Frankly an electric boat is no different from a boat driven by any motor. You can have an outboard motor with a battery, in which case you will remove the battery from the boat for charging. Torqeedo are the leading manufacturers of outboard motors and pods although other companies are developing similar products as electric outboards become more popular. A pod motor has the actual motor in a pod attached to the propeller and submerged below the boat. This can make it more vulnerable for example to fishing line damage and obviously makes maintenance more tricky as the boat will have to be pulled out of the water for access.
Most of the boats we sell are fitted with an inboard motor, pretty much like you have in your washing machine, with speed variation supplied by a controller, and coupled to an appropriate battery pack designed to give you the range (number of hours cruising) you require at a given speed, with recharging available from an onboard charger which is plugged into a shore mains supply. The motor is usually hidden under the floor and either directly coupled to the prop shaft or attached with a drive belt. In some cases there will be a generator on board which will require fuel of some kind, petrol or diesel, to power it. We usually consider this to be a hybrid rather than a pure electric drive system.
Depending on which kind of battery your expert recommends for your particular usage the charging will take up to one hour for each hour of operation. This is the case for conventional lead acid batteries, both gel and wet. The latter tend to be cheaper but do require some maintenance while the former require no topping up or regular attention other than charging appropriately. You should expect regularly maintained batteries to last up to 8 years and sometimes even longer.
Some people like to leave their boats on trickle charge when not in use while others prefer to disconnect from the mains when fully charged. There are arguments in favour of both methods but the net result is similar. Ideally batteries should not be fully discharged as this is detrimental to their long term health. Gel batteries should definitely not suffer this fate or they will fail prematurely and need replacing. However there are simple battery management systems available which allow you to monitor your battery condition from your smart phone both while the boat is in operation or in storage.
Battery manufacturers may also offer AGM batteries which are sealed like gel batteries and have a faster rate of charge. However they are also more expensive than wet or gel batteries as well as more sensitive to overcharging, and their performance tends to decline gradually as they discharge. In electric cars Lithium Ion batteries are used as they have a better storage capacity to weight ratio and can be charged more quickly. They are ideal on sailing boats for auxiliary power as they don’t mind being inclined at odd angles. They are the only solution if you want to go fast for water skiing activities or simply for higher speed usage. The main drawback at the time of writing is cost. Inevitably the cost will come down in time and other power storage solutions will become available.
For years we have been using lead acid batteries which have the advantage of acting as ballast in a conventional displacement craft. Many boats require ballast to sit correctly in the water so having the weight low down, even under the cockpit floor, and evenly distributed throughout the boat can be a positive advantage.
This section of the website will be updated regularly as new products appear and we will try to evaluate them. Please feel free to send in any comments or tell us about any experiences you have with electric boat technology and we will publish if we consider it useful for our readers.