Bilge Check Valves:
An Overlooked Design and Maintenance Item That Can Literally Sink You
Here's a little boat maintenance job you might feel a little uneasy about doing, and you might not want to do it unless you have a drydock or diver nearby. It will determine whether or not your boat is an accident waiting to happen, and whether your last surveyor was doing his job.
This little job is also an often-overlooked requirement of the US commercial fishing Industry Vessel Safety Act of 1988:
Sec. 28.255 Bilge pumps, bilge piping, and dewatering systems.
(f) Except where an individual pump is provided for a separate space or for a portable pump, each individual bilge suction line must be led to a manifold. Each bilge suction line must be provided with a stop valve at the manifold and a check valve at some accessible point in the bilge line to prevent unintended flooding of a space. (Emphasis added)
Open up all your sea chest valves. Now, without turning on any pumps, open up your engine room bilge suction valve, shaft alley bilge suction valve and lazarette bilge suction valve.
If you're a crabber, you probably have an emergency bilge suction off your crab manifold. Open it and the associated sea chest as well. If you're an RSW Seiner, trawler or salmon tender you may have an emergency bilge suction valve off your RSW manifold. Open it, too.
Now listen for running water. If you hear any, hopefully you can close your sea chest and suction valves to effect repairs. If not, send that diver overboard to plug your sea chest or drive straight to your favorite drydock if you can't get your sea suctions to close tight. That is often a problem area as well. You have discovered that:
a) your check valves are leaking, or
b) you are missing these critical check valves entirely.
Some of you unfortunate souls will find that there never was a check valve designed or installed in the system. crab and RSW manifolds are often overlooked as are bilge lines to bulbous bows that sometimes are plumbed to serve as ballast or fresh water fill piping as well.
crab and RSW manifold suction and discharge check valves to the tanks are not mentioned in the Safety Act regulations or on the Coast Guard's radar. They were a feature of the case specific Pacific Northwest designs for the North Pacific and bering sea, but often overlooked on Gulf of Mexico vessels and conversions.
Many vessel losses were caused, more likely than not, due to the lack of check valves in the crab and RSW suctions and discharges, causing back flooding of the tanks, slack free surface effect and shifting of the partial load of water to capsize the ship. Theoretically their shut off valves would prevent this, but crews operationally often leave them open. Flow alarms have been installed but fail as often as check valves. Insurance companies caught wind of this and started demanding tank level alarms. How often have you actually tested those level alarms to ensure they are functional? Those who do test them still find failures.
Where did insight on this issue come from?
I served as an International SOLAS and loadline surveyor for the Norwegian Det Norske Veritas Classification Society. Most of these Classed vessels follow basic rules for check valves. However, the US authorized inspections I conducted under the commercial fishing Vessel Safety Act on behalf of the United States Government was significant for non-Classed vessels, such as many North Pacific fishing vessels.
The US and International loadline inspection rules designed for blue water merchant vessels, which require inspections of check valves every five years, do not scale down well to smaller vessels. The check valves on fishing vessels just seem to foul and deteriorate faster.
My observations were that four out of every ten typical crabbers and RSW trawlers had deteriorated check valves that failed to hold water. Another two out of ten had none installed, even though they had a previous USCG Safety Act sticker posted on their pilothouse windows, attesting to the misguided assumption that they were fully compliant.
The differences between poorly designed Gulf of Mexico-built vessels were emphasized in the determination of seaworthiness trial in 2003 of the MARCO 108' F/V West Point, as depicted on page 234 of Captain Sig Hansen's 2010 book "North by Northwestern."
The F/V West Point's lawyers set out to prove that by purchasing a MARCO designed and built crab boat, the "Cadillac of the Fleet", the owner had done his due diligence. Other shipyards, notably Gulf yards, had a poor track record. Their ships, designed for the Gulf of Mexico, capsized in Alaska. In most cases, MARCO vessels were higher priced vessels than their competition, with owners willing to make the extra capital investment in order to have the "Best Available Technology" (BAT). Availability of this BAT was well known with prospective owners queuing up for delivery and sometimes selling their positions for great capital gain.
F/V West Point's defense attorney Rod Fonda put me on the stand to introduce as evidence a little ditty that had been sung over the years by fishermen in the Elbow Room and the Smoke Shop. Sung to the tune of Janis Joplin's "Mercedes Benz" deriding the competitors and their poor safety history compared to the MARCO designed and built vessels. There were no mandatory regulations for their design, so owners who desired vessels to fish themselves and pass on to their children relied on BAT:
"Oh Lord won't you buy me a MARCO crab boat
My friends all fish (others) and don't stay afloat
Worked hard all my lifetime singing this sorry note
Oh Lord won't you buy me a MARCO crab boat"
The case was dismissed. Please consider verifying that your bilge check valves are operational before you set sail for fishing.
John Douglas Dixon, P.E. is a Naval Architect and Marine Engineer and General Manager of Pacific Fishermen Shipyard and Electric. Since 1974, Mr. Dixon has worked as a member of the naval architecture staffs of Global Marine, MARCO Shipyard and Guido Perla Associates. In 1991 he was trained in Norway as a Ship Surveyor by Classification Society DNV, conducting compliance surveys for the US fishing vessel Safety Act, International Loadline, SOLAS, MARPOL and OSHA for International commercial vessels and the US fishing fleet.