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ContinuousWave: Whaler Performance
Low End Power Missing
|Author||Topic: Low End Power Missing|
posted 03-15-2004 12:36 PM ET (US)
I have a 1985 Outrage 18 with a Johnson 140 V4.
When I get on the throttle from a dead stop, the RPMs come up and the prop spins, but the boat just lags. The rear end digs in, the front lifts up and we go forward slowly. Then, the front sits down, the boat is up on plain, and away we go. I've had it up to 35MPH and there seemed to be a little more to go.
Is this just how a whaler handles or is something missing here?
posted 03-15-2004 12:52 PM ET (US)
Need more info. What are the dimensions of the propeller and what is the engine speed at wide open throttle (WOT)? Your symptoms sound like an overpropped situation.
If fitted with the correct propeller and the motor is strong, it should almost leap out of the water with that engine. Anybody not hanging onto something when the throttle is advanced suddenly would probably be thrown towards the rear of the boat if it is propped correctly.
posted 03-15-2004 12:58 PM ET (US)
I have no idea what the prop is.
Max speed is around 35mph at 6000 rpm.
What is ideal all-around prop?
What about counter rotating prop?
posted 03-15-2004 01:07 PM ET (US)
Look at the prop. There should be a number stamped somewhere on the housing. Is it stainless or aluminum ? How many people on board ,how much gear and was internal tank full when you say it was lagging ?
posted 03-15-2004 01:07 PM ET (US)
Internal fuel tank.
posted 03-15-2004 01:29 PM ET (US)
The prop is stainless, I will look for id tonight.
Does stainless give more power?
Three men on board but one was my buddy Jaime and he counts as two. Probably 700lbs in human carcasses.
The internal fuel cell was full.
Also, we had a full cooler of beer.
posted 03-15-2004 01:50 PM ET (US)
I believe stainless holds better at higher rpms. I have an 87 Outrage 18 with a 150 hp Yamaha and stainless prop. When I have a full load of folks on board, mine takes a bit longer to come on plane as opposed to when there are only two of us. The proping experts will respond at some point but they will need the numbers off the prop and also what holes the engine bolts are using mounting the engine to the engine bracket mounted on the stern.
posted 03-16-2004 04:28 PM ET (US)
Sounds like the problem is the cooler of beer ;). I suggest drinking several and then evaluate performance. I think you will find it a much more pleasant experience.
posted 03-16-2004 05:25 PM ET (US)
Another possibility (related to your other thread) is a heavy hull. I really think that might inhibit your performance some. Before you go changing props, let's figure out where that water is coming from and go from there?
Reference thread: http://continuouswave.com/ubb/Forum3/HTML/005729.html
posted 03-16-2004 10:25 PM ET (US)
Do you have the engine trimmed out too far when you start off? Try trimming all the way in and punching it.
posted 03-18-2004 03:36 PM ET (US)
By "trimming in" do you mean lowering the motor as far as it will go?
posted 03-18-2004 05:37 PM ET (US)
I'd still like to know the dimensions of the propeller. If it is an OMC propeller, they usually have the dimensions stamped on the hub, and you should find something like 14 x 17, 14 x 19, etc. It's most unlikely that the motor was properly fitted with anything less than a propeller with a 17 inch pitch.
Assuming your WOT tachometer and speed readings are accurate, and your motor is fitted with a 17 inch propeller, your propeller at WOT is showing 27 percent slip which is way too high. It should be 6 to 10 percent at maximum. Even if it is equipped with a 15 inch pitch propeller (unlikely in my experience), slip is at 18 percent which is still too high.
As a reference point, I had an 18 Outrage with a Johnson 150 V6 turning a 14 1/4 x 21 inch OMC Raker propeller through a 1.86:1 gearcase. Even with four adults (175 lbs on average) and a nearly full fuel tank, if the throttle was immediately advanced from neutral to WOT (some would call that "punched") from a dead stop there was practically no delay in the boat becoming on plane. Anyone not holding onto the console railing and braced would likely be found on their rear end at the stern.
With the little extra data you have supplied (particularly assuming the tachometer reading is correct), I suspect that your low end power missing problem might be best explained by a "spun" propeller hub rather than an overpropped situation. A spun hub means that the propeller shaft can rotate relative to the prop such that slip occurs between the propeller shaft and the propeller. If this happens, the motor is not getting "full traction" in the water, particularly in high load situations like accelerating onto plane and WOT.
If you have a spun hub, you will not have very good acceleration even though the motor seems to be getting up to speed and your WOT speed will suffer. Both of those things seem to be happening in your situation.
You can determine whether you have a spun hub by marking a straight line running from the inside to the outside parts of the propeller hub on the adjacent sides of the rubber sandwiched between these two parts. If the lines on the inside and outside are no longer aligned with each other after use, you have a "spun" hub.
posted 03-18-2004 06:29 PM ET (US)
The boat is at my Mom's house so I had my little bro inspect the prop.
He says is says 13 3/8 x 17.
What do you think?
If this is no good, what would you recommend as a good all around prop?
posted 03-18-2004 08:08 PM ET (US)
Sounds like you might have an SST propeller. What is the model year of the motor? For some model years on and after 1985, Johnson equipped the 140 with a V6 gearcase. If you have one of these models with a V6 gear case, then the propeller diameter of 13 3/8 is too small. The V6 propeller with a 17 inch pitch usually had a diameter around 14.5 to 15 inches.
Even if your 140 has a V4 gearcase, the diameter of 13 3/8 still seems to be on the small side. Bombardier currently offers the 17 inch pitch SST in two diameters, 13 3/8 and 13 7/8. I'm not sure whether the smaller diameter is intended for the 3 cylinder engines and the larger for the V4 engine.
You'll get lots of different opinions on what is a good prop here. Before going there, however, the prop experts are going to need to what gearcase you have.
posted 03-19-2004 01:13 AM ET (US)
Thanks so much for the help!!!
Hate to do this, but how do I figure out what year and gearbox my motor has? I can't even find the motor id for my insurance guy.
posted 03-19-2004 07:16 AM ET (US)
On the side of the transom bracket there should be a plate with the serial number and model id. Those numbers should help solve the mystery.
Another way to tell which gearcase is to measure the diameter of the gearcase opening where the propshaft comes out. If it is about 4 3/4 inches, then its a V6 gearcase. If it is about 4 1/4 inches, its a V4 gearcase.
I'm not sure that a V4 prop will even fit on the V6 prop shaft due to the possibility of a different number of splines, so I lean towards thinking you have a V4 gearcase.
I would check for a spun hub.
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