Twin engine failures

Just curious how common the loss (can't be fixed at sea) of one engine is on a twin engine boat.

Ted

I towed someone last weekend who had lost both engines. Of course it was from running out of fuel...

I've never seen any hard figures, but it's always seemed reasonable (to me) to assume that it's much more common than a single engine boat losing an engine. I just looked on the BoatUS Seaworthy site and didn't spot anything particular to this situation, though there are some items in "The Most Common Insurance Claims" that might be relevant.

I had an overheating issue that plagued me for a few months when I first got the boat. I needed a haulout for that one, as the problem was a broken check valve in the lower unit. That put me down one engine.

I had a coupler strip out, which was another haulout repair. Down one engine.

I had a fuel filter pack up on me, which knocked one engine out. I thought I had a spare, but didn't. Turns out replacements are extremely hard to find. The same trip I had a fuel pump die on me. Down one engine.

I had lots of problems with my shift/throttle cables not wanting to stay properly adjusted for any amount of time, causing either/both engines to stall out at inopportune times.

I was never stranded without any either engine, aside from that one time I found out that my fuel gauge was way off... like 30% off.

After all of these calamities, I decided to get myself a Towboat US membership. I never used it though, thankfully.

When I was commercial fishing, all our boats were singles and we had our share of breakdowns. Some, often filters, could be fixed at sea and some we towed each other in.

I've owned my twin engine boat since 1976 and have had too many to count engine failures in one engine. Some simple ones were repaired underway, some we just chose to proceed to harbor on one engine, and several could only be repaired at the dock.

I've never been towed with this boat.

My old outboard boat had twin 250's and every now and then one would suck some sand up and overheat alarms would go off. Never left me offshore though.

Lost one engine (only once) while underway due to a fuel starvation problem. Not a filter issue. Proceeded back in on one screw. My trannies can freewheel without damage.

Were I a better mechanic, I could have fixed it underway - if there is a next time, I can handle it now.

One engine failure in 6-700 hours of operation over 5 years. Due to the PO's use of a marginal part.

Have owned single screw boats since 1986 and have many thousand of hours on the engines with only one breakdown. A Cat 3208 raw water pump pully separated due to failure of the tack welds that held the two halfs together. I sent it back to Cat and they sent me another one. The pullies need stronger welds and I noticed the new pully did have marginally better welds. I do not know if Cat made the pully or it was outsourced.

In our waters there is a problem with twins being impacted to the running gear, usually to both the port and starboard damaged together.

All else being the same, the odds of losing one in a twin is twice that of a single......
Odds of losing both VERY remote, unless it's a fuel starvation/contamination issue.

But, there are way too many variables and as Keith said, no good date.

I mean, are single engine operators more likely to maintain their motor because it's the only one they have? Are single engine boats more likely to operate at 65%/hull speed -1 whereas twins want to plane and are at WOT to get there more often?

Good science is a lot of work.......

I've had two breakdowns in a single at sea. It was a clogged fuel filter (new boat to me, first time in rough weather in a long time). It was fixed at sea. Second was a failed starter. Mallotized it and it never did it again.

We've had two singles and one twin. No the two singles did not add up to twins. Just luck I think, never had an issue with the singles, Cummins and Yanmar. The twins are Cummins, yard installed incorrect alternator on starboard, tore two belts before 3rd mechanic told me the alternator was wrong, all were from yard that installed it. A couple of weeks ago, I was taking Amazing Grace to Deltaville and the port engine slowed then quit. I limped in on one, lot of fun docking in wind, and later discovered part of wiring had worked loose, engine ground wire had come out of poorly made connection.

This spring I figured out what was my enduring fuel pump issue of the last 2 years.
It got progressively worse that random engine shut down due to no fuel.

My monel tank brass pickup tube had rotted and split. So port engine closer to tank would keep running while starboard engine would randomly quit with pump sucking air.
Pickup is missing the bottom 6 inches.
So yes fuel tank brass corrosion does occur with E10 gasoline.

E10 by its nature wants to create acids, and due to it getting microscopically wet while not yet phase separated even so creates galvanic current corrosion in the fuel itself. Brass is less noble than Monel so is anodic and corrodes.

Typically I run both engines from port tank.


That happened after E10 showed up in 2006. So in 10 years, the brass was wasted away destroyed by E10.

Wayfarer said:

I had an overheating issue that plagued me for a few months when I first got the boat. I needed a haulout for that one, as the problem was a broken check valve in the lower unit. That put me down one engine.

I had a coupler strip out, which was another haulout repair. Down one engine.

I had a fuel filter pack up on me, which knocked one engine out. I thought I had a spare, but didn't. Turns out replacements are extremely hard to find. The same trip I had a fuel pump die on me. Down one engine.

I had lots of problems with my shift/throttle cables not wanting to stay properly adjusted for any amount of time, causing either/both engines to stall out at inopportune times.

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Dave, please don't take offense, but I'm not sure I'll invite you out for a trip on my boat. Your luck may rub off.

I had a 5.7L Crusader engine trashed by a failed exhaust riser. It was the delivery run. The risers were 12 YO, way overdue for rreplacement. Shut the engine down after 100 miles to check fluids and oil level went up 2 inches. Nice to have twins. New long block time.
Also had a 140 Evinrude block sieze up 20 miles off the beach. Again, twins got me to port.

I've not done this much (boating), my wife were out just after we bought the boat. Port engine died, would not restart. Thank heaven I own tractors, I new right away it was a fuel problem, however; I had never laid eyes on Racor filters or anything like it (marine) fuel systems. I changed the filter while the wife drove the boat (spooked her to death) from the flybridge. Tried a re-start that didn't happen. I worked like a cat on a hot roof to bleed the fuel system frm the 1st filter thru the injectors before it re-started. Two of those monsters in the bottom of the boat has got to better than one, right?

It appears that most diesel engine failures are fuel related, second to raw water supply. A twin engine boat is no better than a single engine boat if both engines share a common fuel supply.

I lost one engine last year due to massive oil loss.
Fortunately I caught it before any damage was caused beyond the cause of the oil loss.

Latter 1950's through now in 2016 I've been towed in twice while engine were down. 1st time was single screw with totally blocked fuel line... 2nd time was twins running off one tank that had gone dry. 1st one was multi mile CG tow into Block Island. 2nd was 1/2 mile side tow in narrow canal to yacht harbor slip.

We've had four boats with twin engines and had single engine failures on all four which required coming home on one. The first was a catastrophic failure where the engine through a conrod thought the side of the block, second a gearbox failure, third an injection pump failed and fourth a fuel filter failed.

The other engine got us home safely in all cases.

Lost a raw water pump just last week on the way to Gulfport. Second engine saved the day.

May depend on what one calls a failure.

I have had major fuel and oil leaks on a single but continued on to port where with twins they would have been shut down.

Also true of alternator failures where a broken belt may take out the cooling system

dhays said:

Dave, please don't take offense, but I'm not sure I'll invite you out for a trip on my boat. Your luck may rub off.

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I like to think I got all of my mechanical bad luck out of the way in one big lump. I'm all set now

Running on one Engine

I've had both single and twin engine boats, and in two cases was glad to have twins. One was related to a damaged prop, where I came home on one engine. The other was a belt snapped. I was able to go below and replace it, while my wife was able to pilot the boat into what was moderate seas.

kulas44 said:

It appears that most diesel engine failures are fuel related, second to raw water supply.

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What is the source of data for this claim? Not saying you're wrong, just want to vet the underlying data.

kulas44 said:

It appears that most diesel engine failures are fuel related, second to raw water supply. A twin engine boat is no better than a single engine boat if both engines share a common fuel supply.

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Fuel system vs fuel alone are very different failures. So is a plugged filter due to lack of maintenance a fuel or fuel system failure? Or how about the guy who uses 2 micron primaries and swears he is getting bad fuel because his filters plug up all the time? So many variables.

And raw water supply - know of several cases where planing boats ran hot because they were propped wrong, cooling systems were just fine though.

But the premise of the thread is that failure modes for twins vs singles are different? Most engine failure modes seem owner or bad mechanic related. Maybe it is true, twin owners are not single minded and hire stupid mechanics.

I've never had an engine failure with my twins nor did I ever have a failure with my previous single. However, I did have a steering failure on my current boat with twins. I was able to drive it home by modulating throttle and gear input; I easily "steered" her home and backed her into her slip with no drama at all.

I've had twins and singles. Had a gear failure on the twin, came home on the other. On the singles, never had a propulsion failure. Did have to get towed when a new rudder arm fractured, apparently a casting flaw. At the time had no provisions for backup rudder control, that has been remedied. Have had a few issues with the single engines, leaks, impellers, stupid tank management by me, etc, all easily remedied without mission failure.

I still prefer the single, even though there will remain an increased chance of needing a tow. To me the tow option is just another tool in the tool kit. Use it if you need it.

Twins will have a higher probability of having a problem, but a much lower chance of needing a tow. And that problem may ruin trip plans, whether a tow is needed or not.

One of the guys in our marina had one of his big block gassers fail. He was exiting the fuel dock on his way to the marina and one engine stalled. It wouldn't re-start because the starter crapped out.
He had to get towed in. (he has trouble docking with both so he didn't dare try it on one)

Lost Detroit diesel starboard engine. Spun the main bearing. Port engine got us in.

what I've noticed with twins is when one goes the other is often right behind it. Even if each engine has separate everything they will still share common traits like same age, make, hours so weknesses with one are also in the other. If you wish avoid the twin engine pitfalls and seeking 2nd engine for dependability you should chuck that idea and get a single engine with a get home or wing engine or even a hybrid like the greenline. These systems will get better fuel economy and save 50% on maintenence costs as well. The greenline 33 can go 1,000 miles on 100 gallons of fuel the most economical powerboat made i think.

bfloyd4445 said:

The greenline 33 can go 1,000 miles on 100 gallons of fuel the most economical powerboat made i think.

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Where do you get those numbers? On diesel, the 33 per their website has a range of 700 nm and that is on 132 gallons of diesel. On electric it has 20 nm.