I thought this was awesome and thought I'd share it.


I see tons of posts on chine walk and persistent challenges new high performance boat owners experience learning to manage it. Most of the information I found in my research came from very experienced pilots and at some point of competency it becomes difficult to translate second nature to a series of steps that equate to a good learning process for new drivers. The following is the approach I took as a new high performance boat owner, and the sum of my research.

The Boat: 2009 Basscat Cougar FTD, 250 ProXs, 26 Fury - Manual Plate, Hot Foot, Pro-Trim, Dual Power Poles

Setup vs. Driving: Setup and driving skill are two completely different animals, but they are commonly confused. I found myself trying to blame boat setup for my lack of driving skill. As a new high performance boat owner, the sooner you reconcile yourself to the fact that you cant drive, the better off you will be. I know you have been in boats your whole life, but the world changes when you cross the 70mph boundary and there is little hull in the water. It's just a different set of physics at work, your general boating skill becomes largely irrelevant. Deal with it.

Steering and Equipment Safety Check: Seastar hydraulic steering isn't the perfect solution for the types of speeds the 20ft Basscats can achieve. If the system is properly maintained and bled tight, it does a great job, but I keep running into people with so much slop in their steering I wouldn't be comfortable at idle speeds. Check your steering. With your boat on the trailer, remove your trailering equipment and trim down as close to level as you can get without the skeg hitting ground.. Grab your engine and attempt to turn the engine without moving the wheel.. Watch the point where the steering bar enters the end of the hydraulic cylinder. If you can move the engine enough that the steering bar slides in and out of the cylinder more than a 1/16 or 1/8 of an inch, your steering likely needs to be serviced. Loose steering cant be tolerated, its become a standard pre-flight checklist item for me. Check every one of your engine mount bolts, both from the engine to the plate, and from the plate to the hull, you'll be amazed at what works loose over the course of a year or two.

Loading: The way in which your distribute the weight in your boat plays a huge part in it's handling characteristics. A general rule of thumb is load your boat with the heaviest items to the rear and left of the boat. Fuel is your biggest variable in weight distribution.. Gasoline weighs ~6lbs per gallon.. That means that a 26 gallon tank is worth about 150lbs of ballast.. I typically burn from the right tank first. Too much weight forward and you wont settle in on the pad, too much weigh right will exaggerate your boats tendency to begin the chine walk chain reaction.

Setup: The Cougar hull is relatively easy to get very close to optimal by paying attention to a few very simple behavioral characteristics. You can work your butt off trying to get an accurate reading of how far below the pad your engine is, only to find out that every boat is different.. Light steering torque at speed and trim, a slight cavitation at break over, and water pressure in the safe range (above 12-14psi) are what you are looking for. Load all of your regular equipment in the boat, and fill up to about 1/2 of your total fuel capacity.. This puts you right in the middle of your total weight range at typical load considering that your fuel level is constantly changing. You can adjust your engine height on the water, grab a swim suit and some wrenches, find a sandbar, and get to it.. Start with the leading edge of the inner jackplate (the piece the engine is bolted too) level with the outer plate (bolted to transom), most will require raising the engine slightly from there. Test run the boat and look for the clues you are close. Raise the engine in 1/4" increments until one of 2 things happen; you have excessive steering torque (boat wants to turn right and you have to hold uncomfortable steering pressure to the left), or your water pressure drops below the safe range at high throttle (mine runs in the 15psi range at around 60mph).. When you find the upper limit, lower the engine in 1/8" increments until the negative behavior goes away. When it is right, your steering torque will be present and noticeable, but not uncomfortable or require constant pressure to hold a constant course, your water pressure will be above minimum safe (12-14psi), and with your motor trimmed all the way down, you will experience a slight cavitation as the boat breaks over onto plane.. Set it and forget it for now.

Understanding Chine Walk: At low speeds, the entire beam (width) of your boat is contacting the water. This creates a great deal of stability from left to right. As your speed increases, and your prop and hull lift the boat from the water, less and less of your total beam width is in the water, reducing stability around your roll axis (left to right). At very high speeds, you have very little of the overall width of your boat in the water, as a result your left to right stability is greatly reduced. With this reduced stability, engine torque comes into play in a large way. All other factors being equal, perfect water, no wind, no wakes, etc, your boats engine torque is trying make it lean to the right when you are at high speeds.


When engine torque causes your boat to lean over far enough that you have more of the right side of your boat in the water than the left, it increases drag on the right side momentary, causing the nose to swing slightly to the right. This misaligns the keel of the boat with your direction of travel and inertia combined with the chine lift shifts the boat to the left side.. This series of pops back and forth is chine walk. Uncorrected, this leads to an uncontrollable situation of left / right walking accompanied by swings of the nose of the boat. Learning to recognize when the boat begins to shift to the right, and correcting the lean of the boat before the chain reaction begins is where you need seat time.


Prop oscillation can also occur if your engine is too low, but is not the same thing as chine walk, and has a much different feel.. Prop oscillation is felt in the rear of the boat and is commonly described as the boat �getting loose�. On plane, a good portion of the weight of the boat is literally being carried by the lift generated by the prop itself. If the prop is carrying too much weight it can lift the hull far enough out of the water that directional stability is compromised. Its similar to what happens when you attempt to stir paint with a drill and paint stirrer.. The paint stirrer wants to run around in circles in the bucket because it has nothing to stabilize it. The same thing happens when your prop is delivering more than its fair share of the lift for the boat, you have to keep enough hull in the water to stabilize the prop from oscillating against the weight of the boat.. This is the reason why raising your engine can increase it�s high speed stability to a degree.


Learning to Drive: First you never drive "through" chine, you prevent it before it happens.. Chine walk is the chain reaction you allowed to happen because you failed to keep the boat upright on the pad. You never trim up far enough, or go fast enough, that the foundational reason for the roll instability of your boat goes away. You still have engine torque and you still have very little hull in the water. Your boat will chine walk at 80mph just as quick as it will at 65 or 70mph..

Getting out of chine walk is the first thing to learn. Most everyone will have read posts about how to drive with chine, but there are only random comments about how to safely get out of chine. Remembering that a part of chine walk is that the keel of your boat is not aligned with your direction of travel is key to internalizing this message.. If you drop your boat into the water quickly by chopping the throttle, and the nose lands when you are misaligned, your boat will turn or spin on you, and you cant stop it. NEVER chop your throttle quickly to stop chine walk. SLOWLY reduce throttle while trimming down to dampen and then stop the chine.. As you lower your nose, more of your keel is in contact with the water and begins to dampen the chine progressively from the rear of the boat to the front. If you chop the throttle and allow your nose to fall quickly, chine walk will stop instantly, but it is highly likely you wont be going in the same direction anymore, and you'll be lucky to still be behind the console.

That being said, the cougar hull has a trim / speed correlation, not at throttle / speed correlation.. If you run wide open throttle, and full trim down, your not going to chine walk and your speed will not be anywhere near the capability of the hull. Understanding that leads us to a logical path for learning to cope with chine walk tendencies. Run up to full throttle, trimmed down and learn to control your speed by bumping up and down your trim. This will teach you to be active on the trim switch and use it as one of your primary control inputs. Remember that throttle is power, trim is speed. At high power, as you increase trim, the hull will begin to lift and the nose will begin to stand up.. Eventually you will reach the edge of the stability envelope (using only trim to control speed), where you are loosing enough of your beam to allow engine torque to impact your roll attitude (the right side will fall and your nose will pitch slightly to the right), this is the beginning of the cycle of chine walk and it is VERY subtle to recognize at first. Trim up until you find it at full power, then trim down under full power to control it.. Do this until the trim switch is your friend.. Once you have reconditioned yourself to control your speed and stability with trim, you can start trying to control the chine with steering input, knowing you can get out of trouble with the trim alone.

Correcting with steering is a very subtle maneuver (especially at the low end of the envelope), it's not violent in any way. Run up to full throttle and begin to trim up, paying attention to the level of the boat from left to right, the boat will lean ever so slightly to the right just before the nose swings right, the key is to correct the lean to the right with a slight left steering input before the nose swings. If the nose swings, your too late, you let the right side of the beam drag, trim down and start back up.. Since you are controlling speed with trim, it's ok to miss it, your just barely outside the stability envelope and a bump down on the trim will clean her up.. This edge of stability is where you need to spend your "seat time".. This is where you learn to feel what the boat is telling you. Remember that the steering input is quick, but small.. Right on the edge of stability it is literally a 1-1.5" steering input to the left that you hold there for just about a second, then return to neutral steering position and get ready for the next cycle. You will find that there is a rhythm, the torque will impact the roll attitude of the boat at regular intervals, the pace gets faster as you move farther from the stability envelope, so as you begin to push your boundaries be prepared for this change. Very experienced drivers can find the balance of constant left steering pressure that stops the cycle from starting at all, but it is like trying to stand on a basket ball, lots of practice required..

Overtrimming: Overtrimming does nothing but exaggerate the problem that creates chine walk by reducing the amount of keel in the water.. Yes it is very cool looking to throw a 20ft high rooster tail with the nose of the boat pointed at the stars, but it is just wasted fuel and wasted effort trying to keep the pointy end out front.. Your rooster tail should be no higher than the top of your cowling, the nose will lift plenty as speed increases and it starts trying to fly.. Keep the prop hooked up, you'll find that once you get your speed to a certain point, your hull will keep a pad of air under it that keeps the attitude nose high even when you trim down a bump or two.. This aligns your prop thrust vector much more efficiently with your direction of travel and builds more speed.. Your prop is pushing you forward, your rooster tail is telling you your using gas to move the boat, and you are literally flying the nose.. Similar to ground effect in aircraft..

The wrong way: Attempting to trim up to get the nose high attitude and then pushing the throttle to the edge of stability is the wrong way to learn to feel the boat and its very dangerous. Forcing your nose up with a high trim setting puts the longitudinal stability (generated by having keel in the water) solely reliant on throttle position. You end up with much farther down to go on your trim before you can stabilize the boat at a given steady throttle input. It also creates a scenario where reducing the throttle not only increases drag and slows you quickly, but its literally like dropping the nose of the boat from a sling. Find the edge of stability with TRIM not with throttle, it is a much more controllable and safe way to learn how to drive your boat, feel it's attitude changes, and learn the subtleties of preventing chine walk with steering inputs.

Just thought I would share what I have learned while it was still fresh in memory.. You'll find that when you get the feel of controlling the chine tendency with steering, speed with trim, and stability with both, you'll be skinning her back in no time.

JT

Note: I recognize that this is written as if engine torque and prop torque are the same thing, and they are not, but in terms of a learning curve for newer drivers, this concept I think is easier to manage, and the result is the same.

Good info.
Thanks

Learning to drive - There is a great point. I've seen quite a few folks could do with some lessons on that. Me included.

Bump for my buddy with a new to him Bullet