Head system rebuild

[HeadScratcher]

I have a Nauset Coastal 27'. Made quite a few multiday trips on her this past summer. I've rebuilt the head (which is working fine). But we're getting some bad odors from around the holding tank. My plan is to replace the holding tank and all the hoses. They are 30+ years old. Two questions:
1) There is a fitting between the vent hose and the outside vent. What is this and is it necessary (see attached photo)? It reduces down from 1/2" to what looks like 1/4" tubing. At one point I thought the vent might be plugged, and we were getting some back gassing. But at this point, I figure its time to redo the whole thing
2) Can someone recommend a good quality sanitation hose to use as a replacement. What we have now is 1 1/2" white. I want to buy something that will contain odor, hold up over time, and not cost a fortune.
Also, any tips you can offer for doing this job would be appreciated. It seems pretty straightforward, except for running the hose through some tight spaces

 

[Diesel Jerry]

I have a lot to say on this but I am busy with the kiddos today. I will comment with my suggestions asap.

 

[TCL]

Definitely wait for Jerry to chime in, in the meantime…
I don’t like the small vent line. You need the tank to have good air flow so that it does not implode when you are sucking it dry. It’s also good to have a “Fart Filter “ on the vent line, but they also can cause a restriction.

 

[Diesel Jerry]

If building a custom tank take this drawing into consideration. Again I apologize for the slapdash nature but my graph paper is at work. If it were me I would do 2) 3/4” vents going to opposite sides of the boat for good cross flow. Best thing to do would have those vents far apart on the tank. I would do a plate at the top of the tank and have all fittings and even the macerator mounted to it. Use a pick up tube rather than a fitting at the bottom of the tank.
Side view.

top view

 

[Diesel Jerry]

Oh and no other than Vetus hose.

 

[CaptainHinckley]

If I may, we just went through this a couple years ago. Complete install of head and system. buy this book, it’s a quick read and inexpensive.anything smaller than 3/4” is to small imho. Also any obstructions in the path from tank to fresh air ithat inhibits free exchange is bad including carbon filters. Our boat has been odor free with two 3/4” vents, one each side of the vessel no filters just enzymes after pumping out. We’ve had to leave tankage for two weeks once with no odor. Follow the book. I can’t say that about some of my friends production boats when we have been rafting up Best ch

 

[Raider Ronnie]

The head in my Flowers stinks after flushing.
ive been told it’s because the flush is salt water.

 

[islander]

Make sure you have an unobstructed ventilation line to the holding tank. I also make sure I use fresh water for flushing. Salt water has unseen critters that contribute to a less than pleasant smell.

 

[HeadScratcher]

If building a custom tank take this drawing into consideration. Again I apologize for the slapdash nature but my graph paper is at work. If it were me I would do 2) 3/4” vents going to opposite sides of the boat for good cross flow. Best thing to do would have those vents far apart on the tank. I would do a plate at the top of the tank and have all fittings and even the macerator mounted to it. Use a pick up tube rather than a fitting at the bottom of the tank.
View attachment 121913 Side view.
View attachment 121914
top view

Thanks for the insight. I believe I'm just going to go with an "off the shelf" tank. Todd makes a 9 gallon unit that matches exactly what's in there now.

 

[HeadScratcher]

View attachment 121915 If I may, we just went through this a couple years ago. Complete install of head and system. buy this book, it’s a quick read and inexpensive.anything smaller than 3/4” is to small imho. Also any obstructions in the path from tank to fresh air ithat inhibits free exchange is bad including carbon filters. Our boat has been odor free with two 3/4” vents, one each side of the vessel no filters just enzymes after pumping out. We’ve had to leave tankage for two weeks once with no odor. Follow the book. I can’t say that about some of my friends production boats when we have been rafting up Best ch

Good call on the book -- I will track it down. Hopefully that can explain what that fitting is on my vent line and whether or not its necessary. So you're saying no smaller than 3/4" on the ventline? What kind of hull fitting did you use to connect the vent line to?
Thanks for the suggestions!

 

[Diesel Jerry]

Good call on the book -- I will track it down. Hopefully that can explain what that fitting is on my vent line and whether or not its necessary. So you're saying no smaller than 3/4" on the ventline? What kind of hull fitting did you use to connect the vent line to?
Thanks for the suggestions!

Look at Hamilton Marine for the thru-hull fitting. Many will work. There are some that have a screen built into them. If you use one of those remove it.
I understand completely on going with an off the shelf tank. As pointed out earlier if there is any way you can switch to a fresh water flush that will help greatly. There are several ways to do it to.
In theory you want everything to run down hull to the tank, but I am here to tell you in my 10+ years of doing this I think I have only seen 3 to 5 boats that it was done that way. It just isn’t an option in most cases. What I do is use hard PVC pipe for all low spots and long strait runs.

 

[P18Flirt]

Did a similar project a few years ago... Replaced tank, hoses, head, diaphragm pump etc to redo entire system.

As other say, use the best hose... I used Trident and very happy with it. For the vent, I ran 3/4" hose through carbon filter to vent on side of starboard side hull.

The one thing I did per my mechanic recommendation is not install a Y valve. Instead I did a T fitting for the hose that let the waste either go overboard via the diaphragm pump, or out via the deck fill if using a pump out boat. Super simple and pleased with performance.

My system is salt water and rarely smells at all... we tend to cycle it a good bit, clean the bowl often and pump out often. I also pour fresh water through sometime when boat may not be used for a bit to helps flush out the salt water critters.

Good luck with the project.

Here is a pic of what I did showing the T

 

[HeadScratcher]

This is very helpful -- thanks!
Did you add the access hatch on the top of the tank or did it come with it? I'm guessing that is not a bad thing to have in case you need emergency access.

 

[chortle]

The white Trident 102 hose is good hose, easy to work with and does not pass odor. Don't underestimate the "easy-to-work-with" part of the equation, most other hose rated for holding tanks does not flex well and is difficult to fit over barb fittings. Shields does make a super expensive lifetime warranty hose called Poly-X, its $25 or $30 a foot. I used a one foot piece to connect my head outlet to the rigid PVC pipe drain for two reasons. One, it mated to the hose barb connection on the bonze fitting on the head outlet and Two, it was going to be filled with fluid 24/7 because the head was about two feel lower than the top of the holding tank. No way around that geometry so I used the best stuff I could get. It was good to work with and zero problems for the past 10 years.

Use solid PVC pipe wherever you can, especially wherever your tank product is sitting inside the tube. You can't make the vents too big. Plastic-Mart will make a custom tank, any shape and size, connections whatever size wherever you want. Well placed vents only smell if you fill the lines with stuff. A well ventilated tank won't smell. Two vents are double plus good.


You can use these for thru hull vents, no screens is fine but check them regularly for mud dauber wasp nests as they will clog up the vent and make them not vent.

All the advice about downhill is important but difficult to do. Do your best and redouble your efforts to put in a dedicated fresh water flush tank, makes all the difference in the world. It is more expensive to put in a drain with a valve as shown below but it helps when you have to, eventually, remove the tank. It gives you a means to flush it out and plug it shut before you drag it out of the boat.

 

[P18Flirt]

This is very helpful -- thanks!
Did you add the access hatch on the top of the tank or did it come with it? I'm guessing that is not a bad thing to have in case you need emergency access.

Tank is from Ronco and came with ports installed. I built several mock-up tanks based on dimension they had until I found one that fit my space, and maximized size.(ended up with 20 gallon tank). Once I chose, they let me mark a diagram where all the holes in the tank are cut and then they installed fittings. Nice quality tank and would recommend.

 

[HeadScratcher]

The white Trident 102 hose is good hose, easy to work with and does not pass odor. Don't underestimate the "easy-to-work-with" part of the equation, most other hose rated for holding tanks does not flex well and is difficult to fit over barb fittings. Shields does make a super expensive lifetime warranty hose called Poly-X, its $25 or $30 a foot. I used a one foot piece to connect my head outlet to the rigid PVC pipe drain for two reasons. One, it mated to the hose barb connection on the bonze fitting on the head outlet and Two, it was going to be filled with fluid 24/7 because the head was about two feel lower than the top of the holding tank. No way around that geometry so I used the best stuff I could get. It was good to work with and zero problems for the past 10 years.

Use solid PVC pipe wherever you can, especially wherever your tank product is sitting inside the tube. You can't make the vents too big. Plastic-Mart will make a custom tank, any shape and size, connections whatever size wherever you want. Well placed vents only smell if you fill the lines with stuff. A well ventilated tank won't smell. Two vents are double plus good.
View attachment 121955

You can use these for thru hull vents, no screens is fine but check them regularly for mud dauber wasp nests as they will clog up the vent and make them not vent.
View attachment 121956
All the advice about downhill is important but difficult to do. Do your best and redouble your efforts to put in a dedicated fresh water flush tank, makes all the difference in the world. It is more expensive to put in a drain with a valve as shown below but it helps when you have to, eventually, remove the tank. It gives you a means to flush it out and plug it shut before you drag it out of the boat.

View attachment 121959

I really appreciate this information -- so helpful. I hadn't thought about hard plumbing with PVC. Probably a lot cheaper that the flex pipe. With the hose fittings in the tank -- did you glue those threaded end into the tank or just thread them tight?
I like the idea of the service drain.
I don't know if we have the space in the boat to incorporate a fresh water flush, but, theoretically, we wouldn't need a tank larger than the holding tank, correct (water in, water out)? I'm wondering if I could put a small tank in and "T" of my raw water intake -- so that I could choose either a fresh water or sea water flush?
Again -- this is really good info. A great start for my spring project. I'm in a bind right now because the yard where I store the boat doesn't have a pump out, and we have a little water left in the tank. I don't dare haul it out until it's pumped dry. So I've added some non-tox and will let it sit until the weather warms up. My hope is that once we launch in the spring, I can have our marina pump out, and then I can do all the work at the mooring. If I'm in early enough, they might even let us use a slip for a day or two (so that I have access to power).
If I can pull this one off, my wife will be SOOO happy.

 

[Genius]

An easy fresh water flush trick is to plumb it into the sink drain. Normally it will pull seawater, if you want fresh water flush...close the seacock and run the fresh water. No chance of cross contamination. Also easy to winterize

 

[HeadScratcher]

Brilliant!
Any insight as to what the fitting is on my vent line (from my original post)? I'm still wondering what purpose this serves and if I need to incorporate another version of this in the rebuild.
Thanks.

 

[Genius]

Can’t take credit... think that was Diesel Jerry’s idea a few years ago.

 

[Diesel Jerry]

Can’t take credit... think that was Diesel Jerry’s idea a few years ago.

I am at the advantage of working on 3 to 4 systems a year for the past 10 years. I get to see what works what won’t. Some… I learned the hard way.
There is no way in hell if I did my own tank I would put a fitting at the bottom of it. I have a different perspective than most because I have to work on so many.
Another myth is that you need a separate tank to supply the head if going f/w. A simple check valve will do. I usually do 2 check valves for piece of mind. Just be careful not to tie into a pressurized part of the FW system if the head is not built for it.