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Old 16-10-2012, 11:23   #31
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Re: Outboard Powered Circumnavigation

Roy,

Doing an outboard power circumnavigation on a displacement boat is certainly possible, and not really all that difficult. At least relative to doing it at planing speeds.

Just chop the drive leg off, replace it with a sail drive, drop it in an outboard well, add appropriate sized and pitched prop, then load up a bunch of fuel. It may be an expensive way to get around but I don't see anything particularly difficult about it.
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Old 17-10-2012, 10:30   #32
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Re: Outboard Powered Circumnavigation

Umm, let me get this straight... 1989 to 2012 is, what, 23 years? And let's see, what technologies were commonly available? And how many folks have attempted it since then? I think it is far easier to criticize and denigrate the actual achievements of those who took risks and succeeded, than it is to leave the keyboard and the dock and actually participate in a genuine adventure. I think you are out of place in your comments. You really need to get out into the world yourself and reduce your idle chatter. it will give you the street creds that you are risking with this line of discussion. The original poster is clearly looking for an adventure, and was asking if anyone had done anything similar to his dream. The dream is the first step. The research is the second. The building and prep are the third. Then, going for it, risking failure or even worse, is what passes before our eyes as we are having our last moments. Nobody remembers the killjoy, the naysayer, or the doom and gloom prophet. You get it?
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Old 17-10-2012, 11:03   #33
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Re: Outboard Powered Circumnavigation

Roy,

You have no idea what type of sailing or boating I have, and I won't go through my résumé here. But I have been directly involved in a number of record setting attempts, and worked with a number of major racing programs, and distance attempts.

You are right that the first step is to dream, the next step is to identify what people before you have tried, and what worked and what didn't. The next step is to see what technology is out there, and what would have to be created to make an attempt technically possible.

Right now the state of the technology is such that an outboard cannot cross the Atlantic at planning speed. This isn't an opinion, it is simple fact. Uscg like saying I want to take a balloon to the moon might be a dream, but that doesn't make it remotely technically possible.

The fact that the OP suggested a record attempt that is currently technically impossible doesn't bother me, it is that he has spent so little time even trying to figure out where the state of the art technology is, and what he could reasonably expect to need to create to do so.

From the bottom up outboards are designed in such a way as to ignore fuel efficiency. They have other advantages, but for this concept the OP has intentionally selected the worst tool for the job, and then made the attempt all about trying to force it into compliance.

So lets look at the problems an outboard presents to this type of attempt

1) prop efficiency is directly related to prop size. The larger the prop is the more efficient it can be. But an outboard is inherently limited in size because of the leingth of the drive leg, and the cavitation plate.

2) the gearing hub and drive leg create massive drag at high speeds. Again this can't be removed, because of the inherent design of the thing

3) planing is incredibly fuel inefficient. Because they require the motor to produce enough power to not just drive the boat, but also to lift it.

4) outboards are severely limited in the size of the vessel they can power at planning speeds.

So what can we do to fix these problems... Well 1) can be amelorated by adding a deeper drive leg, but at the cost of huge parasitic drag from the extra wetted surface. 2) can be improved by shortening the drive leg, and removing it from the water, but this negatively effects 1). 3) can be eliminated by slowing down, but this is outside the attempts challenge. 4) restricts the size of the boat which also restricts the available fuel capacity, it is this relatively huge fuel capacity that is required because of the inherent limitations of 1-3 above. Fix the fuel efficiency problem and there may be some hope.

But there is no way forward within the design limitations placed on the challenge. Because the OP has specifically selected equipment that is inherently a poor choice to try this.


If instead he had asked what it would take to beat a powered distance record, we could be talking about different designes, and realistic technology to implement to achieve that. Realistically the cheapest way is to design a larger version of what currently holds the record, or try and find a design that is more efficient that the current holder.
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Old 17-10-2012, 11:12   #34
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Re: Outboard Powered Circumnavigation

Again, let's review the facts (as I see them): San Francisco to Oahu is about 2200 miles (or more), 8 1/2 days is about 200 hours. That means about 11 knots average speed. The vessel, deliberately, had a planing hull and was built with high strength/low weight materials, and had a waterline of about 40 feet. Using the math, that gives us a planing speed of just under 9 knots. Strikes me as pretty efficient use of less than 400 gallons of diesel, doesn't it?

I failed to mention that, for the first half of the trip, we had head winds, not the trades we had hoped for. That got our attention as we began to consume more fuel than anticipated. Thank goodness we dealt with this using our seamanship training and adjusted course and speed to match the prevailing conditions. Still, we averaged the speeds and fuel economy to succeed with left over fuel.
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Old 17-10-2012, 11:28   #35
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Re: Outboard Powered Circumnavigation

The Yanmar Endevor was not a planning hull. Is was an insainly low prismatic coefficient displacement hull. This was rejected by the OP when he indicated he wanted to be planning.

Secondly the Endevor had a cruising speed of 8.33kn, and a top speed of 11kn. Assuming your numbers are correct, then she had pretty significant current or wind assist.

Is it possible to build a boat powered by an outboard that could break this record? Sure. Build it 100' long with a waterline width of 5'. Then put outriggers on it to keep it upright. The 20:1 leingth to width ration would give a displacement speed far in excess of what would be needed (though not to break the outright powered speed record). Even a 40' boat with a waterline leingth of around 4' would give a displacement speed far in excess of the stupid 'nominal hull speed formula' most sailors use, which has no relationship to anything in the real world.

But none of that meets the limitations of the OP. he specifically indicated planning. And I stand by the fact that no planning hull can carry enough fuel for this attempt. Unless they have a nuclear reactor on board.

If I am wrong, I would love to see the numbers on a boat because it is something I am unaware of. But the Endevor isn't it.

You need plaining, not efficient displacement, outboard powered, and a range of let's say 2000 miles.
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Old 17-10-2012, 11:34   #36
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Re: Outboard Powered Circumnavigation

Somewhere in my dim memory, i recall that back in the sixties, mercury wanted to prove their outboards could run 1000 hours non-stop. They rigeed at boat and ran it it in big circles at full speed around at track, switching drivers and fuel tanks at full speed. The engines survived no problems.

1000 hours at say 15 knots means 15000 nautical miles ormsay about hallf way round (not quite).

No reason it can't be done if organized as above. But requires a huge sponsor purse, lots of drivers, good weather, and luck.

I doubt if any of the major manufacturers want to underwrite this, but first step is to ask them......
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Old 17-10-2012, 11:40   #37
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Re: Outboard Powered Circumnavigation

Fact check: Yanmar Endeavor was a trimaran powerboat with planing hull configuration, designed to use the specific engines and props chosen. If you need confirmation, I suggest you contact the designer. The figures don't lie. We probably would have averaged the design speed had we encountered less adverse winds and seas. Still, we did it. That's hard to deny.
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Old 17-10-2012, 12:22   #38
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Re: Outboard Powered Circumnavigation

Quote:
Originally Posted by biltong View Post
Some years ago, a Zodiac RIB with a GRP cabin and 75HP Yanmar or Tohatsu diesel outboard stopped in Knysna South Africa and their aim was to circumnavigate using Soy Diesel. It seems that they had drums dropped off at designated stops along the way. Not sure where they came from or if they ever completed their goal. Anyone else have any info on this? Sometime in the late 1990's.
Guy called Brian I think:

I used 100% biodiesel as the exclusive fuel during a 2-year, 35,000 mile circumnavigation of the world in a 24' Zodiac Hurricane about 10 years ago. It worked great and I had no technical or performance problems with it whatsoever. It's far less polluting for the air and water, and is a pleasure to use because diesel smell is eliminated entirely. I would recommend it highly over petroleum diesel in any application.
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Old 17-10-2012, 12:35   #39
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Re: Outboard Powered Circumnavigation

There was also Enda, the first person to cross the Alantic by RIB is Enda O'Coineen about 1982, he sailed and motored.

I met him a few years later. He wore a wetsuit for most of the trip which rubbed him badly.

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Old 17-10-2012, 13:07   #40
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Re: Outboard Powered Circumnavigation

Sunrider was powered by a 180hp Mercruiser diesel stern drive. And did in fact have supply vessels meet him offshore for underway refueling. While still a rough trip, this would generally disqualify it from the record books, since records usually require the boat to be self contained.


Edna as you mentioned sailed and motored.

Roy,

I don't doubt the boat did it, I just don't understand the relevance to this conversation. The OP wanted to do it in a plaining boat, operating at planing speeds. The Yanmar Endevor was a fast displacement design. They are two completely different things. It's like saying you can tow an 40 shipping container behind a miata, because F-350 duelies have moved them around before... Yes they are both vehicles, but radically different things.
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