ArticleBoatingService Repair

Cowling Clean

A cowling, often referred to as an engine “hood” or “cover,” conceals an outboard marine engine and protects its internal powertrain and vital components from sun, sand and sea. A cowling provides drag reduction, substantially reduced noise and diminished vibration, in addition to increased engine cooling by effectively channeling airflow through specialized vents and ports. The top cowling detaches from the lower motor housing with either two or three latches. Even though cowlings do their work at the back of the boat, they are on the front line of the harsh marine environment and see the very worst the ocean has to offer with a constant barrage of corrosive seawater and finish-fading UV rays. Lets not forget repeated exposure to exhaust fumes and oily residue, which left to accumulate will ultimately take their toll on even the shiniest cowling’s lustrous paint job. Engine manufacturers are now going to great lengths to build motors from high-tech polymers and high-grade alloys in an effort to combat corrosion. They are also applying advanced multi-step protective clear coats resistant to UV degradation to help retain an outboard engine’s shiny, new appearance. Yet even with these advanced measures, keeping cowlings looking new for many seasons still requires some effort on our part and is the subject of this issue’s Service & Repair.


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After hundreds of hours of service, cared for cowlings still look new. Photo: Steve Dougherty

Unless you are brand new to boating, it’s obvious your outboard engine(s) needs to be thoroughly washed after each use. We’re not talking about flushing the motor with freshwater—that’s a different topic. We’re talking about thoroughly washing the exterior of the engine from top to bottom with a mild, biodegradable detergent and soft sponge (avoid introducing excess water into the intake/vent ports). If your boat is moored at a marina or residential dock, an extendable deck brush with a soft bristle head will help with tough-to-reach lower units. Obviously, on a trailer access to the entire engine is not a problem. Make it a point to stay away from abrasive brushes and harsh, corrosive soaps that will eventually wear on any new cowling’s impressive finish. After washing, a few fanatics go as far as applying a thin layer of corrosion inhibiter. It’s not necessary, but the extra measure certainly doesn’t hurt. To whatever lengths you decide to go, do not be under the impression that rinsing off the engine with freshwater alone is enough to keep it looking shiny and new, because it’s not. Neglecting a routine schedule of washing with periodic waxing will ultimately result in a faded, used finish.

Even though cowlings do their work at the back of the boat, they are on the front line of the harsh marine environment…

Possibly the best line of defense against the harsh elements includes manufacturer approved fabric engine covers usually made of UV-resistant Sunbrella®. Fabric engine covers can be purchased from your local outboard dealer or directly from the manufacturer website. The latest and greatest fabric cowling covers have recently been introduced from our friends Down Under and are fully vented and specifically designed to protect the engine while the vessel is underway. Called Splash Covers®, they are sewn from fleece-lined Polysoft®, a marine grade fabric which is both waterproof and breathable and custom cut to fit your outboard’s cover like a tight-fitting second skin. The result is 100% protection from fading, scratches and corrosion. Even the most careful crews inevitably scratch their outboards with rods, gaffs, sinkers or lures. With Splash Covers®, your engine will always look just the like it did the day you bought it.

If you trailer an outboard-powered boat then you have to understand the value of protecting your motor. You may not realize it, but as you drive to and from your favorite boat ramp barely visible highway fragments are kicked up and may leave unsightly nicks and scratches. Worse yet, damaging asphalt particles and tiny pebbles may work their way into your engine area, resulting in lost fishing time and costly repairs that could have easily been avoided. Even when not on the road acid rain and damaging UV rays constantly beat down on an engine cowling and eventually take their toll—so keeping it covered will keep it looking new.

If the damage has already been done or if you’ve purchased a pre-owned boat that was missing a little bit of the tender loving care it deserved and you want to freshen up the boat’s appearance, unsightly cowlings with major scratches and faded decals can be replaced or refurbished. Ebay isn’t a bad place to look as dealers often clean house with extra engine covers they might have lying around. The option also exists to refinish the cowling either on your own with fine sandpaper, factory approved primer, paint and clear coat and decal kit, or through your local auto-body shop. If the price is right but money is tight you can try trading out a fishing trip to help offset the cost.

Taking good care of your engine means giving it the attention it deserves both inside and out. The extra effort not only keeps your ride looking sharp; preventative maintenance lengthens the life of your motor and goes a long way toward retaining your vessel’s highest resale value.

Seal the Deal

Where the cowling meets the lower engine casing is often a thin rubber seal. Without proper care this rubber gasket may eventually rot or tear and prevent a watertight seal. If the integrity of the seal were to be jeopardized, salt spray will ultimately find its way onto the head and other vital components of your motor, leaving abrasive and corrosive salt crystals everywhere. With technologically advanced outboards containing more sensitive electronic sensors than ever; extra care must be taken to ensure the engine’s vital components are kept dry and free of foreign particles. Periodically treating this rubber seal with a silicone-based lubricant will ensure years of trouble-free service. While you are at it treat the latches.