View Poll Results: I've used a backup on my single-engine boat
Because of a problem with the main engine 1 4.35%
Because of a shaft/prop problem 0 0%
Because of a fuel supply problem 1 4.35%
Never 5 21.74%
I don't have a backup, just the main engine 16 69.57%
Voters: 23. You may not vote on this poll

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Old 05-19-2016, 09:11 AM   #21
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Thread drift is like the tide it seems - you ain't going to stop it. *sigh*

No Mast - thanks. So 1 event and 1 "near" event, both on the main engine without compromised supporting systems (fuel, prop/shaft).

TwistedTree - I don't disagree with most of your points. However, I do think there is value in understanding the MTBF of major elements of the propulsion system. How one chooses to address the three choices you cite is in part determined by the the likelihood of a problem occurring. Certainly statistics can't absolutely predict what will happen to a you in the next 60 seconds but there is still value there imho.

In a likely hopeless attempt to clarify things, I was looking for hard data to decide the value of an auxiliary propulsion option on a to-be-purchased single-engine, offshore-capable trawler that will spend some limited time offshore.

Anyone else have experiences to share (including "I've got a backup engine and have never needed it")?
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Old 05-19-2016, 09:28 AM   #22
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I thought this thread was about how to install a diesel outboard (nevermind its not available in USA) on a Mainship 34 against the owners will. Or an electric trolling motor to the bow effectively making a Mainship bass boat against the owners will.
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Old 05-19-2016, 09:58 AM   #23
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Quote:
Originally Posted by twistedtree View Post
You can look at failure rates and probabilities all you want, but any statistician will tell you that a failure can still happen anytime. And any boat owner can confirm this.

So I think the real question is what are you going to do when any given failure occurs. You have three choices:

1) Work around the problem. This is where redundant/backup systems come into play.

2) Fix the problem. This is where carrying spares, tool, and knowledge come into play.

3) Call for help.

Where you are cruising is a major factor in how you approach all of the above, and will typically result in very different decisions between different boats. If you cruise the ICW or other populated areas, many boaters will skip right to step 3 and call for help. No need to carry spares or know how to fix anything. But the further away you get form civilization, #3 ceases to be an option and you must be able to handle the problem in steps 1 and 2, i.e. work around the problem or fix it. This is where you see boats with critical systems that are redundant, and with spares tucked in every corner of the boat.
There's no towing service where we live, and few boats, so we have a 9.9hp outboard kicker mounted to the swimstep on a swiveling bracket. Have not needed it because of a breakdown...yet.

It's a Lehr propane ob which doesn't need to be winterized (coldest we've gone out in so far was -15C, or 5F) and the propane stays good for years (decades?) so it starts right up every time with little coddling from me.

Theory is, with a 20lb propane tank, the Lehr 9.9 would give us over 10 hours of fuel at 3/4 throttle to either get back home or get to a safe anchorage...then we could work on the main engine in relative comfort/safety, or wait for help if it came to that.

Badger is our first boat and I'm no mechanic, so the kicker gives me relative peace of mind.

Only once have we had engine trouble...we anchored in a small, completely exposed bay to do some fishing and the engine wouldn't start. The trouble shooting section in Nigel Calder's book had us up and running in under 15 minutes (corrosion on terminal between ignition and starter) so not a serious breakdown.
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Old 05-19-2016, 10:15 AM   #24
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Originally Posted by CPseudonym View Post
I thought this thread was about how to install a diesel outboard (nevermind its not available in USA) on a Mainship 34 against the owners will. Or an electric trolling motor to the bow effectively making a Mainship bass boat against the owners will.


Quote:
Originally Posted by MurrayM View Post
There's no towing service where we live, and few boats, so we have a 9.9hp outboard kicker mounted to the swimstep on a swiveling bracket. Have not needed it because of a breakdown...yet.

It's a Lehr propane ob which doesn't need to be winterized (coldest we've gone out in so far was -15C, or 5F) and the propane stays good for years (decades?) so it starts right up every time with little coddling from me.

I forgot about those. Sounds workable.

FWIW, we used to have a single engine diesel -- earlier model, 34' Mainship III -- and never had a breakdown, never needed auxiliary propulsion.

-Chris
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Old 05-19-2016, 10:21 AM   #25
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We've got a single engine and I'm looking for a way to mount the 15hp dinghy engine as an auxiliary should it be needed. I like the swim platform idea above! In the 100 or so hours we have used the trawler so far we have not needed auxiliary propulsion.
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Old 05-19-2016, 10:50 AM   #26
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I've never owned a single engine boat, so I'm not sure my input is relevant. I can count 6 major times when I was glad to have multiple engines and drive trains. Four were mechanical issues with one engine or another, never both thankfully. The remaining two were fuel issues. There were also several more minor issues when one engine just decided to stall out, usually due to a shift cable that refused to stay properly adjusted, and usually when I was making a dock or a lock and really needed it. As often as not, it would fire back up within a minute or two, after some swearing and furious throttle jiggling.

It was an exciting three summers.

The next boat will have a single diesel and a bow thruster. I doubt It'll have any kind of backup powertrain for simplicity's sake, but I'm going to keep that main engine as clean and happy as I possibly can. My backups will be 1. anchor, 2. repair, 3. dink, and 4. towboat US.
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Old 05-19-2016, 12:11 PM   #27
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I was on the boarder, but voted Yes to using backup due to a main engine issue. I didn't actually have to use the backup, but if I have been an hour or two further away from port, I definitely would have. Twice my main engine developed a serious coolant leak and was well on the way to becoming completely disabled. Another hour and I would have been running on the wing engine with no hope of repairing the main even though I had most of the required parts on board. I think this is a good illustration of how a backup can be required.
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Old 05-19-2016, 12:28 PM   #28
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Originally Posted by danderer View Post
TwistedTree - I don't disagree with most of your points. However, I do think there is value in understanding the MTBF of major elements of the propulsion system. How one chooses to address the three choices you cite is in part determined by the the likelihood of a problem occurring. Certainly statistics can't absolutely predict what will happen to a you in the next 60 seconds but there is still value there imho.
Yes, I completely agree. It's all about probabilities. But since you don't know WHEN something will break, I argue you need to sort out what you will do when it does break. How screwed will you be? If you are in the middle of the ocean and your engine dies and you have no alternate, you are pretty screwed. If the same happens off the coast of Florida, oh well, no big deal and you'll have a good story to tell.

I went so far as to create a giant document that walks through every critical system on the boat and addresses "what if" various things break. It was a great exercise, and drove my spare parts strategy. It also exposed some vulnerabilities that I didn't expect. It's not a necessary exercise for most boats/boaters, but if you plan to venture to remote locations, I would recommend doing it.
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Old 05-21-2016, 08:18 AM   #29
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My backup is TowBoatUS.
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Old 05-21-2016, 09:00 AM   #30
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I'm a single engine boater.

98% of my perceived boat use will be with in range of Tow Boat US, Seatow, or the USCG. For the other 2% of the time I'm comfortable with the laws of probability. Simply, Charles Lindbergh flew across the Atlantic once. The odds of engine failure on that one trip were pretty small. If he had done the flight numerous times, the odds of having a failure increased dramatically, ruling out a single engine aircraft.

If I felt the percentage of time out of the tow boat zone were high enough to warrant back up propulsion, I would have twins.

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Old 05-21-2016, 09:11 AM   #31
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Aren't two engines twice the problem and twice the expense?
Only to the naysayers and agitators. Now about those twins in Singapore -----
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Old 05-21-2016, 09:24 AM   #32
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Aren't two engines twice the problem and twice the expense?
Yes.

The risk of both engines failing on the same day are exponentially smaller than just one (with the exception of shared fuel or battery source). However, statistically one of two engines failing is twice as likely as one. While they won't burn twice as much fuel for the same speed, almost all other costs (purchase, installation, and normal maintenance) will be twice as much.

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Old 05-21-2016, 09:52 AM   #33
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However, statistically one of two engines failing is twice as likely as one.
Is that really true?

I've seem some anecdotal data suggesting that some twin-engine owners (of both boats and aircraft) may have the feeling that--because they have two engines--each engine may not need to be maintained to quite the same level a single-engine would be. Or to put it another way, a SE owner might be a bit more obsessive maintaining their sole power source.

Again, this is just anecdotal but jives with some things I've seen.
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Old 05-21-2016, 10:10 AM   #34
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Is that really true?

I've seem some anecdotal data suggesting that some twin-engine owners (of both boats and aircraft) may have the feeling that--because they have two engines--each engine may not need to be maintained to quite the same level a single-engine would be. Or to put it another way, a SE owner might be a bit more obsessive maintaining their sole power source.

Again, this is just anecdotal but jives with some things I've seen.
I agree with what you are saying.

If that were the case, then one of two engines (in a twin engine boat) failing would be more than twice as likely as a single engine boat.

Statistically it's probably better to say that the risk of a single engine failuring increases as a multiple of the number of engines in the boat.

Ted
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Old 05-21-2016, 10:12 AM   #35
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Greetings,
Mr. d. Having had both a single and twins, it's not that big a deal, for me anyway, to double up the maintenance (oil changes etc.) when one does it. Yes, more time and more expense but...

Could possibly be that single or twin owners who defer maintenance are just naturally negligent and # of engines is not really a factor. I'm sure we've all seen YW listings where the living quarters show well but the ER spaces are disasters. Just skewed priorities IMO.
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Old 05-21-2016, 10:48 AM   #36
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TwistedTree - How one chooses to address the three choices you cite is in part determined by the the likelihood of a problem occurring.
Another factor in determining how to plan for failure is the cost of the solution. Belatedly doing some research on Nordhavn (wing-engine) and KK (hydraulic drive on the main shaft powered by the generator)--well, it turns out the backup is cheaper than I would have thought: it'll add about 2% to the cost of a new build.

Seems like that is a no-brainer for doing any offshore work, regardless of the stats.
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Old 05-21-2016, 11:57 AM   #37
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I've moved a 16000 lb 38' sailboat a couple miles with a 2hp motor on the dink. Tied the dink on the 'hip' so the admiral at the helm and I could speak. Got up to about 4 kts in calm (had there been wind...). Drove right up to a mooring and moored.

Thinking that our 26000 lb 39' trawler ought to move with a 15hp motor on the dink, but I doubt that she'd be as easy to control as the sailboat was.
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