Montana Boating Laws: Registration, Operation, and Penalties

Montana’s boating laws, enforced by Montana Fish, Wildlife & Parks (FWP), cover vessel registration, required safety gear, operator age limits, reckless and impaired operation, noise thresholds, and aquatic invasive species prevention. A general violation is a misdemeanor punishable by a fine of up to $500 and up to six months in jail, and intentionally introducing an invasive species is a felony that can carry two years in prison and a $25,000 fine.¹

Which Boats Must Be Registered

Every motorboat, sailboat with a motor, and personal watercraft kept in Montana must be registered through the county treasurer’s office in the county where the boat is kept.² The assigned number goes on both sides of the forward half of the hull in block characters at least three inches tall, in a color that contrasts with the hull.

Fees, collected by the Montana Motor Vehicle Division, are set by vessel length:³

Under 16 feet: $65.50
16 feet to under 19 feet: $125.50
19 feet and longer: $295.50

Manually propelled boats — canoes, kayaks, rowboats — are exempt at any length. Non-motorized sailboats under 12 feet, government-owned boats, and a vessel’s lifeboat are also exempt.⁴

Safety Equipment You Must Carry

Every motorboat and vessel must carry a U.S. Coast Guard-approved personal flotation device in good condition for every person on board.⁵ Children under 12 have to actually wear a properly fastened life preserver whenever they’re on a motorboat or vessel under 26 feet that is in motion. The trigger is the boat being underway, not simply being on board. Vessels 16 feet and longer must also carry a throwable PFD that’s immediately available.⁶

Coast Guard-approved portable fire extinguishers are required, with an exception for open-construction outboard motorboats under 26 feet that aren’t carrying passengers for hire. Any vessel operating or anchored away from a dock between sunset and sunrise must display navigation lights as prescribed by FWP.⁵ Sirens are prohibited on all vessels except those used by law enforcement or authorized government agencies.

Who Can Operate a Boat

Age controls who can run a motorized vessel. Children 12 or younger cannot operate a motorboat or personal watercraft powered by a motor rated above 10 horsepower unless an adult 18 or older is on board with them. Teens aged 13 and 14 have two options: complete an approved boating safety course and carry the certificate, or have an adult 18 or older on board.¹

FWP offers home-study and online courses for anyone 13 or older. The resulting motorboat operator’s safety certificate satisfies the requirement for 13- and 14-year-olds operating without an adult. Montana doesn’t require boating education for adults, though courses approved by the National Association of State Boating Law Administrators (NASBLA) are generally recognized in other states.

Renting has its own rule: you must be at least 18 to rent a motorboat or personal watercraft with a motor over 10 horsepower.¹

Reckless Operation and Boating Under the Influence

Montana prohibits operating any motorboat or vessel in a reckless or negligent manner that endangers life, limb, or property. The statute specifies what that includes: weaving through congested traffic, jumping another vessel’s wake within 100 yards of that vessel or its waterskier, buzzing other boaters, swerving at the last second to avoid a collision, and speeding in confined areas.⁷

If an officer sees a vessel operating without adequate safety gear, overloaded, or in another way the officer judges especially hazardous, the officer can order the operator back to shore and require the boat to stay there until the problem is corrected.⁷

The same statute makes it illegal to operate a motorboat, personal watercraft, or motorized sailboat while under the influence of alcohol or drugs. The prohibition also applies to waterskiing, surfboarding, and similar activities towed behind a motorboat. A conviction carries the general boating penalty of up to $500 and up to six months in jail.¹

Personal Watercraft Rules

Jet skis and wave runners follow all the motorboat rules and pick up a few more. Every operator and rider on a PWC must wear a Coast Guard-approved life jacket at all times, not just children. If the PWC has a lanyard-type engine cutoff cord, the operator must keep it attached to their wrist or life jacket.¹

PWC operators must hold to no-wake speed within 200 feet of any dock, swimmer, swimming raft, non-motorized boat, or anchored vessel. Stand-up PWC and any PWC towing a waterskier must travel at the minimum speed necessary to operate when leaving from or returning to a dock or shore. These buffer zones produce a lot of citations on busy summer weekends.

Noise Limits

Every internal combustion engine on a motorboat must be muffled, either through underwater exhaust discharge or a functioning muffler, and the muffler cannot be modified with cutouts. A motorboat or PWC that produces noise above 86 decibels measured at 50 feet, or exhaust noise above 90 decibels measured one meter from the muffler at idle, is presumed to be a public nuisance.⁸ FWP can require a dockside test to measure exhaust levels.⁹

Flathead Lake, Echo Lake, and Swan Lake are stricter: a motorboat or PWC operating near the shoreline cannot exceed 75 decibels measured at the shoreline.¹ Exceptions exist for state-sanctioned regattas and races, boats operating under a special FWP permit for engine tuning and speed trials, and government vessels used for enforcement, search and rescue, firefighting, or research.⁹

Aquatic Invasive Species Requirements

Boaters approaching a department inspection station must stop for inspection as directed.¹⁰ Vessels entering Montana that don’t pass an inspection station must be inspected before launching in any Montana water body.¹¹

After pulling a vessel out of any water body, you must remove all aquatic vegetation from the boat, trailer, and equipment before leaving the launch area. All compartments that hold water, including bilges and livewells, must be drained without impacting state waters, and drain plugs must be disengaged before transporting the vessel on land or a public highway.¹² If the vessel doesn’t have a drain plug that can be disengaged, you must take reasonable steps to dry or drain all spaces that hold water. The plug can go back in once water has drained.

If an inspector finds invasive species on your vessel, or if the vessel contains residual water from infested waters within the past 30 days, department staff will decontaminate the boat before it can launch.¹¹

Reporting an Accident

If you’re involved in a boating collision or accident that causes death, a disappearance, personal injury, or property damage exceeding $2,000, you must immediately report it to the sheriff’s office or game warden in the county where it happened. Standardized accident report forms are available at the county sheriff’s office, from game wardens, or at any FWP office.⁴ Failing to report can create legal exposure on top of whatever happened on the water.

Penalties for Violations

The general penalty for violating Montana’s boating laws is a misdemeanor punishable by a fine of up to $500 and up to six months in jail.¹ That covers most violations, from missing safety equipment and expired registration to reckless operation and boating under the influence.

Invasive species violations escalate with intent:

Negligent violation: misdemeanor, fines up to $700 for a first offense and $1,400 for subsequent offenses.
Knowing or purposeful violation: misdemeanor, fines up to $1,950, plus forfeiture of your fishing license and the vessel sticker required to operate on Montana waters.
Intentionally introducing an invasive species: felony carrying up to two years in prison, a fine of up to $25,000, or both. The court can also require you to surrender the vessel involved and pay restitution for cleanup costs.

A civil penalty of up to $2,500 may also apply to other invasive species violations not listed above.¹³ Officers can issue a warning instead of a penalty when that better serves the public interest, and no penalty can be issued for failing to stop at a check station if adequate signage wasn’t posted at a reasonable distance.

Insurance

Montana does not require boat owners to carry liability insurance. Lenders and marinas often require proof of insurance as a condition of a boat loan or slip rental, and given the size of potential property damage and injury claims from a boating accident, basic liability coverage is worth considering even without a legal mandate.

1
Montana Fish, Wildlife & Parks. 2025 Montana Boating Laws
2
Montana State Legislature. Montana Code 23-2-512 – Identifying Number
3
Montana Motor Vehicle Division. Boat, Personal Watercraft and Motorized Pontoon Registration
4
Montana Fish, Wildlife & Parks. Boating Rules and Regulations
5
Montana State Legislature. Montana Code 23-2-521 – Equipment
6
Legal Information Institute. Montana Administrative Rule 12.11.301 – Personal Flotation Devices
7
Montana State Legislature. Montana Code 23-2-523 – Prohibited Operation and Mooring – Enforcement
8
Montana State Legislature. Montana Code 23-2-526 – Overloading – Overpowering – Noise Limitations
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Montana State Legislature. Montana Code 23-2-521 – Equipment
10
Montana State Legislature. Montana Code 80-7-1011 – Check Stations
11
Legal Information Institute. Montana Administrative Rule 12.5.706 – Aquatic Invasive Species Quarantine Measures Within Invasive Species Management Area
12
Montana State Legislature. Montana Code 80-7-1010 – Invasive Species Management Area – Regulation
13
Montana State Legislature. Montana Code 80-7-1014 – Penalty