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I have a 1996 Dauntless 15 with the fishing package and deleted bow rail. It is powered by a 1996 Mercury 75 elpto. It is a wonderful flats/bass boat for my purposes and I'm super happy with it.

I don't have any mechanical problems with the motor but I do have environmental/noise concerns as well as limited range for the areas I boat. I am interested in repowering with a four-stroke motor but I really don't want to loose the performance of the current motor.

I'm interested in real world numbers and performance data of the lightweight Yamaha F-70 as well as the Mercury command thrust 60 on this hull. I sometimes am fully loaded and sometimes lightly loaded. The Mercury 75 elpto really shines with a maximum load aboard as it jumps out of the hole in shallow water.

I'd appreciate any thoughts or insight into repowering and how much performance I would loose with those two power choices.

Thanks all.

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Hoping someone can chime in with performance numbers regarding these two power choices on this hull. I don't want to dump 8-9 boat dollars into a choice I would be disappointed with.

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Going from a 75 hp to 70hp motor will be negligible for WOT. You may even gain some speed due to the age of your existing motor.

Note that 4 strokes have a different power band so mounting height and prop selection are going to be key.

The F70 is a highly regarded engine for the 15 Sport owners due to its low weight, power and efficiency.

I would not go down in hp, regardless of brand. The Dauntless is a heavy boat.

Get detailed price quotes from Yamaha and Mercury. Staying with Mercury could save you $1k in rigging.

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Thanks for the reply.

I was thinking along those lines. I am hoping someone will eventually chime in with real world numbers, fuel burn, rigging information, and propeller selection. Not just for my benefit but for anyone looking to repower their Dauntless 15.

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Have you revisited this thread and Jim's performance #'s?
http://www.whalercentral.com/forum/vi...rowstart=0

You might want to contact him offline to get him to post additional results from the past 12 months.

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I have the F-70 on my 15 Super Sport and I am very happy with it. I often have my 4 grandkids and one adult and me aboard for water skiing and it pops right up. I went with the stock prop that came with the engine and mounted it high on the transom as recommended by the guys here. It seems to use less fuel that the 2000 Johnson 40 that was on it when I got it. I don't have any numbers on fuel burn. It is scary fast with just me aboard and we cruise most of the time at about 3500 rpms going from place to place. There are some earlier posts here from when I got the F-70 two seasons ago. The F-60 may have done fine but the weight and money difference were not much and I've never heard someone say they wished they had less power.

[Edit to correct model name]

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the OP mentioned Dauntless 15 and many of the following posts mention (Super) Sport 15
Aren't those completely different boats and weight????
Besides that do not go with a Mercury 60 as that is not enough power (great engine but not enough for a 900+ lbs BW)

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Thank you gentlemen. And thank you Phil T for the link and information. I will continue to welcome any comments and suggestions regarding repower options and performance numbers. Thanks again.

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What did you repower with? Performance numbers? What did the 75 Mercury get for mph at wide open throttle

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To update this thread and answer the above question, no I did not re-power my Dauntless 15. I have had too many life occurrences and now a kid in college. The 75 ELPTO Mercury runs perfectly and I can’t justify the new motor to burn a little less fuel a little more quietly.

My 1996 Dauntless 15 mercury 75 ELPTO combination will reach 40-42 mph wide open depending on current and wind direction at 5300-5500 RPM’s. Fuel burn is about 8GPH wide open and 4GPH best cruise.

Any Dauntless 15 owners who have re-powered please feel free to post your performance numbers, especially for a Yamaha f-70.