2018 Mercury 20 Hp 20MH Outboard Motor

The 2018 Mercury 20 HP 20MH Outboard Motor is a manual-start, tiller-steered engine on a 15-inch short shaft, with manual tilt and a 115-pound dry weight.

Manual start on a 20 HP block

Pull-cord starting keeps this motor simpler than the electric-start 20EH built on the same 20 HP engine, and without a starter or battery to wire in, it is also lighter. An optional 12-amp, 138-watt alternator can be added for owners who want charging capability without stepping up to the electric-start model.

Fitment

Matching this short shaft to the right transom matters more than most buyers expect; mounted too low, a 15-inch shaft like this one leaves the gearcase and prop too shallow, and a boat built for Mercury's 20-inch long-shaft version will not get full performance from it. Tiller steering keeps throttle and shift at the handle rather than routing them to a console.

Why some owners skip electric start

A manual-start outboard like this one has fewer parts that can fail, since there is no starter motor, solenoid, or battery wiring in the circuit; for a backup motor or a boat used only occasionally, that simplicity can matter more than the convenience of turning a key.

Servicing a carbureted 20 HP engine

Keeping the fuel system clean matters on any carbureted outboard, and running the tank low before long storage periods, then refilling with fresh fuel, is a simple habit that avoids most of the hard-starting complaints owners report after a winter of sitting.

Common questions

Can I add charging capability? Yes, an optional 12-amp, 138-watt alternator is available for this model.

What is the gear ratio? 2.15:1, and this new motor carries Mercury's standard three-year warranty.

Specifications