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Which of the Following is Recommended Maintenance for an Inboard Boat?

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which of the following is recommended maintenance for an inboard boat

As you sit the boater exam, you might stumble across the question, “Which of the following is recommended maintenance for an inboard boat?” To answer, mandatory maintenance for a gasoline boat includes the engine and hull zinc.

A small dent in the transom can wait, but a leak in the oil case must be taken care of immediately. You should annually replace damaged engine parts and corroded hull zincs. Failing to do so in time might lead to irreversible damage.

In this article, we’ll explain more about the function of each one, the steps you should take to maintain them, and tips on general boat maintenance. Read below!

Table of Contents

What is the Recommended Maintenance for an Inboard Boat?

Inboard engines have a service life of 1500 to 2000 hours, which is 10 to 20 years of continuous use. That is great value for the price. But if you maintain inboards improperly, they might perish shortly after a few years.

So, what is recommended as part of the annual maintenance program? You can do many things to care for your vessel, such as washing the boat’s exterior, deep cleaning its interior, and checking for dents on the hull.

But the recommended annual maintenance is replacing corroded hull zincs and deteriorated engines. These are what you need to prioritize.

1. Maintaining the hull zincs

Hull zincs or hull plates are sacrificial metal pieces. They are installed on the trim tabs or near the shafts to protect metal parts under the water. They give up their electrons and corrode, so other metal components are safe. A boat might have one to two hull plates.

You should change them once they dissolve about half. If you ignore hull zinc yearly boat maintenance, other underwater metal components will suffer from galvanic corrosion, which includes the propellers and the boat bottom (if you own an aluminum one.)

Having hull zinc replaced by boat services is around $20.

2. Maintaining the engine

The idea of replacing the engine might freak you out, but you don’t have to remove and reinstall the entire piece. Most of the time, you only need to fix damaged or contaminated components.

The procedure varies from simple tasks like flushing the motor and changing the oil to complicated mechanical work like welding leaks and fixing electrical lines.

Follow the general guideline below to inspect the current condition of your boat and take it to the service when needed. All boaters should be able to perform the basics of this checklist.

Boat Yearly Maintenance Checklist

1. Engine

Every time you start an inboard motor, you should see water discharged from the raw water pump. It is located inside the boat and is usually driven by a V-belt. The boat’s cooling system is blocked if you don’t see water coming out of the pump. Continuing to run your boat will dry out the motor, cause it to overheat, and stop working.

Besides, you must flush the motor at least once a year to prevent dirt and debris from building up in the compartment. Follow these steps:

  • Connect a freshwater hose with the flusher and attach it to the engine cooling intake hole
  • Turn the flusher unit on and let it run for five minutes
  • Add flushing agent to the cup on the flusher, turn it on, and run for 30-40 seconds
  • Turn off and remove the flusher

Leaving the agent in the cooling system helps to protect the motor. However, always refer to the product’s label for the specific procedure of the agent you choose.

2. Oil and filter


Similar to car maintenance, boat owners need to change the engine oil after a time of use. Most inboard motors require replacing oil every 100 hours of running, which is about three to six months. Ideally, a new oil filter should be installed with every oil change.

Here is how to replace the engine oil and filter:

  • Start the engine and run it for a while to bring it to operating temperature
  • Connect an inboard boat oil change pump to the dipstick
  • Aim the tube at an oil pan and pump until oil starts to exist the pump
  • Change the oil filter and fill the engine with new oil

As you pump the oil out of the engine, notice its color. Water might have penetrated your oil compartment if it turns milky or its level unexpectedly goes up on the dipstick. Consult a qualified marine mechanic right away.

3. Fuel lines

Check for cracks in your fuel lines by wiping them with a clean cloth. If there are any tiny splits on the lines, the cloth will get a distinctive smell of gasoline. You can use this trick for both inboard and inboard/outboard maintenance.

4. Propellers


Propellers are key to performance and fuel efficiency. You should dismantle the propeller to remove the fish lines that get caught in it, grease the shaft, and look for any damages. Don’t forget to make sure all joints and nuts are tight and secure.

5. Batteries

Every month, check and make sure the batteries are in good condition. You should:

  • Disconnect the batteries from other devices
  • Clean up any dirt or grime with a cloth
  • Clean the terminals
  • Refill the battery cells with distilled water

6. Electrical lines

Faulty electrical systems are one of the main causes of onboard fire hazards. Does your VHF go dim once in a while? Do the sidelights suddenly flash sometimes? Examine and fix your electrical lines before the problems turn serious.

Note that many boats run with AC power, which can kill. So, turn off all sources before you start working.

7. Hull and trailer


Are there any scratches, dents, or water leaks on the hull? Do the drain plugs still fit securely? Do the bilge pump and sidelights function perfectly? These are all the questions to ask when inspecting the hull.

In addition, have a quick scan of the trailer whenever you load your boat. Check the rollers, winch cables, and lights. If there are corroded spots, sand them off and repaint the area to prevent them from spreading.

8. Other joints, connections, and fluid levels

Last but not least, walk around your boat at least once a year to see whether there appear any noticeable scratches, dents, and splits. Make sure the cleats are in place and the dock lines are in perfect condition.

You should also periodically look into other fluid levels, such as steering gear oil and coolant. They should be replaced and refilled when needed.


To sum up, the answer to “Which of the following is recommended maintenance for an inboard boat?” is replacing deteriorated engine parts and corroded hull plates. But it would be best if you also took good care of other important constituents, such as engine oil, oil filter, electrical lines, and batteries.

Having a checklist will ensure you never miss any important parts during motorboat maintenance. So, save our article and refer back to it every year. If you think the article can help one of your friends, please share it with them. Thank you for reading!

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