Q: Your answer about replacing a hydraulic steering cylinder ("Sore-Arm Skipper," November '06) prompted me to write. I have an outboard on my pontoon boat. The steering is hydraulic, and it seems there's something wrong with the cylinder that turns the motor. It goes one way smoothly but seems to "stutter" when I turn the other way. The problem has been getting worse.  -  James Chrisman, Osage Beach, MO

A: Steering problems raise serious safety issues. Remove the boat from service, and don't use it until any steering defects are repaired.

There's most likely nothing wrong with your steering cylinder. You describe the typical symptom of low fluid. Behind the steering wheel is a rotary hydraulic pump that sends fluid one way or the other through the system to actuate the steering cylinder. When that pump gets low, the first symptom is the stuttering you describe.

Manufacturers specify that the system should be checked and topped off at least twice each operating season. Low fluid from normal use is your problem because it came on gradually. Rapid deterioration in performance indicates a leak. Either way, inspect your system before topping off the hydraulic fluid. Look for symptoms of leaking fluid, such as drip marks on the bulkhead. Repair any leaks before putting the boat back into service.

Highly refined hydraulic steering system oil is available from marine stores. Vintage French wine is cheaper by the quart, but you'll only need a little to top off your system. A single bottle can last several years. Using the wrong oil, like A.T.F. (automatic transmission fluid) or high-viscosity oil, can cause stiff steering and other problems.

There's a filler cap on the helm behind the steering wheel. Remove it carefully and place it where it can't fall in the bilge or tumble overboard. This isn't an ordinary cap. It's vented and an important part of the steering pump.

Topping off can be done by simply refilling the reservoir from the bottle of oil. Use a miniature funnel to fill the reservoir to 1/2-inch below the top. Rotate the helm both directions several times. Re-check the fluid level. Never overfill. The level should always be that 1/2-inch below the top.

If air has gotten into the lines, you'll have a "burp" of oil back out through the filler hole. To avoid a mess, hold a clean rag beneath the helm while you turn the wheel. Wipe up any discharge. Be sure not to get any dirt into the workings of the helm. Replace the cap.