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Old 15-01-2016, 00:44   #106
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Re: Videos of Anchors Setting

Engine thrust tested.

Panope has a Yanmar 3JH3E, 40 HP engine. The propeller is a fixed, 18 inch diameter X 10.5 inch pitch. The gear reduction box has a ratio of 2.61 in forward gear and a ratio of 3.16 in reverse.

The boat makes 3 times more thrust in forward as it does in reverse at the same ENGINE rpm. I believe that much of this discrepancy is due to the propeller being much less efficient in reverse. Another factor is the higher gear reduction ratio of the reverse gear compared to forward.

Here is a table showing the results:


And here is the video:

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Old 15-01-2016, 08:35   #107
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Re: Videos of Anchors Setting

Same video has above, uploaded to the proper YouTube channel.

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Old 15-01-2016, 15:34   #108
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Re: Videos of Anchors Setting

Your numbers for reverse thrust are similar to mine.

I wrote in post 1447 of nolex 77's thread Photos of Anchors Setting

*****

"...I have a Pacific Seacraft 34. It has a 3HM35F Yanmar engine turning a 17x10 2 blade fixed propeller. The transmission ratio is 2.14 in forward and 2.50 in reverse. The lower propeller speed in reverse really hurts the reverse thrust. With the engine turning at the same speed, the reversing prop pumps less water per unit of time and pumps it at a lower velocity. [F=d(mv)/dt and all that...] In addition the prop has a slight airfoil cross section, so in reverse it is like flying upside down without raising the airplane nose.

I own a 0-2000lb Dillon dynamometer and have measured my reverse bollard pull. I get 110lb at 2000rpm, 170lb at 2500rpm, 240lb at 3000rpm and 300lb at 3500rpm.

There are a couple of magazine articles where the reverse bollard pull of sailboats have been measured with different propellers.

http://www.flexofold.com/upload_dir/...onthly_low.pdf

http://www.propelspecialisten.dk/dow..._test_2008.pdf

https://books.google.com/books?id=yJ...20pull&f=false

They are great evening reads. It is hard to draw solid conclusions from the data as the all the props are not perfectly (or equally) matched to the engines, but there is still lots to learn."

*****

It is comforting that you get similar measured reverse thrust results with a similar engine/clutch/propeller. It is not comforting that the reverse force is so small. My reverse setting force is only a small fraction of the ultimate strength of my anchoring gear and only a small fraction of the force that I bought the gear to resist.

When I back down hard, I am not really testing my anchoring system.
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Old 15-01-2016, 16:59   #109
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Re: Videos of Anchors Setting

Dude, these videos are AWESOME. I'm also really glad that you got your hands on an Excel. I believe it's the only decent convex anchor on the market. I wish it was available in North America when I was looking for an anchor, but the Manson Boss I picked up is doing well.

There must be 30 Deltas in the marina in Port Townsend. Surely someone will lend you one? As one of the most common anchors to be fit to new boats today, I think it's important to do a good test of it.

I have a 45# Manson Boss in Vancouver. I'm willing to take it off my boat and lend it to you, but I have no idea how to get it to you. Ever come up this way? I could get it to a friend in Blaine if that helps and you could pick it up there. It's not a common anchor, but it's one of the few new generation anchors with no roll bar that's available in North America (the only one at the time I bought it only a couple years ago as the excellent Spade was very expensive here at that time).
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Old 15-01-2016, 18:52   #110
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Re: Videos of Anchors Setting

Quote:
Originally Posted by wsmurdoch View Post
Your numbers for reverse thrust are similar to mine.

I wrote in post 1447 of nolex 77's thread Photos of Anchors Setting

*****

"...I have a Pacific Seacraft 34. It has a 3HM35F Yanmar engine turning a 17x10 2 blade fixed propeller. The transmission ratio is 2.14 in forward and 2.50 in reverse. The lower propeller speed in reverse really hurts the reverse thrust. With the engine turning at the same speed, the reversing prop pumps less water per unit of time and pumps it at a lower velocity. [F=d(mv)/dt and all that...] In addition the prop has a slight airfoil cross section, so in reverse it is like flying upside down without raising the airplane nose.

I own a 0-2000lb Dillon dynamometer and have measured my reverse bollard pull. I get 110lb at 2000rpm, 170lb at 2500rpm, 240lb at 3000rpm and 300lb at 3500rpm.

There are a couple of magazine articles where the reverse bollard pull of sailboats have been measured with different propellers.

http://www.flexofold.com/upload_dir/...onthly_low.pdf

http://www.propelspecialisten.dk/dow..._test_2008.pdf

https://books.google.com/books?id=yJ...20pull&f=false

They are great evening reads. It is hard to draw solid conclusions from the data as the all the props are not perfectly (or equally) matched to the engines, but there is still lots to learn."

*****

It is comforting that you get similar measured reverse thrust results with a similar engine/clutch/propeller. It is not comforting that the reverse force is so small. My reverse setting force is only a small fraction of the ultimate strength of my anchoring gear and only a small fraction of the force that I bought the gear to resist.

When I back down hard, I am not really testing my anchoring system.
Actually, for the airplane analogy, it is even worse than you described. Not only would the plane be upside down, you would have to fly it backwards! This means the sharp, trailing edge must now become the leading edge. And sharp leading edges are highly susceptible to aerodynamic/hydrodynamic stall.

I agree that backing down is not a good test of anchor performance/holding. I think this why it may be a good idea to use some momentum when setting the anchor. The abrupt stops and jerks that the boat receives is a good indication of what is really happening.

Steve
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Old 15-01-2016, 19:15   #111
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Re: Videos of Anchors Setting

Quote:
Originally Posted by cwyckham View Post
Dude, these videos are AWESOME. I'm also really glad that you got your hands on an Excel. I believe it's the only decent convex anchor on the market. I wish it was available in North America when I was looking for an anchor, but the Manson Boss I picked up is doing well.

There must be 30 Deltas in the marina in Port Townsend. Surely someone will lend you one? As one of the most common anchors to be fit to new boats today, I think it's important to do a good test of it.

I have a 45# Manson Boss in Vancouver. I'm willing to take it off my boat and lend it to you, but I have no idea how to get it to you. Ever come up this way? I could get it to a friend in Blaine if that helps and you could pick it up there. It's not a common anchor, but it's one of the few new generation anchors with no roll bar that's available in North America (the only one at the time I bought it only a couple years ago as the excellent Spade was very expensive here at that time).
Thanks Chris,

I am just now planning a trip North to Desolation Sound but this will not occur until Summer time. And by then, I very well may be burned out on anchors. But you never know...........

Steve
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Old 19-01-2016, 20:04   #112
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Re: Videos of Anchors Setting

Today I tested the Excel at the Sand/Gravel site (Point Hudson). A fair amount of current was running and somehow this has once again resulted in the camera becoming fouled for portions of the videos. Fortunately, the new camera mounts is basically indestructible so no damage to it or the camera.

Steve

Video #33
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Old 19-01-2016, 21:33   #113
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Re: Videos of Anchors Setting

Here is the Excel at the same Sand/gravel site but this time with 2.5 to 1 scope.

Steve

Video #34

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Old 19-01-2016, 23:18   #114
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Re: Videos of Anchors Setting

45 pound Mantus Anchor.

The anchor has the largest physical dimensions of this group of 45 pound anchors. When stowed, the toe does extend aft of Panope's stem. However, the small hull guard (that was custom made for the Manson Supreme) works perfectly to protect the hull paint.



First test is at the "normal" test area of "sandy mud". 3.5 to 1 scope.

Steve

Video #35
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Old 20-01-2016, 03:15   #115
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Re: Videos of Anchors Setting

Good stuff, thanks!
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Old 20-01-2016, 04:47   #116
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Re: Videos of Anchors Setting

Impressive how well the new gen anchors work. That Excel and the Mantus seemed to just dissappear into the mud. Its pretty clear from these videos that the CQR and Bruce anchors of old are totally outclassed, and it seems hard to really pick a fault with any of the new Gen anchors. Thanks for doing all this work, and posting the results, really useful stuff.
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Old 20-01-2016, 06:39   #117
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Re: Videos of Anchors Setting

Snow, These new anchors really are a a great improvement. I am planning another "commentary" video were I analyze the results of the Manson, Spade, Excel, and the Mantus. These anchors are all excellent but I will do my best to pick (nit-pick) out any faults that I find.

Here is the Mantus at 2.5 to 1 scope.

Steve

Video #36

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Old 20-01-2016, 11:00   #118
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Re: Videos of Anchors Setting

Steve, again thanks for the great effort. These videos are truly informative. Together with Noelex's thread we have a great resource.


S/V B'Shert
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Old 20-01-2016, 15:00   #119
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Re: Videos of Anchors Setting

More great cruising cinematography Steve

How are you retrieving the rode? I ask becuz I wonder if you can give us an impression of which anchors are more difficult to break free of the bottom?

I'm assuming an anchor that is more difficult to break out, is a better holding anchor in that it has penetrated deeper into the substrate.
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Old 20-01-2016, 16:59   #120
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Re: Videos of Anchors Setting

Thanks BB,

Quote:
Originally Posted by BigBeakie View Post
More great cruising cinematography Steve

How are you retrieving the rode? I ask becuz I wonder if you can give us an impression of which anchors are more difficult to break free of the bottom?
I use a Simpson Lawrence 555 manual windlass. The Fabulous Four (Manson, Spade, Excel, Mantus) all have a similar "feel" (lots of force required) when retrieving. Maybe, just maybe the Manson requires a bit more breakout force than the others.

The anchor that requires the greatest breakout force per pound is without question, the Fortress. My 10 pound, FX-16 needs nearly the same force to retrieve as the 45 pound Fab Four.


I'm assuming an anchor that is more difficult to break out, is a better holding anchor in that it has penetrated deeper into the substrate.That's a tough assumption to make. For example, an anchor with a short shank will require more breakout force than a similar anchor with a longer shank (leverage will be better with long shank when pulling vertically). However, shank length will have little affect on holding power as the normal pull will be inline with the shank.

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