Re: Products for rust?
The steering arm is almost always the first thing to degrade when a motor is operated in salt water unless the sacrificial anodes are maintained in excellent condition.
Following the steering arm, the other steel and stainless steel parts and fasteners will also degrade. Washing and flushing with fresh water and Salt Away whenever possible, followed by water displacing products like WD40 will help. Grease such as BRP Triple Gaurd can help to protect exposed steel areas of the steering arm and the covers of trim motors.
On the trailer, the galvanized parts will show less signs of corrosion because they are galvanized (zinc) until the zinc is eaten away, after which they too will rust. If the trailer is painted, the paint is usually on the outside only, so that the metal inside of the tubing is exposed.