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  Sport 13, first time out

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Author Topic:   Sport 13, first time out
arnereil posted 09-06-2003 02:15 PM ET (US)   Profile for arnereil   Send Email to arnereil  
I have a 2002, Sport 13, purchased used, with low hours.

I put it in the water for the first time today. The only accessory I have is a Doelfin on the a/c plate.

The motor has about 15 hours on it. At wot, the tach reads 4,900.

When I trim it up, it get the usual porpoising. I trim it all the way down and it plows a little and I start to hear the exhaust noise. So, I trim it back up a bit, get rid of the exhaust noise, and get about the top speed out of the boat.

4,900 seems a bit low. The motor is not raised, and being in it alone I can not see how far below the water surface the a/c plate is. But, out of the water, the a/c plate is about one inch below the bottom of the boat.

So, can the motor (should the motor) be raised one hole?

Is the Doelfin usually beneficial on this size Whaler?

Thank you for any constructive comments.....

whalersman posted 09-06-2003 02:32 PM ET (US)     Profile for whalersman  Send Email to whalersman     
arnereil,

I would first start by taking the doelfin OFF and raising your engine up 1 hole... Try that and see how she performs..

I would only use a doelfin as a last resort when nothing else works..

You don't mention what size engine you are running or what size prop..
I assume you are running a 40hp engine...
You may also be over propped... Too much pitch...

Joe

Moe posted 09-06-2003 02:33 PM ET (US)     Profile for Moe  Send Email to Moe     
What motor is on it?

What prop is on the motor?

--
Moe

arnereil posted 09-06-2003 02:45 PM ET (US)     Profile for arnereil  Send Email to arnereil     
Sorry, guys.... yes, 40 h.p., tag near a/c plate says 13x26...2.00:1
whalersman posted 09-06-2003 02:48 PM ET (US)     Profile for whalersman  Send Email to whalersman     
You may have to take the prop off to see the diameter and pitch sizes.. It could be stamped on the outside but may be stamped inside the hub..
Look for something like 13x17.... The diameter is the first number and the pitch is the second generally....

Larry, Moe, and Curly Joe

Moe posted 09-06-2003 05:24 PM ET (US)     Profile for Moe  Send Email to Moe     
That doesn't sound even close to a prop spec for this motor. Also keep in mind the motor might pick up more rpm as it gets more hours on it.

FWIW, Whaler installs the anti-ventilation plate of the 60 HP Bigfoot, right at the bottom of the 150 transom (they use the middle of 5 holes spaced 3/4" apart in the motor mount). The water intakes start about 1-7/8" below that plate, so raising them one hole or 3/4" would be pretty risky for the water pump suckin' air trimmed out or in turns. That's what you need to watch for. I would first consider moving the motor up one hole if it doesn't put the water intakes too high.

I haven't compared the old/new 13 hulls, but the stern of the 150 is less deep-V than the 15 Classic, so the transom bottom isn't as deep in the water, when deciding where the AV plate should be relative to it. The conventional wisdom of AV plate 1" or so above the transom bottom probably isn't a good idea on the 150. Not sure about the new 13/130.

I agree with using the Doelfin, et al, as a last resort. With only you aboard, porpoising will be more likely, and if that's the way you'll mainly operate, you may have to resort to that. After the motor raising decision, I'd work on weight distribution. A good sized cooler loaded up, would help if placed between the bow locker and forward seat, but would hurt if placed in the stern. Try to avoid anything back there. The cooler would even help on the port side between the seats. A passenger, especially on the forward seat, would make a big difference.

Just some thoughts... hope they help.
--
Moe

arnereil posted 09-06-2003 10:10 PM ET (US)     Profile for arnereil  Send Email to arnereil     
I'll take the doelfin off and try it... the 13 seems to ride a bit bow-high... and i figured out why they went to the center console on some models... I have to slide to the middle to even the boat out, otherwise it lists to starboard. I have thought about moving the battery to the port side, but the gas tank being near potential sparks doesn't sound good...

Anyway, thank you all for your input. I'll do some experimentation and report back.....Arne

Seawolf posted 09-06-2003 11:11 PM ET (US)     Profile for Seawolf  Send Email to Seawolf     
Howdy,
I have a similar setup, also a 2002 with a 40 Merc. I,ve also had to experiment a bit and now have it about the best it's gonna be. The original prop, which you probably have is a 10 3/8 with 14 pitch. I also got about 4900 the same as you when I bought my boat, and it wallowed and porpoised too much. WOT range should be 5000-5500.
I have the motor raised to the highest hole so the AV plate is about 1.5 inches above the keel. Easy to do, and I notched out the black molding so the motor brackets lay flat on the transom.
I also dropped down a pitch to a 10 1/2 X 13, which now gives me close to 5500 trimmed out on smooth water. $90 at West Marine, one of those 2 piece Hustler props. It's cupped well and works great.
I also have the doel fins. I've tried with and without, but overall I like them. In smooth water there's not much difference. But in chop they help alot. With the motor up high they don't seem to hurt my top speed, and gas milage is maybe better and certainly not worse than without.
The key thing is raising the engine all the way, that solves the porpoising. Next was going down a pitch and the doel fins help the boat stay on a nice plane.
What I'm not happy with is that I can't plane at a lower speed. I've got to be going at least 3300 rpm and about 15 mph to stay on plane.
Like you, I have to stand most of the time, especially when planing, to balance the boat. But I dig it, makes me feel good.
Alone with my hound, I get close to 50 miles with the 6.5 gallon tank. If I carry a spare tank of gas, I tie it up close to the bow to balance the load.
Hope this helps.
arnereil posted 09-07-2003 08:20 AM ET (US)     Profile for arnereil  Send Email to arnereil     
SeaWolf.... I appreciate your time in responding in detail, such as you did. I'll try your fixes one step at a time, as it seems you've "been there, done that". All of your fixes seem quite logical.

I've also been surprised about the time (and throttle necessary) to get on plane and the speed necessary to stay there, but after looking at the boat, the wetted hull does not start at the very front, but back further. My guess is this to allow the boat to float better (flatter), with some of the weight overhanging on the front to balance off the motor, gas tank, battery, (and me) which are all nearer the back.. But, it also gives a smaller amout of wetted area to keep the boat on plane.... Too bad they didn't move the seats/steering up another foot or so for better balance. btw, i've checked the seat height (where the console is mounted. it is 2 inches lower than driver's seat height, so moving the battery under that seat on the opposite side for better balance might be more than i want to handle.

I'm assuming when raising the motor, a block of wood has to be put between the motor bracket and the hull so the motor doesn't just hang on the bolts?

jimh posted 09-07-2003 11:08 PM ET (US)     Profile for jimh  Send Email to jimh     
Just bolt that motor on to transom. Even the big guys with 200-250 HP engines do it that way. On a 40-HP motor, no sweat.

The 13x26 notation on the transom probably refers to the number of teeth in the gears of the lower unit, thus the 2.00:1 gear ratio. Most of the new Mercury engines seem to come with those decals on them.

It is not unusual for an outboard engine to have to be run at 3000 RPM or more to sustain the boat on hydroplane. That is because the engine can't develop enough torque/horsepower at lower crankcase speeds. The boat demands a certain amount of horsepower to stay on plane, and you have to run the engine fast enough to get that much power. If that results in you going 20-MPH, well that is how it works.

If you had an engine that was able to develop enough torque at lower speeds to keep the propeller turning, you might be able to sustain hydroplane at lower speeds. But even guys with 400-HP on the transom run into this dead zone where the boat either goes 25-MPH or 5-MPH.

I have an older Mercury 50-HP engine; it probably puts out about the same horsepower as your 40-HP. I went from a 16-inch to a 15-inch to a 14-inch propeller. You want the revs to be in the 5000-5500 range at wide open throttle.

arnereil posted 09-08-2003 07:33 AM ET (US)     Profile for arnereil  Send Email to arnereil     
Jim, I finally bit the bullet and went out with my glasses and a magnifying glass.... The part number on the prop shows it to be a 10-3/8x14, std for a 40 black max. Which I should have done in the first place.

I've done some checking on Hustlers, which appear to be a decent looking prop, and will start experimenting..

ANYONE: Does the fact that wot is 4,900 mean the motor is 'working too hard'? Or to put it another way, should the motor be able to operate in its spec'd rpm range if it is set up correctly.... ?

My assumption is that it may be lugging a bit if it can not hit it's spec'd max rpm range.....Arne

RonCT posted 09-16-2003 10:18 AM ET (US)     Profile for RonCT  Send Email to RonCT     
I have a 2002 Sport 13 w/ 40 Classic. Used 2 seasons - very strong performance. I hit 5500 RPM and 33 MPH with original 14" pitch aluminum prop. Engine is mounted on the lowest position and I trim it up to get to Maximum. This is how it came from the dealer / factory.
Bigshot posted 09-16-2003 10:41 AM ET (US)     Profile for Bigshot  Send Email to Bigshot     
Jack it up to at least level with hull bottom, you'll get the extra rpms. Prop is good size.
Moe posted 09-16-2003 12:01 PM ET (US)     Profile for Moe  Send Email to Moe     
As with an aircraft wing, the "stall speed" of a planing hull boat depends upon the hull design, the weight it's carrying, and where in the boat it's carrying it. More weight, higher stall speed, and vice versa. You can add devices such as trib tabs and wings to function like flaps on an aircraft wing, and provide more lift at a given speed, while lowering the stall speed some. In the case of motor wings, I don't think that would be by much.

While the torque of a motor rises from idle to its peak at a certain rpm, and then falls off, the torque developed by the motor at a certain rpm at less than WOT is a function of throttle position.

If a motor is maintaining a speed just above the stall speed, it is providing sufficient torque. With additional throttle, it will provide additional torque, and the result of torque in excess of that required to maintain a speed is acceleration of both engine and boat.

The problem with smaller motors is that their torque peak occurs at an rpm higher than that required to maintain the minimum stall speed. Their torque curve is typically narrower than a larger engine, and falls off from the peak more steeply. When they encounter drag (such as a wave) that lowers engine rpm, the motor produces less torque, even with the same throttle setting. This in turn slows the boat toward the minimum stall speed, which increases the load on the motor, and drops its rpm more, and this snowballs into the boat falling off plane. As a result, boats with smaller motors, even on smaller boats (which are affected more by waves), have to be run at a speed a bit further above the minimum to keep the rpm drop from getting the boat too close to stall speed.

Big motors typically have wider torque curves, and often reach peak torque at a lower rpm. They're typically on larger boats with more inertia not affected as much by the same sized waves, can be run closer to the stall speed, because they don't drop as much in rpm, and the torque doesn't drop as much for a given rpm drop.

On any planing hull, there's a gap between where the hull starts plowing through the water, and its minimum planing speed. Fuel mileage is terrible in this gap, but it's often a sweet cruising speed. This is the speed range where displacement and semi-V hulls just plane rule.

Only reaching 4900 doesn't mean the engine is lugging. That occurs at low rpms and can be destructive because the flywheel doesn't have the inertia to smooth out the large power pulses, resulting in surging in the drivetrain.

What it means is that you don't have sufficient torque to the water to continue to accelerate. In this rpm range, the torque is falling as rpm increases and you've reached a balance point. Using less pitch will decrease speed at that rpm, however it will provide additional torque multiplication. That additional torque to the water will allow rpms, and thus boat speed, to increase, to a point. Whether the maximum boat speed is lower, the same, or higher than the original depends on how rapidly the torque is dropping off at the higher rpm, relative to the increase in multiplication provided by the lower pitch.

I use torque in these writings, where others may use horsepower. Horsepower is just (torque X rpm)/5252.

--
Moe

arnereil posted 09-16-2003 12:42 PM ET (US)     Profile for arnereil  Send Email to arnereil     
Well, so far, I've moved the engine up as high as it will go, bottom hole set in mount. I cut a spacer that fits snugly between the top of the transom and the engine.

I installed a 2 piece hustler prop. The prop hub is only splined on the outer 1/3rd of the hub. The front 2/3rds has a larger inside diamater than the shaft. This lack of 'centering' allowed the prop to chaff against the lower unit housing. I removed the prop and removed the hub and turned it a 1/3rd of a revolution and reinserted it (the hub and prop have 3 'keys' to lock the hub to the prop). This reduced the interference so it is barely noticeable. I looked at the stock prop and it was worn on one side because of interference with the housing (about 1/3rd of its circumference). So, i can live with it. The stock prop has splines about 2/3rds of its length.

I started the engine without the prop and checked the shaft visually (with it in gear) for being bent. It runs true.

I don't understand why the turning point hustler isn't made to fit tight on the shaft, it has about 1/8 inch larger id than the outside od of the shaft. So, on the shaft, near the engine, i wrapped electrical tape around it till the prop hub was a snug fit... that did the trick... but it's a dumb situation if you ask me..

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