Fresh Water VS. Salt Water boating


What would happen to a fresh water boat in the sea?
Can you convert it?

Main things a salt water boat faces that fresh water-kept boats do not (or do so to a lesser degree): Increased corrosion of iron and aluminum components, especially engine blocks, exhaust manifolds and risers and drive systems. Fouling by marine organisms.

There really are no significant differences between a “freshwater boat” and a saltwater boat. There are some systems that saltwater boats employ to combat the above. Do a search on “bottom fouling” and “Mercruiser Sea Core” to better understand some of the problems and how designers are trying to overcome them.

the only “conversions” that are typically done to boats to make them more suitable for salt are to add a closed cooling system, a mercathode system, perhaps some kind of freshwater flush system for the engine and maybe more stainless or anodized components/fasteners, etc. You should run fresh water through your motor after it’s been in salt. Corrosion in salt water is a big issue. There are anti-corrision systems that can be installed involving a sacrificial hunk of metal (anode) and electricity.

some boats are considered in-land boats only, because their hulls are not made for the open ocean. a bay boat is a good example. there is nothing stopping you from using one in the ocean, though, unless you have a good dose of common sense. that said, some people have crossed oceans on little more than rafts. others haven’t been so lucky.

most boats, though, are built for coastal cruising and in-land waters, so their hulls are made to be used near shore.

salt water is definitely more corrosive than fresh water so saying a boat is a fresh water boat it’s whole life vs in salt water is a marketing thing. you won’t necessarily pay more for a boat that’s never seen salt, but they’ll probably sell faster than their salt water equivalents. there is an exception, though. boats that have only been in fresh water may have raw water cooling, whereas boats in salt may already be set up with fresh water cooling, which is obviously better if you’re boating in salt water.

because of potential corrosion, you will use sacrificial anodes made from different materials depending on whether you are boating in fresh or salt water. I/O’s and raw water cooling are not a good combination for salt water usage. With raw water cooling in salt water, expect to replace manifolds and risers every 5 – 8 years due to running salt through the engine block. that will cost you about $5,000 every 5 – 8 years. it will cost more if you purchase an older boat for which parts are hard to come by. bellows will also require frequent replacement or the boat can easily sink. in salt water, barnacles can easily slice the bellows over time.

I/O’s are also costly to winterize. it’s not unusual to pay $400 per outdrive to have them winterized, removed, stored for the winter and commissioned again in the spring. for a larger, twin engine boat, that’s $800 a year down the drain.

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