Boat not getting on plane

[pwpns]

I have a 99 Stingray 192RX cuddy cabin with a 4.3 mercruiser. I bought the boat last september and took it out on the lake memorial day and the engine blew up about 500 yds from the no wake zone and I have spent most of the summer rebuilding the engine and correcting a problem that caused the motor to backfire and not run right. Finally got that fixed and got it on the lake for labor day, however, the boat would not get up on plane with 4 people in the boat. I did manage to get it on plane with 2 people and it took about a 1/2 mile and me playing with the throttle and the trim all the way down to get it there. With 4 people all it would do was raise the bow and make a big wake the more throttle or up trim I would add would only raise the bow more. I put a little bit bigger cam (comp cams #56-450-8) and a edelbrock 2114 intake and 1409 carb with the 1485 calibration kit. The boat has a laser II ss 23P prop on it with a fin on the outdrive. Is this normal for this boat not to plane or take a long time to. I am thinking about installing nauticus sx smart tabs (the 60lb model) in hopes this will help. I was also wondering if it would be better to go to a 21P 3 blade or a 22P 4 blade for better acceleration. I checked the bilge and there was no water in it either. Im trying to get things sorted out so I can enjoy next season. Could there be something else wrong if this is not normal any suggestions will be gladly appreciated. Thanks

 

[Mark42]

Re: Boat not getting on plane

One thing that can make the boat not get on plane is if there is too much weight in the stern. Besides the motor and drive, are there multiple batteries, or items stored in/under the transom/splashwell that can be removed to reduce stern weight? New gas tanks set too far aft? Added new accessories?

Assuming the motor is the correct size for the boat, have you tried getting on plane with the occupants in different places in the boat? IE have them all move as far front as possible and try to get on plane. If it works, then you know that weight distribution and balance are issues with your boat. Trim tabs will definitely help that condition.

How does the boat perform with just you alone and just a few gallons of gas?

Are you sure the tilt/trim is working properly and nothing is impairing its full travel?

Have you checked for water soaked foam or excess water in the bilge?

The answer to your question is "No, that is not normal". The boat should get on plane even when loaded to capacity within 20-30 seconds or so. And that would be an extreme case.

 

[QC]

Re: Boat not getting on plane

Hey pwpns,

I know this is frustarating, but hang in there and we'll do our best. All of Mark's comments are valid, but I can't imagine it pulling a 23" pitch prop. I am thinking 19", but you need to get some data from a 19 or 21, and then get back to us. We need a starting point and right now we have nothing to evaluate . . .

 

[convergent]

Re: Boat not getting on plane

With 4 people all it would do was raise the bow and make a big wake the more throttle or up trim I would add would only raise the bow more.

In order to get on plane quicker, your trim should be all the way DOWN until you are up on plane. It sounds like you are moving it higher up to try and improve the planing speed which is the opposite of what you want to do. Moving the trim up just helps you after you are on plane to get the bow up a little bit to reduce drag and help you go faster and smoother in calm water.

 

[Bob's Garage]

Re: Boat not getting on plane

In order to trouble shoot your possible problems you need to furnish the rpm at WOT. This will enable the people that can help you to make informed suggestions.

Until this is furnished and analyzed I would suggest you not make any more financial investments into the boat. You may not need trim tabs, and you surely can't determine what prop to get without knowing the rpm you are now running, and you could damage your engine.

So, what's the WOT rpm?

 

[QC]

Re: Boat not getting on plane

So, what's the WOT rpm?

I guess my point was that since he can't plane, he can't get us this . . .

 

[pwpns]

Re: Boat not getting on plane

Mark 42 the only things stored under the engine cover is some life jackets. No new accessories or extra batteries added. There is one battery and the engine which is the same size as the factory installed. I purged the bildge of any water before each run. The tank has not been replaced or moved rearward that I know of. All of our pop and food and some tools I placed in the cuddy. I then had everyone move up top the windshield as soon as I seen we weren't getting on plane and that didn't help either. I haven't had a chance to try it by myself with a little gas. We had about 5/8 of a tank when we running. I did stop the boat and look at the outdrive and the trim cylinders were in as far as they would go. How do you check for water soaked foam.
QC I checked with stingray and the boat came from the factory with a 23P aluminum prop and Michigan and Solas both recommend 23P props for this boat but if a 19P works I'll try it.
Convergent thanks for the info at the time I was trying anything to get it up on plane but I thought you started with the trim down
Bob WOT is 4800
Thanks Guys

 

[Bob's Garage]

Re: Boat not getting on plane

He doesn't need to plane to get the WOT, he just needs to push the throttle fully forward.

Knowing what the engine is doing, as opposed to what it should do has to start with the engines performance numbers, not with the results.

He apparently made a lot of changes to the engines "innards" and those must surely have changed it's performance curve. (This is stuff I do not know!)

Once you guys have the numbers you will be able to make informed and knowledgeable suggestions.

I, on the other hand, will be lurking, hoping to learn from you experienced guys.

 

[Bob's Garage]

Re: Boat not getting on plane

Mark 42 the only things stored under the engine cover is some life jackets. No new accessories or extra batteries added. There is one battery and the engine which is the same size as the factory installed. I purged the bildge of any water before each run. The tank has not been replaced or moved rearward that I know of. All of our pop and food and some tools I placed in the cuddy. I then had everyone move up top the windshield as soon as I seen we weren't getting on plane and that didn't help either. I haven't had a chance to try it by myself with a little gas. We had about 5/8 of a tank when we running. I did stop the boat and look at the outdrive and the trim cylinders were in as far as they would go. How do you check for water soaked foam.
QC I checked with stingray and the boat came from the factory with a 23P aluminum prop and Michigan and Solas both recommend 23P props for this boat but if a 19P works I'll try it.
Convergent thanks for the info at the time I was trying anything to get it up on plane but I thought you started with the trim down
Bob WOT is 4800
Thanks Guys

You need to be careful when changing your prop. If you are running 4800 rpm now you are right at the top of the recommended rpm for that engine.

Each 1" change in pitch is an approximate change in rpm of roughly 200. So by going down in pitch to a 19 changes it by about 4" or 800 additional rpms, bringing it to 5600. You could be looking at another rebuild.

 

[Bob's Garage]

Re: Boat not getting on plane

This is the information on the Stingray site;


1999 Stingray 192RS/RX
Standard Equipment

Hull
5 Year Owner Protection Plan
"Z-plane" Hull, Patent # 5,063,868
NMMA Certified
IMCI International Certification
US Coast Guard Certification
E C ( European Certification)
Custom Engine Vibration Dampers
Auto. & Man. Bilge Pump (500 gph)
Brass Hull Drain Plug and Receiver
Carpeted Floor Storage
Water Resistant Bilge Blower
Performance Notched Transom
Stainless Bow & Stern Eyes

Deck
Bow Anchor Storage
Bow Storage
Curved Safety Glass Windshield
Integrated Swim Platform
Lockable Cabin Doors
Stainless Steel Cleats - 6"
Stainless Steel Fuel Fill
Stainless Steel International Bow Lights
Stainless Steel Ladder
Stainless Steel Ski Tow Ring
Stainless Welded Rails
Translucent Deck Hatch
Walk-thru Windshield w/ Bow Access Step

Cockpit
12V Accessory Plug
All Weather Marine Carpet - 20 oz.
Cockpit Lighting
Custom Back Lit Instrumentation
Custom Steering Wheel
Horn (electric)
Power Trim and Tilt with Indicator
Premium 32 oz. Vinyl with 1/4" Foam Back
Stereo Radio, Cassette Player

Cabin
Cabin Lights
Molded Fiberglass Cabin Liner
Porta-Potti w/ Self Contained Holding Tank

Engine
Fuel Surge Protector
Optional Equipment

Hull
[$335] Shipping Cradle (International Only)
[$231] Two-Tone Hull Color Stripe
[$198] International CE Certification Package
[$238] Hull Blister Protection Option

Deck
[$391] Full Canvas Set w/ Storage Bag (Sunbrella)
[$388] Mooring Cover with/ Storage Bag
[$365] Cockpit Cover w/ Storage Bag (Sunbrella)
[$118] Side Curtains
[$272] Aft Curtain (Sunbrella)
[$93] Convertible Sun Top (Sunbrella)
[$55] Hatch Screen Kit
[$77] Windshield Mounted Up For Shipment

Cockpit
[$192] Hi-Power Sony, Cassette Player (Upgrade)
[$465] Hi-Power Sony, CD Player (Upgrade)
[$135] Twin Lounge Seats (S Models Only)
[$135] Twin Bucket Seats (S Models Only)
[$198] Injection Molded Adjustable Helm Seats
[$168] Woodgrain Package
[$131] Tilt Steering
[$289] Humminbird Digital Depth Finder
[$106] Compass

Engine
[$391] Automatic Fire Extinguishing System
[$338] Power Steering
[$94] Battery On/Off Switch
[$94] Transom Trim & Tilt Switch
[N/C] Aluminum Propeller 17" Pitch
[N/C] Aluminum Propeller 19" Pitch
[N/C] Aluminum Propeller 21" Pitch
[$370] SS Propeller 19" Pitch Laser II
[$370] SS Propeller 21" Pitch Laser II
[$370] SS Propeller 23" Pitch Laser II
[$460] SS High Five 19" Propeller
[$460] SS High Five 21" Propeller
[$460] SS High Five 23" Propeller

Other
[$495] Value Pack Option (R Models only) C

A Electrical System Includes: Shorepower Connector, Battery Charger, Refrigerator, Alcohol/ Electric Stove.
B 8 cylinder motors only
C Includes Options 21,22,26,30,34


SS Props std on Bravo 3 and 300HP and Larger Motors.
Propellers are an exchange up charge at time of order.
Prices and Specifications are subject to change without notice
Power Options
(with light load and SS prop)
3.0LX Alpha 45 mph
4.3L Alpha 56 mph
Specifications
Length Overall feet 19'0"
meters 5.8
Beam inches 91"
centimeters 229
Bridge Clearance inches 49"
centimeters 124
Weight with Base Engine pounds 2420
kilograms 1100
Fuel Capacity gallons 21
liters 80
Water Capacity gallons -
liters -
Ice Box Capacity quarts 36
liters 34
Maximum Capacity people/pounds 8/1315
people/kilograms 8/596
Free Board inches 23"
centimeters 58
Molded Depth
windshield base to keel inches 49"
centimeters 124
Maximum Depth
includes windshield inches 60"
centimeters 152
Maximum Draft
drive down inches 31"
centimeters 79
Bow Depth
bow to cushion top inches 25"
centimeters 64
Bow Depth
maximum depth inches 41"
centimeters 104
Bow Length
maximum length inches 60"
centimeters 152
Cockpit Depth
at helm inches 34"
centimeters 86
Cockpit Width
maximum molded inches 73"
centimeters 185
Cockpit Length
maximum molded inches 114"
centimeters 290
Sleeping Capacity -
Transom Angle 15 degrees
Deadrise Angle 19 degrees

 

[QC]

Re: Boat not getting on plane

QC I checked with stingray and the boat came from the factory with a 23P aluminum prop and Michigan and Solas both recommend 23P props for this boat but if a 19P works I'll try it.

OK, we need to back up. Stingray's are known to be fast so maybe a 23 is in the cards . . . The specs sort of support that.

Convergent thanks for the info at the time I was trying anything to get it up on plane but I thought you started with the trim down

Yes, start with trim down.

Bob WOT is 4800

This is VERY important. Are you saying the your boat, right now, is achieving 4800 at WOT? Or are you saying that it is supposed to reach 4800? Very different. What we want to know is what RPM can you get to now, propped as is, wide open throttle (WOT), loaded as you intend to use her and trimmed as fast she will go. Has to be your boat, your stuff.

He doesn't need to plane to get the WOT, he just needs to push the throttle fully forward.

And if he gets 2800 RPM and doesn't plane. what are you going to glean from that? Pitch? Gear ratio? Engine condition?

 

[pwpns]

Re: Boat not getting on plane

QC that is what mercruiser said WOT should be. I built the engine to handle at least 5000rpm. The engine is new and the mercruiser manual says not to run it at WOT for at least 20 hrs. the couple of times I did get it to plane I had it to 3500 rpm don't know how fast I was going (speedo not working) but seemed to be moving pretty good. One time I dont know if the prop came out of the water but the rpms did jump up to over 5000 rpm before I could throttle it down. Mark42 asked about water soaked foam, how would you check for that. The gear ratio is 1.81:1 Thanks

 

[Philster]

Re: Boat not getting on plane

There should be no 'fussing' to get on plane. The boat should leap from a standstill and be on plane with authority, be it four people or two people... even with a little extra gear in the rear.

Talking about using trim tabs on the boat in question to get on plane is a joke -- an utter joke.

The drive should be trimmed down... of course.

pwpns, you should know that it is rather common 'round boating boards to hear someone say they beefed up their engine and suffered serious to modest power losses or power curve issues. "I can't get on plane" or "I lost 3-4 MPH when I added 30 HP" are not unheard of.

You had an engine issue, and you did some work on the engine, and she has lost grunt. We know it lost grunt from either the problem or the work. She needs to be fully evaluated for performance. How you do that is open to discussion, but she is not making power and/or has a whacked out power curve not suited to marine use.

.

 

[KC4YIN]

Re: Boat not getting on plane

One thing that hasn't been mentioned is the ignition system. Is it properly tuned since rebuild and is the SPARK ADVANCE working correctly?

 

[ziggy]

Re: Boat not getting on plane

have you seen this? http://forums.iboats.com/showthread.php?t=295070
in the oem service manual there is likely a list of possible causes to not reach wot too.

 

[Bob's Garage]

Re: Boat not getting on plane

QC that is what mercruiser said WOT should be. I built the engine to handle at least 5000rpm. The engine is new and the mercruiser manual says not to run it at WOT for at least 20 hrs. the couple of times I did get it to plane I had it to 3500 rpm don't know how fast I was going (speedo not working) but seemed to be moving pretty good. One time I dont know if the prop came out of the water but the rpms did jump up to over 5000 rpm before I could throttle it down. Mark42 asked about water soaked foam, how would you check for that. The gear ratio is 1.81:1 Thanks

Okay, so based on this post, you have not reached WOT as of yet. As a result, you do not know how the engine is performing. You are only stating what WOT should be.

I also submit that you should know whether the prop came out of the water or not, for as a boat operator you should be aware of your boats relationship with the water. It sounds like you may be in denial, concerned that the jump in rpm may indicate a bigger problem.

One way to check for excessive weight would be to weigh the boat and trailer, and then the trailer alone. This can be done at a truck stop, gravel pit, or even the landfill. Around here we have a couple BP stations with scales where you can be weighed.

And I agree with Philster that it is not unheard of to "mess around" with a marine engine, thinking it is just a fancy car engine, and change it's characteristics for the worse.

This is the information I found on your cam, which doesn't sound like a marine part to me:

"Magnum camshafts are very aggressive and specifically designed for the street enthusiast looking for more power with that Pro Street sound. Intended for performance oriented vehicles that will see little street use. The idle characteristics of your engine will change due to the increased duration and overlap of the Comp Cams Magnum Cam Series. The hydraulic roller cams do dramatically decrease friction, as well as lifter wear. As far as power, the roller profile allows the design of more lift, and a greater area under the curve giving much better top end power without sacrificing bottom end. You will notice a racey idle with the 280-grind while the 292 and 305-grinds will produce a rough or ''rumbly'' idle. Stock components are incompatible. Changes are needed in rear end gear ratios, headers and the torque converter. Magnum Cams will affect your power accessories to a certain extent. The 280 and 292-grinds are the biggest cams that should be used with power assisted brakes, air conditioning, etc. You should remember that the bigger the engine is, the less the cam will affect the vacuum which affects your power accessories. The smaller your engine is, the more the Magnum Camshaft will affect your power accessories. Most late model vehicles have a vacuum canister. If your vehicle does not have a vacuum canister, it may be necessary to add one.

Camshaft & Lifter Kits are indicated by a CL in their part number and include Camshaft and Lifters.

Complete Kits are indicated by a K in their part number and include Camshaft, Lifters, Timing Chain & Gears, Valve Springs, Spring Retainers, Spring Locks and Valve Springs."

 

[convergent]

Re: Boat not getting on plane

I used to do some drag racing many years ago and if my memory is correct, most of those cams like you've described shift the power curve up the RPM range. I blew up a 350 Chevy by shifting its peak power up to 7800 RPMs from about 6500 RPMs on the high end. You had to increase the "launch" RPMs to work properly with these cams. I used an automatic transmission and had to go to a 5000 RPM stall converter to work with this cam. All of that would lead to a boat's holeshot going down since you need the lower RPM power curve to get you going.

 

[QC]

Re: Boat not getting on plane

Yeah, I am leaning toward Philster's assessment too although you should go through the list that Ziggy supplied.

With that said, I am now concerned about reversion which you should do a search on in the I/O section. Annnnnnd, if you have shifted the RPM up, although not correct for a marine application, a lower pitch prop could be in order.

 

[Philster]

Re: Boat not getting on plane

IF that (very aggressive, race circuit cam) is the case: Jeeze Louise, she's a top-end motor prone to sucking in water at low RPM now.

Sucking in water with an aggressive cam, especially with the duration like that, is a very possible scenario.

If you moved all the serious power to the top AND created a situation wherein the engine can suck back water into the cylinders (because the aggressive cam creates just enough valve overlap on the exhaust stroke), you might have carved out one serious problem for yourself.

If the cam is anything close to that, you need to check for water reversion. Water reversion happens when the water that is dumped into the exhaust slowly works its way back into the cylinders, because an aggressive cam creates a suction action on the exhaust stroke because of the valve overlap. Low RPM running will see water going back to the engine.

I'm not sure about your cam. I'm not saying this is happening. What I am saying is that a cam like that = ALARM in my head. I'd worry that the power curve is completely jacked up for marine use (where we have one gear and need a power curve that allows to pull from 600 RPM and to hum at 4800 rpms). The other ALARM in my head is about water reversion, which I've explained.

Even a mild cam upgrade needs the builder to address water reversion. An aggressive cam upgrade might mean that the only answers are resonators or a dry exhaust.

EDIT: Ouch. Read up further on that cam. That is not a cam for boating. The idle suffers because of overlap (it's an aggressive cam), and not intended for much street use = do not put that into a marine engine unless you are an experienced marine engine builder, or have consulted with one.

.

 

[pwpns]

Re: Boat not getting on plane

The cam came recommended to me by comp cams It is not a 280 -292-305 grind it is a 266 grind and is listed as having good low and midrange power the LSA is 112 and that is within the 109-112 LSA recommendation for marine cams. I'm attaching a link to the spec sheet http://www.compcams.com/Company/CC/cam-specs/Details.aspx?csid=575&sb=2
when I was posting in the motor section ACHRIS one of the gurus over there said it looked like a good cam for the motor. If anyone has any experience with this cam that is bad please let me know. I checked the plugs regulary when I was trying to get the motor running and never seen water or corrosion on the plugs. Is there a chance the engine coupler could be slipping as the prop is a solid hub design.