Water Tank Mystery

[rjhicks]

First, let me say that I am a beginner at all this, and I'm not particularly handy at these types of things but trying to learn. We recently purchased a 1985 Hunter 28.5 and have been really happy with it so far. We are novices but trying to learn the ins and outs of sailboat ownership. I apologize ahead for the length of this post and perhaps not using all the correct terminology. That being said, here's the issue we had over the weekend:
Not knowing how long the water in the fresh water tank had been sitting there (previous owner not available for questions), we decided to purify the system following the excellent recommissioning information found on this forum.
Added the bleach, pressurized the system, let the water run in the galley and head sinks until we smelled the odor of bleach, shut them off and let sit overnight. Returning to the boat the next morning, we opened the faucets on both sinks (after opening the seacock) and allowed the tank to empty. Refilled the tank, repeated. Refilled the tank again, and began draining. This is where the problem began.
As we began adding water to the tank, it very quickly began overflowing out the opening where the fresh water is added. Sorry, not sure what this is called.....but where you add fresh water. For our boat, it's in the anchor locker. We knew we had not added enough water to refill our 17-gallon tank. We turned on the water pump, opened both faucets and it drained for just a minute and then stopped.
So, the situation is this: The water tank is acting as if it's full, but when we turn on the faucets, no water is coming out. We can hear the water pump kick in when we turn on the pump. I will also add that the system had been working for us until this incident.
Sorry for the long question, but any guidance you can provide would be appreciated.
Signed,
Two new, very happy, but very dry, Hunter owners.

 

[MitchM]

my guess is blocked filters: 1) go to your sink faucets. unscrew the filter that is on the faucet, left makes loose counterclockwise. leave the filters off, try your water pump. if it pumps water thru the sink faucets your problem is fixed. 2) if not, find a cylindrical water filter usually located on the inlet side of the fresh water pump. be sure pump is off. the filter should unscrew to be cleaned. this should be done before you fill the tanks with water. since your tank has water in it, warning: you may get a large amount of h 2 0 coming out of your freshwater tank through the hose that used to be connected to your fresh water filter. you are opening up the line from tank to filter if you do this filter cleaning.

 

[Skipper]

Tank vent is clogged, or vent hose collapsed.

Check the vent at the exterior outlet. Also you can disconnect the vent hose from the tank and blow through it to see if any resistance.

 

[jssailem]

Water backing out of the tank fill is often called tank burping. Happens because tank can not vent the air in the tank as you add more water. Skipper has it right. Look at tank vent for evidence that some critter is using it as a home.

 

[JamesG161]

I apologize ahead for the length of this post and perhaps not using all the correct terminology. That being said, here's the issue we had over the weekend:

Never worry, must like helping, and being helped.
Deck Water Fill is good term.
All inventory tanks, fuel and water, need an Inlet air vent.
Liquid volume OUT = Air volume IN. If this is not true.. no out water flow.

The air vent is normally a hose/pipe off the top of your tanks.

Test you normal tank vent line by leaving you Deck Fill cap OPEN and then try your pump again.
If it pumps work, close the Deck Fill cap, and try again. Failure of pumping mean restricted vent, as @Skipper suggested.

Do you have a water tank level sensor?
Does you "topped off " Fill line stay full?
Jim...

 

[Capt jgw]

You probably have a 1 1/2" fill hose with a 3/4" garden hose or nozzle stuck in it to fill the tank, and a 1/2" or 5/8" vent line probably with a screened vent fitting on the end. Do the math. If you're forcing water in faster than the air can escape, it's going to burp. And the longer the vent hose is the worse the problem. You can even burst the tank that way. If you find that the vent is not blocked, you'll just have to slow down the flow. It helps to try not to completely block the fill fitting with the hose nozzle too. Any low spots in the vent hose will hold water which will effectively block the line, so check for that as well.
Your fuel fill can do the same thing so be careful with that the first time if you haven't done it already. Spraying fuel all over the place can get you a $5000 fine, so go real slow til you know how yours acts.

 

[rjhicks]

All great suggestions and information. I have a lot to check into. Little did we know when we bought the boat that we'd eventually need to become plumbers, electricians, mechanics, etc. Really appreciate the input from this great community. Thank you.

 

[All U Get]

So are your deck caps labeled water, fuel, waste? Don't want to fill the wrong tank.

All U Get

 

[Capt jgw]

All great suggestions and information. I have a lot to check into. Little did we know when we bought the boat that we'd eventually need to become plumbers, electricians, mechanics, etc. Really appreciate the input from this great community. Thank you.

That's called boat ownership!

 

[jssailem]

All great suggestions and information. I have a lot to check into. Little did we know when we bought the boat that we'd eventually need to become plumbers, electricians, mechanics, etc.

You and many others. I find thinking of my boat as my own city. I as the owner am responsible for it functioning the way I want it to function. Plumbing is just one of the many boating joys....

 

[rjhicks]

So are your deck caps labeled water, fuel, waste? Don't want to fill the wrong tank.

All U Get

Yes, they are all labeled.....faded, but labeled.

 

[rjhicks]

A quick update on the issue.

As to an earlier question, no, the boat does not have a tank level sensor. So, we're kind of guessing as to when the tank is full. If it flows out the inlet, then we're thinking it is full.....or maybe the line is blocked.

Anyway......

We headed out to the boat last night armed with all your great suggestions. First thing we did was leave the fill cap off and open the faucets to see if that helped. We did have running water at both the galley and head sinks for a while, then it stopped again. Next, we located the vent line and used some heavy line from a weed whacker to try to snake it down the line and see if it was blocked. There was resistance, but not sure if that was from something clogging the line or the tight curves in the line. I didn't force it too hard as I was afraid I'd puncture the line. Then, we opened the access panel in the v-berth, located just below the anchor locker. I can see the lines for filling the tank, the drain from the anchor locker and the vent line. Removing the vent line from the thru-hull will be an adventure as I can just barely get a hand on it, but that's my next step. Once I have it loose, maybe I can examine it more closely and clean it out. I also checked the pump but ran out of time before I could check the filter.

Did I mention it was a windless 100 degrees last night here in Texas? On the upside, there was a tremendous strawberry moon and I would have missed that if I had not been out at the marina.

Thanks again for your help.

 

[Skipper]

we located the vent line and used some heavy line from a weed whacker to try to snake it down the line and see if it was blocked. There was resistance, but not sure if that was from something clogging the line or the tight curves in the line.

The most notorious place for a fresh- water vent hose clog is at the outlet topside. Most likely culprits being mud wasps.

 

[Capt jgw]

If the vent outlet is just a plain through hull, you can stick the garden hose nozzle in it and give it a blast to clean it out. If its a fuel type fitting, there should be screens in it to keep the bugs out. More likely blockage is just a low spot in the hose trapping water.
When you're filling the tank you should be able to hear and feel air coming out of the vent, and if the vent is lower than the fill, water should come out there first. If its not doing either, it's blocked.

 

[jssailem]

RJ
You are making progress. I find the solving of the problem is done one step at a time.
I would have thought the weed wacker line flexible enough to go around any possible bend. If the bend is that sharp then it is possible the vent is closing. The water line should be strong enough (often 1/16 inch plastic) not to be punctured by weed wacker line.
That said if you had the fill line open there was no issue of getting enough air. So I would no worry about the vent line at this time.
I would look at the supply line between the pump and the tank fitting. I would start at the pump end, working back to the tank. Remove the water supply line from the pump. When you remove the line, water should immediately flow, expecting gravity providing the force and the water line connection below the tank. This will allow water to, perhaps gush, out of the water line. Raise the water line end above the level of the water in the tank will stop the flow. So will a thumb over the end of the line.
No water. You have something blocking the water in the line. Reconnect the water line to the pump and move upstream towards the tank looking for the blockage. May be something that moves in the waterline up to the time it plugs the line. When you shut off the pump the suction relaxes and the blockage settles till you turn on the pump again.
My best guess. Good luck. Stay safe in the heat.

 

[JamesG161]

That said if you had the fill line open there was no issue of getting enough air. So I would no worry about the vent line at this time.

Yes, if the pump stopped with that fill line cap OPEN.

Only 3 things will stop the motor on the pump...
1) 12VDC power loss
2) Discharge pressure switch
3) Failing pump motor that heats up.

If you water pump is a Shurflo®, then my guess is 2)...
A replacement switch is cheaply available and easily changed.
Jim...

 

[rjhicks]

Yes, if the pump stopped with that fill line cap OPEN.

Only 3 things will stop the motor on the pump...
1) 12VDC power loss
2) Discharge pressure switch
3) Failing pump motor that heats up.

If you water pump is a Shurflo®, then my guess is 2)...
A replacement switch is cheaply available and easily changed.
Jim...

It is indeed a Shurflo.

 

[JamesG161]

Can you post the model number on the side of motor? Did the pump cut off with the deck fill line open?
Jim...

 

[Siren Sailor]

I would have to at least give Mitch's faucet and pump filters a try before getting too involved elsewhere. I have had similar problems when moving a lot of fresh water through my system. My 34 has a shut between the tank and pump that will keep the whole tank from emptying while the filter is cleaned. Lots of crap can accumulate in these old systems and bleach seems to loosen it up. Good luck. gb

 

[dave.smith]

I know that this is an old thread, but did you ever get it resolved?
I have the same issue and in my case the water inlet line is actually clogged with mud.
I guess the previous owner kept the fill cap off, never washed the anchor after using it and let the whole mess flood.