disappointed with twin screw fuel economy

Blue Heron said:

Gentlemen, The real question regarding singles or duals should be - 15 or 18 year single Malts?

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Ahhh, the important things in life. Fine wine, quality beer or a good scotch. A pleasant and drinkable 15 year old is fine but will not say no if offered an 18 year aged. Of course there's nothing truly wrong with a quality blend in my book either.

If you find yourself in the Delta region of California for some odd reason send me a PM so we can exchange phone numbers, meet at my boat to research/discuss the issue further.

Seriously though, we spend more money on gas going to and from the boat than we use in the boat.

CPseudonym said:

Ahhh, the important things in life. Fine wine, quality beer or a good scotch. A pleasant and drinkable 15 year old is fine but will not say no if offered an 18 year aged. Of course there's nothing truly wrong with a quality blend in my book either.

If you find yourself in the Delta region of California for some odd reason send me a PM so we can exchange phone numbers, meet at my boat to research/discuss the issue further.

Seriously though, we spend more money on gas going to and from the boat than we use in the boat.

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Craig says

"Seriously though, we spend more money on gas going to and from the boat than we use in the boat"

What on earth are you driv'in Craig?

Thinking of making older boats more efficient frequently brings to mind a dreamboat of mine ..... A 32 GB w twin 27hp 3cyl Yanmars. That's not a wild dream either as so many sailboats have that engine finding one used shouldn't be a problem. And 32 GB boats are fairly numerous too.
Hmmmmm and that gives rise to dreaming of being younger.

Luckily we don't have many of those. Leaving my slip I'm more conscious of our speed, but I make no wake really at those speeds.

I honestly don't recall my actual idle speed, but it's up there. I'm guessing 3-4 knots.

SomeSailor said:

I honestly don't recall my actual idle speed, but it's up there. I'm guessing 3-4 knots.

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I'm the same, 3-4 knots at 600 RPM idle with one engine in gear. I'm closer to 5 knots with both in gear. I usually alternate engines going through the marina, coasting in neutral in between to keep the speed down in the tighter spaces.

manyboats said:

Craig says "Seriously though, we spend more money on gas going to and from the boat than we use in the boat"

What on earth are you driv'in Craig?

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The vehicle driven is not the point of my remark Eric, the distance traveled using our boat is. According to Navionics on my iPhone I'm currently 42.4 nautical miles from the boat, 62 miles driving in the car. We seldom get more than 5 miles from the berth before anchoring, 20 miles each way is a long cruise for us. Granted. I'm a freshwater boater in an admittedly unique boating environment.

I'd love to know how many miles are being put under the keels of forum members boats on an "average" trip? I'd also like to hear how many "average" trips per year are being taken? Many members currently have their boats pulled for the season or have had them on the hard for storage or repair. Still others boats leave the slip once per year if that so I'm sure it varies.

My observation since joining this forum is the overwhelming majority of these boats have not been over 100 miles from home port except for delivery purposes. And if they have been that far afield its an annual or semi-annual trip at best. Let's face it, there's more uses for a boat than long distance cruising although most of us dream about doing it someday.

Craig just Funn'in on the car miles.

Some Sailor and Edelweiss .... it sounds VERY much that you're both considerably over propped. I get rated rpm (3000) at WOT and idle about 900 and have a much slower boat speed at idle even though my Willard has extremely low resistance at less than 4 knots. Willy was over propped when we bought her. Could only get 2750 rpm at WOT. After we took out 1" pitch there was a big difference in idle speed.

Edelweiss how long does it take to warm up your engine so it will idle dependably in gear? 600 rpm idle seems too slow. I set mine up to 8-900 rpm cold to insure that my engine won't quit when shifting gears coming out of the slip. Warm in neutral idle is 1000. If you think that's high consider that my Mitsu is a 3000 rpm engine.

Most diesels right after start are reliable/warm enough to put into gear and idle the vessel....if not something is wrong....

I don't think I've ever had one stall...hundreds of different vessels even in reasonably cold weather (down to 20F)

psneeld said:

Most diesels right after start are reliable/warm enough to put into gear and idle the vessel....if not something is wrong....

I don't think I've ever had one stall...hundreds of different vessels even in reasonably cold weather (down to 20F)

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That's what I was thinking. If it won't reliably idle and shift into gear at 6-700, it's either got blow by, or needs a valve job.

What the heck is a 'come home' system? An outboard? A dinghy?

My sailboat of 29 years had two engines, one diesel, one wind.

Our trawler has twins, and I have motored in on one engine a couple of times, always amazed that the one engine maintained a good speed : fuel consumption ratio. But, I love an alternative source to get me home.

manyboats said:

Edelweiss how long does it take to warm up your engine so it will idle dependably in gear? 600 rpm idle seems too slow. I set mine up to 8-900 rpm cold to insure that my engine won't quit when shifting gears coming out of the slip. Warm in neutral idle is 1000. If you think that's high consider that my Mitsu is a 3000 rpm engine.

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Idles in gear within a minute of cold starting. Engines are 6.354M. Perkins Idle Spec. is 625 in neutral and 2800 WOT and it performs as rated (See below)Double click the thumbnail twice and it will enlarge the image.

manyboats said:

Edelweiss how long does it take to warm up your engine so it will idle dependably in gear?

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?? If a diesel starts it will run ... they are not like a gasoline engine where enrichment devices are required to keep running until the fuel is consistently vaporized.

obthomas said:

I'm going to challenge you that you are a psuedo trawler and not like most of us that are patterned after fishing boats with displacement hulls.

You are describing yourself as a cruiser, maybe a long range cruiser. Planing and so fassssst so un-trawler like .

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Yeah, that prob'ly makes me just a wannabee

In my defense, I can at least say that most things we do with the boat are way more trawler like than sportfish like

-Chris

manyboats said:

Some Sailor and Edelweiss .... it sounds VERY much that you're both considerably over propped. I get rated rpm (3000) at WOT and idle about 900 and have a much slower boat speed at idle even though my Willard has extremely low resistance at less than 4 knots. Willy was over propped when we bought her. Could only get 2750 rpm at WOT. After we took out 1" pitch there was a big difference in idle speed.

Edelweiss how long does it take to warm up your engine so it will idle dependably in gear? 600 rpm idle seems too slow. I set mine up to 8-900 rpm cold to insure that my engine won't quit when shifting gears coming out of the slip. Warm in neutral idle is 1000. If you think that's high consider that my Mitsu is a 3000 rpm engine.

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I idle at around 600 (digital tachs) and don't have any problem with dying when put in gear. In fact, my manuals say not to engage / disengage the transmissions above 800 RPM. I have the original manuals and it hits all the numbers spec'd there.

CPseudonym said:

We seldom get more than 5 miles from the berth before anchoring, 20 miles each way is a long cruise for us.

My observation since joining this forum is the overwhelming majority of these boats have not been over 100 miles from home port except for delivery purposes.

Let's face it, there's more uses for a boat than long distance cruising although most of us dream about doing it someday.

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Couldn't agree more! We boat about the same way. Twenty years ago, we did a lot of cruising but now that we're older, not much at all. ====>

RickB said:

?? If a diesel starts it will run ...

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Geez! Someone actually said it!

sunchaser said:

And those who believe their Floscans are infallible.

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Yes!

I have floscans, and have had them on several boats.

On my current SD boat, I have them calibrated for my fast cruising speed. At that speed they are within 5% or so.

They are not nearly as accurate at displacement speed.

If I calibrated them for displacement speed then they would be inaccurate at fast cruise speed.

Overall, with our mix of cruising speeds the totalizers come out within 10% or so on average. Reading the dial, and then quoting that GPH would not be accurate at all.

The very best measure of fuel consumption, and the one I use, is to operate the boat in a variety of sea states at a fixed RPM, and then use your actual fuel fillup quantities.

RickB said:

?? If a diesel starts it will run ... they are not like a gasoline engine where enrichment devices are required to keep running until the fuel is consistently vaporized.

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More things have to go wrong for a diesel to stop than things that have to go right for a gasoline engine to start.