More Great Tips for Stopping Boat Stink

Posted by Darrell Nicholson at 10:05AM - Comments: (10)

Investing in the most efficient flusher is all for naught if your hoses are second rate. PS looked at electric-flush toilets in February 2011.

As our long-term test of sanitation hose makes its way through another long, hotóand progressively smellierósummer, it is a good time to think about ways to keep your plumbing system from becoming an olfactory horror. Here are some of the tips that hose manufacturers shared with us when we launched our test of sanitation hose.

Hose routing: Always slope pipes and hoses toward the holding tank after the initial rise. Any hose will eventually permeate if sewage is left standing in it. If long runs are unavoidable, consider using well-secured Schedule 40 PVC pipeónot DWV (drain-waste-vent) PVC, which has thinner walls.

Head operation: Always flush enough clean water to move all the waste to the holding tank to prevent standing sewage.

Antifreeze: PVC hoses are not compatible with glycol- or alcohol-based winterizing products. The glycol or alcohol can extract some of the PVC plasticizers, resulting in increased permeability and stiffness. Although the hose will not fail, it may permeate. This does not apply to synthetic rubber hoses.

Oil: Synthetic rubber hoses made of EPDM or butyl rubber may not tolerate large amounts of mineral or vegetable oil. However, small amounts of oil that may find their way into a head as a result of owner maintenance practices should not be harmfulóbut this is one more reason why greasing head pumps with heavy silicone grease at the start of each season is a far better practice than the often-suggested practice of flushing a tablespoon of vegetable oil in the head. In fact, the vegetable oil will only hasten the greaseís washout. This incompatibility does not apply to PVC, neoprene, or urethane hoses.

Wipe test: If you suspect a permeated hose, scrub the hose area clean, wait for several days and then wipe the suspect hose with a damp cloth and sniff the cloth. If it is permeation, the odor will come back soon enough.

Leaks: Although permeation is a common cause of hose odor, it is by no means the only cause. Slow leaks around fittings and hose clamps, and sewage that was inadequately cleaned up are also frequent causes; inspect the ends before assuming you have a failed hose. A crooked clamp or scored barb often allow leaks that will not be cured by tightening a clamp. It is tempting to cure a leak by using a sealer (polyurethane or silicone caulk), but generally, this is a temporary fix and is very bad practice when installing new hose. Instead, fix the problem.

Hose connections: Barbs vs. smooth adapters. SeaLand, maker of the SeaLand hose brand, is a believer in smooth connections. Properly sized, the company claims, they are easier to use, seal better, and do less damage to the hose. This is particularly true with the stiff PVC hoses, like SeaLand OdorSafe Plus, which fits well enough on barbed fittings but is impossible to remove. For high-pressure applications, some type of contoured or barbed fitting is still generally recommended, though many hose makers now specify rounded profiles. Not all fittings are a good match; if fit seems too loose, check with the hose maker.

Hose lubrication for installation: A compatible lubricant can be a big help in getting a hose installed correctly. Read the hose specs to be certain the lube is compatible. EPDM, for example, is not compatible with petroleum, so K-Y, glycol, or glycerine are better choices. Soap will work but can leave a non-drying residue that can interfere with a secure fit, particularly when using non-barbed fittings. SeaLand sells a silicone grease for use with its hose.

Raritan Sani-Flex Odor Shield Hose was the most flexible marine sanitation hose in our test.

Sharp turns: Many sanitation hoses are quite stiff and donít like sharp turns; even if you can bend them to your will, it shortens their life. The manufacturers maintain that it is better to use a PVC elbow fitting as needed than to risk kinking a hose by forcing a turn. The fitting will be larger than the smallest passage in the toilet and should not create a problem.

Fit the hoses a few inches long: Hose removal often involves destruction of the hose. Providing a few extra inches to play with will simplify future repairs, rather like leaving halyards a few feet too long to allow for wear and cutting off knots.

Heat: While many authorities suggest using heat to help a stiff PVC hose onto a fitting, SeaLand does not recommend the practice. A company representative explained that the key is moderation; the hose and fitting should be no more than warm to the touch. The problem is that often, customers take heating too far, the hose is weakened, and failures are blamed on the maker. We found heating with hot water was required with the SeaLand OdorSafe Plus hose; it was awkward, but it allowed us to insert the fittings with reasonable effort.

For more tips on selecting the best heads and plumbing to head odors, check out our ebook on Marine Sanitation, which covers everything from head to hose.†

Comments (10)

I've replaced the hoses in my holding tank installation and have gone nuts trying to verify that I've avoided leaks. Since nights here in NE can still go below freezing, I've poured a small amount of potable anti-freeze in my holding tank to check for leaky connections. All seems well for a day or two but it then starts leaking. I find that I can then tighten the hose clamps a few turns. This is surprising since I tightened them down several times already. I'm beginning to suspect that the anti-freeze is softening the hose. Are you folks aware of a problem with sanitation hose and potable anti-freeze?


Posted by: Rich Carter | April 17, 2019 11:05 AM    Report this comment

I made the drains out of residential 1-1/2" PVC every place possible. Yes, it's not flexible but it should be done at any location where the sewage pools inside the drain, like adjacent to the bottom fitting of the tank. This makes a huge difference.
I also re-plumbed the vent hose using 1/2" CPVC, which is easy to route. Make this vent positive slope all the way back to the tank.
I also have had great success with one PVC pipe serving as the tank inlet and outlet. Incoming waste keeps the pathway clear so pumpout is never clogged.

Posted by: Wayne Richard | June 14, 2018 1:32 PM    Report this comment

AWAB clamps have a SOLID band instead of a perforated band like the hose clamps you are used to seeing. Rather than the worm drive engaging in the perforations of the band (which obviously reduces the strength of the band) the worm drive engages raised (embossed) ridges (opposite concept of typical clamps.). This makes.fie A much stronger, full proof hose clamp. "ABA" is another manufacturer of this style, along with "AWBA."

Posted by: KMan | June 14, 2018 9:36 AM    Report this comment

AWAB is the brand name of a high quality hose clamp. Cheap clamps often fail due to corrosion of non-stainless components.

Posted by: Drew Frye | July 22, 2015 10:41 PM    Report this comment

AWAB is the brand name of a high quality hose clamp. Cheap clamps often fail due to corrosion of non-stainless components.

Posted by: Drew Frye | July 22, 2015 10:40 PM    Report this comment

Could someone explain to me what an AWAB clamp is please?

Posted by: Captain Mudbank | July 22, 2015 10:25 PM    Report this comment

Has anyone thought about 3/4" Pex (crosslinked polyethylene) for a vent line? I spoke to the manufacturer of my polyethylene holding tanks and they don't seem to have permeation issues. There seems to be regular PEX, Ox barrier PEX and a radiant floor Pex.

Posted by: Mark B | September 14, 2012 1:27 PM    Report this comment

flush with fresh water; collect rainwater. Use plenty of water. empty holding tank often. blow fresh air into the top of the holding tank constantly. you can make a ventilator cheaply out of a bait tank aerator. this prevents the growth of anaerobic bacteria. Anaerobes are responsible for the stink. scrub the vented air by putting an activated charcoal filter into the vent line. build your filter cheaply out of pvc pipe and fittings from the home store and buy charcoal at the pet store. Add a few ounces of holding tank treatment if you like. Do these things and there will be no stink. guaranteed.

Posted by: MARKHAM A | July 18, 2012 10:49 PM    Report this comment

The real key is to use the right fittings. I struggled in upgrading my shields hose for MONTHS and had given up until I discovered that shields makes their own fittings. These fittings are extra long but do not have barbs so they install onto the hose easily. No need to heat the hose or even use lubricant! I can't tell you how pleased this information made me!!

Posted by: gcaptain | July 18, 2012 3:40 PM    Report this comment

Refitted our boat using trident hose a few years ago. As you touched upon..Good clamps are critical! I spent more money on AWAB clamps than I did on hose and valves!! Double clamped every connection! I don't want to have a leak in the system (bad), or have a clamp fail on the water intake (or any seacock!) and sink the boat due to a $3 clamp from the autoparts store that fails! The extra money on top quality clamps (AWAB, ABA, etc) allow me to sleep just that much better at night!

The trident hose does soil easy, as mentioned. I did find a fairly easy way to clean them. I take bathroom cleaning wipes and wrap the hose with them, and leave them on overnight. Usually like new looking, or close to it, when they are unwrapped. Unsure if the wipes I use have bleach in them or not, or what the active chemical is, but it doesn't seem to be harming the hose.

Posted by: Phantomracer | July 17, 2012 1:31 PM    Report this comment

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