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Old 08-06-2012, 08:49 PM   #61
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In the interests of fuel economy, do twin engines use twice the fuel use of an identical single engine, to produce the same boat speed in the same boat?
No. Given the same boat, say a GB36, the twin engine version will burn more than the amount burned by the single, but less than twice the amount. Our GB36 twin with two FL120s cruises at 8 knots with both engines turning at about 1650 rpm. A GB36 with one FL120 will need to run at a higher rpm to achieve the same speed through the water, assuming the same propeller specs.

Or put another way, the one engine in the single engine GB36 will have to run at a higher power setting to achieve a given boat speed than either of the engines in a twin-engine GB36 will have to run to achieve the same boat speed. Higher power=higher fuel burn.

So the fuel burn in a twin will be what, half again as much as the fuel burn of the single engine version of the same boat? But not twice as much. There are probably formulas to get accurate figures.

While a bit apples and oranges, our two FL120s need to turn at 1650 rpm to achieve a boat speed of 8 knots. The more-powerful Cummins engine in the single-engine GB36 we chartered before buying the boat we have now had to run at 2,000 rpm to achieve the same 8 knots. Not as good a comparison as a GB36 with one FL120 and a GB 36 of the same vintage with two FL120s but you get the idea.
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Old 08-06-2012, 09:01 PM   #62
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No. Given the same boat, say a GB36, the twin engine version will burn more than the amount burned by the single, but less than twice the amount. Our GB36 twin with two FL120s cruises at 8 knots with both engines turning at about 1650 rpm. A GB36 with one FL120 will need to run at a higher rpm to achieve the same speed through the water, assuming the same propeller specs.

Or put another way, the one engine in the single engine GB36 will have to run at a higher power setting to achieve a given boat speed than either of the engines in a twin-engine GB36 will have to run to achieve the same boat speed. Higher power=higher fuel burn.

So the fuel burn in a twin will be what, half again as much as the fuel burn of the single engine version of the same boat? But not twice as much. There are probably formulas to get accurate figures.

While a bit apples and oranges, our two FL120s need to turn at 1650 rpm to achieve a boat speed of 8 knots. The more-powerful Cummins engine in the single-engine GB36 we chartered before buying the boat we have now had to run at 2,000 rpm to achieve the same 8 knots. Not as good a comparison as a GB36 with one FL120 and a GB 36 of the same vintage with two FL120s but you get the idea.
Good explanation...

My reading and experience has shown that so few examples are available of the exact same boat with the exact same parameters there's very little "hard facts" on the subject...BUT...what I have sen is the single will burn a little less than any twin combination unless the single is way overpowering the boat anyhow.

Twins aren't THAT much more...but more in the best case scenarios...so it's more preference versus unbelievable savings.
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Old 08-06-2012, 09:12 PM   #63
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To add to what psneeld said, the reasons I have heard given from the people I know or have talked to who made a decision to buy a single-engine boat over a twin all had to do with reduced maintenance and service costs, more space in the engine room, ease of service, maintenance and repair, less noise, less vibration, and of course, lower purchase cost of the boat (usually).

I don't recall anyone telling me that they chose a single over a twin because of the reduced fuel burn. Like psneeld, I just don't believe it's that signficant of a difference assuming the same cruise speed envelopes for both boats.
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Old 08-06-2012, 10:35 PM   #64
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[QUOTE=Marin;97482]To add to what psneeld said, the reasons I have heard given from the people I know or have talked to who made a decision to buy a single-engine boat over a twin all had to do with reduced maintenance and service costs, more space in the engine room, ease of service, maintenance and repair, less noise, less vibration, and of course, lower purchase cost of the boat (usually).

I don't recall anyone telling me that they chose a single over a twin because of the reduced fuel burn. Like psneeld, I just don't believe it's that signficant of a difference assuming the same cruise speed envelopes for both boats.[/QUOTE]

Of course it depends on total fuel usage a year....like FF pointed out in one post....loopers, retirees, world cruisers...yeah there's a number in there either you can or can't live with....and it does depend on what engine setup....burn enough fuel and even a 1% difference adds up at $4.00/gallon...but for many that's not evenly remotely an issue.

Take a KK42 that's happy with 65hp and try to compare it with a GB42 with twin TA 475hp 3208s and there's no efficiency comparison....no matter how you run the boat. Take a second KK42 and look at the fuel burn if it had twin 45hp Yanmars and I bet you could make an arguement between the 2 camps.
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Old 08-07-2012, 05:57 AM   #65
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Higher power=higher fuel burn

Sometimes , depends where the efficient operation for the engine is.

And fuel is only one concern , under loading might be another , that is far more expensive than just fuel.
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Old 08-07-2012, 08:03 AM   #66
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The OP talked about getting a low buck trawler. I don't know what the situation is in his area but in the PNW the cheapest useable trawlers are converted fish boats. But the OP has lots of ideas about the features he wants and if he's looking for a GOOD economical boat a flybridge should not even be part of the picture unless a great boat is found and it just happens to have the FB.
.............
It appears the OP is looking for a low buck trawler but hasn't owned or operated a trawler before and may have come up with his ideas about the features he wants from various outside sources. Upon further research, he may change his ideas somewhat.

One thing I question is his insistence on twin engines. Many high end, long distance trawlers use single engines. Many commercial fishing boats do as well. I think he would be wise to keep an open mind on this.
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Old 08-07-2012, 08:37 AM   #67
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Being a new trawler captain, I have come to rely on my twin engines. Especially in docking and manuevering. I appreciate the redundency and when I actually had a casualty, I could get back to the dock.

All good things.
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Old 08-07-2012, 09:13 AM   #68
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All the boats I've owned were single engines, outboards or I/O on boats up to 32'. I guess we were just young and foolish daredevils back then. I'd be fine with a single engine boat.
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Old 08-07-2012, 09:15 AM   #69
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Absolutely bareboat charter a week somewhere first. We did the Virgin Islands on a Grand Banks but the Chesapeake has some nice options. It gives you some real life chances to see what you like or don't like. In our case it gave us an incurable disease, called "trawlering". We like you, thought we had 10 years to decide but once we had the bug we couldn't wait. The economy helped... we saw boats asking prices go down 50% in 3 years. Once we got over the fact that we could get the same and in some cases better features in a newer vessel for the same money by giving up the "Grand Banks" name we were there. We wanted glass on the flybridge but we wanted it new so we picked a boat that didn't have it which was less money and added it.

There were other compromises but I'm finding I can live with them or in some cases I was wrong in what I thought I wanted. The things we added weren't that expensive and made the boat "ours".

We like the twins for manuvering and have cruised up and down the Chesapeake all summer on the same tank of gas.
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Old 08-07-2012, 09:27 AM   #70
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Sometimes I think I should just sell the house and buy a bigger boat!

1975 52' Steel Charter/LRC Steel Six Pack Passenger Power Boat For Sale
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Old 08-07-2012, 10:14 AM   #71
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Sometimes I think I should just sell the house and buy a bigger boat!
That boat has some design characteristics that would be good for the PNW (particularly AK, where the boat is located) - but "9' 6" deep" (this might be where the paravanes run?) and "7 ft 7 in draft" would be problematic elsewhere. A turbocharged main with 7,000 hours - even one as low stressed as this one - may be due for some maintenance (though a rebuild kit looks cheap enough). And the exterior maintenance has clearly suffered - I see a fair amount of corrosion, plus look at the water damage from the leading pilothouse windows. And 2500 gallons of fuel tankage is a problem, not a feature - unless you're going to be permanently cruising.

My verdict: bring your checkbook!
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Old 08-07-2012, 10:31 AM   #72
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Trawlering is just the type of boat you are using.

Cruising is usally the activity that many discuss here.

You can cruise in anything....just depends on what amenities you desire to take along and how hard you want to work getting there...rowing, sailing or motoring...(plus others if you want to get carried away)...

So if you don't know if you like cruising you need to do it in many different kinds of boats anyhow. Somemight like cruising at 30 knots...others are fine at six. Some like the journey, some like the distinations and some like both about the same.

So if you don't know if you even like cruising...saying you want a trawler and a specific kind/style at that is kind of silly without lots more investigation.
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Old 08-07-2012, 11:25 AM   #73
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Trawlering is just the type of boat you are using.

Cruising is usally the activity that many discuss here.

You can cruise in anything....just depends on what amenities you desire to take along and how hard you want to work getting there...rowing, sailing or motoring...(plus others if you want to get carried away)...

So if you don't know if you like cruising you need to do it in many different kinds of boats anyhow. Somemight like cruising at 30 knots...others are fine at six. Some like the journey, some like the distinations and some like both about the same.

So if you don't know if you even like cruising...saying you want a trawler and a specific kind/style at that is kind of silly without lots more investigation.

Well said!

The best boat decisions are based on what you want to do with the boat. Imagine yourself using the boat, and make the layout fit your needs.

Do you boat in rainy areas??? Then a outdoors covered place would be great. Do you like to fish? Then a boat with a cockpit might be in order.

The boat should fit your cruising intentions, not the other way around.
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Old 08-07-2012, 11:46 AM   #74
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I have owned loads of boats and twins are great for docking however once we were 70 miles from the coast and lost a engine due to a head gasket, Running on one motor i overheated it and damaged the 2nd engine. Bad call on my part I am looking at a trawler type cruiser now with aft cabin 2 heads nice galley and it had gas twins that i would remove sell or part out and replace with twin 4cly rebuilt diesels . My current trawler is wooden former shrimp boat we have rebuilt thousands of man hours in the end i will have about $20,000 in the complete boat so it is a personal deal what you want what you need and what you can afford. Every boat i have owned had either engine issues or water damage even smoked electrical systems .Or i would not be able to afford boating like we do on a Fixed income.
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Old 08-07-2012, 12:13 PM   #75
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When I was thinking about trawlering, I put an add in Boat/US magazine saying I'd like to be paying crew for on the water trawler experience. We gained valuable insight on those adventures and in most cases payment was refused.
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Old 08-07-2012, 12:47 PM   #76
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That is a great way to understand the abilities of different boats, My father owned 2 or more sportfishing boats as i grew up i thought that 35mph in a 55 ft boat was the norm. Then i took a ICW trip over 900 miles at 12 MPH changed my life slow and easy was fine with me. I still love my center console at 70MPH but for travel 12 MPH 1 GPH fuel burn and a slower lifestyle.
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Old 08-07-2012, 03:09 PM   #77
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Life in the slow lane.
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Old 08-07-2012, 03:48 PM   #78
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It's pretty common when folks ask for a boat recommendation to ask how they plan to use the boat, but if someone has never boated before or has limited boating experience, he or she won't really know how they end up using a boat. I know when I bought my first boat, I never planned on cruising the Atlantic ICW in a trawler.

Even if they think that's what they want to do, considering the substantial investment a turn key, seaworthy boat is, it would be wise to read a lot of boating forums, magazines and books, and talk to a lot of boat owners before narrowing down the choices and options. There are a couple annual boat shows featuring trawlers and larger boats and if possible, attending these and actually boarding the boats would be a good investment.
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Old 08-07-2012, 04:38 PM   #79
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We've talked this one to death years ago and ther'e is no answer because ther'e is no way to get an apples and apples comparison. Too many variables.
But remember if you're going to compare you've got to compare boat w the same amount of total power or you're just mak'in noise. Same type of engine too. Ect ect.

I see you're not talking about twins v/s singles anymore. I must have been on a different page. Sorry.
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Old 08-07-2012, 08:46 PM   #80
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Really good replies as always. We do have experience but all on rivers and lakes with smaller vessels. This time, we will move aboard, live, and cruise the rest if our days away. We love boating and love the water.

Slow and steady is great for us. To me, getting there is half the fun.

I am not at all sold on twins. A single screw is fine but it would be reassuring to have a small Get Home engine just in case. I suppose though that if an engine is well taken care of it should perform just fine. That us what I always did in the past and I have never been let down yet by one.

Great forum as I have said. Much appreciated!!!!
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