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Author Topic:   170 MONTAUK Re-power Above Maximum
Nottoo posted 07-17-2015 12:47 AM ET (US)   Profile for Nottoo   Send Email to Nottoo  
[Has] anyone re-powered [a Boston Whaler 170 MONTAUK] with a 115-HP outboard engine?. What was the performance? I know that the maximum power suggested for the hull is 90-HP, but, if the weight is the same for a 115 as a 90, then I don't see any problem with the higher power engine. Thanks in advance for the help.
msirof2001 posted 07-17-2015 01:01 AM ET (US)     Profile for msirof2001  Send Email to msirof2001     
Make sure the insurance company is aware that you are over the maximum rating.
jimh posted 07-17-2015 11:51 AM ET (US)     Profile for jimh  Send Email to jimh     
Thirteen years ago, when one of the first 170 MONTAUK hulls delivered, it became the topic of a lengthy series of articles here on CONTINUOUSWAVE. See

Later, the owner of TABASCO, Ray, admitted that he had almost immediately re-powered the boat with a 115-HP version of the Mercury engine. Read this comment and many more in the long thread of comments that were posted about the CETACEA article on TABASCO at

You should find a great deal of information about the 170 MONTAUK and the re-power of it with a 115-HP Mercury FourStroke engine in those pages.

In generally I do not try to collect statistical information about how often some modification has been done. You can figure that if a modification can be done to a Boston Whaler, someone has probably already done it. It is better to ask for information than to ask if anyone has done something. Considering that in the 13-years the 170 MONTAUK has been available, and that practically the first hull delivered was re-powered to 115-HP, you should get a good idea of the potential for such things to occur.

I know that the maximum power suggested for the hull is 90-HP, but, if the weight is the same for a 115 as a 90, then I don't see any problem with the higher power engine.

Your position is quite reasonable for you to have, but you need to be cognizant of the possible risks associated with increasing the horsepower of your boat beyond the manufacturer's recommendation. This is a frequently asked question, and a well-researched answer is given in the FAQ. See

endus posted 07-24-2015 12:48 PM ET (US)     Profile for endus  Send Email to endus     
We recently re-powered our 2004 170 with the E-Tec 90 H.O. which is basically a de-tuned 115.

I think this engine is a good choice and I'm not sure I would want much more power. In anything but flat calm seas the boat can definitely have a tendency to be a little too fast for it's own good. I wish we had a chase boat taking pictures of us as we hit a couple of waves going a little faster than we should have been...

We might be able to take a little more pitch on the prop as I am topping out at about 41 MPH on flat water, and I believe others have hit 45 or so. It feels like that may affect how it rides in heavier seas as well...with a little less torque I think the boat might accelerate a little slower in waves and be more controllable.

We run exclusively in salt water. If you are a lake person that's probably a different story. In flat water as long as you're not heading in to the wind the boat feels great at top speed.

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