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Author Topic:   Montauk Cruising Performance
montaukmax posted 11-03-2001 10:54 PM ET (US)   Profile for montaukmax   Send Email to montaukmax  
My 74 Montauk is powered by a 90HP Merc 2-stroke. The boat is new to me and I am uncertain of the exact engine age (serial number is illegible).

Watching my performance today, I noticed that I burn about 6 gal / hour cruising at 4500 rpm and 25-27 MPH. WOT puts me at 5600 rpm and 33 MPH.

I was just curious how this would compare with other Montauk owners out there. My boat was a police boat and has had some modifications done to it. The windshield has been extended to a height of 6 ft. It looks kind of funny, but does keep the spray, rain, and wind out of your face. I also imagine it creates a lot more wind resistance, reducing speed and efficiency.

Thanks in advance for any comparative numbers you can provide!

Barry posted 11-04-2001 07:35 PM ET (US)     Profile for Barry  Send Email to Barry     
My '74 Montauk with '89 Merc 90 likes to cruise between 20 and 30 mph. The 20 mph is around 3000 rpm and the 30 is a little over 4000. Top speed is about 40 mph at 5500 rpm. I'm running a 19" Stiletto ss prop, jackplate, and Doel Fin.
TightPenny posted 11-04-2001 07:56 PM ET (US)     Profile for TightPenny  Send Email to TightPenny     
I burn about 4 gal/hr with a 2001 90 hp Johnson on my Montauk
JBCornwell posted 11-04-2001 08:13 PM ET (US)     Profile for JBCornwell  Send Email to JBCornwell     
My Son's 2000 Montauk/90 Merc 2 stroke gives about the same results as Barry and TightPenny's boats.

My '80 Montauk/DF70 2001 Suzi, of course, uses a LOT less fuel but is almost as fast.

Red sky at night. . .
JB :)

compounder posted 11-05-2001 08:32 AM ET (US)     Profile for compounder  Send Email to compounder     
Recently returned from a 500 mile ICW trip in my Montauk powered by Yamaha C-90.

I usually cruise at about 4000 rpm which is 28-30 mph. We averaged 4.7 mpg. I did not attempt to calculate gal/hr but the 4.7 mpg should translate roughly to 6gal/hr.

Tightpenny needs to re-calculate. I don't think there is a Montauk/90 combo out there that is going to burn only 4 gal/hr at normal cruising speeds.

Bigshot posted 11-05-2001 09:52 AM ET (US)     Profile for Bigshot  Send Email to Bigshot     
Montaukmax, how many cyls is your 90? Reason being if it is a 6cyl you are underpropped. 6cyls redline at 5200 and that would explain you lower speed. My 90hp Yammagucci runs 27-28mph at 3700-3800rpm and burns roughly 4gph. Top speed is about 42-3.
montaukmax posted 11-05-2001 03:42 PM ET (US)     Profile for montaukmax  Send Email to montaukmax     
Thanks for the great information!

Bigshot, my Merc is a 3-cylinder oil injected 2-stroke.

I imagine I am losing some speed to the condition of the prop. While it doesn't have major damage, the edges look like it was driven through pea gravel and most of the paint is gone. I am planning on a new stainless prop, but having trouble choosing a pitch (can't tell pitch on current prop, don't know lower unit gear ratio because I can't read the serial number...).

csj posted 11-07-2001 08:56 PM ET (US)     Profile for csj  Send Email to csj     
My 77 whaler with a 85 Johnson tops out at 41.2 mph at 5000 rpm's. Your lack of speed is probably your prop, as stated by others.
Bigshot posted 11-08-2001 11:37 AM ET (US)     Profile for Bigshot  Send Email to Bigshot     
That is not a problem, e-mail Clark. All the 3 cyls 90's have the same ratios(75 too probably. My friend has a 96? 90hp and he replaced the foot with a 88 80hp. I would ask around. OMC and yamaha use a 17 for 90s I assume Merc too but you never know.
lhg posted 11-08-2001 12:08 PM ET (US)     Profile for lhg    
It sounds to me like the Merc 90 is pretty tired, or simply has something wrong with it. Most Montauks will run around your speed of 34 mph with only a 50HP on them. New, I would think that engine would push your Montauk about 44mph.

A friend had an in-line 6 Merc 90, and it would run about 47mph on his Montauk. And Clark Roberts I think has indicated that the larger displacement 3 cylinder Merc 90 would run close to 50mph on a 17, properly set up. I do know that the 90 Merc had its displacement increased about 6 years ago. It's now the fastest 90 on the market, and will pretty much keep up with Yamaha's new 4 stroke 100.

Eric posted 11-09-2001 11:56 AM ET (US)     Profile for Eric  Send Email to Eric     
I have a Nauset (virtually the same as a pre-1977 Montauk), with a 99 Johnson 90. I have never used more than 3 gallons/hour, unless running wide open for most of the time. At cruise, I get around 2.5 to 3 gallons/hour. Yesterday I ran offshore, ran the boat 3.8 hours and used 11.5 gallons. I did almost no trolling, or extended idling to affect the numbers, and ran pretty fast on the way in (5100 rpm for about 10 minutes, 4900 for about 10 more). I also had a full throttle blast the last few miles.
This works out real well with the previous history with my rig, as I have gotten as good as 2.3 gals/hr when cruising on the river. I've been tracking the numbers since rigging the boat, and they've been consistent from the start of break-in.
I don't know why I'm getting fuel consumption numbers this good. My motor is old technology: four cylinder, carbed 2 stroke. I've added a baitwell, and carry a moderate amount of other weight. Still, I'm happy with the results.
TightPenny posted 11-09-2001 02:41 PM ET (US)     Profile for TightPenny  Send Email to TightPenny     
Compounder:

Gallons burned divided by the amount of time added to the engine hour meter equals gallons per hour.

Unless my mathmatical abilties have failed me completely, the boat is getting around 4 gallons per hour for my normal fishing cruises. My daddy didn't waste all of his money sending me to Stevens Tech.

I fish, I don't fly. I seldom open it up to WOT since the Atlantic just won't let me, nor will the chop in the Barnegat Bay.

compounder posted 11-09-2001 08:39 PM ET (US)     Profile for compounder  Send Email to compounder     
Tightpenny,
That sure is some swell mathematics you learned at Stevens Tech, but montaukmax stated that he burned about 6gal/hr CRUISING at 4500 rpm and 25-27 MPH and asked for COMPARATIVE numbers from others with similar rigs. You chimed in with 4gal/hr, inferring that this was a figure resulting from CRUISING at 25-27 MPH.

Now, see if your daddy has some more loose change, head on back down to Stevens Tech and bone up on some "Reading & Comprehension!"

FISHNFF posted 11-12-2001 01:36 AM ET (US)     Profile for FISHNFF  Send Email to FISHNFF     
My 17 Alert/Montauk with a Merc 90 4S burns about 3.6 GPH. This is based upon my last 3 trips out. 19 NM to the fishing grounds, WOT first 3 miles, then 23-27 knot cruise. 3-4 hours trolling, then the reverse back. Figuring about 1 gallon for trolling (love those 4 strokes!), that leaves 5.5 gallons for 38 miles, or 6.9MPG. 38NM travel distance averaging 25 knots burning 5.5 gallons gives 3.6GPH. Friends with 70 Suzuki's/Evinrude 70 4S burn 5 gallons total for the same trip.
FISHNFF posted 11-12-2001 02:03 AM ET (US)     Profile for FISHNFF  Send Email to FISHNFF     
As for speed, My Merc 90 4S has a 2.07 lower gear ratio and turns a 17" Ballistic SS prop 5800RPM trimmed out for 38.3 KnotsGPS, or 44 MPH.
TightPenny posted 11-12-2001 01:55 PM ET (US)     Profile for TightPenny  Send Email to TightPenny     
Considering that the others are reporting similar results as I get on my Montauk, and considering that the rig setup is similar, it appears that contrary to compounders comments, I believe that my reading comprehension is adequate.

Compounder has challenged my mathmatics, my reading comprehension and I am sure that he will challenge something else before he is done. Perhaps typographical errors will give him something else to complain about, so I will try and proof read my post.

Montaukmax had requested comparisons from other Montauk owners, and I complied with my generalized summary of my actual fuel consumption tracked over this season.

My typical fishing trip includes about 16 miles of bay running which is done at about 3500-4500 rpm (25-30 knots) depending on the wave height and traffic. Another 20 miles or so of running at 15-20 knots in the ocean.

I concluded that this is similar to Montaukmax, and offered my experience, and the results of tracking my fuel use and distance traveled.

I apologize if this conclusion and my offering this information on this forum offended compounder. Obviously it did, because he immediately challenged my mathematical abilities. I really don't give a hoot about him and his opinion as to what is normal or not.

As another point of information to montaukmax, my Montauk at WOT hits about 5300 rpm pushing a 17" Michigan Wheel SS cupped prop. It hits about 37 knots in calm water when doing so. And I don't care if compounder agrees with the results.


compounder posted 11-12-2001 02:48 PM ET (US)     Profile for compounder  Send Email to compounder     
Don't cry mate! You didn't offend me at all.
Just trying to point out that your figures were for your "typical fishing trip" while montaukmax's figure were for CRUISING....apples & oranges so to speak.

As to the content of your post, I appreciate your offering it....just as I do hearing about all Montauk experiences.

Don't feel bad though. I've found that most males have some compulsive need to exaggerate
fuel mileage and genitalia size.

Maximus posted 11-12-2001 02:57 PM ET (US)     Profile for Maximus  Send Email to Maximus     
1996 Johnson V4 90HP on 1967 Montauk
Cruies nicely at 4000 RPM 27-30 MPH
Top Speed 41.7 fully trimmed
triblet posted 11-12-2001 08:23 PM ET (US)     Profile for triblet  Send Email to triblet     
Maximus: 41.7 MPH or 41.7 knots?

Chuck

TightPenny posted 11-13-2001 01:47 PM ET (US)     Profile for TightPenny  Send Email to TightPenny     
Feel bad, heck no. Why would I exaggerate. I have no need to. I just state the facts as I understand them.

I believe that an individual who expects exaggeration, is one who actually exaggerates. Understandably, these type of individuals base their expectations on their own experience and habit.

I prefer to offer my experiences and opinions on this board and others. Most members of these boards, I've found, if they don't agree, they just post contrary opinion.

It is the rare to see an individual on this board or any other board who exhibits the need to criticize other's opinions. I guess there always must be one of these, and like other objectionable objects, I guess it is best to just ignore them, and go about constructive posting.

Macman posted 11-13-2001 05:29 PM ET (US)     Profile for Macman  Send Email to Macman     
It's funny, but I never keep track of this stuff. I cruise at a speed where the engine sounds good, and barely pay attention to gas consumption. I can get about a weekend out of my 19 gal. tank. Thats how I calculate mileage and consumption. According to my GPS,
at 4500 rpm I do about 26 knots..wide open at 5300/5400 rpm about 31 knots. That 2 people, 1/2 tank gas, calm seas, trimmed up.
(70 Yam.
compounder posted 11-13-2001 08:06 PM ET (US)     Profile for compounder  Send Email to compounder     
Enough whining TP.....let's get back to Whaler-oriented posting!
Maximus posted 11-13-2001 10:53 PM ET (US)     Profile for Maximus  Send Email to Maximus     
Chuck:

41.7 MPH per my eTREX GPS

Motor was trimmed way up...hit about 5600 RPM on dead calm water.

Tom W Clark posted 11-14-2001 01:27 PM ET (US)     Profile for Tom W Clark  Send Email to Tom W Clark     
compounder, you need to recalculate your manners. You are out of line.

TightPenny made himself perfectly clear. In the context of this thread "cruising" refers to the speed at which the boat is run, not the purpose of the outing. Cruising speed, as opposed to displacement speed or wide open throttle (WOT) speed is speed at which a boat comfortably panes and gets you where you need to go in a reasonable time frame.

I can assure you the motor (and its appetite for fuel) does not know whether you are taking the family on a weekend trip, or a day's fishing excursion. If the boat is going 25-30 mph then it's going 25-30 mph. Hardly "apples & oranges".

I'd be surprised at a Montauk that couldn't cruise at better than 6 gph. My 18-Outrage with Johnson 150 burned 6 gph while planing at 20 mph and about 8 gph at 25 mph (form the FloScan I had). That boat is half again as heavy and has half again as many cylinders and displacement.

compounder posted 11-14-2001 08:33 PM ET (US)     Profile for compounder  Send Email to compounder     
Tom,
Don't take this as an apology because it is not!

In re-reading the thread I don't find anything having to do with "manners," at least as far as my posts go. As far as "out of line" goes, only jimh will decide that on this board.

This all started because of the off-hand remark I originally made about re-calculating, only because I assumed the guy did not accurately determine his fuel consumption. His original post only contains enough information to lead us to believe that he can achieve 4gal/hr while cruising at 4500 rpm and 25-27mph. Re-read the posts and this is the only conclusion you can come to.

If any on-line manners are to be questioned, they would start with TP's post in which he attempts to be a smart*ss by using a condescending statement about calculating gals/hr and his daddy not wasting money on his education. In retrospect, at that point I should have stopped posting, but I couldn't resist.

If TP's first post had contained the proviso that he was referring to a mix of WOT, trolling, cruising, etc. we would not have ventured down this path. He instead chose to give the impression that he achieved greater fuel economy in comparable circumstances.

As to the "apples & oranges" cliche, if you don't understand that fuel consumption differs at a mixture of trolling,cruising & idling and cruising at a steady 25-27 mph, you must also have attended Stevens Tech.

Your attempt to define cruising "in the context of this thread" is lame at best....montaukmax defined it in his original post as 25-27mph.

I never made reference to "purpose of the outing" and neither has anyone else. TP mentioned "normal fishing cruises" once.

Also, I'll stand by my statement that Montauk/90 combos don't usually achieve an economy level of 4gal/hr cruising at 4500 rpm and 25-27mph. This is based on my personal experience and that of at least 4 fellow members of the local Power Squadron. You can confirm this by going to Yamaha's website, looking under "Performance Bulletins." There are numerous boats listed there powered by 90's and similar enough to Montauks to draw the same conclusion.

So, Tom, when you next decide to lecture a fellow boater......do your homework!

Tom W Clark posted 11-15-2001 12:30 PM ET (US)     Profile for Tom W Clark  Send Email to Tom W Clark     
Yes, letís do some homework, follow along if you can.

Letís define cruising speed as 25-27 mph. TightPenny said his typical fishing trip ď... includes about 16 miles of bay running which is done at about 3500-4500 rpm (25-30 knots) depending on the wave height and traffic. Another 20 miles or so of running at 15-20 knots in the ocean.ď

Letís average his bay running at 27.5 knots and his ocean running at 17.5 knots. Now lets convert knots to mph. 27.5 knots = 31.6 mph, 17.5 knots = 20.1 mph, so 16 miles @ 31.6 mph and 20 miles @ 20.1

Doing a weighted average calculation yields an average trip speed of 25.2 mph. Iíd say this is pretty comparable to 25-27 mph.

Nowhere does TightPenny say his typical fishing trip involves any WOT, extended idling, or trolling. When you said: ďJust trying to point out that your figures were for your "typical fishing trip" while montaukmax's figure were for CRUISING....apples & oranges so to speak.Ē I suspect you made the false assumption that any fishing trip necessarily involves trolling with the main motor for an extended period. This may account for your confusion. You and I could argue about this but perhaps we should just invite TightPenny to clarify this important point.

Now, you may call TightPenny a liar, but you canít fault his math.

I also suspect TightPenny is correct about individuals who see their own worst traits in others, projecting, so to speak. I gently and respectfully suggest you take your own advice regarding homework and whining to heart yourself.

TightPenny posted 11-15-2001 03:08 PM ET (US)     Profile for TightPenny  Send Email to TightPenny     
For the record, when the bay is flat, I like to blow the carbon out of the engine. As to trolling, only once this year on my whaler.
compounder posted 11-15-2001 07:42 PM ET (US)     Profile for compounder  Send Email to compounder     
Thanks, Tom for clearing up my "confusion."
I was beginning to think I was the only sane one and everyone else was "confused." I guess I had it backwards, huh?

If I am to believe I have been relieved of this "confusion," I can now assume that a trip that entails any combination of speeds that leads to an average of 25-27 mph will yield the same fuel consumption figures that a trip that is a steady cruise at 25-27 mph.
I'd have to get out on the water and try that, but right now, I just don't believe it.

Tom, you sound like a logical thinker and I appreciate your technical input, but the psycho-babble is beneath you. Let's stick to the original performance aspects of the discussion.

jimh posted 11-15-2001 08:38 PM ET (US)     Profile for jimh  Send Email to jimh     
[Moderator Hat=ON]
Fellas! Better to talk about the boats than the people who own them.
[Moderator Hat=OFF]

--jimh

compounder posted 11-15-2001 08:54 PM ET (US)     Profile for compounder  Send Email to compounder     
Thanks jimh! I'm a little surprised you haven't already zapped this thread for us.
Bigshot posted 11-16-2001 09:04 AM ET (US)     Profile for Bigshot  Send Email to Bigshot     
I'm enjoying it!

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