How do I choose an outboard motor for a pontoon boat?

Choose an outboard within your pontoon boat's approved horsepower and engine-weight limits, then match its power to your usual load and required speed. Check the capacity plate and manufacturer's specification first, because tube design, engine mounting and passenger weight matter more than length alone.

Check limits and load

Find the maximum horsepower, permitted engine weight and passenger or load limits in the builder's documentation. Some plates give only part of this information, particularly on older boats. Use the exact model and year when checking with the builder.

A twin-tube pontoon and a three-tube tritoon of the same length can have very different power ratings. Larger tubes, lifting strakes, reinforced engine pods and different steering systems can change what the boat will safely carry and how it performs.

Include passengers, fuel, batteries, fishing equipment and coolboxes when describing your normal load to a dealer. Six adults can add roughly 450 to 550 kg before their gear goes aboard. A demonstration with two people tells you little about how that boat performs fully loaded.

Never exceed the builder's horsepower or engine-weight limit. Before fitting a replacement engine, have the engine pod inspected if it shows corrosion or cracks, or has been modified.

Match horsepower to use

Use these starting ranges for recreational pontoons, subject to the individual boat's rating:

• Quiet fishing and sheltered-water pottering: roughly 25 to 60 hp on smaller boats carrying light loads, where speed is unimportant.
• Family cruising on an 18 to 22 ft twin-tube boat: commonly 60 to 115 hp; the upper end usually suits regular passenger loads better.
• Heavier 22 to 26 ft boats and livelier cruising: often 115 to 150 hp, where approved.
• Towing and higher-speed tritoons: commonly 150 to 250 hp or more, but only on hulls and steering installations designed for it.

For a 22 ft twin-tube boat carrying six adults, compare approved 90 hp and 115 hp installations before settling for a smaller engine. Ask for performance figures with a similar load, including cruising speed, engine rpm and fuel consumption.

Extra horsepower does not guarantee a proportional increase in speed. A basic twin-tube hull may gain little at the top end, while a tritoon with lifting strakes can make better use of additional power. For waterskiing or pulling an adult on a towable, ask for evidence that the complete boat performs adequately when loaded.

Shaft, propeller and controls

Pontoon engine pods vary. Outboard shafts of 20 inches and 25 inches are common, and some installations require longer versions. Match the shaft to the builder's specified mounting arrangement. Measuring from the deck to the water is unreliable.