
volvo and regal evidently already have.

The motor builders have vastly more resources at their disposal for developing props. And a company like mercury have an in house foundry to develop and produce the alloys that go into prop making. Mercury will make the most cutting edge stuff. You might see an improvement with an enertia. (The enertia is also sold as the Quicksilver Q3 for significantly less). But it won’t be much improvement.

 

[Appollo]

FYI update went back to the 3 blade 19 pitch. It is definitely the best performing for the boat. Guessing I’ll trade up next year to more cubic inches

Thanks

 

[tpenfield]

FYI update went back to the 3 blade 19 pitch. It is definitely the best performing for the boat. Guessing I’ll trade up next year to more cubic inches

Thanks

Yup, probably the one that originally came with the boat

 

[jimmbo]

It is an entirely different 4.3 than most of us are familiar with, this one is an AL block and is indeed rated at 5800rpm, there is also a 280hp version of it too. They all have an 11:1 compression ratio.
To the OP, you still have to prop it for WOT, not to attain a given speed at a given RPM. Actually you can, but don't expect a long engine life.