1999 Conquest 23, twin Mercury OptiMax 135-HP

Optimizing the performance of Boston Whaler boats
StormWarning
Posts: 30
Joined: Mon Oct 19, 2015 12:32 pm

1999 Conquest 23, twin Mercury OptiMax 135-HP

Postby StormWarning » Mon Oct 19, 2015 4:21 pm

We just took a trip to Venice, Louisiana, and I have the itch to take my 1999 Boston Whaelr 23 CONQUEST down there. It has twin Mercury OptiMax 135-HP engine with 250 hours.

What is the MPG of [a 1999 Boston Whaler 23 CONQUEST with twin Mercury OptiMax 135-HP engines]? I never go more then five to ten miles at a time, and I never fill up the 125-gallon fuel tank. I have no idea what MPG the boat will get. I am wondering because in Venice it is long runs to the ground, 50 miles each way.

That trim tabs on my 1999 Boston Whaler 23 CONQUEST seem to be small. Has anyone enlarged them?. Mine are 12-inch wide and 8-inch long. I am struggling with the ride in two-foot chop. In larger waves [the ride is] great but around two-foot chop the boat's ride beats me up.

jimh
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Re: 1999 Conquest 23, twin Mercury OptiMax 135-HP

Postby jimh » Mon Oct 19, 2015 6:21 pm

My wild guess about your boat's MPG at a moderate cruising speed of 28-MPH is 2.7-MPG.

I advise you to contact Boston Whaler. They usually have records of extensive boat tests for all of their more recent boats, and those boat tests include reports of fuel economy at various speeds. They usually publish them on their website. You might find the boat test data on-line, too.

Peter
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Joined: Sat Oct 17, 2015 7:52 am

Re: 1999 Conquest 23, twin Mercury OptiMax 135-HP

Postby Peter » Tue Oct 20, 2015 8:28 am

I agree with Jim's wild guess. I would expect more than 2.5 and maybe up to 3.0 MPG at cruise. At low off-plane speeds the MPG will be considerably higher, in the range of 5 to 6 MPG. For a 50 mile run, I would use 2.5 MPG for fuel use calculations purposes until you know better.

StormWarning
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Joined: Mon Oct 19, 2015 12:32 pm

Re: 1999 Conquest 23, twin Mercury OptiMax 135-HP

Postby StormWarning » Tue Oct 20, 2015 11:02 am

The only thing I could find online was for the outrage 23 which as I understand it is the same hull but holds more fuel and the test claimed 3.1mpg. http://www.boattest.com/review/boston-w ... 23-outrage

Another interesting thing is there is a hidden fishbox in the floor of my conquest. Wonder why it was not used. it is there on the outrage. Wonder if it holds water and is holding water.

jimh
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Location: Michigan, Lower Peninsula
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Re: 1999 Conquest 23, twin Mercury OptiMax 135-HP

Postby jimh » Tue Oct 20, 2015 11:40 am

Performance is always related to weight and horsepower. If the hulls of a CONQUEST 23 and OUTRAGE 23 were the same, it is very likely the CONQUEST would weigh more. This would reduce the performance, that is, more horsepower would be needed to achieve the same boat speed with a CONQUEST version than an OUTRAGE version. On that basis, if the OUTRAGE version got 3.1-MPG, then the CONQUEST version would get a lower MPG.