Fuel contaminants and deposits will reduce power. Sediments constrict fuel flow, clog filters, and score piston linings. This problem is aggravated at sea. Rougher seas work against the engine; the motion will slosh particles from the tank bottom into the fuel pickup. Heavy conditions are the most likely times for a dirty fuel problem to rear its ugly head. Preventative maintenance is the easiest cure. Liquid fuel additives are available which combat dirty fuel and engine wear by adding more detergents, stabilizers and water dispersants to keep you reliably powering through all conditions.
Fuel treatment is easy preventative maintenance anyone can perform. From biocides to inhibit algal growth in diesel tanks to octane boosters or stabilizers for winterizing gasoline, these simple measures will go a long way to maintaining optimum performance in your engine.
Fuel stabilizers are a good start since fuel typically sits longer on a boat than a car. Hard starts and engine knocks are symptoms which result from gasoline octane loss or cetane loss for diesel. These are a result of fuel oxidation and phase separation. Visible dark sludge settles with time to the fuel tank bottom. With the transition to E-10 gasoline, phase separation is accelerated. The increased ethanol attracts water and strips hardened sediment within the fuel system, sending these deposits downstream to your engine. You could compare the benefits of fuel stabilizers to vitamins for your body. Your engine survives without it, but benefits are proven over consistent long term use. Stabilizers slow the aging, i.e. oxidation, of fuel, which lead to problematic symptoms.
Additives like Biobor JF eliminate growth of harmful slime-producing fungi that clog filters and pipelines, attack rubber fuel system components and whose waste products aid in the corrosion of metal surfaces. This can be used in diesel fuel and light oils such as transmission fluid. An exciting new product is Star Tron, which protects by actively fights growth with enzymes. These enzymes work for you to eat dislodged sludge and deposits. Racor offers Conditioner Plus for either diesel or gasoline. This diluted multifunctional additive cleans and protects, improving combustion and fuel economy and lowering exhaust emissions. MDR Stor-N-Start Fuel Stabilizer works well with inboard and outboard engines, as well as with any engine that sees significant storage time. These products all have stabilizing qualities. More than one additive may be used in a tank, but be sure to read the instructions for compatibility and follow recommended quantities, as too much is not always better.
If you are already experiencing symptoms such as engine knocking and frequently clogged filters, fuel tank cleaning may be in order. MDR offers a product called Water Probe Indicator to detect the presence of water in your gas or diesel fuel tank. Should there be detectable amounts, products such as MDR E-ZORB Water Remover can help. StarTron again uses enzyme technology to pioneer a fuel tank cleaner. This eats sludge and sediment in older tanks. Should these fail to help, fuel polishing by looping fuel through a filtration system and back to the tank is a more costly but aggressive approach.