A properly-operated cat will remain more level and straight when running then many monohulls

by Lenny Rudow

Cat Advantage 9: Cats are easy to learn to drive


Get into an outboard-powered monohull of your choice, trim the engine(s) all the way down, and run fast into a following or a head sea. You’ll find that in most cases the bow digs in and shoves the boat off-kilter as it strikes the waves, because full trim is too much trim. The engine is forcing the bow down, even as it enters the water and buoyancy naturally forces it up. There's only one thing it can do - go off to one side or the other. An inexperienced boater may simply think the boat's design is flawed, but improper trim is the problem, and improper trim is usually the reason why a power cat might slew off in an odd direction, too.


Run a powercat with the incorrect trim, and it'll act just as weirdly as a monohull would. Unfortunately, few inexperienced boaters think to adjust the trim regularly and as a result, are left with the impression that the cat they're riding, and maybe all cats, act strangely because of a design problem. Not so.


The key thing to remember here is that some cats are very trim-sensitive (others aren't to the same degree) and a competent operator will constantly adjust the trim to match conditions. In most cases it's a good idea to start off with the trim set at neutral, and make minor tweaks up or down until the most comfortable position is reached.


Often, weight distribution plays a role in this problem as well. When everyone aboard is on one side of the boat, causing a notable list, the hull on that side of the boat will dig in more than the other. Naturally, this causes the boat to angle off in the direction of the excessively submerged hull when it strikes waves. Alleviating this problem is easy: trim the opposite hull's engine down, and the over-weighted hull's engine up. This will return the boat to a level riding position, and end the angles.

Even with all four anglers hooked up and fighting fish from the same side of the boat, 

static stability on this Glacier Bay 22 is far better then the norm.

One oddball we need to mention: The Glacier Bay 22 tends to wobble back and forth from port to starboard, particularly in a beam sea, even though static stability is far better than it is on most boats. As far as I can tell this is unique to the model (I own one myself) but it can be alleviated by mounting the motors on a small inward angle, and adding hydrofoils to the lower units. New models ship from the factory set up properly, so usually this is an issue with older boats that were dealer-rigged. And IMHO, it's a small price to pay to have one of the smoothest-running hulls in the world underfoot. The motion is gentle, predictable, and something you get used to after running the boat for a while, anyway. Problematic? No--just different.

Remember that many cats are weight-sensitive forward of the helm, and that this symptom can be exacerbated if you add a lot of weight to the bow. The bottom line is that you want the two hulls riding evenly through the water. Forcing them to do otherwise can create undesirable riding characteristics, for sure--just as it would do with a monohull, or any other type of boat on the water. But if you take the time and effort to run the boat properly, cats don't exhibit these problems any more or less then monos. In fact, in many cases a properly-operated cat will remain more level and straight when running then many monohulls, particularly wide-beam deep-V's with lots of deadrise, which often tend to shoot off in one direction or another when climbing the back of a wave in following seas. Which is "worse" when you take these issues into account? That's a call every individual has to make on his or her own. Just remember that all boats have their plusses and minuses, and those minuses will be made worse if the boat's not being run properly. That can lead to rumors like this one--rumors that aren’t accurate, in the least.

Yup, she's still sitting level with us all on one side