• Home
• Forum
• Classifieds

Previous Entry
« JRC JHS-770S/780D, "Direct call by AIS"

Next Entry
NKE Regatta processor, wicked fast »

ActiveCaptain: Data delivery changing, but free access assured
Ben Stein said: Kim, I can't remember where but I know I read that Gar...

Furuno MIBS 2018: from TZT2BB megaMFD to GP-1x71F plotter fishfinders
Nigel Spork said: Ian This has annoyed me as well. Not a lot of benefit...

AIS issues: Garmin, Navico, McMurdo, AMEC and SRT
Simon - SRT CEO said: Hi Jim, TUV SUD and BSH are the gold standard of test ...

Simrad RS35 VHF & HS35 wireless handset, testing pretty well
Ben E said: Navico says that there's no meaning to the RS-35 being ...

Nautic-On, Brunswick's smart take on boat monitoring
Hartley said: Hi BenS, 10 mw at 1.9 GHz - doesn't sound like it sho...

Sonar wars flare: Humminbird Mega, Garmin UHD, Lowrance FishReveal & more
Ben E said: Sure enough, Simrad just put up their NOS 59 update, ve...

NMEA OneNet 2013, already ahead of the curve?
Ben E said: NMEA has posted the OneNet presentation given at METS l...

Airmar 2018 part 2: Ultrasonic and EM speedo mysteries unraveled, plus new UDST800
LarryR said: Hi All, We have two DX900+ units on our 60' cat and we ...

Lowrance MotorGuide Xi5 SmartSteer trolling control, life changing
Ben E said: Lowrance is out with a NOS59 software update for many o...

Beta testing FloatHub boat monitoring, and the wonders of marine WiFi
tulsi chowdhury said: as marine electronics have gained a lot of popularity, ...

"My" magazines:
Power & Motoryacht
Sail Magazine
PassageMaker
Soundings
Soundings Trade
Yachts International
Maine Boats, Homes…
Marine Electronics

Electronics favs:
The Marine Installer's Rant
Compass Marine
SailBits
Signal K Google Group
Pacific Yacht Systems
Ed's Boat Tips
i-Marine Apps
Navigation Mac
gCaptain
Alan Spicer Marine
Equipped to Survive
GPS Tracklog
…forums:
The Hull Truth
Cruisers & Sailing Forums
SSCA Discussion Boards
Continuous Wave
macsaililing.net
BoaterEd
…companies:
Garmin On the Water Blog
FurunoUSA Support Forum
Raymarine Support Forum
Digital Yacht Net
Victron Energy

Other favorites:
MV Dirona
Wave Train
Indigenous Boats
SetSail
Attainable Adventure Cruising
Three Sheets Northwest
Waggoner Guide
Scuttlebutt
Sailing Anarchy
Corke’s DIY
Sea Fever
VOJ (Ibsailn)
Ken’s Blog
Megayacht News
Power Cat World
Marine Cafe
Kennebec Captain

Suggest a link or story

This work is licensed under a Creative Commons Attribution, NonCommercial, NoDerivs 2.5 License.

Hi, Ben...
It seems like something a PO might have done to prevent guests or relatives from 'draining the cistern on a Saturday night' and waking up to empty freshwater tanks a hundred miles from the dock!
I'm still unravelling wiring mysteries on my 40 year old motorsailer.

Reverse-engineering mine is something of a nightmare... dense cable bundles, many of which are overlays on the original 1987 installation. Nothing is labeled, and there are phantom runs left over from long-departed gear.

I bought a Brady IDpal labelmaker with some cloth labels, and every time something is identified a take a moment to tag it. Long process, but it helps...

Steve

(Only slightly off topic)
Steve, do you use a shrink-tube labeler for your many wiring runs? I've got a Dymo Rhinopro on the way for when I finally get serious about the rewiring project(s).
Lee

Ben,

You now have a sea water to fresh water interface. I hope a good quality check valve is installed in the fresh water supply line to the shower.

Butch

Note that the whale type connections may be ok if you are going to have the system pressurized all the time but its easy to create an accidental leak if the system is unpressurized a good part of the time to conserve on water, because the pressure in the line helps seal the joints. I think the dual hose clamp setups are more reliable for offshore use for this reason, even if slower to construct, and the hose typically used for that bends more easily so there may be fewer joints too.

I have the Whale snap-together type connectors throughout the boat's fresh water system and it does not matter if the system is pressurized or not there are no leaks - not a single one. I have even pulled apart connectors and modified or winterized and plugged them together again and still no leaks. I find the connectors are simply outstanding and easy to work with.

In reference to whale-type connectors leaking on depressurizing:
On our 44' sailboat with two heads,etc., every weekend we shut off our water pump...after 7 years there have been no leaks. When new the connectors did leak occasionally for a few months but I suspect the connections became hardened and have remained drip free.

A lot of OEMs are using the whale/QUEST plumbing system; and semi-compatible fittings are available in many hardware stores and home improvement centers.

Ben, it looks as if yours is missing little retaining clips that snap around the fittings to lock them in place, they can help ensure that the joint is leak free.

If the joint does leak, 9 times out of 10 it is because the end of the tube has a burr or is not cut properly, and a bit of sanding on the cut face will do the job.

I have always said "I don't work on boats, I perform boat archeology". It sounds like you are well on your way to an advanced degree

Lee, I don't use a shrink-tubing labeler. As beautiful as that stuff is in service, much of my labeling is involved with reverse-engineering already-wired stuff... so I use the cloth labels on the Brady IDpal. Those work great, with excellent adhesive and reliably dark printing (better than their polyester labels, which seem to skip a little).

-Steve

Ben, there's a major health hazard reason they didn't do what you just did.

Take your hose full of saltwater, disconnect it from the salt supply, plug it in to the fresh supply, so some hosing.

While you're hosing, Osmosis will be working to try to move some of the saltwater including the bacterium and other matter it carries back upstream. Maybe it only makes it one millimeter to drop some of that bacterium to the inside of the fitting.

You disconnect the hose and go along with your business. The baterium start to flourish. Soon, your water tanks are a garden.

Any time that a fitting can be connected to "dirty" water you need an air gap fixture. Take a look at the solenoid devices used for hooking up freshwater flush toilets. Same risk, same need, same reason. So the PO didn't get around to installing an air gap device yet, so he supplied the fitting with saltwater in the interim.

I'd disconnect unless you plan to have two different washdown hoses and never allow them to get swapped by even the most accident prone crewmember, until you get an air gap fitting.

Uh, is it time for us to say a mass for Ben as he connects to freshwater his washdown device that has already been plumbed to the sea perhaps since the original installation? Of course not!
I remember once making peace with the 'baterium' in the freshwater tank of my first 'real' boat by pouring in a bottle of cheap wine, a procedure that the previous owner (a dear friend and real salt) swore would 'sweeten the water'. The resulting microbial garden resisted all efforts of eradication, ensuring that ample bottled drinking water accompanied my sailing adventures.
We get salt water into our freshwater tanks often just by sailing in 'fun' conditions. Every blue wave that lands on my decks will deposit a few drops past the aging deck fill o-ring or even down the vent if it's 'fun' enough!
Oh, and I always manage to drink some when I go for a swim!

Flee,

Perhaps it's a bit early for a mass for Ben but it's never fun to find your fresh water tankage contaminated with salt water. It's certainly no fun on a voyage far from port. The bacteria issue can probably be cleared up with a shot of Clorox even if the flavor lacks appeal. At least the Clorox won't send you to the hospital whereas some bacteria clearly can put you into a hospital.

I don't think anyone has come up with a reasonable scenario as to why a prior owner went to the trouble of plumbing the 'fresh' outlet to the 'salt' line. If he didn't want to anyone to wash down with fresh, or was paranoid about the mixing, why not just shut off the well hidden fresh valve inside the cabinet, or just cap the fresh line that once went to it (I think).

And, seriously, what are the chances of saltwater that's sitting in the hose getting back through the hose outlet valve or against the pressure flow all the way to the fresh tank?

Ben,

I believe the chances are very good. Extremely good if you have guests cruising aboard.

Lacking a diagram of your system I must say I could be very wrong. If your system was owner installed in a typical owner installation all it would take for backflow to occur is for both valves to be open at the same time. That's a very possible scenario.

Butch

I don't have a diagram, Butch, but this system is pretty obvious, and pretty normal.

The boat has hot and cold fresh water plumbing that involves a tank, a pump, a pressure tank, and a hot water tank. It flows to the head sink, head shower, galley sink, cockpit shower, and (now) the cold side flows to that hose outlet labeled "Fresh".

The saltwater system is dead simple: sea valve (ahem, now the correct name for seacock, I'm told), pump, and hose outlet marked 'Salt'. Period.

It is absolutely impossible to mix these systems, unless you attached the same hose to both the Fresh and Salt outlets shown in the picture at top. There is no hose aboard the boat that could do that, and even then I think you'd have to turn off the freshwater pump and turn on the saltwater pump to get salt into the fresh system. Never going to happen.

What Mark has warned me about is the possibility that if I wash down with saltwater and then reattach the same hose to the freshwater outlet, somehow that limp saltwater remaining in the hose is going to creep back into the pressurized freshwater system. I'm dubious, and that's why I'm asking about it.

You have two different types of water, creating essentially a gradient. Systems want equilibrium. Depending on flow restrictions, osmosis and some other effects will work to equalize the system, with salt water working it's way to mix with the fresh.

Salt is a good example because the effects with salt are relatively strong.

http://en.wikipedia.org/wiki/Water_potential

Not sure about bacteria migration though, interesting.

Ben,

I was thinking the interface would be in the shower system rather than the wash down system. If the shower is fresh water only then my comment is null and void. However, some deck showers are both to allow fresh water conservation by using salt water for washing followed by a fresh water rinse.

Butch

Ben, the issue is the incompressibility of water, the osmotic potential, the motility of some organisms, reproductive capability of those organisms, and the health harazd significance of certain pathogens, etc.

Try this concept. take a glass of water. Put a drop of food coloring at the side of the glass as gently as you can, with no "pressure". Give it time, the color will spread through the entire glass.

Now take that to a loosely defined "pressurized" scenario. Make the glass of water instead a pipe full of water, open at one end, that you're holding "open end up". Put the drop of food color on the inside of a pipe cap. Screw the cap on, then at the other end of the pipe, open a supply valve to charge the pipe up with pressure. Wait. Even with no "flow", and contrary to the "pressure", the color will still disperse through the entire pipe full of water.

If you now replace the pipe cap in the above with a 10' hose charged full of colored water attached onto the supply pipe instead of a pipe cap, same thing. Sure you'll push some fresh water into the hose full of colored water to make up for the empty space at the ends before they join, but wait long enough and the pipe and the hose will equalize to a consistent color.

Now drain the hose. Some coloring will be left clinging on the inside walls of both the hose and the supply pipe.

Now run other water through. Drain, repeat. You'll progressively rinse and dilute, but it'll take a while to get the color off the inside of the hose and the pipe.

But hey, food coloring is meant to be consumable so no problem there. But if instead of food color we're talking about bacteria or viri or other microbes or microorganisms which actively reproduce themselves, you've got a bigger scenario. The osmosis helps them quickly surf their way "in the door", but once there, they can go hog wild.

That's why this is different than swimming in the ocean and getting a mouthfull of saltwater which is in relative stasis. Getting those same contaminants into your relatively virgin freshwater supply without their normal adversarial conditions (salinity and pH) and they can proliferate.

In the case of seawater with dissolved solids and particular contaminations, it's a bit more complex. But they'll spread. How quickly depends on salinity and temperature differentials, volume of saltwater in the hose, time left at flow-less stasis, etc. I really should defer to a plumber here, but I don't know any boating plumbers to get to jump in here.

Another simple solution: use two different, incompatible quick disconnects for two different hoess so that the hoses can't be swapped, and you'll be fine. That's the cheapest solution I can think of other than cost of a second hose and nozzle.

I blame the media...
I mean, several posters seem to actually think that a few, and I mean very few, drops, ounces or even hosefuls of seawater mixing into their 'pure' freshwater tank(s) could somehow pose a threat to their health?
I've got news for them: the 'pathogens' are already there!
Every surface they touch, every surface the freshwater touches is teeming with bacteria, viruses, dinoflagellates, amoebae, dust mites all delivered by the sea spray, sea breeze, domestic water supply and their own bodies! Don't think that 'treatment' that our tap water gets removes all microbes, either. Only distillation can do that.
There is nothing unique about the bugs present in coastal seawater. After all, we put them there!
A hypothetical sea-borne E-coli bacterium that gets into a fresh water tank would encounter desert-like living conditions not to mention the presence of chlorine or chloramine.
I pose that that the introduction of tiny amounts of good old marina seawater into a boat's fresh water system has never harmed and will never harm a healthy boater, period.
I leave it to the guys sounding the alarm to show us the fire.
Respectfully skeptical,
Lee Stone

I agree with both

- #1 Small amount of contaminants can make it back thru the pressurized system to the fresh water pump. Moreover, once the water stops moving along the hoses the pressure is identical from one end to the other end such that there is no "pressure" pinning the contaminants at the distant end of the plumbing.

- #2 So what / show me the fire ... since fresh water tanks already have some contaminants, no big deal in a little bit more. What is presented here is quite different then the risks of contaminants and salt water getting in thru a poorly maintained deck fitting or otherwise, where the drinking water could contain so much salt as to be unusable in a survival situation and contaminants could include those that have not been diluted in an ocean of salt water.

Maybe this is a myth … but I have been told the hose should be short enough the end cannot accidently be left overboard reaching into the water. Something about a vacumm being formed pulling in water. Applies equally to your home, not leaving the end of a fresh water hose in a bucket or swimming pool.

What bacteria live in sea water that would really rather be living in fresh water? Aren't there more than enough bacteria that like freshwater anyway?

When removing the deck fill cap from freshwater tanks and filling them with a hose, I've never bothered to sterilize the hose or the area around the deck fill. Both sit out (one on the dock, one on the deck) and get doused with sea spray, sea water, etc. Why isn't this problem affecting all of us every day?

I recall eating all natural mud pie was OK, but that was some sixty years ago. Most of my generation bathed in mud puddles, and certainly swallowed more than a petrie dish full of seawater at the beach. We survived. Flourished, even, and raised children of our own (to become microbiolgists?)

Or is that why I have age spots and arthritis, and glasses?

Thanks for visiting Panbo.com Home | About | Archives | RSS Feed