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#520904 - 09/10/11 06:58 PM Fresh water vs. Salt water boats
Sara Offline
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Registered: 09/04/11
Posts: 65
What are some of the main differences besides cooling systems? What would happen to a fresh water boat in the sea? Can you convert it?

Sorry for my ignorance.

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#520908 - 09/10/11 07:57 PM Re: Fresh water vs. Salt water boats [Re: Sara]
Andyk2 Offline
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Registered: 06/12/05
Posts: 914
Loc: Huntsville, AL
Others will give you more informed answers but there is no difference per se. You should run fresh water through your motor after it's been in salt. Corrision 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.
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#520909 - 09/10/11 08:19 PM Re: Fresh water vs. Salt water boats [Re: Andyk2]
Puddle Pirate 2 Offline
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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. I'm sure there are others, but these are the ones I'm aware of.
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#520914 - 09/10/11 11:28 PM Re: Fresh water vs. Salt water boats [Re: Puddle Pirate 2]
CharlesS Offline
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Registered: 06/10/10
Posts: 1976
Loc: Bryson City, NC. 28713
If I were planning on keeping a boat in salt water all of the time, I would tend towards an inboard with a closed cooling system, or a salt water rated outboard. There are many folks who successfully operate I/O's with open cooling and do well with them, however eventually corrosion takes it's toll. You can find closed water conversion kits for I/O's for around 1K to 2K, which will effectively isolate the engine from exposure to salt water, but will not protect the outdrive and manifolds. If you are thinking about a trailered boat, a good flush with the garden hose and muffs after an outing will prolong engine life significantly.
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#520915 - 09/11/11 02:50 AM Re: Fresh water vs. Salt water boats [Re: CharlesS]
tpenfield Offline
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Registered: 08/29/05
Posts: 2031
Loc: Cape Cod, MA
Fresh water tastes a bit better than salt water.

The reference to fresh vs. salt water is the boat's history, not it's design or components.

My boat has been in salt water for 20 years, so it is a 'salt water' boat.

A closed cooling system is a bit better for salt water. Outboard engines are better for salt water, as you can tilt them up out of the water when not in use. This reduces the biggest problem with salt water - galvanic corrosion.

The other factor is marine growth, which is more substantial in salt water. Therefore anti-fouling paint is a must with salt water (unless day launched of course)

If you are a fresh water boater, you have less to worry about.


Edited by tpenfield (09/11/11 02:53 AM)
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#520919 - 09/11/11 06:17 AM Re: Fresh water vs. Salt water boats [Re: tpenfield]
HotByte Online   content
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Registered: 01/17/03
Posts: 8587
Loc: Barnesville, GA
A few other things I considered when I was thinking about taking our previous "fresh water" boat to the coast and putting in salt water.
- The biggest thing the salt water will hurt is resale value because so many, right or wrong, think once in salt water the boat will begin falling apart.
- If boat is on a painted steel trailer with boxed tubed framing, launching in salt water will get salt in areas you can't clean and trailer life will be greatly reduced. Notice most aluminum and galvanized trailers made for salt are I beam or C channel frames.
- A Mercruiser Alpha drive does not have an engine mounted sea water pump so many of the flush systems (VP Neutrasalt, Salt-away etc.) and full closed cooling systems will not work unless you mount a pump on engine and install a sea water through hull pickup for it.
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#520923 - 09/11/11 06:39 AM Re: Fresh water vs. Salt water boats [Re: tpenfield]
BToran Offline
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Registered: 08/06/05
Posts: 4756
Loc: Northport, New York
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 sacrifical anodes made from different materials depending on whether you are boating in fresh or salt water.

i agree with charles. i/o's and raw water cooling are not a good combination for salt water usage. although some like tpenfield have had good experiences with this combination, they are the exception.

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.

i learned this the hard way with my first boat. the risers were available but the manifolds had to be shipped in from sweden. this was on a boat with a king cobra engine / outdrive.

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.

when we upgraded, my "must have" list included inboards and fresh water cooling.

you're definitely asking the right questions, but experiences many of us have learned the hard way is why we're saying don't rush the purchase of a boat.

i mentioned in another thread that even a free boat can ruin your bank account if it's got issues. getting an older i/o with raw water cooling for use in coastal ny waters would be a mistake in my opinion.
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#520936 - 09/11/11 11:14 AM Re: Fresh water vs. Salt water boats [Re: BToran]
Lou C Offline
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Registered: 01/20/03
Posts: 1446
Loc: Long Island NY
Have to agree with all that's been said. For a boat used in salt and more importantly moored or docked in salt, a raw water cooled I/O is the most maintenance intensive choice. Adding closed cooling helps, but you still have to be concerned about galvanic corrosion of the transom mount and drive and of course the manifolds/risers if the closed cooling is only a half system. Note that an engine run with raw water cooling, can't be converted if its been run long enough for the block and heads to rust inside, that rust will flake off and clog the heat exchanger.
For full time salt use, only an outboard or inboard with closed cooling is the best for the long term....
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#520940 - 09/11/11 12:10 PM Re: Fresh water vs. Salt water boats [Re: BToran]
Sara Offline
Lieutenant

Registered: 09/04/11
Posts: 65
Awesome, thanks for the input. I asked because I saw some great deals on single i/o raw water cooled boats but the one I'm looking at next week has 2 inboards with heat exchangers. It's looking like that's the better choice for leaving the boat in saltwater year round. It's a shame to trade skier/wake board speeds for 1 mpg and reliability. You don't see too many skiers in the hudson though : )

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#520945 - 09/11/11 01:32 PM Re: Fresh water vs. Salt water boats [Re: Sara]
Puddle Pirate 2 Offline
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Registered: 03/25/04
Posts: 4162
Loc: Eastern PA
Sara, keep in mind that there are 2 types of closed cooling systems (that use heat exchangers). One recirculates coolant through the block, but not the exhaust manifold and risers. This is more common. A few have systems that recirculate coolant through the exhaust components.

The reason I say this is that the manifolds and risers will still need replacement about every 4-8 years depending on who you talk to . So dont think you're covered just because it has closed cooling. Some also say closed cooling has it's own set of problems, but I dont know what they are, since I have not had closed cooling
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#520946 - 09/11/11 01:45 PM Re: Fresh water vs. Salt water boats [Re: Puddle Pirate 2]
Sara Offline
Lieutenant

Registered: 09/04/11
Posts: 65
I see what your saying. I've been reading up on the different kinds. I've found that you can "Acid boil" out the scaling in some systems as preventative maintenance but the cost of replacing the manifolds and risers every 4-8 years beats the hell out of replacing the engines.

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#520952 - 09/11/11 02:41 PM Re: Fresh water vs. Salt water boats [Re: Sara]
BToran Offline
Admiral

Registered: 08/06/05
Posts: 4756
Loc: Northport, New York
A fresh water cooling system means you only have to clean out the risers and heat exchanger. Much easier and cheaper than doing the manifolds.
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1996 Carver 320 Voyager
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#520958 - 09/11/11 03:36 PM Re: Fresh water vs. Salt water boats [Re: BToran]
FreshWaterLover Offline
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Registered: 10/22/09
Posts: 2394
Loc: Burbank, IL
Keep in mind that reading and learning about doing such things makes it seem SOOO much easier than it really is in practice, especially if you haven't had a lot of mechanical experience in the past. This isn't some "macho guy" saying this, I'm a woman too, and a new boater. I was new like you last year, and like you was reading up on all of the maintenance I could do "myself"... uh huh. Right. I've managed to do a few minor things, but the rest I've left up to the pros while I go about learning the still incredibly intricate operation of the boat itself. Over the years, I hope to develop more mechanical skills, but I don't think it's a 'breeze' anymore, haha. No matter how much you read, and how determined you are... you ARE going to spend money on mechanics, at least in the beginning.


Edited by FreshWaterLover (09/11/11 03:37 PM)
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#520964 - 09/11/11 03:46 PM Re: Fresh water vs. Salt water boats [Re: FreshWaterLover]
Sara Offline
Lieutenant

Registered: 09/04/11
Posts: 65
I plan on paying to have most work done on it for me but the knowledge is what helps me keep the costs down. I usually buy parts for my car and take them to a mechanic that has the cheapest labor/quote. I don't want to take my boat to the marina mechanic and hear him say "Your Dossenforper fly-wheel has a crack in the stirrup....it's going to cost $2,000"

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#520965 - 09/11/11 03:48 PM Re: Fresh water vs. Salt water boats [Re: Sara]
FreshWaterLover Offline
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Registered: 10/22/09
Posts: 2394
Loc: Burbank, IL
Yep, but bear in mind it is a lot easier to drive around for miles to the best mechanic... it's not as easy with a boat, especially a large one.
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#520976 - 09/11/11 06:02 PM Re: Fresh water vs. Salt water boats [Re: FreshWaterLover]
Lou C Offline
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Registered: 01/20/03
Posts: 1446
Loc: Long Island NY
And not only that, many mechanics won't work that way because they buy parts at a mechanics discount. In Sara's situation, the best thing would be to find out for whatever marina she's going to be in, who is the best mechanic that is local to them. In some cases mobile marine mechanics will go to your boat or marina but they may charge more.

Sara in your case the thing that would be most helpful, is learning how to maintain the systems your boat may have. The good thing is on older boats, the gas engine systems are simple, if you have good access to the engines themselves. Simple old school Chevy small blocks are common, with a single 4bbl carb, sometimes even still using points and condenser ignition systems. Then learning how to maintain other systems, fresh water, sanitation, etc. It's a lot different than automotive stuff. Once you learn the maintenance end of it, then the repairs are not as complex. I started out being a pretty good driveway mechanic , of 30 years woth when I got the boat. At first I did just winterizing, fluid changes and tune ups. Then I took on drive maintenance (removal and reinstallation, impeller changes, painting with anti fouling, etc). So now, the only time I take the boat to the shop (not been there in about 7 years) is if I had a seal leak in the drive. I do starters, water pumps, and carb replacements too. Basic stuff.
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#520979 - 09/11/11 06:13 PM Re: Fresh water vs. Salt water boats [Re: Lou C]
Sara Offline
Lieutenant

Registered: 09/04/11
Posts: 65
I just meant that I like to be an educated consumer. The boat I have my eye on has twin 350 cubic inch Chevys with heat exchangers. Good'ol car parts.

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#521042 - 09/13/11 04:51 AM Re: Fresh water vs. Salt water boats [Re: Sara]
Al Offline
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Registered: 01/14/03
Posts: 14984
Loc: Vagabond Wanderer from Mich.
Most modern engines; MerCruiser, Volvo, Cruisader, all use Chevy blocks. You will find some Ford blocks in some Volvos in the mid-90s vintage. But Chevy is pretty much standard for gas 4, 6, and 8 cylinder engines these days.

However, in all cases, they have been modified with marine parts, especially starters and alternators as they have to be ignition isolated (won't cause a spark or at least sparks are contained within a sealed unit).
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