How far can you go?

[Factor]

Or buy a boat that sails well and motoring range doesn't matter

[tuskie]

Originally Posted by Factor

Or buy a boat that sails well and motoring range doesn't matter

That's not really helpful. Can the boats that you sell sail in calm conditions?

[tuskie]

Lagoon 400 fitted with 2 X 40hp Yanmar 3JH5E engines, saildrives with 3 blade Flexofold props. Two 200 L tanks plus 60 L reserve in jerry cans. Fuel consumption 2 L/hr each @ 1800 rpm. Speed in calm conditions with clean hulls: one engine 5.0 knots, two 6.5 knots.
Range from 400 L on one engine is approx 1000 nm.

[Factor]

Originally Posted by tuskie

That's not really helpful. Can the boats that you sell sail in calm conditions?

My last Cat had 300 hours on the engines when I sold it after 5 years, and we went far and wide on it as well as using it locally two or three times a week. Your comment about calm is of course irrelevant, it doesn't take long to count the days where there was absolutely no wind at all. What matters is how well a boat can sail in 10 knots or less, withe the right sails and some attention to detail, many boats can actually sail okay in that, in that 8-10 knots of breeze the old 1000Xl could do 5 up wind, 8 reaching and 6.6 broad reaching, (Job or scrececher or spinnaker and good roachy main)so yeah I sailed on days many boats were motoring, sailboat hull design is inefficient for motoring, if people are concerned about motoring they should buy a motor boat.

I am old enough to recall that engines on boats were once referred to as auxiliaries.

[ransflyer]

Thanks to everyone for your input.

I think tuskie's post is proof that less HP can be more efficient, i.e. a couple 40 HP engines (rather than two 55 HP) will get better mileage, especially if you can get by with just one running.

Tips and tricks to improve motoring range or mileage was my purpose in posting, but I also wanted to hear as many specifics as possible. What is your longest measured motoring run? How long did it take? How much diesel did you use? What were the conditions?

I certainly agree that sailing uses less fuel than motoring and is absolutely my preference, but that wasn't the original question. I'd love a lighter, better sailing setup but there are tradeoffs like making sure my wife is happy and comfortable.

[tuskie]

Originally Posted by Factor

Your comment about calm is of course irrelevant, it doesn't take long to count the days where there was absolutely no wind at all.

We're north of Cairns at the moment (25/9/2016) and it is calm, no wind, zero breeze. Yesterday was less than 4 knots all day, and so was the day before.
Yes mate, calm happens. Talk to cruisers who have spent long periods in SE Asia and see their engine hours. The alternative is to wait very long periods of time for favourable winds. Do your boats carry enough beer for that?

[ransflyer]

tuskie,

Isn't beer much lighter than diesel? Sorry that was off topic.

[StuM]

Originally Posted by ransflyer

tuskie,

Isn't beer much lighter than diesel? Sorry that was off topic.

Nope, diesel is about 15-20% lighter than beer.

Specific Gravity:
Beer: Slightly over 1 (1.01 - 1.05)
Diesel: 0.83 (approx, it varies quite a bit)

Still OT, but we can't let errors remain uncorrected, can we?

[tuskie]

LOL. Good to have adequate supplies of both diesel and beer. And rum, and wine. And water and electricity. ... Hey, StuM, do you get much calm weather up your way?

I think the difference is that we have a sailing boat to live on and take us to nice places. Others, have sailing boats for, well, sailing. We go to places when and where we think the weather will be nice. Not rainy, cold or too windy. Isn't that what cruising is all about? Sailors go sailing when the wind is right, usually. Unless they're racers, who go when and where the race starts. The bottom line is that we cruisers see a lot more calm (arbitrarily less than 5 knots) than sailor/racers do. Even though by far the majority of our seamiles are done under sail, we still need and use motors more.

At the moment we are out on the Great Barrier Reef, spearfishing and SCUBA diving (but not at the same time!). We chose to go out here because we hoped for calm weather. We have to motor between reefs because it is now blowing all of 2.6 kts TWS. We coud have waited in the river for a bit more wind but who would want to miss this glorious calm? Some "real sailors", perhaps?

[downunder]

Originally Posted by tuskie

LOL. Good to have adequate supplies of both diesel and beer. And rum, and wine. And water and electricity. ... Hey, StuM, do you get much calm weather up your way?

I think the difference is that we have a sailing boat to live on and take us to nice places. Others, have sailing boats for, well, sailing. We go to places when and where we think the weather will be nice. Not rainy, cold or too windy. Isn't that what cruising is all about? Sailors go sailing when the wind is right, usually. Unless they're racers, who go when and where the race starts. The bottom line is that we cruisers see a lot more calm (arbitrarily less than 5 knots) than sailor/racers do. Even though by far the majority of our seamiles are done under sail, we still need and use motors more.

At the moment we are out on the Great Barrier Reef, spearfishing and SCUBA diving (but not at the same time!). We chose to go out here because we hoped for calm weather. We have to motor between reefs because it is now blowing all of 2.6 kts TWS. We coud have waited in the river for a bit more wind but who would want to miss this glorious calm? Some "real sailors", perhaps?

This is the weather divers seek and undoubtedly for safety reasons one will use more fuel navigating amongst the reefs.

Many of the real sailors avoid the GBR like the plague.

Guess you will stop in on the Cod Hole whilst you are in the area??

Hold it according to some all the coral north of Cairns has been destroyed by coral bleaching. diving must be terrible.

[ransflyer]

StuM,

I was making a joke about all those little bubbles in beer, but you are definitely right and I was wrong.

Back to topic:

What about other ways to get more miles from your tank?

1. Is a prop and straight shaft more efficient than the extra gears etc. in a sail drive?
2. Is there one brand of folding prop that will give me more distance per gallon? I assume if only one engine is pushing, having the other prop folded will help a measureable? amount.
3. What prop pitch or design will allow good engine efficiency (operating in the best part of the power band) while pushing the boat at say 65% of hull speed? Or is it even possible to figure that out with so many variables?
4. Is all this just not really going to make much difference?

[admiralslater]

We looked and made an offer on a fantastic custom Crowther 46 called Key of D . The seller had it built to his specs .and one of the features was the two to three thousand mile motoring range.It was a while ago so the details are hazey. The hulls below the cabin soles on each side where fuel tanks . It carried I think 6 to 7 hundred gallons the idea was that he could always get to shore from just about any where at low speed on one engine. Don't ask me all the details as I don't remember. The boat was well thought out and the skipper had 10s of thousand s of miles on her .He was not a nut job . Before you ask it was just not the right boat for us


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[downunder]

Originally Posted by admiralslater

We looked and made an offer on a fantastic custom Crowther 46 called Key of D . The seller had it built to his specs .and one of the features was the two to three thousand mile motoring range.It was a while ago so the details are hazey. The hulls below the cabin soles on each side where fuel tanks . It carried I think 6 to 7 hundred gallons the idea was that he could always get to shore from just about any where at low speed on one engine. Don't ask me all the details as I don't remember. The boat was well thought out and the skipper had 10s of thousand s of miles on her .He was not a nut job . Before you ask it was just not the right boat for us


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Very practical vessel for cruising much of the Pacific where there are light winds, currents and poor and variable uality fuel. Tanks do not always have to be filled.

[mikereed100]

We have a 46' custom cat, 9 tons, 2 Nanni 3.30's, 29hp. In flat seas with no wind or current we do about 5 knots at 2,400 rpm burning 1.75 liters on one engine. With two 300 liter tanks this gives us about 1,700 miles range. We are pretty fanatical about sailing whenever possible and can make 4 knots with 4 knots TWS on the beam. However, we seem to spend a lot of time in areas with either no wind or very fluky wind such as SE Asia, the Inside Passage and the Sea of Cortez so this range has come in handy.

[a64pilot]

From a pure motoring perspective, nothing is as efficient as a fixed two blade prop, three will give you more "bite" and a smoother prop, but that third blade is drag, no free lunch.
However, it is drag if you have two and are only motoring one one, and is not variable so that it can remain efficient at varying speeds and power, for that you need a variable pitch prop, but they don't make ones for small boats I don't think.
So that takes us to the Autoprop, which is a self pitching, feathering prop, it excels in motor sailing, my IP is not speed boat, I can manage 3 kts or so in six kts of wind on the beam, but I can motorsail at 1000 RPM at 6.5 kts in 5 to 6 kts of wind, something that with no sails up takes 2000 RPM. I think my fuel burn is about 1/3 a gl an hour at 1000 RPM, I know it's 1 GPH at 2000 RPM.
So for a pure efficiency standpoint and motoring slowly for best MPG or motor sailing, due to its ability to change pitch according to conditions, I think the Autoprop is as good as us small boat guys can get.

How far can I go? More than anything else that is going to be a question of how much fuel am I allowed to stack on deck and how slow are we willing to go. Let me toss a couple of 100 gl bladders up there and the answer will be quite a long ways.


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