Ideally keep the overall length, including outboard, of your tender at least 0.5 metre shorter than the beam of your boat. This helps avoid mishaps when docking, especially if you reverse into a pen. When calculating the total or ‘working’ weight of the tender ensure you include the additional weight of the outboard motor, battery, lift jackets, anchor, fuel tank(s) when full and other gear you normally have in the tender when using it and will remain in the tender when you lift it onto the swim platform.