255 CONQUEST Twin 200-HP

Optimizing the performance of Boston Whaler boats
Fishpimpii
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255 CONQUEST Twin 200-HP

Postby Fishpimpii » Tue Dec 01, 2020 2:30 pm

I’m repowering my 2002 255 CONQUEST with new twin SUZUKI 200-HP engines. I fish out here in the Pacific Northwest. I am more Interested in [power at low speed to] get over swells or power [when accelerating from a standing start] than top speed.

The dealer is guessing that the right propellers will be [of unknown material and unknown number of blades with] 16-inch diameter and 21.5-inch pitch--but he did NOT sound confident; he wanted my opinion.

Give me any suggestions or input for propellers.

Thanks--Jeff

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Re: Whaler 255 conquest twin Suzuki 200’s prop?

Postby biggiefl » Tue Dec 01, 2020 3:29 pm

According to Suzuki's boat tests online with boats with twin 200-HP engines:

--5,900-lbs boat ran 48.7-MPH with 16 x 21.5 propellers

--5,900-lbs boat ran 60.5-MPH with 16 x 26 propeller

--6,200-lb boat ran 51.8-MPH with 16 x 23 propellers.

What is [the boat's total] weight?

What is boat speed?

What is the engine gear ratio?

I think your dealer is correct; or 23-pitch depending on speed. Since you mentioned more grunt than speed, start with the 21.5-pitch.
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: Whaler 255 conquest twin Suzuki 200’s prop?

Postby Phil T » Tue Dec 01, 2020 4:28 pm

You don't specify 3 or 4 bladed props.

You want to go with 4 bladed for better grip.
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1992 Outrage 17, 1992 Evinrude 115

Fishpimpii
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Re: Whaler 255 conquest twin Suzuki 200’s prop?

Postby Fishpimpii » Tue Dec 01, 2020 7:24 pm

The dealer is suggesting stainless steel three-bladed propellers.

Their suggestion of the 16x21.5 sounds like the place to start.

From old whaler performance data with VERADO engines, a 255 CONQUEST should weight about 7,200 to 7,500-lbs.

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Phil T
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Re: Whaler 255 conquest twin Suzuki 200’s prop?

Postby Phil T » Tue Dec 01, 2020 7:49 pm

Since practically no one offers props for testing I would use a prop specialist.

Two respected sources I recommend and members have used include:

Ken Reeves of Prop Gods
http://www.propgods.com

JT props aka Dan's Discount Props
https://dansdiscountprops.com

Between the two, they sell all the various brands.
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1992 Outrage 17, 1992 Evinrude 115

jimh
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Re: 255 CONQUEST Twin 200-HP

Postby jimh » Tue Dec 01, 2020 10:23 pm

If the dealer is willing to suggest a set of propellers and let you test the performance of those propeller, you should agree to buy the dealer's suggested propellers, but only on the basis that if you are not happy with the performance you can try a different pitch or model with full trade in credit for the propellers the dealer suggested. This will tend to lock-in a sale of two propellers for the dealer, but give you a chance to try at least one or two sets of propellers.

What model are the SUZUKI 200-HP engines? I see three different in-line four-cylinder 200-HP engines listed: DF200A, DF200AP, DF200SS.

Are the engines both standard rotation? Or is one counter rotation?

Fishpimpii
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Re: 255 CONQUEST Twin 200-HP

Postby Fishpimpii » Tue Dec 01, 2020 11:58 pm

jimh wrote:If the dealer is willing to suggest a set of propellers and let you test the performance of those propeller, you should agree to buy the dealer's suggested propellers, but only on the basis that if you are not happy with the performance you can try a different pitch or model with full trade in credit for the propellers the dealer suggested.
[The] [d]ealer [is] not offering me to try various propellers and return [them for credit] as far as I can tell. [The dealer is] just [offering] propellers, installation, and water test[ing] [as] part of their install package.

jimh wrote:What model are the SUZUKI 200-HP engines? I see three different in-line four-cylinder 200-HP engines listed: DF200A, DF200AP, DF200SS.
The engines are latest 2020 25-inch-shaft length four-cylinder [with electronic shift and throttle remote controls]. I believe the model [designator] is 200ATX2.

jimh wrote:IAre the engines both standard rotation? Or is one counter rotation?
One [engine] will be counter[-rotating].

A guy with [a 255 CONQUEST and twin Suzukizi 200-HP engines is using] the same propellers that the dealer suggested [i.e. 21.5 x 16-pitch], and he says he’s happy with performance.

Unless I hear some compelling [reason to get] different [propellers], I will buy the [16 x 21.5 propellers the dealer suggested].

The dry weight of the boat and engines will be about 6,300 [lbs], but fully loaded with [a third engine for auxiliary], full fuel [tank], three or four guys, fishing gear, ice, etc., I am betting [the total boat weight will be] closer to [8,000-lbs].

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Re: 255 CONQUEST Twin 200-HP

Postby jimh » Wed Dec 02, 2020 8:49 am

Fishpimpii wrote:Unless I hear some compelling [reason to get] different [propellers], I will buy the [16 x 21.5 propellers the dealer suggested.
I think you have answered your own question.

Fishpimpii wrote:[The] [d]ealer [is] not offering me to try various propellers and return [them for credit] as far as I can tell. [The dealer is] just [offering] propellers, installation, and water test[ing] [as] part of their install package.
This engine purchase with installation, with new electronic shift and throttle remote controls, new propellers, and probably all new rigging harnesses, and likely with new gauges or instrumentation, is probably going to cost more than $40,000. I would expect that for a customer who is spending that amount of money, the dealer would be a bit more flexible about propeller testing.

If the 16 x 21.5 propellers do not do well in the water testing, are you saying you have to eat the cost those two propellers and buy another set?

Fishpimpii
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Re: 255 CONQUEST Twin 200-HP

Postby Fishpimpii » Wed Dec 02, 2020 10:16 am

jimh wrote:I think you have answered your own question.
Actually a guy on The Hull truth answered my question [December 1, 2020], but he had only owned the [255 CONQUEST for] a few weeks. He didn’t have anything to compare the 16 x 21.5 propellers against, and he didn’t have any data like maximum engine speed or calculated propeller SLIP. He just liked how things were performing.

jimh wrote:If the 16 x 21.5 propellers do not do well in the water testing, are you saying you have to eat the cost those two propellers and buy another set?
I believe if the propellers didn’t perform well in the water test the dealer would switch them out. But the water test will be on calm water in a river and probably with light load during break-in period, and most normal use will be offshore in the swells. I just want the best propeller I can get.

I figured this was the place that a few people might have been through this before with this boat and these motors or similar.

Thanks!

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Phil T
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Re: 255 CONQUEST Twin 200-HP

Postby Phil T » Wed Dec 02, 2020 11:21 am

I would not expect a dealer to swap out a prop once used. Those days are gone.

I suggested a prop expert given changing props is a $800-$1600 decision for you.
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jimh
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Re: 255 CONQUEST Twin 200-HP

Postby jimh » Wed Dec 02, 2020 11:41 am

Fishpimpii wrote:I believe if the propellers didn’t perform well in the water test the dealer would switch them out.
That is what I would expect, too, from a dealer that was selling me a re-power package of twin engines, rigging, installation, and propellers.

A general problem with twin engines and one counter rotating engine is an unwanted left-hand-rotation propeller becomes a rather odd-duck for reselling it; the number of engines that could use it is much less than there would be for a right-hand-rotation propeller.

Fishpimpii
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Re: 255 CONQUEST Twin 200-HP

Postby Fishpimpii » Wed Dec 02, 2020 11:45 am

Phil T wrote:I suggested a prop expert...

Thanks. I will reach out to one as well.

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Re: 255 CONQUEST Twin 200-HP

Postby jimh » Wed Dec 02, 2020 1:44 pm

Once you get the re-power finished and have tested propellers, let us know that propellers you decided to buy and what performance resulted.

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Re: 255 CONQUEST Twin 200-HP

Postby kwik_wurk » Fri Dec 04, 2020 9:01 pm

I’m with Phil T on going with a four-bladed propeller instead of a three-bladed propeller.

Anecdotally, on a similar 24-foot boat with twin F150 engine and 9,000-lbs total weight, I noticed [that changing to a four-bladed propeller produced] a difference in two areas: stern lift; and better handling at slower planing speeds especially in making turns. The [propellers compared] were [made by] different manufacturers and had altogether different profiles; that could have explained the difference [in boat performance that was observed].

Also propellers with four blades will be typically slightly smaller diameter--which has its [own] trade-offs.

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Re: 255 CONQUEST Twin 200-HP

Postby Fishpimpii » Sat Dec 05, 2020 1:54 am

My plan is to first get a set of three-bladed propellers the dealer is recommending.

Then in Spring 2021 I will get a set of four-bladed propeller for use when the boat is loaded heavily [for angling in the ocean]. After running [the three-blade propellers] I will figure out what size four-bladed propellers are right for heavy offshore running.

The combination [of two sets of propellers in different blade pitch and different number of blades] should cover [the two uses for the boat]: calm water light cruising; running on slow plane in the ocean. I can [change the propellers] depending [on boat use]. And I will have a spare set if case of damage to a propeller.

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Re: 255 CONQUEST Twin 200-HP

Postby jimh » Sun Dec 06, 2020 9:43 am

I think this discussion of propellers that will be bought in the future and the effect they will have on the boat performance in the future has reached its conclusion. The thread is now closed to further comments. I hope the topic is revived when propellers have been purchased, tested on the boat, and results can be presented.