Twin engine failures

[AusCan]

It would be hard to argue that two engines are not more reliable than one. Maybe much more reliable.
But is it worth the trade-off?

The risk of having unprotected props & rudders is much more difficult to assess. This risk has the potential to be much worse than just a breakdown.

 

[BandB]

It would be hard to argue that two engines are not more reliable than one. Maybe much more reliable.
But is it worth the trade-off?

The risk of having unprotected props & rudders is much more difficult to assess. This risk has the potential to be much worse than just a breakdown.

I think the risk of having unprotected props and rudders is overstated. Most twin engine boats are designed with some protection and the protection singles think they have is often overrated. By not being centerline, twins gain some there as well.

As to whether the reliability of twins is worth the trade off, that's such an individual thing. We like and only have twins but I'm not going to argue for a moment against singles. We do understand that choice.

 

[psneeld]

Not sure most twins have some prop protection...many do, many dont....

Have owned and towed plenty of both.

Singles due to engine or fuel, twins often due to grounding and running gear issues.

 

[bfloyd4445]

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.

Think. The company keeps a... I think 15% safety margin in their numbers so that brings the gallon age to about 110 and then it takes the D engine about 2.5 hours to charge the batts which in pure electric can run the boat for 20nm. Gives you 700 miles on the thumper and anther 300 more or less on the silient giant<electric>. So, that makes 1,000nm per tank. I rounded to 100 gallons. I ran my numbers by greenline and they said my numbers were close to theirs if you take into consideration the use of the electric motor. Email them they will explain. If you know of any other vessel that efficient please let us know.

 

[twistedtree]

Think. The company keeps a... I think 15% safety margin in their numbers so that brings the gallon age to about 110 and then it takes the D engine about 2.5 hours to charge the batts which in pure electric can run the boat for 20nm. Gives you 700 miles on the thumper and anther 300 more or less on the silient giant<electric>. So, that makes 1,000nm per tank. I rounded to 100 gallons. I ran my numbers by greenline and they said my numbers were close to theirs if you take into consideration the use of the electric motor. Email them they will explain. If you know of any other vessel that efficient please let us know.

Huh? Where does the fuel come from to charge the batteries?

 

[bfloyd4445]

Huh? Where does the fuel come from to charge the batteries?

out of the 132 gallon tank. Then when batts are charged you turn off the diesel engine and turn on the electric and go for 20nm. Simple. The main D engine charges the batts in conjunction with solar cells of the roof during the day giving even more range than what you would achieve at night when you would have to rely totally on the D engine to charge and propell your boat

 

[twistedtree]

out of the 132 gallon tank. Then when batts are charged you turn off the diesel engine and turn on the electric and go for 20nm. Simple. The main D engine charges the batts in conjunction with solar cells of the roof during the day giving even more range than what you would achieve at night when you would have to rely totally on the D engine to charge and propell your boat

I expect the advertised range of 700nm is running purely on diesel since that is the most efficient. Charging batteries then running them down via an electric motor is less efficient that just running the diesel to turn the prop directly. If the boat could go 1000 miles on a tank as you describe, why wouldn't the company advertise that?

 

[bfloyd4445]

I expect the advertised range of 700nm is running purely on diesel since that is the most efficient. Charging batteries then running them down via an electric motor is less efficient that just running the diesel to turn the prop directly. If the boat could go 1000 miles on a tank as you describe, why wouldn't the company advertise that?

The electric motor is more efficient than the d you have it backwards. They are conservative and state a 700nm range on the 33 because the hybrid system is an option and not standard. D engine only you get 700nm range.But if you opt for the hybrid option you have the option of running on pure electric which gives you an aditional 20nm range before batts need recharging., Takes 2.5 hours to recharge the batts via d engine alone. During the day with the sun shining you have the roof mounted 11kw solar pANELS ALSO CHARGING THE BATTERIES SO MY NUMBERS ARE CONSERVATIVE ALSO BECAUSE I DIDNT FACTOR IN THE SOLAR INPUT JUST USED THE FACTORy NUMBERS FOR engine generator charging. opps cap lock. sorry I wasnt shouting on most of my computers i have removed that dumb key.

 

[nmuir]

Back to the original question....

Happened to me twice. Once with an old gas-powered twin express cruiser (sorry!) a water pump seal failed. Got back to a harbour on the other engine.

Another time on the trawler with an transmission oil pump leak that drained all the oil. I could have locked the transmission and got home, but easier to simply get to safe anchorage on one and fix it there. Docking/anchoring on a single with a locked transmission would have been 'entertaining'.

 

[bfloyd4445]

Back to the original question....

Happened to me twice. Once with an old gas-powered twin express cruiser (sorry!) a water pump seal failed. Got back to a harbour on the other engine.

Another time on the trawler with an transmission oil pump leak that drained all the oil. I could have locked the transmission and got home, but easier to simply get to safe anchorage on one and fix it there. Docking/anchoring on a single with a locked transmission would have been 'entertaining'.

That's true. But as you said you could have locked it and got home so in that case a single would have been fine. A water pump seal failure would have put water in the bilge but you could have still used it if you had to right?

failure with twins will always be twice as frequent as with a single. I had a power steering hose split on a brand new boat with less than thirty hours one time. Boy did that make a mess but a fellow boater lent a hand and we improvised allowing the steering to function till i made port and called the dealer. Lucky it was in the bay

 

[twistedtree]

Just to clarify the probabilities for failures of twins......

Let's say a single engine and drive train has an expected failure rate of once per 1000 days, i.e. 1/1000, for a failure that will disable the boat.

A twin engine boat will then have twice the failure rate, i.e. 2/1000 or 1/500. But, because you have twins, the failure is no longer disabling.

To disable the boat, you need two failures, one in each engine. That's 1/1000 times 1/1000, or 1/1,000,000.

So statistically you will have twice the number of things to repair, but you mean time to being disabled goes from 1/1000 days to 1/1,000,000 days.

Now that is ONLY looking at the engine and drive train. Other things can disable a boat too. People have mentioned the fuel system as a likely cause, and for that you need to look at the probability of "failure" of the fuel system, not the engine(s). If you want to significantly reduce the probability of a fuel system disabling you, you need to adopt some sort of day-tank approach where you quarantine new fuel, then filter it and run off some store of known-good fuel.

 

[twistedtree]

The electric motor is more efficient than the d you have it backwards. They are conservative and state a 700nm range on the 33 because the hybrid system is an option and not standard. D engine only you get 700nm range.But if you opt for the hybrid option you have the option of running on pure electric which gives you an aditional 20nm range before batts need recharging., Takes 2.5 hours to recharge the batts via d engine alone. During the day with the sun shining you have the roof mounted 11kw solar pANELS ALSO CHARGING THE BATTERIES SO MY NUMBERS ARE CONSERVATIVE ALSO BECAUSE I DIDNT FACTOR IN THE SOLAR INPUT JUST USED THE FACTORy NUMBERS FOR engine generator charging. opps cap lock. sorry I wasnt shouting on most of my computers i have removed that dumb key.

These boats are for people who want to believe, but never took physics. It's too much of a side track for this thread, so if you want to discuss, just start a new thread.

 

[Art]

These boats are for people who want to believe, but never took physics. It's too much of a side track for this thread, so if you want to discuss, just start a new thread.

There have been threads on TF and other forums discussing electric motors on boats and all the assorted support systems they need. Suffice it to say; powering marine electric propulsion engines for pleasure crafts never meets the economy and speed people wish for. This is due to loss factors regarding energy creation, energy storage, energy transferal, energy use, hull drag, cumulative motor weights... as well as... a myriad of other items.

I feel bad for the souls who continue to try and make the elusive "Electric Powered" cruiser boat become a reality. Many I've seen go broke in so trying.

Electric cars - OK... at the drop of a hat it can be plugged in some place. But, there are still loss factors regarding energy creation, storage, transference, use... etc, etc.

What most electric car owners do not realize: Although the electric "grid" is increasing reception of electricity input via solar, geo thermal, wave, tidal, wind and other "green energy" actions/reactions... dirty burning coal is still by far the primary electric energy generator throughout the world. And, although advancements have been made for cleaner burning coal; due to loss factors (some are mentioned above) there currently is more pollution created by electrically re-charging a car each and every night than by utilizing a really clean burning, efficient hydrocarbon powered engine.

That said... If enough "green energy" electricity creation devices can become amply placed into use, then the tide of pollution factors will rest in favor of electric cars.

Side Note: Being there are over 1.5 billion hydrocarbon powered vehicle engines in existence with each made of metal that can be melted for return to use in manufacturing... what would be done with the really dangerous compounds inside modern-design batteries if eventually 1.5 billion electrically powered vehicles became a reality? Just thinking out loud!

Happy Energy Daze! - Art

 

[BandB]

These boats are for people who want to believe, but never took physics. It's too much of a side track for this thread, so if you want to discuss, just start a new thread.

Electric is great if you want to go 20 nm. Of course if you want to go 20 nm or less then what does it really matter what your fuel usage is? Show me an actual 1000 nm trip taken on 100 gallons and then I'll believe those numbers of 10 nmpg. Until then the best I'll buy on Greenline is 6 or 7 nmpg, perhaps 8 and others have achieved that.

Then try going south in the gulf stream on electric. Or anywhere against a strong current when your 4 knots becomes 2 knots or 0 knots.

Greenline apparently does have some owners in Europe. If they're happy, that's fine. However, I have a feeling their happiness comes more from doing something unique than any savings. We're seeing progress on electric cars and perhaps one day we'll see it on electric boats. Until then the market of all electric will be owned by Duffy. Great if you just want to cruise the Fort Lauderdale canals for two or three hours in silence.

When we see technology advance to give autos a range of 1000 miles on one charge, then we'll have the technology for a true electric cruiser.