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I took the family out tubing last weekend for the first time on our new to me Montauk 150. It took a long time to get up any speed and in a tight turn it would go off plane. I talked with a prop dealer and he suggested a Michigan Vortex B Series 941411 - 13-7/8" x 11"p 4 blade prop. $88 delivered. He said this would increase rpm by 400 rpm. My current prop a 13-3/8" x 14" Vengeance. At WOT I am running about 6000 rpm with about 450 pounds on board. With the family we were about 650 pounds on board. I am concerned about over revving the engine with an 11" pitch. Does it have a rpm limiter? The next step up is a 13-7/8" x 13" but the dealer said that would not give me enough pulling power. I just wanted to get a second, third.. opinion before ordering.
The Montauk 150 has a reputation of being underpowered compared to other models of similar weight and size.
With a full load, you will need a prop that allows the engine to accelerate as well as help lift the stern. Tubing requires the same type of prop.
The Montauk 150's Mercury 60 hp motor is equipped with a Vengeance 13 3/8x14 stainless steel prop from the factory. With just the operator, no gear, low fuel, it will get to 35mph at 6,000 rpm's at WOT. Not a speed demon.
If you drop down 2" in pitch, you will gain rpms but loose a bit of speed. Given the load, I think you are close to ideal with a 12".
Remember, prop size is NOT universal. There is diameter and pitch of the blades. Changing one of the elements changes alot.
To keep a connection to the current performance benchmark, you want to stay wih the same make and model of prop and just change the pitch , not the diameter. If you do change, you will be taking a bit of a guess.
There is a rev limiter but if you hit it the prop is definitely inappropriate.
Pulling a tube with 4 people in a Montauk 150 will challenge the motor. You may want to have 2 props. The factory supplied prop for cruising and a second one for tubing.
If the dealer recommends a prop, will he take it back for exchange if its the wrong one (usually not)?
In general, I would stay away from generic prop dealers/shops, as most don't know what they are talking about and generally sell aftermarket brand props such as Michigan Wheel, an average brand. I think this guy is giving you bad information and pushing the line he sells.
I would stay with Mercury manufactured props for that engine, and they are the world leader in outboard props anyway. They know their prop technology, and have generally invented most of the prop technology used today (such as venting and interchangeable hubs) and copied by others, and make the best.
The Vengeance is a good SS prop, but i hear it is fairly aggrressive in pitch, and generally underrated in pitch a little. Yours may be running like a 15" pitch.
For your situation you should be looking at the 4 bladed aluminum Spitfire, a brand new technology. See here:
Mercury also makes the same prop in their Quicksilver line, called a Nemesis, for a few dollars less and available on line. You can get these without having to buy another hub kit. You would want the 13" pitch from what I can tell, but be careful of overeving with a light load.
For absolute best performance, and if you have the Bigfoot/Command Thrust gearcase, you can get the Spitfire in SS, called Spitfire X7. But it's about 3 times the cost, and for a boat that only runs in the 30's, generally SS is not needed. Mercury's aluminum props perform surprisingly well.
The best on-line pricing I have found for Mercury's high end SS props is here. They also sell the Mercury aluminum line. I have bought several props from these folks.
been there done that didn't make a difference see http://whalercentral.com/forum/viewth...d_id=22713
Must get a 70HP or more for the Montauk 150 or an older 2-stroke to be a sports boat.
Will pull an adult on a Big Mabel tube with 600 lbs in the boat, but she still doesn't jump up quick and must have the second adult sit up front.
I went back to my "std" Vengeance as that is the best all around prop for this engine and boat.
We are lucky that it only takes a minute to change the props with the Spitfire so I do keep it on hand for when I know we are going to play, but again it isn't a speed boat.
Thanks for all the advice. I am going to order the recommended spitfire prop, 48-8M8026560, 13.8" x 11"p. I don't want to spend the $$$ for a stainless prop for occasional use. The spitfire comes with the hub kit so it is not much more than the Michigan Wheel. Top speed is not an issue as the kids don't like to be pulled full speed.
I love the Montauk 150 it is the perfect boat. Keep it small, keep it fun, right?
My first Whaler was a '04 130 sport, great boat but we outgrew it. I pulled a tube with it, one kid. I then bought a '91 25' walk-around, way too big and I did not keep it long. Then I bought a 20' Ventura, great boat but a lot of work to take out alone. I had it for 10 years, sold it for more than I paid for it and almost enough to buy the Montauk 150. I wanted the 170 but it wouldn't fit in the garage and I didn't want it to end up weathered like my Ventura from sitting out.
Whaler36340 wrote:
Thanks for all the advice. I am going to order the recommended spitfire prop, 48-8M8026560, 13.8" x 11"p.
Let me know how that 11"p will do compared to my 13"p I ended up with. i.e. in time to plane and WOT rpm and speed. I like to know.
Yes the Montauks 150 are great little boats.
I finally had a chance to try out the new Spitefire 13.8" x 11"p prop. It made a BIG difference! It was like having a shot of nitrous for the start.
I have to throw a wrench in this information because I also added a SE Sport 400 no-drill Hydrofoil.
With two people on board and two people in the tube, about 625 pounds of people total plus 100 pounds plus of stuff, we were able to get on plane in 5-7 seconds. Max RPM's loaded 5900-6000. The bow never came up high enough that I could not see sitting down. Before I was NOT able to get on plane with four people, two in the boat and two in the tube, it had to be two and one. Now it acts like we could add two more people. Top speed with or without the tube in the water was 24-26 mph, with the old prop it was 32-35mph depending on which side of the lake we were on.
Without the tube in the water the engine reaches 6,000 rpm at 3/4 throttle, and you don't get any more speed even with one person, 26mph was it. The downside is you have to be careful not to exceed 6000 with a light load.
This will not be my every day prop because I lose so much top end. I will use it when we are tubing, because it is great for tubing. Compared to a friends 18' bow rider with a 115 FS we were able to out run them slightly pulling tubes. He had about the same people and gear load, but his boat weighs double what my Whaler weighs.
***The only issue I had was at idle speed there was a notable vibration from the engine, but as soon as you picked up a little speed it went away. My theory is the prop wash is cavitating against the hydrofoil, but that is just a theory. I will try it without the hydrofoil when I get a chance.
I am assuming you have the "bigfoot" gearcase on that engine. If so, the vibration you are getting is most likely clutch rattle. On that engine you should be using a Flo-Torq III hub kit, designed to eliminate that problem.
It sounds to me that a 13" pitch might have been a better all around solution, which should bring top end up to 30-31 mph.
Finnegan you are right. I have the 13" 4 bladed for pulling a tube and at WOT I will not over rev. still get up to 5900/6000 rpm with just a slight (2-3 mph) drop in speed.
Yes with the boat loaded and pulling, she does get onto plane a little faster and easier but loaded standard (2 people + gear (600+lbs) the standard Venegance SS prop is smoother and not using a stop watch you couldn't tell the difference in time getting onto plane compared to the aluminum 4 bladed prop and top speed is better (when needed).
I use the same Flow-Torq III for both props as they are inter-changeable for these "Big-Foot" 60HP Mercs.
Finnegan you are possibly dead on. The hub kit they included with my prop is a FLO-TORQ II. I can't get the sleeve out of my Vengence prop, without force, so I just ordered a FLO-TORQ III sleeve , $35, and I will use the metal parts from my SS prop. I should be able to get $20+ out of the FTII kit on ebay.
I went with the 11 pitch because someone said the 13" pitch didn't make a difference on his Montauk 150, "been there done that didn't make a difference", EJO.
I am happy with my 11" pitch for tubing, we can't get the kids out with us very often. I was thinking a boat upgrade, but a $150 prop solved my problem. It takes 5 minutes to change the prop.
Regarding the Flo-Torq III hub, the parts are not interchangeable with the "II". Both the metal spline and the drive sleeve with wires in it, are different and must be used together.
So you not only need the plastic "wire" 2 part sleeve, you also need the longer bronze spline.
I use a regular socket wrench, with 1-1/16" deep socket and large size "breaker bar" handle. This is the best prop wrench you can buy and will last a lifetime. With this, the socket fits into the prop against the black drive sleeve, once the spline is removed, and setting the prop on the ground, you can easily knock the drive sleeve out, hitting the socket with a hammer.
You should use the Flo-Torq III hub kit with Vengeance prop also. Four stroke outboards are particularly suseptible to clutch rattle, expecially with SS props. But it can happen with aluminum props also.
