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Author Topic:   Montauk speed
alvispollard posted 01-24-2004 09:24 AM ET (US)   Profile for alvispollard   Send Email to alvispollard  
How fast does the Mercury 60 hp efi bigfoot 4 stroke push a montauk with full load (1400#)? WOT and cruising (4000 rpm)?
jimh posted 01-24-2004 09:47 AM ET (US)     Profile for jimh  Send Email to jimh     
According to a chart published a few years ago, a 60-HP 4-stroke Mercury ought to hit about 37-MPH.

See:

continuousWave-->Whaler-->Reference-->16/17-->Repower
http://continuouswave.com/whaler/reference/16-17/repower.html

Moe posted 01-24-2004 12:55 PM ET (US)     Profile for Moe  Send Email to Moe     
It might hit 37 mph with the 280 lb motor, 20 lbs of safety gear, a 150 skipper, and one 6 gallon tank of gas, with a 15" prop. That's slightly better than the 900 lb 150 Sport does with the same light load and 15" prop, but the old Montauk has a better aspect ratio (length to beam).

But with 1400 pounds total in a 950 pound classic Montauk hull with a hull factor of 200, pushed by 60HP, the Clark Robert's Formula in the continuousWave Reference section predicts a maximum theoretical speed of 32 mph. However, with a hull factor of 180, perhaps more appropriate for the displacement of the Montauk loaded to 2350 pounds, it predicts 28.8 mph.

With a 13" prop driven through 2.33:1 gearing, at 6000 rpm and with 9% slip, the Propellor Calculator in the continuousWave Reference section predicts 28.8 mph. At 4,000 rpm with 20% slip, this would be 17 mph or right about 15 knots.

The Mercury Prop Calculator, set for Flats Fishing Boat with Weight of 2350 pounds and the FourStroke 60 EFI BigFoot selected, predicts a top speed of 28.4 mph and recommends the 13" prop.

--
Moe

jpwilliams posted 01-25-2004 09:43 PM ET (US)     Profile for jpwilliams  Send Email to jpwilliams     
Moe's figures are interesting, and they are close to the actuals I got when testing my '92 Montauk w/ '02 Merc 60 EFI 4-stroke BigFoot for BOATING Magazine (Motorhead, 12/02 issue). Note the 4-blade 13.25 X 13 SOLAS wheel, which gives great lift at slow planing speeds and excellent trim control. Fuel figures are from the SmartTach. The boat has old water-based ablative copper on the bottom (Woolsey Neptune). The battery is in the console.

Test Boat Power: Single 60-hp Mercury EFI BigFoot 4-stroke 4-cylinder outboard with 60.8 cid, 2.56" bore x 2.95" stroke, swinging a 13.25 x 13 4-bladed Solas Alcup 4 aluminum prop through a 2.30:1 reduction. CARB Emission Rating: 3-Star, Ultra-Low Emission Engine

Boat Name: 1992 Boston Whaler Montauk
Fuel Capacity: 24 gal.

RPM MPH GPH Level dB-A
1000 4.0 0.2 0 64
1500 5.6 0.4 1 68
2000 6.4 0.6 2 70
2500 7.4 1.0 4 75
3000 10.0 1.4 6 78
3500 12.6 1.9 7 81
4000 17.6 2.2 4 82
4500 21.8 2.7 2 82
5000 25.6 3.6 2 86
5500 28.2 4.5 2 92
6000 31.1 5.4 1 89
6500 0.0 0.0 0 0
7000 0.0 0.0 0 0
No. of people on board: 2
Fuel level: Full

I haven't checked speeds with heavy loads, but this Merc is happy shoving any load that's legal (and prudent) in my Montauk, and the low planing speed is a great asset in rough water here on the Chesapeake. I put 78 hours on the engine in '03, with all sorts of loads at all sorts of speeds in all sorts of seas. Total fuel burn was 53 gallons. Sweet rig!

Clark Roberts posted 01-26-2004 09:13 AM ET (US)     Profile for Clark Roberts  Send Email to Clark Roberts     
Mark King and I played with props on his beautiful Montauk with new Merc 60 4S Big Foot and found that the 13" pitch alum. prop that came with rig produced best performance . As I recall we squeezed 32-33mph(per GPS) at WOT (about 5600 rpm)and two of us aboard (over 400lbs). We didn't raise engine but may have gotten more speed if we had. The hull factor for the classic Montauk should be 200 it seems. I just put a 2004 Merc Classic 60 2S (std foot) on my Montuak, swinging a 12" Quicksilver stainless prop and mounted on a TH jackplate (5" set-back and about 4 inches up) and hit 35mph at 5600 rpm. Engine has a rev limiter at 5700rpm so am dialed right in. After engine gets about 50 hrs on it (now it has 5hrs) it may hit rev limiter and if so I will try a 13" pitch stainless (hummm , I think have one hanging on the wall).. Happy Whalin'... Clark.. Spruce Creek Navy/Great Lakes Navy
Clark Roberts posted 01-26-2004 02:57 PM ET (US)     Profile for Clark Roberts  Send Email to Clark Roberts     
Should have said "hull factor of 180 seem about right"...
Moe posted 01-26-2004 03:11 PM ET (US)     Profile for Moe  Send Email to Moe     
Clark, there's something about these props on the 60HP 4S EFI BigFoot.

The prop calculator says your 5600 rpm through 2.33:1 driving a 13" pitch prop at 32 mph is NEGATIVE 8.15% slip.

We're seeing negative slip numbers with this motor and the 15" prop on the 150 Sport with real-world GPS averages of bi-directional runs.

I gotta believe these props have more pitch than they're rated for.

--
Moe

Clark Roberts posted 01-26-2004 05:34 PM ET (US)     Profile for Clark Roberts  Send Email to Clark Roberts     
Moe, my engine has the std foot, as mentioned above, with 1.64:1 gear ratio... not 2.33! That's not a typo, it's 1.64:1 so at 5600rpm prop is spinning at 3414rpm. With a 2.33:1 lower unit gear ratio on the big foot model at 5600 engine rpm the prop would be spinning at 2403rpm.
Moe posted 01-26-2004 06:02 PM ET (US)     Profile for Moe  Send Email to Moe     
Clark, this is what I was responding to:

Mark King and I played with props on his beautiful Montauk with new Merc 60 4S Big Foot and found that the 13" pitch alum. prop that came with rig produced best performance . As I recall we squeezed 32-33mph(per GPS) at WOT (about 5600 rpm)and two of us aboard (over 400lbs).

That's what produces negative slip numbers, as you note, with the 2.33:1.

--
Moe

weekendwarrior posted 01-27-2004 10:51 AM ET (US)     Profile for weekendwarrior  Send Email to weekendwarrior     
Not the same exact motor but in the same class, I've got a 50HP Honda on a 17' Montauk (1996). My top speed is right about 32mph gps, though that is just past the 6000rpm redline of my motor so the only time I did it was to satisfy my curiosity of how fast it would go. At 5000rpm (cruising speed) my speed is in the low 20's (22-24 mph). With a 11gal tank of gas, couple of fishing buddies and a full 22gal livewell my top speed is around 27-28mph. I haven't done any scientific speed measuring, this is just from memory of glancing down at the GPS while running around. Since you would be 10HP more I would expect slightly higher numbers for your 60HP motor. In real life I find that this is plenty of power for most days in the ocean, the days that I can run around full speed are pretty rare.
alvispollard posted 01-27-2004 02:02 PM ET (US)     Profile for alvispollard  Send Email to alvispollard     
I concur with you, weekendwarrior, about the speed in ocean waves. On Lake Erie with the closeness of the waves, I find that 25 mph is about max with 2' waves. 3' cuts it down to teens and 4'+, the boat is going 65 mph, heading home on the trailer. The ocean is a little faster but the only times that I'm running 30-40 mph are in the sound and on the Ohio river. I think the Mercury 60 hp four stroke bigfoot is the most practical boat for fishing in the ocean. My Mercury 100 has been nice for pulling my kids skiing but they are now grown. My next motor is the Bigfoot. Range, no oil issues, economical and quiet. Sounds like a perfect retirement boat for inshore and on perfect days offshore fishing.

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