A trimaran is a boat that features a main hull known as a vaka and two outriggers on either side of that hull known as amas. The amas are attached to the vaka with struts, and in between the outriggers and main hull, nets called trampolines are sometimes secured to create a deck. When choosing a small trimaran, it helps to first determine how and where you will use the vessel. Think about how many people are likely to be on the small trimaran at once, the body of water on which it will be used, and how much you are willing to pay for the boat.
The cost of the small trimaran can vary depending on several variables. The materials used to construct the hull will often have one of the biggest impacts on the cost. Plastic hulls are likely to be the least expensive, while Kevlar can be more expensive. A small trimaran with a wooden hull will be one of the more expensive materials, but it will also be one of the most attractive; if aesthetics are important to you, a wooden hull may be a good option. For low cost, think about plastic. If durability and light weight are prime concerns, consider Kevlar or other composite materials.
Some features that may be very useful to you include telescoping boom arms that can retract to make trailering the boat much easier; bilge pumps that can help remove water from inside the hull; foot pedal steering units that make steering the vessel far easier, especially when the sails are not in use; and cockpit covers for the small trimaran, which will keep water and debris out of the cockpit when the boat is not in use. Trampolines can sometimes be strung between the main hull and the outriggers to provide more storage space or sitting space for passengers. Be sure the small trimaran you are considering can accommodate such fabric trampolines to add to the versatility of the vessel.
Take note of the sail configuration of the small trimaran you are considering. Most vessels of this type will feature a main sail and a jib, which is useful for steering the boat under sail power. It is possible to find a trimaran with a jib attached to a boom, which can add to the steering capabilities of the vessel. Make sure the sails are easy to unfurl and control from the cockpit. This may require a test ride, or at the very least a dry-land test.