How To Soundproof A Boat Engine Compartment(Causes and Tips)

Engines make a sound! And boat engines are no different. Boats usually have powerful motors and sometimes more than one. And the motor makes high-frequency noise which sometimes crosses the limit of 100 dB.

Though it’s natural for boat engines to make sound, sometimes it makes the sound more than it should. Several technical and environmental causes make the engines sound a lot. 

Seemingly, you can’t make the boat engine completely noiseless, but by applying the tips below on how to soundproof a boat engine compartment, you can reduce it. 

Also, the causes and benefits of soundproofing your boat engine compartment you’ll go through. Let’s check them out!

How Many Types Of Boat Engines Are There

Understanding the boat engine is a must, whether you are a newbie or a boating expert. In addition, to properly soundproof the board, you have to know the types of boat engines available. There are 4 significant types of boat engines available. But two of them are most common inboard and outboard engines. Here’s a short brief of all the types to help you understand better:

Inboard engines: These are four-stroke automotive engines, mainly for marine use. These engines are placed in the hull midsection or front of the transom. The engine drives the propeller via a drive shaft through the hull. A rudder controls the steering of the inboard engine boats.

Outboard engines: The outboard is a portable, self-contained package with an engine gear case and propeller attached to the boat’s transom. A tiller or steering wheel, which swivels the engine to direct propeller thrust, controls the steering.

Sterndrive Engines: Sterndrives are also known as inboard outboards because they combine the features of inboard and outboard engines. A four-stroke sterndrive engine is mounted inside the boat and connected to a drive unit via the transom. This drive unit resembles the lower section of the outdrive’s outboard, which swivels like an outboard engine to steer the boat. 

Jet Drive Engines: A jet drive engine propels a boat by forcing a jet of water out the back of the boat and into the water. Such an engine is used in jet boats and personal watercraft to direct the jet of water that serves as steering for the boat.

What Causes Boat Engine Noises?

Before you get to solve an issue, you must know what’s causing it. This is in the case of boat engine noises also. And we have found some legit causes that make your boat’s motor noisy.

  • The most common cause of the noise is the boat’s vibration and low maintenance. As you know, the engine needs proper care periodically. 
  • Torn-out parts and loosening nuts and bolts make chuckling sounds. 
  • Not changing the engine oil regularly can weaken the engine, make it harder for the pistons to move efficiently, and cause unwanted noises.
  • Something touching the engine compartments can result in annoying noises.
  • Constant noises can hear if the engine is not properly mounted.

Why You Should Soundproof the Boat Engine Compartment?

High-pitched noises from your boat engine compartment don’t just ruin the peace. They can also cause severe health issues. And sometimes, it can cost you a few hundred bucks of penalty. Here are some more reasons why you should soundproof the boat engine compartment.

Saves You From Penalty

You might not want to give a couple of hundred bucks fine for enjoying leisure. And that’s what your noisy boat can cost you. In addition, different states have different regulations for vessel noises. Like:

  • In New York, the noise level of the boat has to be under 75dB to 90dB. If the limit exceeds, you have to pay a fine starting from $50 to $250. 
  • In Connecticut, the noise level has been limited from 88dB to 90dB. It can cost from $100 to $500 to exceed the limit.
  • In Alabama, the noise level of the boat can’t exceed over 86dB from 50 feet away. Otherwise, you will have to pay fines.

Overall, all the states have their regulations on boat engine noises. And soundproofing your boat engine can help you be safe from being the subject of penalty.

Ensures Proper Insulation

Boats run with a powerful engines and emit a lot of heat. Soundproofing the boats with proper materials like fiberglass composites like R13 or R19 insulation can reduce the heat emission to half of usual and keep the heat insulated in different weather conditions.

Reduces Health Risk 

High-pitched noises are the reasons for severe health risks. As we humans have limitations of hearing from 20hz to 20000hz, which are considered low and high frequency at specific points, exceeding those limits can damage our hearing. 

Also, the sound waves caused by the boat engine become the reason for anxiety and depression. So, by soundproofing the boat, you can reduce the health risks.

Provides Calm Environment

Boating has several purposes. Sometimes it is for peace of mind which 72% of American people enjoy every year. And, sometimes, it is for making livelihood which fishers do. 

No matter the purpose, if the boat makes more sound than usual, both leisure-enjoying and fortune-earning people face losses. Because excessive sound ruins the peace of mind and scares the fish away, besides, it harms the ecosystem. And, with the use of sound-deading materials, you can resist all of them.

How to Soundproof a Boat Engine Compartment?

Soundproofing a boat engine is not a tough task. It is almost like a DIY project if you know the proper way to apply it. However, the way to soundproof your boat’s engine compartment is not one. We’ve listed down the field-proven and effective ways to soundproof a boat engine compartment as tips. Which are:

Use High-End Soundproofing Materials(for Inboard and Outboard Engines)

The use of high-end soundproofing materials is the most effective way to deaden the unwanted noises from the boat engine compartment. Also, very effective for boat engine compartment insulation. You can use fiberglass composites, mass-loaded vinyl barriers, and temporary barriers to deaden your boat engine noise. But you have to choose the material depending on which type of boat engine you have. 

If yours is an inboard engine, you do not have to use so many sound-deadening materials. These engines are insulated by building most of the time. Yet, to reduce noise, you can use marine soundproofing foam panels used in heavy vehicles to protect engines.

Moreover, the outboard engines need a bit more attention. This type of engine is protected by a cover called cowling. The cowling comes protected with a thick layering of sound-deadening materials. So, you first have to check the cowling to see if the layer is okay. If it is not, check the user manual provided by the manufacturer to remove it, then apply new soundproofing materials. Both fiberglass composites and vinyl work efficiently to reduce outboard engine noises. 

Note: Be sure to get waterproof and fireproof sound-deadening materials. And Do not cover your boat engine compartment fully. It can increase the heat and cause accidents. 

Use DIY Muffler (For Outboard Engines)

You can use a slime DIY silencer or muffler to reduce sound emission. Outboard engines emit smoke through the exhaust, and many sounds are also produced. Using some PVC pipes, you can make a fantastic silencer to dead the sound. 

However, this is not a long time fix. You can make this with a ban and a foot or two of PVC pipe with a cover having holes in it. This method of sound deadening is also cost-effective but not so good for getting the best performance from the boat.

You can check this video

Fix the Loose Components (For Every Engine)

Boat engines produce a lot of vibration, and because of the beat, the engine’s components become loose over time. Most of the time, it happens due to low maintenance. So, check your engine for any flexible parts after every long ride. It will help to reduce the annoying chuckling noise. Also, do not forget to change the engine oil on time.

Add Padding on The Floor(For Every Engine)

Padding for Floor Soundproofing

The boat engines produce not only high-frequency sounds but also low-frequency sounds. As the machine makes a lot of vibration, the vibration can result in high pitch buzzing noise. 

You might not feel the noise suddenly, but eventually, you will notice, and it will create an annoying sensation slowly in the ear. To get rid of such unwanted sounds, you have to use thick padding on the boat’s floor. The padding should be 1.5 to 2 inches thick and work like acoustic panels and absorb the vibrations we use to block high-frequency sounds.

Fix the Cracks or Holes (For Every Engine)

Most of the compartments of the boat engine come with built-in soundproof layering. But long-time usage or rolling in the water can damage the compartment and create cracks or holes. If you do not fix them, the sound can leak. So, give your boat engine compartment a check now and get the cracks and holes fixed with quick fixes.

Frequently Asked Questions

Why Is My Boat Motor so Loud?

The boat motor can get loud due to several reasons. The most common reasons which can make your boat engine loud are loose components, torn insulation layering, low maintenance, and lousy engine oil.

Is an Inboard or Outboard Quieter?

The inboard engine is quieter than the outboard engines as the engine remains inside the deck and comes covered by built-in soundproofing materials. However, the newest outboard engines are also pretty noiseless and fast.

Do Outboard Motors Have Mufflers?

Yes, outboard motors come with exhaust systems. Anyway, it is not the same for all outboard engines. Some engines come with shorter exhausts, and you will have to make an extra addition to reduce the noise.

Are Outboards Faster than Inboards?

Yes, outboard engines are more powerful and faster than inboard engines. They produce much more power and have way less carb weight than inboards.

Which Is Faster Sterndrive or Outboard?

The outboards are faster and quicker than the sterndrives. Outboards are smaller in size and very easy to maneuver. Also, outboard engines remain in the boat’s tail like an extension, so the boat gets an extra push.


We’ve given you a few boat engine noise causes and some tips on how to soundproof your engine compartment. It’s now up to you to take these tips and apply them so you can enjoy a quieter boating experience. Remember, the earlier you start, the sooner you’ll be able to hear that sweet sound of silence! 

Adam Houdge
Adam Houdge

I am Adam Houdge, My journey to helping other peoples to have peaceful lives began. With our experience in soundproofing, we recommended tips & techniques that are affordable and easy to install. Read through our tips and techniques, apply them & Say Goodbye to Noises.

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