1987 MONTAUK 17 SUZUKI DF60a

Optimizing the performance of Boston Whaler boats
Egp5789
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1987 MONTAUK 17 SUZUKI DF60a

Postby Egp5789 » Mon Mar 27, 2023 8:01 pm

I got a good deal on a low hour 2014 DF60a with the smaller gear case for my 1987 Montauk 17 after not having much success finding a reasonably priced F70, which was my first choice.

There is a lot of information on here about the F70, and one could easily mount and buy the correct prop on the first try.

I feel like I’m sort of entering a new territory. I haven’t found a whole lot on [a 1987MONTAUK 17 with a SUZUKI DF60a engine].

I couldn’t find any info on propeller selection for the DF60, so I opted for a 11 3/8 x 14 aluminum Suzuki propeller as a start.

The DF60 engine is mounted two-holes-up, per the recommendation from many of the pros here. The cavitation plate is exactly 1-1/2-inch above the bottom of the hull. The top of the water intake is sitting almost perfectly level with the bottom of the hull. I am slightly concerned about that, but I still want to give it a try before dropping down one hole.

The two blind engine mounting holes on the transom have been filled in.

Q1: before I drill new lower engine mounting holes, would it be ok to water test the boat with the DF60a with only the two upper engine mounting bolts in place?

Propeller suggestions welcomed.

ASIDE: I know engine selection, mounting height, propeller selection, etc., have been discussed at length before.

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Phil T
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Re: 1987 MONTAUK 17 SUZUKI DF60a

Postby Phil T » Mon Mar 27, 2023 8:27 pm

In the end you will want to switch to a stainless steel propeller. They are more efficient, and with the limited horsepower, you'll need all the efficiency you can get.

Try starting with a 11-3/4 x 14 Suzuki stainless steel propeller.
1992 Outrage 17
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jimh
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Re: 1987 MONTAUK 17 SUZUKI DF60a

Postby jimh » Tue Mar 28, 2023 2:19 am

See the pinned article at the top of this forum for advice on how to conduct propeller testing and what data to record and present for commentary.

Propeller Testing: What Data to Collect; How to Evaluate that Data
https://continuouswave.com/forum/viewto ... f=7&t=7196

Before drilling any new holes in the transom to accommodate the new engine and its standard BIA engine mounting hole layout, you should read the pinned article at the top of this forum on

Transom Mounting Hole Layout for Shallow Splash Well
https://continuouswave.com/forum/viewto ... f=7&t=5808

jimh
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Re: 1987 MONTAUK 17 SUZUKI DF60a

Postby jimh » Tue Mar 28, 2023 10:14 am

I recommend you read this account of a MONTAUK 17 being re-powered with a 50-HP engine:

https://continuouswave.com/ubb/Forum1/HTML/013113.html

Egp5789
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Re: 1987 MONTAUK 17 SUZUKI DF60a

Postby Egp5789 » Sat Apr 15, 2023 10:02 pm

UPDATE: I ended up mounting the SUZUKI DF60a engine on the MONTAUK 17 at two-holes up, and I am using a SUZUKI propeller 11.75-inch-diameter and 14-pitch. The results are better than I was expecting.

Here is some data taken with just me on the boat, two batteries, and around 8-gallons of gasoline:

Wide-open throttle allows the engine to accelerate to 6,300-RPM, giving a boat speed of 34-MPH.

ENGINE   BOAT    FUEL  ECONOMY
RPM MPH GPH MPG
3500 16.6 1.2 13.8
4050 21.2 1.5 14.1
4850 26.5 2.3 11.5
5150 30.2 2.7 11.2
5700 33.4 3.6 9.3
6200 34.6 3.8 9.1


[Moderator's note: I revised the data to have a better presentation as a table; I computed the MPG from the original data.]

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Phil T
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Re: 1987 MONTAUK 17 DF601987 MONTAUK 17 SUZUKI DF60a

Postby Phil T » Sun Apr 16, 2023 12:26 pm

I would consider going up in pitch in the same model prop to see if you can pick up a bit of speed. A 15" or 16" will still keep you in the recommended WOT range. Can you find a seller that will allow returns?

We prop the engine not for top speed rather for efficient operation at all speeds.
1992 Outrage 17
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jimh
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Re: 1987 MONTAUK 17 SUZUKI DF60a

Postby jimh » Mon Apr 17, 2023 8:32 am

The fuel efficiency of the MONTAUK 17 with that modern four-stroke-power-cycle SUZUKI DF60a engine is impressive. Assuming you have a 12-gallon fuel tank, the range at best cruise speed is going to over 150-miles. That is a lot of ground to cover in a MONTAUK 17 between fuel stops, and you can run for almost eight hours.

How many blades in the propeller?

What family name is given to this propeller line?

What material is the propeller made from?

This information is always important to mention in any report of boat-engine-propeller performance data.

Your testing was probably in the boat’s lightest weight condition. Adding weight in the form of gear or more crew will certainly reduce the boat speeds. With 60-HP there won’t be much power reserve available. Before increasing propeller pitch, first test the 14-pitch propeller with heavier boat loads to see what outcome occurs.

Egp5789
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Re: 1987 MONTAUK 17 SUZUKI DF60a

Postby Egp5789 » Mon Apr 17, 2023 7:29 pm

jimh wrote:How many blades in the propeller? What family name is given to this propeller line? What material is the propeller made from?
The propeller is a three-blade stainless steel Suzuki 11 3/4 x 14.

jimh wrote:Your testing was probably in the boat’s lightest.
I agree, this is the lightest the boat will ever be. I will normally have one other person and a heavy Labrador, but I expect [the boat to reach] at least 30-MPG at WOT, which is enough speed for a MONTAUK 17.

I am very content with the results.