Heads Pong Difference Between Heads

[RunAgroundHard]

Curious situation on my boat. I have two Lavac heads, forward and aft. The forward heads always stinks when I comeback to the boat after leaving her for a week or so, the aft heads never stinks. The seawater in the aft heads remains crystal clear, the forward heads has a slight scum layer over it. Both heads have the standard Lavac Instalations with hoses run up to the deck head before heading back down to the seacocks, and the hoses are the same stiff, white, sanitary grade hose. F’wd heads hoses are longer because of the shear by about a 1.5’. Both heads are on the same side of the boat. The boat faces WSW on her berth, heads on the port side, so they get the sun all day. The boat has a distinct shear from stern to bow, with the bow shearling much steeper than the stern, so I guess the forward heads hull side might see more heat, withe aft heads side being covered by the pontoon a bit more, as well as shaded by my neighbor.

Any idea why one stinks and the other does not? The stink goes away after first flush through and clean seawater is left in the bowl.

 

[Boater Sam]

I suspect that the stinker is holding effluent somewhere in the discharge pipe.
Even sanitary hose eventually lets the stink though. I plumb all lavs with rigid solvent weld waste pipe now and it never stinks.

 

[PabloPicasso]

Longer pipe on stinkier head?
More pumps to clear it.

Which gets used more?

After a a long weekend trip with 4 lads aboard I couldn't shift the pong despite my best cleaning efforts.

Eventually I resorted to pouring a bucket of hot soapy water around the floor and letting it wash through the bilge. That did get rid of the pong, and left some smelly foul looking water in the bilge which I pumped out and cleaned.

All good in the end and sweet smelling too

 

[doug748]

Could be recycling foul water into the inlet from the relative position of the outlet.
Try flushing as normal and then flush through a couple of buckets of clean seawater. See if it helps.

.

 

[RunAgroundHard]

Thanks. Hoses are old. I’ll try the buckets of seawater and see if that makes a difference.

 

[Rappey]

Thanks. Hoses are old.

My hoses are probably as old as my 43yr boat on a baby blake. In the 33 yrs ive owned it I've never had a heads stink.
I Kid myself that old school hoses may have magical properties that newer do not
They are still flexible and don't look their age.
I like doug748's theory. Doesnt a jabsco pump in and out simultaneously ? A blake tends to be in or out.

 

[Bouba]

Change the charcoal filter...if it doesn’t have one...then install one

 

[Mistroma]

How would you describe the smell? If the answer is rotten eggs then it's probably a colony of anaerobic organism in the inlet pipe carrying water to flush the bowl. If it more of a general not very nice smell then it could be pipework.

It it is "rotten egg" smell then many people suggest pouring stuff down the bowl or always pouring in fresh water before leaving the boat. It might help to some extent as there could be some smell from the exit pipework. However, the real answer lies with treating the flush pipe.

Bad news is that this isn't really practical afloat without a modification. I had the problem many years ago and in fact had to treat that pipe yesterday for the first time this year. I put T-pieces in the basin outlet hose and flush water pipe. These were connected by a length of pipe with a ball valve in the middle.

Cleaning procedure:
1) Close sink skin fitting ball valve
2) Close head inlet water skin fitting ball valve
3) Open valve in connecting pipe
4) Fill basin with fresh water or cleaner of choice
5) Pump through enough to completely fill the inlet line and leave for a few hours

Put all valves back to normal positions (N.B. connecting line valve closed) and use as normal.

My aft. head never smells but the forward one does from time to time. The usual theory proposed is that output from the head can sometimes be sucked into the inlet where bugs then grow. I've always thought that sounds very logical and likely.

Only problem is that my forward head doesn't have a holding tank and has only ever been used for peeing since we bought the boat in 2009. It's had the equivalent of 7+ years full time use for 2 liveaboards. The only mechanism I can think of is that it is used more frequently at anchor and in areas where weed fragments are sucked in. The aft head has much less frequent use and only goes direct to sea when underway well away from land. Flush water should be lower volume and cleaner a lot of the time.

 

[Bouba]

Two toilets....two tanks....two air vents... or one, it’s the same theory. If one of the heads is near an open window or door...where the gases in the outside vents can get blown back inside the boat...then that toilet will smell the most. The cure is a new charcoal filter

 

[RunAgroundHard]

How would you describe the smell? If the answer is rotten eggs then it's probably a colony of anaerobic organism in the inlet pipe carrying water to flush the bowl. …

It it is "rotten egg" smell then many people suggest pouring stuff down the bowl or always pouring in fresh water before leaving the boat. It might help to some extent as there could be some smell from the exit pipework. However, the real answer lies with treating the flush pipe …

My sense of smell is poor, hence asked my partner and it’s defo “rotten eggs”, H2S. Your analysis may very well be correct. There is a perforated, domed cover over the Blakes seacock inlet. The inlet had mussels growing inside, and barnacles. I used a metal rod, coat hanger diameter, to poke through the holes and break up the creatures. The aft heads inlet is deeper, well under the turn of the bilge, and I have not experienced creatures behind the aft heads inlet grill. I’ll remove the pipe this winter and clean, or replace. Might grind the grills off the inlets.

My boat doesn’t have holding tanks, straight to sea disposal.

Thanks everyone for your input, appreciate the help, and time taken to respond.

 

[Mistroma]

My sense of smell is poor, hence asked my partner and it’s defo “rotten eggs”, H2S. Your analysis may very well be correct. There is a perforated, domed cover over the Blakes seacock inlet. The inlet had mussels growing inside, and barnacles. I used a metal rod, coat hanger diameter, to poke through the holes and break up the creatures. The aft heads inlet is deeper, well under the turn of the bilge, and I have not experienced creatures behind the aft heads inlet grill. I’ll remove the pipe this winter and clean, or replace. Might grind the grills off the inlets.

My boat doesn’t have holding tanks, straight to sea disposal.

Thanks everyone for your input, appreciate the help, and time taken to respond.

No problem. Definitely recommend the modification as it's cheap and easy to DIY. It's the simplest way to treat the flush side when afloat. You can buy filters, treatment systems etc. at greater cost. The rotten egg smell is a good indicator that it's the flush side. Another big indicator is that it is worst when the heads haven't been used for quite some time, is stinky on first use but clears fairly quickly (i.e. Not much smell if you use it again after only 20-30 minutes).

I'd guess that's a good starting point as you don't have holding tanks with vents and probably fairly short outlet hoses.

Parts for mine were 2 T-pieces, some tubing, a ball valve and 8 hose clamps. I only used single clamps as everything was connecting above the waterline.

 

[PlanB]

On the difference between your heads, we always noticed that the one on the "sun" side smelt, where the other didn't.