CONVERTING SALT WATER BOATS TO FRESH WATER AND VISA VERSA

                                           

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  SALT WATER 2 FRESH WATER 2 SALT WATER

 Is there a difference in the boats, and how to convert my boat?

 What will be discussed is the simple answer. All boats are built to live in salt water or fresh water the big difference is corrosion protection, the anodes and a complete bonding wire system make all the difference. What does this mean and how does this affect the boat? Boats that seem to suffer the worst fate are the boats that are the "Salt Shakers" or salt water boats relocated to fresh water. A great comparison is when you bring a car from Arizona to Toronto and drive them through the first winter they begin to corrode faster than you expect. The environment has already started to affect the metals the car is made from. Salt water boats seem to suffer a similar fate but for different reasons. There are ways to bring this fate into check.

First lets talk about the fresh water boats that are bound for a salt water home.

The anodes we use in fresh water are different than those used in salt water. In fresh water we use magnesium anodes and in salt water we use zinc anodes. The common term for an anode is the "zinc". So what is an anode? The anodes are the sacrificial pieces of bare metal you see attached in a transom block, attached to trim tabs, anodes are bolted to the rams and cavitation plates on your out drive or attached around your prop shafts.  Basically there should be an anode fixed to any large metal pieces that are attached to your boat and are in contact with the water at all times. The anodes are connected to the negative side of your boats wiring system through a series of bonding wires which tie all the anodes together The other source of grounding is thru the bolts that hold the drive train components together. 

 What do anodes do? Well in any water particularly in a marina there are stray electrical currents that escape and travel through the water looking for a ground source to complete a circuit. This stray power will find your boat and the transfer of this stray power will start to corrode any metal parts it can find trying to locate a ground. If it finds a metal source that is attached to your ground system the metal surface will immediately begin to deteriorate. Creating little pits and eventually holes in the metal part. The worst part of this process is it quite often this magic works from the inside out which means by the time you see the corrosion, the part (like a drive) is destroyed. I have seen drives were the props and cavitation plates have holes right through them, looking like Swiss cheese. There is a lot of science to do with the ability of different metals to make a good grounds in different water conditions,  and this is why we use magnesium in fresh water, So if you are converting your boat to full time salt water use then you must plan to change all the anodes to zinc. Remember there are even anodes in the cooling system of your motors, bow thrusters and so on. You must be diligent and find all of the anodes, and you want to be sure that they have all been changed to " ZINC".

If you are going to visit salt water for extended periods of time but plan to return to fresh water, there is a way to protect your boat that will work without any modification to the boat. You will have to purchase a large zinc anode at your local parts store (on a larger boat you may need two). Bolt a large green, black or yellow (BOND) wire to this zinc anode. The wire must be long enough to reach your batteries and hang over the side of the boat a foot or so in the water. Attach a ring terminal  to the other end of the BOND wire that will fit the negative terminal on your battery, attach the anode wire to the negative battery terminal and deposit the zinc anode in the water over the side of your boat. This only works if you have all of your battery negatives in your boat tied together. The zinc anode you attached now becomes the easiest ground for the stray current in the water to find, and you are protected, and it is removable when you return to fresh water.

 

The conversion items are from fresh water to salt water are:

1- Be sure that you have all the metal fittings that are in contact with the water bonded through a group of appropriate sized green wires to the negative system in your boat, these wires must have good clean bolt and nut contact.

 2-A way for you to flush the motors with fresh water after each run in the salt water. It is even a good idea if you have air conditioning to have a  fresh water flush system here as well.

 3- You may need to up grade your anti foul paint to be sure that it is compatible with salt water use.

  4 - All anodes must be changed to zinc. Get out your manuals and do not miss any anodes.

 5- In some cases you will see that running gear has been anti fouled this can be a really bad procedure to undertake, if you are going to do this you must refer to a supplier of anti foul products and follow there instructions, Do not paint any running gear unless you have clear instruction on materials and procedures, this will NOT be the same paint you put on the bottom of your boat!

Going from salt water to fresh water is basically the reverse procedure you remove zinc anodes and replace with magnesium anodes. However there is corrosion that has already started on all the metal fittings that are exposed to the water, and you will find that almost immediately after the boat is in the fresh water any brass fittings will turn green and this will happen quickly. This will happen to items such as engine water pick up thru hulls etc. It is important to immediately put together a clean up plan for this corrosion problem. Other wise this corrosion will become rapid and then you could be facing more repair bills. You need to flush the area of the bilge down with fresh water allow to dry clean up any visible green or  any visible corrosion. After this step purchase some really good anti corrosion spray Mercury Marine and Volvo make products for this application. Spray down any wire connections and exposed metals following the products instructions (you can spray motors and other items down regularly with WD40). If you are planning to bring a salt water boat to fresh water be prepared to spend some money. There will be a host of small issues such as the wires that have been in salt water bilges,  these wires will fail given time. Parts like bilge pumps quite often die, air conditioning thru hulls will turn green, Exhaust manifolds and thermostats will have a shorter life, painted metal components such as radar arches will show bubbles in the paint, even items such as cockpit lights that are plated plastic will loose there luster. A real problem is electronics will act up because the small pins in there connections will be corroded from the salt air.You may chase these kinds of problems over a year or two until you get them all sorted.

 After you have been around boats awhile you can generally pick out the boats that have come from really salty water like the Gulf of Mexico. The wear and tear of the salt water combined with the sun will make for a boat that will cost you more money to own than its fresh water counter part. There are always deals coming from salt water conditions. The question you have to ask yourself is? Is it really going to be a deal over the lifetime of the boat.

 If you for any reason feel the boat has had any amount of sinking in salt water run away fast.

Conversion items from salt water to fresh water

1- Anodes must be changed to magnesium, again be sure to get them all

2- A complete anti corrosion program

3- Be prepared to have to repair or replace parts more quickly than a fresh water boat.

4- Be sure that you cannot use the macerator to discharge any head holding tank water over board!

Manufacturers have worked very hard on newer boats to prevent salt water damage to components, these systems are usually part of the motor package, you must remember most of the boats produced end up in salt water somewhere. So yes even your boat can easily live in either environment. In any environment maintenance is the key to a reliable boat and a good looking boat.

 Any questions feel free to email your questions to boatnutmedia@gmail.com

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