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My Mercury 50Hp Bigfoot properller has taken some abuse from floating wood. What replacement propellor do I want? My current prop has two blades with some of the edges missing. Can the prop be repaired? Can this imbalance damage the engine?

Yes, the imbalance can damage the bearings in the foot if they're missing enough material.

I'd recommend a three blader, perhaps with a 14" dia. Not sure of the pitch - I have the Merc 60.

My next screw will be SS. Less flex, more cost.

Gotta spend those boat dollars before I waste them on food.

Michael

The Yamaha high thrust has similar specs. I use a three bladed 14x11. If you are heavily loaded, you might start with the 14x10 to get your revs up toward 6K

B, you spinnin that 14 with a 60 hp?

Just read your bi-line that you have a T50.

duh.

I have three standard Mercury 14 in. props for my 50-hp bigfoot in 14, 11 & 10 pitch. I have worked my way down to the 10 pitch for ease of maneuverability around docks. I found with the 14, and even some with the 11, that I would have to shift back and forth from neutral to forward to keep speed down and engine running to make a safe approach to dock. My 26X is a little on the heavy side with a extra battery, 18 gal water capacity, 13 gal holding tank, and two nine gal fuel tanks. Will not comment on weight of skipper and crew! Top speed with 10 pitch is not impressive 12-14 knots, but that is about as fast as I want to go through the beautiful St. Johns River, so I'm happy to have the good maneuverability of the 10 pitch.

Some bigfoot owners here on pontoon boats use a 14x3x10, or a 13x4x10 to keep revs up and still have lots of maneuvering torque at low speeds. I was sold on my four blade as soon as I tried it coming into the dock.

My Merc 50 is not a bigfoot so the size isn't relevant for you, but I can tell you that four blades really is nice at low speeds forward or in reverse.

I have a lightly loaded 26x with a 2003 merc 50 4s bigfoot. I have tried two different 14" diameter pitches , the 14x11 gave me a little over 20 mph, 5400 rpm, the 14x9 gave me 18 mph and would turn over 6000 rpm. (empty ballast ) I have two 14x11 props. The 14x9 would probably be good for a heavy boat. It is available cheap $ 35 plus shipping, if anyone wants it , it is a new prop used x 20 min. needs a merc hub kit
Tom 26x

Here is some info from one of my earlier post, it may be of some help.

(Posted: Tue Jan 10, 2006)

I use a 13P when I am running at sea level and when I am running at home ( Colorado ≈ 5000 feet) I use a 10P. I also copied some info from two of my earlier post, this might help; that information is below the chart.

Graham

I scanned this table from my service manual
SPECIFICATIONS


-
Mercury/Mariner 60 EFI (4-Stroke) 2.3:1 Bigfoot
Special soft rubber hub propellers designed to reduce clutch rattle
Wide Open Throttle RPM: 5500-6000
Recommended Transom Heights: 20", 25"
Right Hand Rotation Standard
Gear Reduction: 2.31:1
IMPORTANT: These specially designed rubber hub propellers are rated for 60 horsepower MAXIMUM.

13-3/4 D x 15 P, 2000-2500 boat wgt., 16-18 boat length, speed range 25-32
14 D x 13 P, 2300-3200 boat wgt., 17-20 boat length, speed range 23-27
14 D x 11 P, 3000-4300 boat wgt., pontoon, speed range 17-21
14 D x 10 P, 3500 + boat wgt., pontoon/work, speed range 14-19
14 D x 9 P, 5500+ boat wgt., House boat/work, speed range 1-16



1st post
Do you have a tachometer on board? If so, run your boat at W.O.T to see what your RPM is. You want a prop that will allow the engine to run in the top part of its recommended full throttle range, W.O.T. Mercury specs for the 50 HP Bigfoot is 5500-6000 W.O.T. Each engine manufacture and engine will have a different spec. It would be wise to check your owners manual if you have one or contact a dealer and give them the serial number. They will be able to tell you for sure. Perfect prop size is a bit allusive because it can change depending on conditions. Sea conditions, boat weight, engine condition and the condition of the prop will have an effect on performance. Weather also plays a role in Horsepower. The air density; air temp, barometric pressure and humidity can rob up to 14% of the HP. The hotter and more humid the less power you will have at the prop, hence changing props between Colorado, Washington or going to Florida. So a dry spring day will give more power over a hot humid August day.

Outboard engine companies use the I.S.O. (International Standards Organizations) for engine testing to obtain HP. The test values are produced at sea level, 30% relative humidity, air temp of 77F and a barometric pressure of 29.1 .

Changing props will give a 150-350 RPM difference between pitches sizes. If the RPM is to low you would change to a smaller pitch. For example when I am running at sea leave I use a 13P and when I am running at home ≈ 5000 feet I use a 10P. This change brings my R.P.M into spec and increases boat speed. At 8000 feet the 13P runs at 3500RPM/13 mph and the 10P is 4500RPM/19 mph. The 10 is still under spec and I could probably go with a 9, but I hardly run at 8000 feet.


2nd post

I have 2002 26X with a 2003 50 EFI Bigfoot.

I just installed the smart craft system monitor a few weeks ago. One of the functions is fuel flow rate. I did some test but I left the info in the boat. I am working out in Washington in the San Juan Island area for the summer. I had to come home for a week. I can give you a rough idea now and then in about a week; I can give you the actual test data.

Test conditions;
Sea level, full ballast, 4 adults, 1 small dog, mast up and all my gear on board, 18 gallons of fuel, 14 D x 13 P. bucking a ≈2.5 mph current and 10 mph wind.

16 mph, 4200 RPM, 3.5 GPH
10 mph, ≈ 2 GPH, I think the RPM was around 3000
5 mph, ≈ .8 GPH, I think the RPM was around 2,000

Pre-smart craft system monitor I did a test run. Sea level, No ballast, 2 adults, 2 teenagers, mast up and all my gear on board, 18 gallons of fuel, 14 D x 13 P. bucking a small current but smooth water with no wind. I ran at 17 MPH nonstop for 37.08 miles or 32.25 NM before one tank ran dry (9 gal tank but only 8 gal in that tank). The run was from Shilshole to Port Susan.

I have two props; 14D x 10P and a 14D x 13P. I use the 10 for Colorado. I did a test with both props at Steamboat Lake - Elevation: 8,000 feet. With the 13P I could only hit 13mph WOT. With the 10 I hit 19 MPH. The lake was like glass. So choosing the prop size clearly makes a difference. Changing props (per Mercury) will give a 150-350 RPM between pitches sizes.
All Speeds were checked with GPS

I also found that when cursing less than 7 MPH, if I trimmed out with out the prop breaking the water and still running the cooling water, greatly reduced the steering effort. Tail wagging was greatly reduced. It was like turning on a power steering pump and steering felt balanced. When I drop some keel I tracked straight.

As Moe points out, sea conditions will also effect speed and fuel consumption. Another factor that affects the horsepower is the weather. The air density; air temp, barometric pressure and humidity can rob up to 14% of the HP. The hotter and more humid the less power you will have at the prop, hence changing props between Colorado, Washington or going to Florida.
Outboard engine companies use the I.S.O. (International Standards Organizations) for engine testing to obtain HP. The test values are produced at sea level, 30% relative humidity, air temp of 77F and a barometric pressure of 29.1 .


I do all of my own engine work so I purchased the factory service manual for the 40/50/60, 4 Cyl, FourStroke EFI engines, years 2002 & newer, serial # OT409000 and above.

I always put my boat on the truck scales to check the weight before I had cross country.
On this last trip; the boat, trailer and gear weighed 3560 LBS. So take out the trailer weight of 710# and add the ballast of 1400# and 700# for crew of 4 adults puts my boat at ≈ 4950 #. So based on the chart running a 13 P prop is wrong for my set-up and the 11 would be better. So when I get back to Washington (next summer, 06) I am going to test the 10 out. Ill let you know how it goes.

Another issue is the engine should be installed so the anti-ventilation plate is in-line or within 1 (25mm) below the bottom of the boat. If it is not, they do make an extension kit that mounts between the drive shaft housing (under the bottom cowl) and the gear housing.

Mike - I have a new 14x3x11 spare prop that you are welcome to try if you want to try optimising your pitch..

I use a 14x3x10 on Catigale with the MERC BF EFI 50 HP

Im in Albany of course..

I have the 14 x 3 X 10 SS prop. My top speed has been 17.5 without ballest. However my RPM's is 5150 at WOT. I have a 2006 and it is regulated by a computer.

It does stop and reverse the boat very well at the dock, Everybody is impressed.

Finally got a chance to run the motor up and test the prop I have been using all summer

I only get to 5000 rpm unballasted with full crew of 600# or so, so I am overpropped. Top speed was 14 mph, down about 4 mph from the performance with the 14x3x10

What I do like about this prop is a jump in mid rpm performance...I get 7 mph at 2000 rpm and 9-10 mph at 3000 rpm, which is my favourite range for cruising.

I rarely go above 10 mph on the river, so my inclination is to leave the 11 pitch on and enjoy it where I like to cruise.

Today, the river was painted with fall colours on both sides, sunny and 65F...we went past the Half Moon replica ship and had a great day.

I've decided to work on getting my rpms up to spec. I'm running at 14 X 3 X 11P Quicksilver Prop (number stamped on hub, 2030911P). at max throttle I'm at 4000 rpm and about 9 kts. I decided after reading this thread that I might be over propped and possibly have a throttle setting that is a little conservative. I checked my set screw and it was almost all the way in. So I backed off the screw by on turn and will give it a try in a couple of weeks. Anyone else experience a conservative throttle setting? I figure I'd work the throttle setting before looking at another prop.

Thanks,
Bob

fishheadbarandgrill - any feedback now? I wish you let us know

so far, I'm in similar situation.
Merc BigFoot 60hp, , and at the WOT I always get 4000 rpm! ballast, no ballast - all the same.
And I can not count on proficiency of the installers... There were issues to doubt about them (for example, they insisted that after first 20 hrs I have to come back to them for an oil change, which Mercury manual doesn't say!).
As far as I remember, I have even checked how the installers did the work - in case of wrong set-up, if they choose 6-cyl engine setting, the 4000 rpm on gauge would mean effective 6000 rpm on a 4-cyl engine! No, here they did right...
I didn't even dare to look at GPS speed, just to limit my sorrow , as it is obvious that speed is closer to sailing speed, and less than 10-12 mph in fresh water, here at sea level!!! Goodbye water-skis and wakeboard! (one of the reasons I got after watching the presentation video, silly me).

Tomorrow I'd have a look and will know what prop is there (BTW, is it printed on the prop? where?), maybe it'll give a hint.

Anyway, the easiest explanation would be that there is special throttle setting for first 20 hours, and guys just forgot to remove it, and they didn't even know it is there. Oh, how I wish it would be true.

If I were in US, I would call Merc and I would know in few minutes, but here I have nowhere to call to.

Herschel wrote:I have three standard Mercury 14 in. props for my 50-hp bigfoot in 14, 11 & 10 pitch. I have worked my way down to the 10 pitch for ease of maneuverability around docks. I found with the 14, and even some with the 11, that I would have to shift back and forth from neutral to forward to keep speed down and engine running to make a safe approach to dock. My 26X is a little on the heavy side with a extra battery, 18 gal water capacity, 13 gal holding tank, and two nine gal fuel tanks. Will not comment on weight of skipper and crew! Top speed with 10 pitch is not impressive 12-14 knots, but that is about as fast as I want to go through the beautiful St. Johns River, so I'm happy to have the good maneuverability of the 10 pitch.

Hi Herschel,

Was your 4 blade prop a Quicksilver Nemesis Propeller or a MERCURY Spitfire Pontoon? ... These are 13.8 x 10" is that the one?

All the best,
Neo