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Old 02-07-2014, 10:27 PM   #1
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Major chine walk!! please HELP

Hi guys!

I have a scary problem, chine walk! and torque steering!

if it helps my boat is a sharp 19 so the guy who sold it to me said (I think it's a predator?)
Engine is a Mercury 1995 115hp 20 inch pitch laserII

My problem is that soon as I go near the power (above cruising speed) I immediately get torque steer then scary chine walk and have to reduce the power to maintain control!

what can I do to stop this? people have said about hydraulic steering and hydrofoil fins??

cheers
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Old 02-07-2014, 10:35 PM   #2
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Chine walk

Alright fella, I'ld try raising your motor, looks like she's deep from your previous pic and min twin cable or hydraulic steering, solid mounts help too.
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Old 02-07-2014, 10:58 PM   #3
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First things first make sure your mounts are good, that there's no play in the steering and tilt bushes and that there's no play in your steering system itself
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Old 02-07-2014, 11:09 PM   #4
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Quote:
Originally Posted by Paul E View Post
First things first make sure your mounts are good, that there's no play in the steering and tilt bushes and that there's no play in your steering system itself
Okay, the current steering is a teleflex cable rated to 150hp... but has been sunk and needs replacing! as for the mounts and bushes as pretty solid, the engine is mounted "low" would that effect it?
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Old 03-07-2014, 06:01 AM   #5
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Yes. There is so Much gearcase in the water that have to push away. The water that you get the chine walk effect.
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Old 03-07-2014, 08:32 AM   #6
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This is a video of my old one. (apologies for the music but my brother loves to edit videos lol).

At the end of the video you will see me flushing out the engine and just how high you need to mount engines on Sharps.

You want the top of the bullet in line with bottom of transom. You need it mounted in the centre.

Hydraulic steering was a must in my case as 200hp. I think anything over 60hp should be hydraulic anyway. Baystar will be fine for 115.

Even with all the above, when you get to around 60-63mph you get some chine walk but if you keep going through it, it disappears. my sharp used to do 70mph with a worked Laser 2 23p on a Blackmax 200hp.

I hope this helps.
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Old 03-07-2014, 09:06 AM   #7
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Lifting it probably will help yes, but unless you have the steering and other stuff sorted then it's pretty pointless
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Old 03-07-2014, 12:29 PM   #8
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Is there a little Skegness bolted to the underside of your trim plate, above the gearbox, adjusting that will help your steering
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Old 03-07-2014, 01:33 PM   #9
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Quote:
Originally Posted by shape josh View Post
I have a scary problem, chine walk! My problem is that soon as I go near the power (above cruising speed) I immediately get torque steer then scary chine walk and have to reduce the power to maintain control! what can I do to stop this?
Josh - Chine walk is pretty common in performance boats. Luckily there is lot's that you can do to mitigate the problems.

Quote:
Originally Posted by ring-21-yamaha View Post
Alright fella, I'ld try raising your motor, looks like she's deep from your previous pic and min twin cable or hydraulic steering, solid mounts help too.
From your initial descriptions, I agree with ring-21-yamaha's suggestion, as it may be that your engine is mounted too low - so try raising the motor in controlled increments.

Here's some more info on Chine Walk and how to fix it...

The chine walking experience refers to the situation occurring with high performance vee-hulls as the boat accelerates, lift increases and the running surfaces raise out of the water. As hull speed continues to increase, the wetted surfaces are sufficiently diminished on the vee-portion of the hull that it becomes challenging to “balance” the hull on its keel (either vee or pad). To counteract, additional driver steering input is necessary in order to maintain the hull in a balanced state.

If left unchecked, the boat will rock from side to side with increasing motion and drama. The boat is now “inherently unstable” – this means that if left alone, the “imbalance” of the hull is more likely to get worse on it’s own, not better (the worse it gets, the worse it gets). So the hull will now start to rock from port chine to starboard chine – back and forth.

Chine walking is predominantly characteristic of vee-hulls, with deeper Vees (more deadrise), hulls with deep or narrow running pads and hulls with a Veed pad or hulls with no pad. These bottom designs are just more inherently difficult to balance at higher speeds.

Here are some established steps toward minimizing chine walking:
1. Check & adjust steering. There should be no play in the steering mechanism. And a dual-cable or dual-hydraulic setup should be used for high performance hull setups. For cable setups, be sure that you have all of the slack adjusted out of it, so the cables are slightly pre-loaded against each other. Same for hydraulic, ensure it's adjusted so there is no play in the wheel and carefully bleed the lines to remove all air from the entire system.
2. Use solid mounts - Stock rubber motor mounts allow for too much slack movement between steering wheel and engine. Solid mounts are much tighter and provide much better steering control at high performance speeds.
3. Clean Hull Lines – make sure that any non-designed irregularities such as hook, rocker, bumps or other notches in the running surfaces are removed or faired away. You can use a long straightedge to visually inspect your running surfaces and fair out the imperfections.
4. Weight balance of hull – Although this is a tricky thing to optimize for all speeds (since the dynamic balance of a hull shifts significantly throughout the operating velocity range of the boat), the onset of the chine-walking phenomenon usually occurs at a particular speed for each hull and you can focus on correcting balance at that bothersome speed. Try to situate movable payloads close to the static center of gravity (CofG) – both longitudinally and laterally. This can often be a trial-and-error experience, but you’ll see the results of weight balance changes immediately in the handling of the boat. Optimize portable equipment, batteries, oil tank and fuel tank positions. Also situate passengers for the best weight balance. An equally balanced passenger/driver load will help allot, so if the driver’s seat is positioned much to one side, add weight to the passenger seat to help balance the load and make learning to drive the boat much easier.
5. Motor height – You can adjust engine height to minimize the instability. This is easiest to do with a hydraulic jack plate. Remember that as you raise the engine height, a low water pickup may become necessary in order to ensure that the engine gets enough water pressure. Test your rig at different speeds, weight distributions and water conditions to find the best height for each. Often, as the engine is raised on the transom, the reduced lower unit drag can have an improved effect on instabilities such as chine walking. Engine setback can also affect stability, although it is more difficult to experiment with.
6. Propeller selection - The right propeller design can change the balance of a hull as well as make or break its performance. Rake, diameter, pitch, cup and blade number, can all influence the Lift and drag generated at the aft-end of the hull. Most high performance vee-hulls will handle well using medium-rake, large-diameter propellers. High-pitch propellers can make the boat more difficult to drive and ultimately contribute to slower achieved top speed simply because they are more challenging to drive. More blades will also usually improve handling. Propeller testing is also time-consuming, but can really pay off in overall performance and stability.
7. Seat time (experience) – Chine walk on a vee hull can usually be controlled by the driver as he gains more experience and skill with his setup. Unfortunately, there is just no substitute for experience! Drive your hull in different conditions at lower speeds until you are completely comfortable with your ability to “sense” and “correct” for motions of the hull to conditions and speed changes. Then gain more experience at a slightly faster speed, in the same way. Work you way up to higher velocities slowly, under good control. With familiarity, you will develop a sense to predict your hull’s motion and you’ll soon be able to react accordingly to correct it prior to it getting severe. The correct driver input to balance a vee-hull or a pad-vee hull at higher speeds is very minor if the adjustments are made quickly, immediately at the onset of motion (“timing is everything”).
"Timing is everything" - When you sense the onset of chine walking, reduce engine trim and/or throttle. When the motion subsides, you can increase trim and throttle smoothly as the hull drives right through the previous chine-walk speed barrier. Steering adjustments need only be small, but should be made in a timely manner in the opposite direction of the hull bow movement. When the left bow drops or the bow moves left, steer slightly right. When the right bow drops or the bow moves right, steer left. This steering input is done swiftly and in short motions. With practice you will be able to make these small steering inputs "before" the motion actually occurs. Turning the steering wheel slightly into (against) the torque of the propeller as soon as you “sense” the onset of lateral imbalance (side-to-side rocking), can help drive through the chine walk stage too.
8. Minimize Trim Angle - This was mentioned above, but worth saying again. Use as little positive trim as possible. More trim (higher running angle of attack) causes the onset of instability to occur earlier and with more drama. A high-flying attitude is harder to balance. When chine walking starts, it is not likely that you can simply "drive through it" without first reducing trim slightly.

Here is an article with more details on "Chine Walk".
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Old 03-07-2014, 07:00 PM   #10
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Country: uk
Location: Isles of Scilly.....(use google)
Interests: small race boats, big race boat....anything with speed really
Boat name: Joyride
Boat make: Sharp 19' so I was told! I think it's a Predator?
Engines: mercury 1150 thunderbolt 6cyl... Mercury 1995 115hp 4cyl
Cruising area: inter islands

Join Date: Dec 2012
Location: Isles of Scilly.....(use google)
Posts: 129
Massive help!

Quote:
Originally Posted by Jimboat View Post
Josh - Chine walk is pretty common in performance boats. Luckily there is lot's that you can do to mitigate the problems.


From your initial descriptions, I agree with ring-21-yamaha's suggestion, as it may be that your engine is mounted too low - so try raising the motor in controlled increments.

Here's some more info on Chine Walk and how to fix it...

The chine walking experience refers to the situation occurring with high performance vee-hulls as the boat accelerates, lift increases and the running surfaces raise out of the water. As hull speed continues to increase, the wetted surfaces are sufficiently diminished on the vee-portion of the hull that it becomes challenging to “balance” the hull on its keel (either vee or pad). To counteract, additional driver steering input is necessary in order to maintain the hull in a balanced state.

If left unchecked, the boat will rock from side to side with increasing motion and drama. The boat is now “inherently unstable” – this means that if left alone, the “imbalance” of the hull is more likely to get worse on it’s own, not better (the worse it gets, the worse it gets). So the hull will now start to rock from port chine to starboard chine – back and forth.

Chine walking is predominantly characteristic of vee-hulls, with deeper Vees (more deadrise), hulls with deep or narrow running pads and hulls with a Veed pad or hulls with no pad. These bottom designs are just more inherently difficult to balance at higher speeds.

Here are some established steps toward minimizing chine walking:
1. Check & adjust steering. There should be no play in the steering mechanism. And a dual-cable or dual-hydraulic setup should be used for high performance hull setups. For cable setups, be sure that you have all of the slack adjusted out of it, so the cables are slightly pre-loaded against each other. Same for hydraulic, ensure it's adjusted so there is no play in the wheel and carefully bleed the lines to remove all air from the entire system.
2. Use solid mounts - Stock rubber motor mounts allow for too much slack movement between steering wheel and engine. Solid mounts are much tighter and provide much better steering control at high performance speeds.
3. Clean Hull Lines – make sure that any non-designed irregularities such as hook, rocker, bumps or other notches in the running surfaces are removed or faired away. You can use a long straightedge to visually inspect your running surfaces and fair out the imperfections.
4. Weight balance of hull – Although this is a tricky thing to optimize for all speeds (since the dynamic balance of a hull shifts significantly throughout the operating velocity range of the boat), the onset of the chine-walking phenomenon usually occurs at a particular speed for each hull and you can focus on correcting balance at that bothersome speed. Try to situate movable payloads close to the static center of gravity (CofG) – both longitudinally and laterally. This can often be a trial-and-error experience, but you’ll see the results of weight balance changes immediately in the handling of the boat. Optimize portable equipment, batteries, oil tank and fuel tank positions. Also situate passengers for the best weight balance. An equally balanced passenger/driver load will help allot, so if the driver’s seat is positioned much to one side, add weight to the passenger seat to help balance the load and make learning to drive the boat much easier.
5. Motor height – You can adjust engine height to minimize the instability. This is easiest to do with a hydraulic jack plate. Remember that as you raise the engine height, a low water pickup may become necessary in order to ensure that the engine gets enough water pressure. Test your rig at different speeds, weight distributions and water conditions to find the best height for each. Often, as the engine is raised on the transom, the reduced lower unit drag can have an improved effect on instabilities such as chine walking. Engine setback can also affect stability, although it is more difficult to experiment with.
6. Propeller selection - The right propeller design can change the balance of a hull as well as make or break its performance. Rake, diameter, pitch, cup and blade number, can all influence the Lift and drag generated at the aft-end of the hull. Most high performance vee-hulls will handle well using medium-rake, large-diameter propellers. High-pitch propellers can make the boat more difficult to drive and ultimately contribute to slower achieved top speed simply because they are more challenging to drive. More blades will also usually improve handling. Propeller testing is also time-consuming, but can really pay off in overall performance and stability.
7. Seat time (experience) – Chine walk on a vee hull can usually be controlled by the driver as he gains more experience and skill with his setup. Unfortunately, there is just no substitute for experience! Drive your hull in different conditions at lower speeds until you are completely comfortable with your ability to “sense” and “correct” for motions of the hull to conditions and speed changes. Then gain more experience at a slightly faster speed, in the same way. Work you way up to higher velocities slowly, under good control. With familiarity, you will develop a sense to predict your hull’s motion and you’ll soon be able to react accordingly to correct it prior to it getting severe. The correct driver input to balance a vee-hull or a pad-vee hull at higher speeds is very minor if the adjustments are made quickly, immediately at the onset of motion (“timing is everything”).
"Timing is everything" - When you sense the onset of chine walking, reduce engine trim and/or throttle. When the motion subsides, you can increase trim and throttle smoothly as the hull drives right through the previous chine-walk speed barrier. Steering adjustments need only be small, but should be made in a timely manner in the opposite direction of the hull bow movement. When the left bow drops or the bow moves left, steer slightly right. When the right bow drops or the bow moves right, steer left. This steering input is done swiftly and in short motions. With practice you will be able to make these small steering inputs "before" the motion actually occurs. Turning the steering wheel slightly into (against) the torque of the propeller as soon as you “sense” the onset of lateral imbalance (side-to-side rocking), can help drive through the chine walk stage too.
8. Minimize Trim Angle - This was mentioned above, but worth saying again. Use as little positive trim as possible. More trim (higher running angle of attack) causes the onset of instability to occur earlier and with more drama. A high-flying attitude is harder to balance. When chine walking starts, it is not likely that you can simply "drive through it" without first reducing trim slightly.

Here is an article with more details on "Chine Walk".
thanks for all the info guys! I will put it into effect after the weekend (as I'm away)
got to save a few pennies for the new baystar steering but it will be worth it, never experienced anything that scary before and didn't feel safe using all the power even reaching a speed of 53 knots! was enough! but to have full control will be alot more beneficial for the level of enjoy meant... I will let you guys know how I get on!!


again thanks all! and keep the info n help coming for the novice! haha
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Old 04-07-2014, 06:01 PM   #11
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I had a Sharp 19' with a 200 on it and did 76mph with a chopper prop but it was well scary when backing off.
as everyone else says make sure you have no play in mid and steering but bare in mind that you can not eliminate play with only single cable steering so you have no choice but to change it.
be careful with lifting the motor as you wont have low water pickups.
remove the pickups from the side of the gearbox and blank the top 2 holes off.
lift motor so as when trimmed level the top 2 holes are above the bottom of the boat.

Where is your fuel tank? mine was a pig until i moved it to the back

other things to watch for is be gentle when you back off as its so narrow it will try and throw you out plus don't trim in to far as this also tries to roll the boat
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Old 04-07-2014, 06:19 PM   #12
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Country: uk
Location: Isles of Scilly.....(use google)
Interests: small race boats, big race boat....anything with speed really
Boat name: Joyride
Boat make: Sharp 19' so I was told! I think it's a Predator?
Engines: mercury 1150 thunderbolt 6cyl... Mercury 1995 115hp 4cyl
Cruising area: inter islands

Join Date: Dec 2012
Location: Isles of Scilly.....(use google)
Posts: 129
Quote:
Originally Posted by Burty View Post
I had a Sharp 19' with a 200 on it and did 76mph with a chopper prop but it was well scary when backing off.
as everyone else says make sure you have no play in mid and steering but bare in mind that you can not eliminate play with only single cable steering so you have no choice but to change it.
be careful with lifting the motor as you wont have low water pickups.
remove the pickups from the side of the gearbox and blank the top 2 holes off.
lift motor so as when trimmed level the top 2 holes are above the bottom of the boat.

Where is your fuel tank? mine was a pig until i moved it to the back

other things to watch for is be gentle when you back off as its so narrow it will try and throw you out plus don't trim in to far as this also tries to roll the boat
Fuel tank is just in front of the drive and co-driver seats and I think the boat is better balanced?... I will bare in mind when raising the engine I've also been made aware of the torque anode!

The single cable steering is going as soon as replacing it with a baystar hydraulic cable rig,
like said before the engine is pretty damn solid but will check again (well looked after by prev owner)

is there a sweet spot for trimming engine?

cheers
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