Got the latest issue of Bass and Walleye boat. Great artical on chine walk and how to correct it. The artical was written by John Tiger.
Here it is in a nut shell.
Chine walk.
Whats happening:
Chine walking refers to the phenomenon that occures to most fast vee-bottom boats when the hull rises out of the water enough to reduce wetted surface to the point that added steering control is needed to help keep the hull balanced on its keel. At the point of dynamic instability, the hull will begine to rock back and forth from chine to chine.
Chine walk can range from mildly annoying to down right dangerous, with disastrous consequences if the condition is allowed to get out of hand.
Often, those who experience chine walking feel that its some how an inherent defect or fault in the dessign of the hull. Not true; in fact, it is a rare hull that doesn't chine walk some when set up poorly or when in the hands of an inexperienced driver (or both). That said, lets look at some of the desings more prone to shine walking, set up problem that can contribute to the condition, and ultimately, what can be done to alleviate the problem.
DEEPER= WALKER
In general, there are several distinct design characteristics common to hulls more prone to shine walking. They are:
- Deeper vee (steeper deadrise angle)
- Deeper pad (relative to the hull bottom)
- Narrow Pad ( relative to the dead rise angle and hull weight)
- Vee shaped pad
- No pad (hull ends in a vee, or point, rather than a pad)
Hulls with steeper deadrise tend to be more difficult to balance that those with less severe hull angle. This is easy to see when viewing a hull from behind the transom. Ditto for hulls with a deep set of running pads; if the pad extends an inch or more from the hull, it can be tricky to balance up on that extended surface. If the pad is narrow and/or vee-shaped it is inherently more difficult to balance on than a wider, flatter pad. Finally, a high performance hull with no pad at all can be vary difficult to balance at high speeds because there is no flat surface for the hull to ride on as it rises out of the water. Many of these are older hulls, and it is not uncommon for owners for these hulls to modify them by adding a pad and/or lifting strakes to make the hull faster and easier to drive.
While there is noting an owner can do to change the deadrise or other characteristics of the hull with out "major fiberglass surgery" the setup is often far more crucial to the ultimate control of the hull. - and setup is an area where driver/technician input can make the difference between an ill handling hull and one that is extremely easy to drive at speed.
Hull irregularities, such as hooks, rockers and other abnormal running-surface characteristics not purposely designed into the hull by the manufacturer, can also cause handling problems, which include chine walking. A careful inspection of the hull running surface with a straightedge - and a thorough discussion of the handling problem with the manufacture/designer - can help determine if the hull itself is the cause of the trouble.
STEERING, MOUNTING AND PROPELLERS
When I encounter a boat that is difficult to drive, it is most often riggen or set up in such a way that even an exsperienced vee-bottom driver would have some degree of difficulty getting it to run correctly. Set up is key. Ill-handling hulls generally exhibit one or more of the following setup problems.
- Poor balance (weight concentrated too far towards the gunwales;weight spread too far out from center of gravity; weight concentrated too far fore or aft)
- Poor steering setup ( improperly adjusted cables; single -cable installation where dual-cable is required; nonhigh-performance hydraulic application where high performance is required, or improperly bled hydraulic system)
- Type of mounts ( Soft, stock-issue rubber engine mounts instead oh high-performance soild, pinned or hard-rubber mounts)
- Improper engine height ( relative to hull bottom and design speed)
- Improper setback (relative to pacakge, hull and outboard weight; hull length and design, and intended use)
- Propeller choice ( rake, pitch/diameter, style and number of blades)
Hull balance is self-explanatory: Too much weight situated too far from center of gravity and the centerline of the hull will make any hull difficult to handle, especially at higher speeds. Fortunately, most gear is easily movable, so it become a matter of experimentation with stoed gear and passengers in order to arrive at the best possible weight positioning for good handling.
Steering is critical to goo handling. Many cases chine walk are easily cured by properly adjusting the boat's steering system. Cable systems must have all the slack adjusted out by properly manipulating the engine steering connector. Hydraulic systems must be carefully bled to remove all the air from the lines, helm and ram unit. Single-cable systems and nonhigh performance hydraulic systems have no place on performance hulls and should not be used under any circumstances.
A lond-stated axiom of performance-hull setup is that the outboard engine mounts should be replaced with performance versions if the rig is capable of speed over 50 mph. This is true today as it was 30 years ago when the first V-6 outboards were introduced.
Appropriate engine height and setback is a more time-consuming and subjective determination, and can only be derived through detailed testing. Simply put, the boat must be driven with the engine at various heights, in a variety of conditions and loads, for the correct height to be determined. THis is why I have been a long advocated the use of hydraulic jackplated for performance bass boats, as these units make testing and finding the right engine height easy and quick.
Setback has less of an impact on handling that engine height, but is still an important determination. Most boaters won't experimnet, but it pays to start with zero setback and then work back in 2 inch increments untill the best combination is determined.
Finally, propeller choice can often be a crucual element in the high-speed handling. In general, most vee-hull outboards will handle best when equipped with medium-rake propellers with the largest possible diameter and a middle of the roat pitch. Higher pitched propellers may hold the engine to lower revs, but they are more difficult to drive and handle as they exert more torque loads on th eoutboard, steering system and sriver.
A 30- inch-pitch wheel may sound like the wheel to run, but if you can run a 28-inch and still stay near the upper end of your engine's recommended rpm range, you will experience better and easier handling - as well as stronger accelerationi. In addition. a propeller with more blades will generally improve handling over one with a three-blade propeller, a four-blade of similar style and dimersion will usally help.
SEAT TIME
Experience is the best teacher, but many performance boaters simply won't accept that they need to spend more time behind the wheel learning to drive. When the setup is as good as it is going to get, seat time is the only variable left in curing handling idosyncrasies. There are several guidelines to follow when learing how to drive a vee hull that is prone to chine-walking
- Chine walk cannot be "driven through" with out changingengine trim or reducing throttle application unless the driver is a very experienced vee-bottm pilot. Engine trim and/or throttle must be reduced untill the condition subsides, the engine trim and throttle can be carefully increased again untill the new limits are found.
- "Crabbing" the steering wheel (putting the boat in a slight right hand turn, against the torque of the propeller) can help a new driver in getting past the chine walking stage.
- Practicing with a leavier-than -usual, equally balanced load will help immensely, especially when the driver is unfamiliar with the boat. If the driiver's seat is positioned far off to one side, adding 50-150 pounds to the passenger seat ( to simulate passange weight) will help balance the load and make learning easier.
- Practicing in a slight wind chop ( 2 to 6 inches) will make learning far easier that practicing in flat, calm "glassy" water. The chop breakes up the surface tension on the hull and allows for better response to driver input with less chance of overcorrection.
KEEP AT IT.
The best advice possible: keep at it. If a boat is undriveable, there is something wrong with it. Even the best, most experienced pilots have encountered learning curves with new boats. It generally takes new drivers at least 25 to 30 hours of dedicated seat time at high speeds to get used to a new setup. So, fill the tank settle in, go out when boat trafic is light and fire her up. You'll have greater appreciation of what your boat can do and what you can do at the helm under any given situation. You'll be a safer driver as well.
I hope this shines some light on the problems we have been facing in driving the great boats that Checkmate have given us.
I would like to add this. When learing how to drive you new highperformance boat, or when making any top end high speed runs, remember the safety gear. The life you save could be your own.
Here it is in a nut shell.
Chine walk.
Whats happening:
Chine walking refers to the phenomenon that occures to most fast vee-bottom boats when the hull rises out of the water enough to reduce wetted surface to the point that added steering control is needed to help keep the hull balanced on its keel. At the point of dynamic instability, the hull will begine to rock back and forth from chine to chine.
Chine walk can range from mildly annoying to down right dangerous, with disastrous consequences if the condition is allowed to get out of hand.
Often, those who experience chine walking feel that its some how an inherent defect or fault in the dessign of the hull. Not true; in fact, it is a rare hull that doesn't chine walk some when set up poorly or when in the hands of an inexperienced driver (or both). That said, lets look at some of the desings more prone to shine walking, set up problem that can contribute to the condition, and ultimately, what can be done to alleviate the problem.
DEEPER= WALKER
In general, there are several distinct design characteristics common to hulls more prone to shine walking. They are:
- Deeper vee (steeper deadrise angle)
- Deeper pad (relative to the hull bottom)
- Narrow Pad ( relative to the dead rise angle and hull weight)
- Vee shaped pad
- No pad (hull ends in a vee, or point, rather than a pad)
Hulls with steeper deadrise tend to be more difficult to balance that those with less severe hull angle. This is easy to see when viewing a hull from behind the transom. Ditto for hulls with a deep set of running pads; if the pad extends an inch or more from the hull, it can be tricky to balance up on that extended surface. If the pad is narrow and/or vee-shaped it is inherently more difficult to balance on than a wider, flatter pad. Finally, a high performance hull with no pad at all can be vary difficult to balance at high speeds because there is no flat surface for the hull to ride on as it rises out of the water. Many of these are older hulls, and it is not uncommon for owners for these hulls to modify them by adding a pad and/or lifting strakes to make the hull faster and easier to drive.
While there is noting an owner can do to change the deadrise or other characteristics of the hull with out "major fiberglass surgery" the setup is often far more crucial to the ultimate control of the hull. - and setup is an area where driver/technician input can make the difference between an ill handling hull and one that is extremely easy to drive at speed.
Hull irregularities, such as hooks, rockers and other abnormal running-surface characteristics not purposely designed into the hull by the manufacturer, can also cause handling problems, which include chine walking. A careful inspection of the hull running surface with a straightedge - and a thorough discussion of the handling problem with the manufacture/designer - can help determine if the hull itself is the cause of the trouble.
STEERING, MOUNTING AND PROPELLERS
When I encounter a boat that is difficult to drive, it is most often riggen or set up in such a way that even an exsperienced vee-bottom driver would have some degree of difficulty getting it to run correctly. Set up is key. Ill-handling hulls generally exhibit one or more of the following setup problems.
- Poor balance (weight concentrated too far towards the gunwales;weight spread too far out from center of gravity; weight concentrated too far fore or aft)
- Poor steering setup ( improperly adjusted cables; single -cable installation where dual-cable is required; nonhigh-performance hydraulic application where high performance is required, or improperly bled hydraulic system)
- Type of mounts ( Soft, stock-issue rubber engine mounts instead oh high-performance soild, pinned or hard-rubber mounts)
- Improper engine height ( relative to hull bottom and design speed)
- Improper setback (relative to pacakge, hull and outboard weight; hull length and design, and intended use)
- Propeller choice ( rake, pitch/diameter, style and number of blades)
Hull balance is self-explanatory: Too much weight situated too far from center of gravity and the centerline of the hull will make any hull difficult to handle, especially at higher speeds. Fortunately, most gear is easily movable, so it become a matter of experimentation with stoed gear and passengers in order to arrive at the best possible weight positioning for good handling.
Steering is critical to goo handling. Many cases chine walk are easily cured by properly adjusting the boat's steering system. Cable systems must have all the slack adjusted out by properly manipulating the engine steering connector. Hydraulic systems must be carefully bled to remove all the air from the lines, helm and ram unit. Single-cable systems and nonhigh performance hydraulic systems have no place on performance hulls and should not be used under any circumstances.
A lond-stated axiom of performance-hull setup is that the outboard engine mounts should be replaced with performance versions if the rig is capable of speed over 50 mph. This is true today as it was 30 years ago when the first V-6 outboards were introduced.
Appropriate engine height and setback is a more time-consuming and subjective determination, and can only be derived through detailed testing. Simply put, the boat must be driven with the engine at various heights, in a variety of conditions and loads, for the correct height to be determined. THis is why I have been a long advocated the use of hydraulic jackplated for performance bass boats, as these units make testing and finding the right engine height easy and quick.
Setback has less of an impact on handling that engine height, but is still an important determination. Most boaters won't experimnet, but it pays to start with zero setback and then work back in 2 inch increments untill the best combination is determined.
Finally, propeller choice can often be a crucual element in the high-speed handling. In general, most vee-hull outboards will handle best when equipped with medium-rake propellers with the largest possible diameter and a middle of the roat pitch. Higher pitched propellers may hold the engine to lower revs, but they are more difficult to drive and handle as they exert more torque loads on th eoutboard, steering system and sriver.
A 30- inch-pitch wheel may sound like the wheel to run, but if you can run a 28-inch and still stay near the upper end of your engine's recommended rpm range, you will experience better and easier handling - as well as stronger accelerationi. In addition. a propeller with more blades will generally improve handling over one with a three-blade propeller, a four-blade of similar style and dimersion will usally help.
SEAT TIME
Experience is the best teacher, but many performance boaters simply won't accept that they need to spend more time behind the wheel learning to drive. When the setup is as good as it is going to get, seat time is the only variable left in curing handling idosyncrasies. There are several guidelines to follow when learing how to drive a vee hull that is prone to chine-walking
- Chine walk cannot be "driven through" with out changingengine trim or reducing throttle application unless the driver is a very experienced vee-bottm pilot. Engine trim and/or throttle must be reduced untill the condition subsides, the engine trim and throttle can be carefully increased again untill the new limits are found.
- "Crabbing" the steering wheel (putting the boat in a slight right hand turn, against the torque of the propeller) can help a new driver in getting past the chine walking stage.
- Practicing with a leavier-than -usual, equally balanced load will help immensely, especially when the driver is unfamiliar with the boat. If the driiver's seat is positioned far off to one side, adding 50-150 pounds to the passenger seat ( to simulate passange weight) will help balance the load and make learning easier.
- Practicing in a slight wind chop ( 2 to 6 inches) will make learning far easier that practicing in flat, calm "glassy" water. The chop breakes up the surface tension on the hull and allows for better response to driver input with less chance of overcorrection.
KEEP AT IT.
The best advice possible: keep at it. If a boat is undriveable, there is something wrong with it. Even the best, most experienced pilots have encountered learning curves with new boats. It generally takes new drivers at least 25 to 30 hours of dedicated seat time at high speeds to get used to a new setup. So, fill the tank settle in, go out when boat trafic is light and fire her up. You'll have greater appreciation of what your boat can do and what you can do at the helm under any given situation. You'll be a safer driver as well.
I hope this shines some light on the problems we have been facing in driving the great boats that Checkmate have given us.
I would like to add this. When learing how to drive you new highperformance boat, or when making any top end high speed runs, remember the safety gear. The life you save could be your own.
