Tuning Out Chine Walk

Tuning Out Chine Walk

When it comes to going fast, Tight makes it right.

   Time and time again, the new-to-per­formance-boating pilot tried running his HydroStream vee-bottom up and down river. Each time he hit the 65mph plateau, the boat lifted on it's pad, start­ed to fly nicely, then began rocking side­ to-side.

  "He's gonna roll that thing" comment­ed the local bass fishermen at the docks. The driver, although a novice, was smarter (or more afraid) than that, how­ever; he simply throttled back as the "chine walking" became more vicious. Not wanting to see an accident, the men hailed the newcomer in to offer a quick set of driving tips. After all, they'd been there, done that-and now knew the cures for the "Chine Walkin' Blues!"

  Cause & Effect

   If the boat is not set up correctly, even the best drivers can have trouble keep­ing it on the pad. Poor setup can encom­pass many areas.

   Some of the more common problems include improper weight distribution, poor boat balance (remember that engine setback falls into this category!), improper steering application or wrong style hydraulic steering, and improperly adjusted dual-cable steering.It can also include soft or worn-out motor mounts, bad gear-case, poor nosecone design or installation , lack of gear-case torque tab, poor skeg design or damage, and improper engine height. Finally, propeller design can also be a significant factor; as many have experi­enced, a four-blade wheel can help solve many handling problems including chine walk.

   What is chine walk? It always helps to define the problem we're trying to solve; a good working definition of chine walk, therefore, is the condition that exists when a boat rolls back and forth from side-to-side at speed. As this action gets more pronounced , eventu­ally the hull begins landing each bounce" on it's chines (where the hull bottom meets the sides). Chine walk usually surfaces at speeds greater than 50 mph, depending on the boat, motor and setup, as the driver has applied full throttle and begins to use the power trim to gain lift and speed. The rocking is caused by the pro­peller's action on the water it propels through. The water's resistance to the rotating torque of the propeller blades causes the boat to roll up on it's right side. If the boat is trying to balance on the small pad at the bottom, the roll will then increase in intensity; as the boat's port chine hits the water, it will "bounce " back so that the star­board chine hits, and so on. If the driver doesn't correct the problem, the boat could eventually "barrel roll " or flip over.

   A Tight Reign

   The engine's rigidity has a lot to do in the quest for control of this condition and should be a natural place to start looking for solutions. Since the propeller's interaction with the water causes engine movement, the ideal situation is to minimize engine movement through mechanical means.Simply put, the easiest place to start is in the steering system. Single-cable push-pull type sys­tems allow for too much engine movement; the solution for those with single-cable systems is to upgrade immediately to a dual­ cable setup. Adjusted properly, a good dual-cable system can be one of the best and safest steering sys­tems available.

   Since there is no internal cable­ slack adjustment on single or dual­ cable systems, the slack must be adjusted out by manipulating the engine cable adapter.This places the two cables in tension against each other when they run down opposite sides of the boat and in a tension­ compression mode when they run down the same side of the boat The tension-compression or "same-side entry" setup is the common type steering on today's bass boats.

   A Simple Adjustment

   The amount of steering slack can be determined easily by watching the motor's movement as the steering wheel is moved slightly from side to side. If the wheel can be moved back and forth without the engine moving , then there's enough slack to cause handling problems. The key to adjusting a boat's steering is to arrive at a balance. Tightened too far, the system may become difficult to steer, especially for the "muscularly challenged". Too loose and the boat won't be easy to control at speed. Many systems will be difficult to adjust properly without causing binding; the only system that allows for full slack removal while maintaining low steering effort, without binding, is the Quicksilver (by Mercury Marine) Super Ride-Guide. This dual-rack system is the best available, and gives smooth opera­tion with minimal slack. It's amazing, given that the actual adjustment process is so quick and easy, that so many boaters operate their rigs with loose steering. The job takes less than five minutes, and the only tools needed are a couple large wrenches , and a hammer and large screwdriver (for Mercury/Mariner engines.)

   Begin by loosening the large nut that secures the forward steering cable to the engine's forward -most steering tube­ not the one that goes through the stern and swivel bracket assembly. Slide that nut back a few inches on the plastic cable outer jacket. Next, loosen the two jam nuts that secure the forward cable-holding tube to it's mounting bracket (on Mercury/Marin er engines, you'll have to bend the locking tab back; this is where the hammer and large screwdriver come i n handy). Rotate these nuts back a few turns, and then pull the cable-holding tube 1/4 inch from the end of the cable towards the port side of the boat.

   As you pull the tube away, re-tighten the jam nuts to re-position the tube. Temporarily re-tighten the cable nut, and go back to check your work at the steering wheel. The ideal setting is to have the engine move as the steering wheel moves. However, the steering effort should still be manageable. You may have to read­ just to get it exactly the way you want it. When you're satisfied, go back and double check the tightness of all three nuts, and on Mercury/Mariners, don 't forget to re-bend the jam nut locking tabs back over. For boats with "opposite-entry" steer­ing, the cable tube would simply be moved towards the starboard side and re-tightened . That's it. Adjusting your boat's cable steering should be repeated on a regular basis. I make it a practice to do a quick check every third or fourth outing, and tighten things up if they're loose. Making sure the steering's tight will ensure that you don 't give yourself , you r passenger, or on -lookers a cause for concern.

   More Chine Walk Cures

   While loose steering should be the first place to look when trying to cure handling prob­lems, other culprits can be major contributors. Loaded gear can be a problem if it's offset to one side, or all positioned at the stern in an already tail-heavy rig. That's an easy fix-just experiment with moving the weight around. Secured items, like the battery, trolling motor batteries or starting battery can be moved as well, in order to achieve better balance. Hull balance is critical not only for drive ability, but for best all-round performance.

   Boat racers experiment end­lessly with weight placement and engine setback to arrive at the best holeshot , handling and top speed. It's a practice that carries over into bass boats; after all, bassin' rigs are really race hulls with fishin ' decks and a "bit" more weight! The wrong steering sys­tem can make a good-handling rig impossible to drive. The older-style, non high-performance hydraulic systems can't control engine movement and therefore should not be used in high-speed (over 50 MPH) applications. The "no­ feedback" cable systems that are popular now can be extremely difficult to adjust, and therefore slack will always be present with these units. All outboards (except the Mercury 2.5 series high-perfor­mance engines) use rubber mounts to reduce engine vibra­tion. Standard cable and hydraulic steering systems steer the motor through these mounts. Naturally, this setup has inherent slop, which can be reduced by installing harder­ than-standard mounts.

  To check for worn lower mounts, pull the skeg from side­ to side; worn lower mounts will allow excessive play in this direction. Upper mounts can be checked by rocking the power-head fore-to-aft; if the mounts are worn out, the slop will be evident. The best replacements are the solid nylon/plastic units offered by aftermarket shops (Bob's Machine Shop, G­ Force Technology, Hydro-Tec, etc.). Solid aluminum mounts are available as well, but these tend to transmit a lot of vibration and wear to the engine's midsection and upper exhaust adapter OMC engines can use harder rubber "performance"mounts available through any Johnson/Evinrude dealer.

   These products all help to reduce chine walk, and Replacing the stock rubber units with performance motor make for a safer boat. mounts can improve boat handling remarkably; this is an area of setup that can't be ignored. Gearcase irregularities can contribute to chine-walking and poor handling. Older nosecones that have an upper strut that extends too far forward (past the pivot point of the engine) can cause poor steering and tracking. Nosecones that have been misaligned dur­ing the mounting process can cause poor directional stability as well as inefficient gearcase and propeller performance. Damaged skegs, those that have lost material due to erosion, underwater strikes or corro­sion damage, been bent or otherwise misshapen, will also contribute to handling problems.

   Finally, don't overlook engine height as a source of chine walk. Having the engine mount­ed too low is a common cause. There are too many different combinations to give a standard minimum height measurement; therefore, the best recommendation is to raise the engine in increments until a difference is noticed, keeping in mind that water pressure and bow lift will be critical factors in determining bow high you can go.

John Tiger

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