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Old 05-23-2019, 10:54 PM   #1
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Vanes

https://www.powerandmotoryacht.com/b...uel-efficiency

Can’t delete this post/thread.
Was an article “Hull Vanes and fuel efficiency” but I can’t post or delete.
It’s in that mag if anyone cares to search.
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Old 05-24-2019, 11:11 AM   #2
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Insequent came to my rescue and activated the link.
Thank you sir.

I tried to post this several months ago but had even more troubles posting.

Now my TF friends can see what it’s all about.

Basically it’s an adjustable afterplane that gives lift to the stern of a vessel reducing or preventing squatting. A bit like trim tabs but lt seems w far less drag. The other article I saw the Vanes were being used on ships .. not boats.
There has been various discussions in the past about the difference in efficiency of SD hulls and FD hulls. The vanes narrow the gap. But it dosn’t look like an inexpensive contrivance at all so may never be applicable to small boats like rec trawlers.

After reading the link I was surprised that the vane was not articulated like an airplane’s elevator or a boat’s rudder. It’s fixed.

Another think that is interesting is that the vane is actually a foil. Like an aircraft’s wing the top surface has more camber fwd that causes the lift. At this point I don’t see why they call it a “vane”. “foil” may be more appropriate IMO. Or even a wing.

Another interesting thing is the ability of the vane to impart a forward thrusting force to the ship or boat. Sounds much like the ability of a sailboat’s sail to impart fwd force to the sailboat.
There would be three resulting forces resulting from the vane. Back (drag) and up. Part of the up force is back (drag from the parasite friction and lift from the after section of the “foil” lifting up and a bit back.) Probably in the vicinity of the top camber the force is straight up. Bur fwd of that point the up force is/would be vectored not only up but fwd as well. Like the sail on a sailboat.

At first I thought the vane was to control (somewhat) the attitude of the vessel like it would do if the vane wasn’t a foil but a flat plate like the rudder on my Willard boat. But the fixed nature on the vane and the foil take it to a different level.

Anyway I thought it would be interesting for TF discussion and it’s probably remotely possible these vanes may find their way to rec trawlers.
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Old 05-24-2019, 11:19 AM   #3
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Interesting idea but it looks like it mostly applies to faster boats than what most of us use. But the fuel savings do look nice.
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Old 05-24-2019, 12:02 PM   #4
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Comodave,
It seems right in the SD range of trawlers as I recall.
12 to 18 knots were mentioned in the article.
And with aircraft wings things like the shape and camber height can vary the speed where the foil works well. Think of the airfoil of human powered aircraft ... really slow.
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Old 05-24-2019, 01:16 PM   #5
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Yes, my boat will do 17 knots but I never run it above about 9 so the vane probably wouldn’t help, except to lighten my wallet. Where it would shine is in commercial vessels that run every day all day.
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Old 05-24-2019, 01:30 PM   #6
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Old 05-24-2019, 03:48 PM   #7
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Holy cow Tad I had no idea they went back that far.
The first I saw of this was (I think) on you tube .. a video. But it was about freighters having them not small boats.

Well since the’ve been around that long if they were cost effective one would think they would be more prolific. Oh well .. thought it was interesting.

Are hydrofoils flat like sheet metal or do they create lift from other than from angle of attack. As in a piece of sheetmetal. These vanes actually create a fwd force greater than their drag ... I think.
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