Boat Sound Tutorial – Sandy Currie Chair, Policy & Research, Safe Quiet Lakes


The sound that one hears when a powerboat passes by is influenced by:

  1. The speed of the vessel.
  2. The load carried in the vessel.
  3. The location of the load carried in the vessel.
  4. The shape of the hull of the vessel.
  5. The “drag” or “windage” of the superstructure of the vessel as it moves through the air.
  6. The wave height and wave direction of and on the body of water.
  7. The type of vessel.
  8. How the engine(s) is trimmed. This is applicable for O/B, I/O and PWC vessels only.
  9. The presence or lack of a muffler.
  10.  How the engine is exhausted:
    1. Thru-the-propeller hub – O/B & I/O engines.
    2. Thru-the-nozzle – PWC.
    3. Thru-the-transom – I/B engines.
    4.  Type of engine. Common types are:
      1. Two-stroke O/B.
      2. Four-stroke O/B.
      3. Old two stroke O/B.
      4. In-board.
      5. Two-stroke PWC.
      6. Four-stroke PWC.
      7.  Skill of boat operator.
      8.  Attitude of the boat operator.

Regulatory Authority

Vessel construction is regulated by Transport Canada (TC) under the Canada Shipping Act 2001 (CSA 2001).  The number 2001 refers to the year in which it was last updated.  Prior to 2001, the version in use was dated 1985.  Provincial, regional or municipal governments have no regulatory control over the Canada Shipping Act and cannot make any rules concerning how boats are constructed, operated or where, when or how boats are operated.  The only exception are the Vessel Operation Restriction Regulation (VORR) provisions which do give very limited rule making capabilities to the other levels of government.  However, any rules desired by this process can only be made lawful by an act of the Parliament of Canada, thus TC has the power of veto.

There are no scientific regulations that mandate what the sound pressure limits are for marine engines in Canada. In simple terms, the only applicable regulatory requirements related to sound pressure limits are:

  1. O/B, I/O and PWC equipped boats must exhaust their gaseous and sound emissions either through the propeller hub or through a muffler system.
  2. I/B boats must have a operable muffler system that cannot be by-passed unless the vessel is being operated at least 5 miles from any shore.

Note: Many boats are equipped with what is commonly referred to as “Silent Choice” or “Captain’s Choice” systems.  These systems give the vessel operator the choice of either a muffled exhaust or non-muffled exhaust. Canadian regulations require that these optional systems must be “rendered inoperable”, when, and if, the vessel is operated on bodies of water that cannot provide the 5 mile from shore clearance zone.

Common Myths

  1. Loud boats must be illegal – no they are not, they are just loud.
  2. Thru-the-transom exhaust systems are illegal – no they are not, if there is a muffler.

Why No Hard & Fast, Clearly Defined Regulations?

Globally the marine industry regulatory paradigm is far ahead of the North American (Canadian & USA) paradigm.  Most of the developed markets – Europe, England, Australia, Japan and others have very specific and very scientific regulations governing sound pressure emissions – laws that define what sound level is permissible and what level is not.

Canada is not up-to-date despite the fact that the industry would prefer a regulation that is the same as those in place outside North America. In fact, since most Canadian and American boat manufacturers already export into these other markets, compliant product is already on the waters in Muskoka.

Why are we (Canada) behind? Because:

  1. When the industry proposed the same regulatory framework, as used elsewhere in the world, during the CSA2001 review period, various consumer groups lobbied against such rules. TC opted to agree with the consumer groups.
  2. Owners of vintage boats felt that they could not be compliant. This is actually correct in many cases.
  3. Fears that enforcement would be difficult. This is not true as manufacturers have to prove to TC that their products comply with Canadian regulations before they are permitted to be sold/used in Canada. Adding proof of compliance to domestic sound pressure regulations would not be difficult for almost all manufacturers as they already have to do so for export markets.

Note: The testing for compliance to the global sound pressure limit regulations is scientific and cannot be done at the end of the dock using a sound gauge from Radio Shack. Industry uses highly defined ISO Sound Emission Testing Regulations to prove compliance. It would not be technically possible to replicate these tests “in the field”.

The Boater’s Responsibility

Almost everyone in Muskoka owns a boat and most families own boats with motors.

It is unrealistic to think or believe that we can enjoy our powered boats without making a sound.  It is simply not technically possible.

However, we all have a right to anticipate that our fellow boaters will be respectful while enjoying the privilege of boating on some of Canada’s finest lakes and rivers. So how can we go boating, including waterskiing, wakeboarding and tubing and just simple sightseeing at a sufficient speed and yet still keep the sound level of the boat at a reasonable level? Here are some tips:

  1. Don’t overload the boat and evenly distribute the passengers to maximize the efficiency of the hull design. This will reduce the need to always run at full throttle and still permit operations at higher speeds while saving fuel and keeping the sound of boating low. Remember most of the measured sound is from the wind and waves as the boat moves, not the engine.
  2. Stay away from the shoreline. While we have a shoreline low speed zone (30m and speed limit inside that zone of 9 km/hr or 10 km/hr depending upon location), unless you are heading into or away from shore, keep further away from shore than the speed limit regulations require. You’ll get to your destination just as quickly and there will be less sound impact on your neighbours.
  3. Trim your boat’s engine correctly. Most boats have trim systems to adjust the engine angle, even while underway. Use it or learn how to use it better. A properly trimmed engine will make the boat more efficient and increase speed while not requiring more throttle.  It also helps to keep the sound level at a lower level.

Written by Sandy Currie

Chair, Policy & Research, Safe Quiet Lakes