2017 25 Guardian with 300 Suzuki

Optimizing the performance of Boston Whaler boats
25GuardianTX
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2017 25 Guardian with 300 Suzuki

Postby 25GuardianTX » Sun Aug 13, 2017 6:16 pm

Just wanted to share my performance numbers now that I have it dialed in:

--2017 25 Guardian with a Suzuki 300 HP
---Suzuki four blade 15.25 x 20-pitch LH propeller
--150 gallons of fuel
--6-inch SeaStar jack plate

All figures per GPS and Suzuki digital gauges

3900 RPM - 31 MPH at 3.0 MPG
4300 RPM - 34 MPH at 2.8 MPG
4600 RPM - 37 MPG at 2.6 MPG
6150 RPM (Max) - 49 MPH at 1.9 MPG

I'm very pleased with the whole rig. I tried 3x16x17 and 3x16x18.5 in both RH and LH and they didn't have the speed or efficiency of the 4 blade. Also, the LH props were slightly faster than their identical RH counterpart. Who knows but that's how it worked out.

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Phil T
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Re: 2017 25 Guardian w/ 300 Suzuki

Postby Phil T » Mon Aug 14, 2017 10:39 am

Where is the engine mounted?
Load?
So which prop (make, model and size) gave you theses results?

FYI - A Outrage 25 with a Verado 300 (30inch shaft) hit 49 @ WOT so I think you are dialed in.
http://continuouswave.com/ubb/Forum4/HTML/007923.html
1992 Outrage 17
2019 E-TEC 90
2018 LoadRite 18280096VT
Member since 2003

25GuardianTX
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Joined: Sat May 13, 2017 6:34 pm

Re: 2017 25 Guardian w/ 300 Suzuki

Postby 25GuardianTX » Tue Aug 15, 2017 7:47 am

Phil T wrote:Where is the engine mounted?
Load?
So which prop (make, model and size) gave you theses results?

FYI - A Outrage 25 with a Verado 300 (30inch shaft) hit 49 @ WOT so I think you are dialed in.
http://continuouswave.com/ubb/Forum4/HTML/007923.html



I mentioned those above:

Suzuki 4x15.25x20 LH
150 gallons of fuel
6" SeaStar jackplate

I did have the JP at 4 and the engine trim at 68%. I previously has a 25 Outrage with a 300 Optimax and then 250 Suzuki and the best I ever got loaded out of that boat with the 300 Optimax was 48. But, the Opti was tough to prop.

jimh
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Re: 2017 25 Guardian with 300 Suzuki

Postby jimh » Tue Aug 15, 2017 12:06 pm

I am assuming the Suzuki 300 has their innovative and unique gear case that is designed to turn either in standard rotation or counter rotation, as set electronically into the engine controller. It never occurred to me that you'd run a left hand propeller on a single engine--and that the top speeds would be better. That's a surprise.

Were the engine speeds at maximum throttle the same with RH and LH propellers of the same pitch and style?

The reported fuel economy is impressive.

A top speed of 48 to 50-MPH is about all the speed you could ever use in a 25-foot Boston Whaler. The hull can only run at those speeds in very calm water.

25GuardianTX
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Re: 2017 25 Guardian with 300 Suzuki

Postby 25GuardianTX » Tue Aug 15, 2017 11:06 pm

jimh wrote:I am assuming the Suzuki 300 has their innovative and unique gear case that is designed to turn either in standard rotation or counter rotation, as set electronically into the engine controller. It never occurred to me that you'd run a left hand propeller on a single engine--and that the top speeds would be better. That's a surprise.

Were the engine speeds at maximum throttle the same with RH and LH propellers of the same pitch and style?

The reported fuel economy is impressive.

A top speed of 48 to 50-MPH is about all the speed you could ever use in a 25-foot Boston Whaler. The hull can only run at those speeds in very calm water.


Yes, we ran our experiments with a number of RH and LH props that are identical to each other except for the rotation and the LH props were consistently 2 mph faster. Since the 300 Suzuki has the selective rotation, it's the only engine that lets you do the RH/LH testing on the same boat. Changing the rotation of the engine is super simple. It takes longer to change the prop than switch the rotation.

The speed I got is all I think that boat has unless I'm running on fumes. I'm loving the Guardian. My 25 Outrage was great but this 25 Guardian is better in every way.

jimh
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Re: 2017 25 Guardian with 300 Suzuki

Postby jimh » Wed Aug 16, 2017 5:38 am

But were the faster LH propellers faster because the engine speed was faster?

Or, were the faster LH propellers turning at the same engine speed as the RH propellers but they just made the boat go faster?

25GuardianTX
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Re: 2017 25 Guardian with 300 Suzuki

Postby 25GuardianTX » Wed Aug 16, 2017 7:09 am

jimh wrote:But were the faster LH propellers faster because the engine speed was faster?

Or, were the faster LH propellers turning at the same engine speed as the RH propellers but they just made the boat go faster?


Same max RPM but more speed. I would love it if someone could try the same experiment on their boat but they would need a recent model Suzuki DF250AP or DF300AP with the selective rotation to get controlled results.

crow
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Re: 2017 25 Guardian with 300 Suzuki

Postby crow » Wed Aug 16, 2017 8:56 am

Below is a link to the performance numbers for my 1985 Outrage 25 with 2007 Suzuki 300hp.

http://continuouswave.com/ubb/Forum4/HTML/007215.html

Congrats on your new Guardian!

jimh
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Re: 2017 25 Guardian with 300 Suzuki

Postby jimh » Wed Aug 16, 2017 12:31 pm

On the switchable Suzuki gear case, are the gear ratios for standard rotation and counter-rotation exactly the same?

25GuardianTX
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Re: 2017 25 Guardian with 300 Suzuki

Postby 25GuardianTX » Wed Aug 16, 2017 6:04 pm

jimh wrote:On the switchable Suzuki gear case, are the gear ratios for standard rotation and counter-rotation exactly the same?


Yes, they are to my knowledge.

25GuardianTX
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Re: 2017 25 Guardian with 300 Suzuki

Postby 25GuardianTX » Wed Aug 16, 2017 6:05 pm

Thanks for sharing that. It sounds like we are pretty much in the same place. I'm burning a bit more fuel but the Guardian is materially heavier and I've been testing with full fuel.

Shadburke
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Re: 2017 25 Guardian with 300 Suzuki

Postby Shadburke » Tue Dec 12, 2017 10:41 pm

A 2004 Boston Whaler GUARDIAN 25 with twin Yamaha F150 engines swinging 14.25 x 19 P stainless Yamaha propellers: WOT 51-MPH SOG (GPS) at 5,800-RPM.