200 DAUNTLESS VERADO 175

Optimizing the performance of Boston Whaler boats
rpa
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200 DAUNTLESS VERADO 175

Postby rpa » Mon Aug 31, 2020 2:52 pm

Hello All. In the summer of 2020 I purchased a [used] 200 DAUNTLESS with a VERADO 175-HP. The boat came with a stainless steel 17 propeller. The VERAD engine seemed to over-rev very easily, and the 200 DAUNTLESS had a low top boat speed.

I want to do more coastal cruising with the 200 DAUNTLESS at decent speed.

The top boat speed now is 36-MPH. I want to be able to cruise at 40-MPH with top speed of 50-MPH.

What propeller will best suit this set up?

Thank you.
Rod

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Re: speed and performance of my Dauntless.

Postby biggiefl » Mon Aug 31, 2020 3:23 pm

Check the prop hub. Going from 36 to 50 may not be possible with a 175hp.
On my 24th Whaler. Currently in the stable: 86 18' Outrage, 81 13' Sport(original owner), 87 11' Sport, 69 Squall(for sale cheap).

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Phil T
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Re: speed and performance of my Dauntless.

Postby Phil T » Mon Aug 31, 2020 4:28 pm

Regarding "over-reving," the Verado 175hp engine has a WOT range of 5800-6400 rpm's. What was the max rpm's you reached at 39 mph?

Here is the factory performace report for the 2010 model year when a 150hp and 200hp powerplants were offered.

http://bostonwhaler.com.s3.amazonaws.com/resources/200-Dauntless-Performance-2010.pdf

Take special note of the tested boat specs, weight tested etc and the performance curve.

Entering in the Verado 175's maximum rpm (6400), gear ratio (2.08), current prop pitch of 17", slip percentage (5.00), into a prop calculator, it returns a target boat speed is 47. I think 45 is more accurate looking at the Whaler test data.

Do you have bottom paint? Is it smooth?
Is there a T-Top?
Did you trim the engine out significantly prior to noting speed?
1992 Outrage 17
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rpa
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Re: speed and performance of my Dauntless.

Postby rpa » Tue Sep 01, 2020 5:02 am

Thanks Phil.

The hull bottom is smooth, no anti-fouling paint.

I have trimmed the engine up as well, although it won't take much more before [the propeller ventilates].

At engine speed 6000-RPM the boat speed was 39-MPH. The 175-HP VERADO engine sounded like it was about to leave this world.

The 200 DAUNTLESS has no T-Top.

I have trimmed the boat of accessories.

I thought the WOT was 5,800-RPM—a lot less than 6400-RPM. I may have been mistaken.

This is my first foray into the world of four-stroke outboards.I imagined they would run at less engine speed and consume less fuel.

Your help is appreciated.

Rod

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Phil T
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Re: speed and performance of my Dauntless.

Postby Phil T » Tue Sep 01, 2020 7:47 am

Rod -

I was saying trim (out) the engine, not the boat. You may pick up 3-4 mph by doing just that. Switch on the throttle handle.

The current 175hp Mercury FourStroke (not Verado) has a WOT rpm of 5800 whereas the Verado 400hp has an WOT rpm of 6800!
1992 Outrage 17
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Member since 2003

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Re: 200 DAUNTLESS VERADO 175

Postby jimh » Tue Sep 01, 2020 8:15 am

A boat test of a 200 DAUNTLESS with 175-HP VERADO indicated top boat speed was just over 45-MPH. See

https://www.boatingmag.com/boats/boston ... dauntless/

The propeller in that test is ambiguously described.

You won’t be able to go any faster unless you increase horsepower.

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Re: 200 DAUNTLESS VERADO 175

Postby jimh » Tue Sep 01, 2020 8:30 am

Give more details about the propeller in use on the boat under discussion. A “17” propeller could be anything. Give the brand, model, diameter, and pitch.

The VERADO four-cylinder engine is not as quiet nor as smooth as the original six-cylinder larger VERADO engines, so at an engine speed of 6,000-RPM its sound signature is not going to be particularly quiet—in fact with the supercharger it may be unusually loud. Also the unbalanced four-cylinder design may show harsh vibrations at that engine speed.

Distinct from your concept, most four-stroke-power-cycle outboard engines have a rather high maximum engine speed RPM rating, and the engine produces its rated power at or close to its maximum engine speed.

The Brake Specific Fuel Consumption for a supercharged engine at full throttle is going to be higher than most any other naturally aspirated engine. Operating the supercharger takes about ten-percent of the total engine power. This means to make 175-HP at the propeller shaft the total engine power may be about 195-HP, with maybe 20-HP consumed by the supercharger. The fuel consumption will be greater than expected because the engine is burning fuel to make 195-HP but only delivering 175-HP to the propeller. That is the nature of supercharged engines.

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Re: 200 DAUNTLESS VERADO 175

Postby jimh » Tue Sep 01, 2020 8:58 am

Boat tests are usually made with the boat as light as possible in order to show the most favorable speed performance.

Environmental conditions such as air temperature, humidity, water salinity, and water temperature affect performance. Testing with hot and humid air in very warm freshwater will produce significantly lower performance outcomes than testing in cool dry air in cold saltwater.

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Re: 200 DAUNTLESS VERADO 175

Postby biggiefl » Tue Sep 01, 2020 10:25 am

95db is very loud.

Quick question...are you sure it is reading in MPH, not KTs?
On my 24th Whaler. Currently in the stable: 86 18' Outrage, 81 13' Sport(original owner), 87 11' Sport, 69 Squall(for sale cheap).