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### 150 Montauk: Speed with 90-HP

Posted: Fri Jun 21, 2019 6:35 pm
Hi, I have a 2015 150 MONTAUK with the stock engine, Mercury 60-HP.

[Top boat speed is] about 35 [MPH] with just me and light fuel load.

Q1: If [the engine were changed to a] 90-HP, how will [a 150 MONTAUK perform?]

Q2: [What will the] top [boat] speed be [with 90-HP?]

Posted: Sat Jun 22, 2019 8:01 am
Yes, you’ll go faster with a 90. That’s the ONLY upside I see. Otherwise the resale value drops, and there is too much weight aft. For my money, if I wanted to go faster, I’d get a 170 MONTAUK with a 90-HP.

Posted: Sat Jun 22, 2019 12:41 pm
Ever since I got a demo ride the year it was introduced, I have thought the Montauk 150 is underpowered. The Montauk 150 weights the same as a classic Montauk 17 of 950 lbs yet has a max hp rating 40hp less.

With a transom weight limit of 305 lbs. I would consider a E-TEC 90 at 320lbs. I would test the added weight in the rear before you do anything.

With 30% more horsepower I would estimate a WOT speed of 45 with a 90hp. How the hull will handle that is a separate question.

Posted: Sun Jun 23, 2019 11:54 am
Boat speed for moderate V-hull boats is proportional to horsepower to the 0.5 exponent.

If power increases to 90 from 60, then speed would increase by

( 90/60 )^0.5 = 1.22

If the boat speed were “about 35” with the 60-HP, then with the 90-HP the boat speed should increase to

35 x 1.22 = “about 42”

This assumes no weight increase. Any increase in weight reduces the boat speed.