A boat trailer is a trailer

Trailer (vehicle)

A trailer is generally an unpowered vehicle pulled by a powered vehicle. Commonly, the term trailer refers to such vehicles used for transport of goods and materials....

 designed to launch, retrieve, carry and sometimes store boats.

Commercial boat trailers

Commercial hydraulic boat trailers are used by marina

Marina

A marina is a dock or basin with moorings and supplies for yachts and small boats.A marina differs from a port in that a marina does not handle large passenger ships or cargo from freighters....

s, boatyards, boat hauliers, boat dealers and boat builders. Generally this type of trailer is not used for storage of the boat.

Non-hydraulic

Self-propelled

Self-propelled boat movers are not trailers in the strictest sense of the word. They are hydraulically operated boat movers, with their own Prime mover (tractor unit). They share all of the features of hydraulic boat trailers.

Non-commercial boat trailers

This type of trailer is usually used by the boat owner/operator. The trailer is also used for storage.

Roll-on

Roll-on, also known as a "Roller style trailer", uses rubber and/or polyurethane rollers for ease of launching and loading a boat.

Glide path

Glidepath, also known as a "Float-on" style trailer allows the boat to float onto the trailer; after trailer has been partially submerged (usually 3/4 of the trailer). Since its inception it has become quite popular v.s. the "Roller style trailer".