Most of the marine boats have acid lead batteries which are also known as deep cycle batteries, these batteries have a unique design that these remain charged for a long time without any external power source. The fact is that it uses liquid acid to power it which in turn can lose power rapidly, if not properly maintained.
It is a fact that you do not have to buy a new battery for your boat, once you battery does not give you satisfactory service or the original battery has started to fall. The reconditioning of the deep cycle batteries is quite easy and even you can embark on the DIY project.
When you battery power is low you need an external battery charger. For this you may require a crescent crunch, steel wool, a funnel, a bucket and a pair of rubber gloves. You also need additionally some baking soda, distilled water and Epsom salts.
Before you do all this just check any acid leakage, even if the leakage is very less just do not touch it with bare hands, wear the rubber gloves for the safety. Remove the cables from the boat's battery both positive and negative and slowly and carefully remove the battery from the assigned compartment.
Clean the battery's housing as well as the terminals with paste from baking soda and water. You can also use steel wool in applying the paste to the battery.
Remove the plastic plugs which are normally situated at the top of the battery and drain the battery cells into the bucket. Sealed batteries are normally drained by drilling holes in each of the depression of the battery. Use a ¼-inch bit in the drilling holes, while the cells are being drained, mix a quart of distilled water with 8 ounces of Epsom salts and stir it well till the salts are completely dissolved.
After allowing the solution to settle, fill the cells with this mixture with help of the funnel, after having done so seal the cap and reinstall the battery in the assigned compartment.
Once you have sealed the battery hook it to the multi phase charger, it has to be a slow process, never use quick start options. Once you are sure your car battery is fully charged which may take about 60 to 90 minutes, reconnect the cables and put it back in the compartment.
You must ensure to drive for few minutes till your battery is back in the working condition. You must closely watch your battery for few days after it has been reconditioned; you may need recharging if the battery is not working properly.
You must recondition the battery in the open space and always wear protective gears while doing this job. Safety first is the first criteria and never touch it bare hands else you may get an electric current. While dealing with mixture etc, all precautions should be followed as explained.
Apart from reconditioning weak deep cycle batteries, to save cost, you can also build your own wooden boats. What you'll need is a step by step boat construction plan.