Dauntless 16 Re-power with 115-HP

Optimizing the performance of Boston Whaler boats
keithp66
Posts: 22
Joined: Mon Sep 21, 2020 9:51 pm

Dauntless 16 Re-power with 115-HP

Postby keithp66 » Wed Mar 10, 2021 10:08 pm

What is [expected improvement in performance that may result by re-powering] a 2001 DAUNTLESS 16 with a 2000 Mercury 115 two-stroke-power-cycle engine from a Mercury 90-HP two-stroke-power-cycle engine of similar age?

My cost will be $1000 or less.

The 115-HP engine is about 45 lbs heavier than the 90-HP engine.

How much [added draft at the stern of DAUNTLESS 16 results from 45-lbs more engine weight]?

The new engine may not need new controls.

The existing 90 is fine, but it seems to work hard to get the boat on plane.

We are not interested in spending a lot of money on a newer more expensive engine on this great but older boat.

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Phil T
Posts: 2602
Joined: Thu Oct 22, 2015 6:08 pm
Location: Was Maine. Temporarily Kentucky

Re: Dauntless 16 engine change from 90 to 115

Postby Phil T » Thu Mar 11, 2021 10:42 am

You can simulate the change of engine weight by adding bags of gravel or sand to the splashwell.

As for performance, you will probably have to change props with the engine change.

Before I spend any money I would review your boat's current engine setup and rigging. I have a sense there are adjustments you can make that will solve your concerns without having to change engines.

Please provide the following information: (photos are helpful too.)

Make/model and size (or part number) of prop (on outside or inside of hub)?
Mounting height of engine (how many empty holes above top mounting bolt)?
Do you have a foil appendage installed?
1992 Outrage 17
2019 E-TEC 90
2018 LoadRite 18280096VT
Member since 2003

jimh
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Joined: Fri Oct 09, 2015 12:25 pm
Location: Michigan, Lower Peninsula
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Re: Dauntless16 Repower with 115-HP

Postby jimh » Fri Mar 12, 2021 6:47 am

I believe a c.2000 Mercury 115 is the infamous 2+2 four-cylinder engine. Read about this engine:

http://continuouswave.com/ubb/Forum4/HTML/004113.html

My own action in this situation would be to pass on buying a used Mercury 115 2+2 outboard of that era.

A Phil mentions, some improvement in performance may be possible to achieve with the existing 90-HP three-cylinder engine.

keithp66
Posts: 22
Joined: Mon Sep 21, 2020 9:51 pm

Re: Dauntless 16 Re-power with 115-HP

Postby keithp66 » Fri Mar 12, 2021 4:07 pm

After reading some reviews [on the c.2000 Mercury 115-HP 2+2 engine] I think [buying a used one] would not be the right move for us. I would like to move to a 115-HP engine at some point. The DAUNTLESS 16 performance would benefit from an additional 25-HP and increased torque.

I like the E-TEC.

Based on good reviews I bought a $68 aluminum Turning Point Hustler 13.25 x 17-pitch progressive pitch and vented propeller that has a little more rake and cup than the Black Diamond propeller we are using now. If I don't like it I can turn it in towards another propeller.

I'm not going to change the engine height until after testing the new prop. The engine mounting height is [described as what may be a one-hole-up mounting height].

I will use Quicksilver Power Tune to de-carbon the 90-HP engine. I cannot wait [for boating season to resume].

Jefecinco
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Location: Gulf Shores, AL

Re: Dauntless 16 Re-power with 115-HP

Postby Jefecinco » Sat Mar 13, 2021 9:41 am

Changing the mounting height of the engine on a Dauntless 16 takes approximately a half hour, requires no special skills and costs no more than the price of a tube of caulk. A higher mounting height is often the best single performance enhancement possible for your boat.

As a former owner of a Dauntless 16 I highly recommend it.
Butch

keithp66
Posts: 22
Joined: Mon Sep 21, 2020 9:51 pm

Re: Dauntless 16 Re-power with 115-HP

Postby keithp66 » Mon Mar 15, 2021 6:15 pm

Thanks Butch. I have read some on the topic of engine mounting height. I'm not ruling out [changing engine mounting height] for sure. Right now the [Anti-Ventilation] plate is 1.5-inches above the keel. I may raise the engine mounting height by one-hole.

I want to see how much difference a new propeller makes.

Keith

[Nota bene: please read the article on how to describe engine mounting height using the number of holes up from the lowest position.

Also read the article on nomenclature with regard to the Anti-Ventilation plate.

—jimh]