The Offshore Voyaging Reference Site

Details Matter—Engine Failure at Sea

What engine-stopping details are lurking here?

Way back in the mists of time…well, 1987…we set off from my then-home Bermuda, bound for Newport on the US East Coast in my then-boat a Fastnet 45.

As was the way back then, we went to sea first thing Saturday to maximize our vacations from work, rather than waiting for a weather window as most cruisers, including me, do today.

The result was that we got rolled by not one, but two strong fronts in the first four days and so spent much of the time heeled hard over with green water breaking over the deck.

The good news was that I had spent much of the preceding four years since I bought the boat upgrading her and fixing stuff, including all new standing and running rigging as well as new sails, so everything held together with no meaningful breakages.

That is, until the fifth day when, as so often happens on that passage, the wind died completely after the second front (cold), leaving us rolling around in a left-over sea with about a hundred miles left to the much-anticipated burgers and beer at the The Black Pearl.

No problem, we had plenty of fuel and a brand-new reliable engine that I had installed the year before.

All was good as we motored along, with the crew baking in the sun and relishing being on deck out of our foul weather gear for the first time on the passage…for about an hour.

At which point the engine stopped dead.

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Matt Marsh

For what it’s worth, the vast majority of O-rings to be found on anything made in or for the North American market will, regardless of proprietary vendor part number, likely be from the AS568 series. Here’s a nice comprehensive chart of the dimensions for all of them:
So John’s favourite (1-1/2″ ID 3/32″ gauge) is AS568-128 and they are about nine dollars per hundred from any of twenty industrial vendors.
Buna-N is generally the preferred type of rubber for fuel and water. (Viton’s better for hot stuff, eg. on-engine, but doesn’t like winter weather; silicone and fluoropolymers cost more but don’t perform any better.)
They are only meant to last a couple of years in this kind of service.

William Murdoch

Exactly. I bought 100 Buna-N size 222 o-rings in a bag for nearly less than I had been paying at the hardware store of the four my boat uses for it’s 1/1/4″ fuel, waste, and the two water deck fills. The bag gives the cure date (8/2019) and reports a 15 year shelf life. I don’t inspect them. It is not worth the trouble. I just change the things. I’ll never run out. And yes, I clean the grooves and seats, and I grease the o-rings. Easy, peasy. Oh yes, the fuel fill on my Pacific Seacraft 34 is in the cockpit in the bridge deck beside the companionway and under the dodger which is about the best protected from saltwater spot on the deck of the boat.

I also bought a similar bag of o-rings for the Achilles dinghy air fills. They were metric and much less expensive than the ones from Achilles.

James Sarrett

The AS568 series is also very commonly (at least here in the US industrial world) called the “dash” series. So if you’re looking on McMaster or Amazon, the sizes there may also be called “dash sizes”. The actual o-ring size is the number after the dash in Matt’s example 😉

Jim Schulz

Love the “Boat Genie in the Cigar Box” story linked inside Steve D’s article linked above.

Dick Stevenson

Hi John,
I remember, in an earlier boat (little sister to your Fastnet 45, a Northeast 38), where everything was far more suspect, I cut circles out of duct tape to cover the fuel and water fills and taped them closed. It might still be considered by a “belt and braces” skipper.
And another area to watch: standing water can get drawn into the tank through the fill if the breather is clogged if the engine/genset is using fuel or the water is being taken out of the tank.
My best, Dick Stevenson, s/v Alchemy

Rob Gill

Hi John, thanks so much for the tip – the obvious hiding in plain sight.

We have just replaced the hot water cylinder on our Beneteau after nearly 20 years and the 230V element just failed. Whilst readying to remove the old cylinder, we removed the engine heat exchange hoses (supply and return) to discover they had gone completely brittle in the ends adjoining the hose tails.

A moderate amount of force was enough to snap the hose, but from the outside they looked completely normal.

We were fortunate that nothing disturbed them, or we would have lost all coolant and may have cooked the engine before the water temperature alarm sounded.

Still looking for a solution to put an alarm I might see and/or hear on the engine exhaust, being profoundly deaf.

Br. Rob

Dick Stevenson

Hi Rob,
You might consider a Raw Water Failure Alarm by Borel. I have one on the genset and the propulsion engine. They are easy to install.
My best, Dick Stevenson, s/v Alchemy

Steven Hodder

That alarm by Borel is LOUD! But after multiple impeller failures, I’ve also installed a flow switch in parallel with the heat sensor in the raw water line – that way you don’t have to wait for the engine to overheat. There are bronze switches available.

Rob Gill

Hi Dick, John,
My hearing loss is 100% in one ear, so in a seaway or wind, it’s russian roulette depending on which way I am facing in the cockpit if I hear alarms or other sounds (like ships’ engines). The other fun issue is being mono-aural, if I do hear something I have no idea where the sound is coming from, and often it is 180 degrees different from where my brain tells me it is.

A couple of questions please if I may, that don’t appear covered on the Boreal website.

  1. Is the panel water/rust resistant – could it be mounted under our mostly dry hard-dodger? If so I could mount the alarm in the aft facing instrument panel above the companionway (see photo) maximising the chance to either see the flashing light or hear the alarm.
  2. As John suggests, I could later connect a second flasher if the integrated one proves inadequate. But how bright is the panel LED light – we do get sunlight through the dodger windows, but it is well filtered by the window tint.

Many thanks, Rob

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Andrew Craig-Bennett

A little list of fuel issues I have had in a year:
1. Water in fuel
2. Slack unions
3. Hidden crack in body of fuel tank change over valve.

I am getting bored with this!

Alastair Currie

I have raised filling points on my side deck, about 2” high. They do keep deck water run off away from the port but not if we’ll healed and digging the gunwale in.
Sounds good, better than flush fittings, well, one of my sheets has worn a hole in the top of the cap. It’s an almost flat, slightly domed cap that looked polished, with the chrome buffed off. On close inspection I found a small hole in the top, which, when poked, turned into a larger hole.

Fuel lift pump, BMC engine, 4 cylinder, stopped working just off the entrance to the Crinan Canal. Traced the issue to no fuel supply but verified that fuel was getting to the pump. I removed the pump with a view to changing the diaphragm but heard the pump rattle in my hand. A quick blow through the inlet and outlet, identified that the ball seat non return valve seal both ways. I discovered the spring that seats the ball to stop drain back, had broken and I replaced that with ball point pen spring.

Comment on fuel return line. I have twin tanks and when I upgraded the fuel lines and filters, the fitter advised that it is not needed. For 10 years now I have been running with no fuel return line and no issues, even when bleeding air. Perkins 2536 motor.

Alastair Currie

Perkins 2436, correction to the above.

Dan Manchester

O rings will do you no good if you forget to put the filler cap back on as I did once. Easy to miss in the kerfuffle of putting the bowser back without getting fuel all over everything, paying the man, and rushing to get out of the way of the 3 impatient boaters behind you…

Alastair Currie

I have had an experienced Skipper, fill the diesel tanks with water by mistake, even though they cap was colour coded Red. Like your example, it was a rush job to get the boat bunkered, off charter and journey onwards home. At least it was recognised before the engine was started and also owned up.

Dick Stevenson

Hi Alistair and all,
The stupid mistakes I have made…..!
As long as I have been around boats, my capacity to humiliate and embarrass myself when handling Alchemy has certainly improved, but continues to show occasional signs of few restraints.
My best, Dick

Karl Lewis

“[A slightly cracked o-ring] had let a surprising amount of water into the tank, at least a gallon.

Murphy’s Law could really have been written about water: If water can get in/out, it WILL.

Steve D

An excellent cautionary tale John, we can never be reminded too often to inspect our own vessel’s systems.

I was about to share a link to the editorial I recently published on this same subject, and then noticed you already included it. Thanks. It includes one line in particular that is apropos of your column, “I’m often accused by brokers, boat yards and builders of obsessing over small details, often followed by the words, “Steve, what are the chances of that failing?!”. But their characterization of me is inaccurate, I obsess over all details.”

I never apologize for obsessing over details. Every few months I go around my house and touch up scratches on walls and trim (I stock the same paint for those surfaces for just that reason). When I do, my wife often accuses me of being OCD, and I promptly say. “Thank you”. In the world of ocean-going vessels, OCD is a badge of honor.

I do check O rings on every vessel inspection I carry out, including water tank deck fills, getting seawater into those is just as bad, maybe worse, than getting it in the fuel tank, at least in fuel water can be separated. I also check for condensation on the inside of the fuel fill cap. If there’s water there, there’s probably water in the tank as well.

I too like Lubriplate, however, I prefer Superlube’s synthetic grease (it’s FDA rated for water tanks too) specifically for lubricating O rings. It’s clear and so a little cleaner as well.

Since you asked…in the photo of your engine compartment the primary fuel filter utilizes a plastic bowl, one that is not rated for engine room use in that it lacks a 2.5 min flame resistance rating (this is an ABYC requirement). The only option for that filter is to install an optional metallic bowl, but that eliminates the ability to see water and debris. I’d replace it with a Racor 500MA series, which has a clear bowl and a heat shield, which makes it compliant. I’d also include the optional UL listed metallic drain valve.

More on primary fuel filters here (it includes the sub-heading “Details Matter”;-))

Steve D

Another example.

Steve D

Agreed on all counts. When I conduct a vessel inspection I attach a prioritization to every observation, from A, and I’m paraphrasing, this could burn, or electrocute you to D this is an observation, but no action is required.

In 2004 few builders had any knowledge of ABYC Standards, much less a goal of compliance (Sea Ray was a notable exception). It’s better today, with much wider acceptance of the Standards and with many participating in the NMMA/ABYC compliance program, wherein they agree to meet the bulk of the standards. However, even for those builders, I routinely find violations, as the vessels are “type certified”, i.e. an example is inspected rather than every vessel, and the inspectors still miss things like incompatible seacock threads and batteries that move more than an inch (yes, believe it or not, under ABYC Standards batteries can move up to an inch, and fuel tanks up to a quarter inch, once installed, one of the areas where I disagree with the standards). Still, while flawed, it’s a program for which I advocate, as it sets a mandate, if the builder claims the vessel is compliant, and I encounter non-compliance, there isn’t an argument, they should/must make it right. More on the compliance program here

David Bricknell

We lost engine power on a new yacht within shouting distance of a lee a shore on the North French coast in a F6. In the fuel line, the boat builder had used a parallel union sealed with PTFE tape (that eventually dissolves in diesel) which finally failed and let air be sucked in.The filters trapped the PTFE tape and the Nanni engine was robust enough to take the abuse without damage but we had to drop anchor to recover the situation; horrible! The correct part would have been a $5 tapered union with a bead of the appropriate Loctite and this has provnen so since.

Matt Marsh

I recently found a fuel filler hose that had no hose barbs. It was just pushed about 1” onto a smooth copper tube of roughly the right diameter, and clamped.
That seems to have lasted 46 years, remarkably, before a surveyor said “hey wait, those need double clamps”. Of course, adding the second clamp made it pop off under pressure and let fresh diesel go straight from the nozzle to the bilge.
Fixed now, of course, and I still have 16 litres of wet bilge diesel bottled up in the shop, waiting for the hazmat depot to open….

Rob Jackson

Hey John,

Your old Fastnet 45 is two boats away from me on the hard in Norwalk Cove Marina in Connecticut. She’s a beautiful boat and the current owner Terri seems to be taking great care of her.

I work in the film business and I can’t tell you how many times that the reason the camera stopped was that the battery wasn’t charged or the light went down because the switch was broken. Yes, it’s all in the details!

Last September, after a lifetime of sailing on smaller boats, some racing, and a few thousand blue water miles on other people’s boats I finally bought “the” boat. Aeolus is a 1967 Bristol 39 Sloop. Sailing her down from Marblehead to Black Rock, CT last year the engine wouldn’t start after we pulled into a dock to wait for the tide change at the canal. Apparently the batteries weren’t charging. The ensuing day & overnight of running around a small town trying to get the alternator repaired etc is a comedy worth telling another time! (I will be replacing all my deck plate O rings thank you very much)

Thanks for this forum, your excellent writing and deep knowledge of all things marine. And the wonderful posse that sails along with you and their stories/knowledge and expertise.
SV Aeolus (E-o-lus: goddess of the winds)

Eric Klem

Hi John,

Just to add to the horror, I would estimate that 50% of the boats we looked at when buying our current boat had horrifying looking fuel filters, typically with lots of water. On 2 of them, the water level was above the bowl so I couldn’t even see how high it went, I can’t believe the engines even ran. One was with a 1 year old engine and when I pulled off the fill cap, there was no O-ring at all. People like Steve D must have nightmares about this stuff. And then there are the issues with putting hoses into the wrong fills, I actually saw the explosion of a sports fisherman who had pumped gas into a rod holder in Annisquam 20+ years ago.

I have missed plenty of stuff over the years but the one that really spooked me recently was our stuffing box hose. When we bought the boat, the hose had been replaced 1 year before with the proper 6 ply Buck Algonquin hose and new clamps so after looking it over, I decided not to pull it apart (I did replace every thru hull and hose to them). This fall we reached the hose age at which I feel it is appropriate to replace and I needed to change a seal in the transmission that started leaking this summer anyways so I pulled it apart. Much to my horror, I discovered that while the hose was properly sized for the shaft log, the stuffing box was undersized for the hose. They had succeeded in getting a 1-3/4″ hose to seal effectively to a 1-5/8″ stuffing box barb just by crushing it with hose clamps. Thankfully it hadn’t come apart and a new stuffing box was <$100 but boy did that scare me.

In my industry, we try to do a few things to mitigate issues like this. The first is having a defined preventative maintenance program. This usually consists of a combination of actual actions like replacing wear parts, greasing some, cleaning others and checks on stuff. The hardest part is often just getting the list of what needs to be covered by preventative maintenance. The second is to have very prescribed service manuals and training that tell you exactly what parts you need, how to do it and what tests/checks to run to make sure it is right. Trying to apply this to the marine industry brings up tons of problems. The big ones that jump out at me are that the designs of boats are not complete designs in my view, there are lots of legacy products out there with incomplete documentation, boats get customized a ton, the customization is not done by a factory trained representative and the companies that make the systems for customization tend to black box their designs and don’t test and provide instructions for all the possible installations. What my industry does is far from perfect but it does have several major advantages although up front cost is not one of them. Maybe on boats having a preventative maintenance checklist would be a good start but it will have to be different for each boat. We have a general checklist but it says stuff like “rigging inspection” and “check fire extinguishers” which may be too generic.


Marc Dacey

I concur entirely about the generic terminology, which can have a lulling effect. We replaced our standing rigging last year for the simple reason that there is no accepted comparative scale that I know of between freshwater rigging age and salt water rigging age. The lowest age of salt water rigging replacement recommendations seems to be 10 to 12 years, but I have seen (and happily used) freshwater standing rigging three times that age.So we replaced ours to “reset the odometer to zero”. We now have some really heavy-duty laundry line.

We are also replacing a packless shaft seal this year as it is over seven years old, despite having a mere 600 hours or so on our engine (nearly three-quarters of our run time has been the last 30 months). Given the possibility of failure of this part, it would be a false economy to do otherwise and we will be able to paint and service the coupling, etc. in the area. It’s all in the details!

James Ferguson

Yes sadly I have to say that a faulty O-Ring did me in rounding Pt Conception. The long slow sail to the yard in Santa Barbara gave me plenty of time to sort things out. Our fuel tank is under the floor near the galley directly below the cockpit. The fuel tank had an inspection plate secured by a cam. After pumping out the tank and cleaning it, we continued to fuel direct through this plate. Worked amazingly well when you need to take fuel from a truck like we did in Alaska, Newfoundland and other places where the nozzle is to big for your average boat. Worked wonders the next 22 years.

stephen actor

I installed ball valves under my deck fills on my last 2 boats. It was an easy job as there was enough room on both boats. Just need a nipple and ball valve, and reuse the king nipple to the hose. I got the idea from a friend with an old halibut schooner who installed them for a different reason. He was rafted up at a dock next to transient vessels and figured someone put a hose down his fuel fill and stole about a thousand gallons. Not that they would bother with a sailboats small tanks.

Peter Haeussler

So John, are you willing to share your pre-ocean-voyage checklist? I’ve been working on my own, but I’ve been wanting to compare to others. And I’m not finding many of worth on the inter webs. The physician Atul Gwande has a book “the Checklist Manifesto”. I’d love to look through a lot of checklists!

Dick Stevenson

Hi Peter and all,
Error reduction in what I call high ante (meaning error leads to significant adverse consequences) and complex systems managed by, at times, stressed, overworked, hurried and tired people is a fascinating subject. Hospitals are a significant target for these studies as the ante is so high: Every year many patients die because of, what looks in hindsight, to be easily avoidable errors. Atul Gwande has written marvelously in this area.
On Alchemy, we attempt to cover our bases with checklists (or what I also call crib sheets). It has been my mantra for a while, with regards to memory, to operate under the aegis of the belief, “ If something is not written down, it doesn’t exist.”
My best, Dick Stevenson

Alchemy’s offshore prep list is as follows:

OFFSHORE/PASSAGE PREPARATIONS                                 
Updated, June 2017

1.    Check all systems

  1. Bilge pumps
  2. Fresh water
  3. Head
  4. Fuel
  5. All sea cocks work and prop thru hull- no leaks and check hose clamps
  6. Visual inspection of engine & genset
  7. Check spare parts for all systems – order as necessary
  8. Steering, all bolts tightened, gears & wire lightly greased, wire tight, wheel tight—chain, esp. master links—cables—turning blocks secure and lubed—cable clamps and attachment to quadrant—quadrant bolts—quadrant key tight—rudder gland secure and water tight—rudder stop system—emergency tiller access and connection—relieving tackles—autopilot function and drive bolts—wind vane connecting bolts and assembly.
  9. Sails inspection
  10. Inspect rigging, standing and running and the mast & spreaders & chainplates
  11. Windvane

2.    Check all safety gear

  1. New batteries installed where necessary,

3.    Monitor weather system patterns and test weather data collecting equipment
4.    Check that all charts are on board and relevant cruising guides and reference books (esp. small scale charts for bail out areas)
5.    Paperwork: cert of doc., visas, zarpas, recip radio lic. in new landfalls, passport up to date, ins declarations page
6.    Check sextant, almanacs and calculator
7.    Get lots of exercise, sleep etc.: go in good condition

1. Check starboard sail locker w/ emergency gear:

  1. Liferaft
  2. Abandon ship grab bag—charge VHF and check batteries
  3. Jug water-only ¾ full

2. Set up third reef if not already done
3. Engine, genset, filters, fluid levels, belts, etc checked/changed
4. Check all running lights
5. Clean bottom, check zincs

  1. Fuel, propane, and water topped off (jerry cans if wished)
  2. Check batteries in equipment and for spares


  1. Rig jacklines
  2. Inspect and ready harnesses and tethers—have 2 tethers ready to go forward
  3. Lee clothes rigged
  4. Snacks available
  5. Secure (by touch) all hatches and portlights) (tighten dogs)
  6. Stow dinghy
  7. 2nd radar reflector
  8. Get out radar position plotting board
  9. Get out day sheets log
  10. Tie off the books in the back shelf
  11. Bolt rope around hatches
  12. Charge sat phone, VHF, drill batteries, etc.
  13. Tie down or remove anchor and swing metal plates (maybe tape or cover), secure windlass cover forward,
  14. Set trip logs
  15. Clip down cockpit locker hatches
  16. Deflate fenders and store
  17. Change to full propane bottle
  18. Rig offshore preventer
  19. Haircut and nails trim

1.    Dog down floorboards
2.    Cover forepeak cushions
3.    Double up ladder tie down lines
4.    Start anti-seasickness meds at least 12 hours before departure
5.    Dog down bookshelf fiddles
6.    Turn Dorades backwards
7.    Netting over shelves above settees
8.    Remove deck wash hose and close seacock (not if galley washdown is needed)
9.    Remove anchor
10. Pull chain back to amidships
11. Lay rope in lazarette hatch/coaming opening
12. Towels around dodger water flow points

John Cobb

A research paper from 2002 on how complex systems fail. Absolutely appropriate for cruising sailboats, IMO.

Mark Wilson

Dear Dick

Have just printed out your list. Am going to get it laminated.


Peter Haeussler

Dick – awesome list – thanks!

John – I think a post on check lists would be great. Its really useful to see one like Dicks – there’s a bunch of details that were not on my list (thanks! I’ve cribbed your crib sheet!). I’ve also been working on a couple of other simple lists – things to check before leaving the boat for a month or two, and things to check before leaving the dock – even for a day.

John Cobb’s reference – certainly is appropriate for cruisers. A boat is a system of systems, but not all systems have to work together, which seems to be more what the paper is referring to. Sometimes it is just ONE thing that breaks that makes things fail catastrophically. Other times there is a cascade of things that cause failures, which is more what the paper is about.

James Sarrett

One more handy thing about o-rings: If you aren’t sure what size you want, the rule of thumb is to measure the seat and go one “dash” size down with the same cross-section. i.e. if you take out your calipers and get that the cap is a 1.5in ID (-29) you can pretty safely assume a 1 5/16 (-28) will fit and seal.