What is Too Much Rode?

[Sunsetrider]

Not real experienced at anchoring yet, just local drop nd eat. For my upcoming voyage south in my 25 foot pocket trawler I have as my main, a 22 lb fake rocna with 15 ft chain and 150 feet nylon rode. In the hold I have a 12 lb claw with 10 ft chain and 100 ft nylon, and will get a danforth as well. 22 lb claw at home. Lewmar horizonal windlass because I’ll be single-handed.

Does this arrangement seem sensible? Most of you have fAr larger vessels, I am trying to make sense of the comments as relates to my situation.

[a64pilot]

I’d say try to go all chain for your main depending on where your going, coral is unforgiving of Nylon for instance, and instead of a Danforth, see if you can get a Fortress.
Yes they look similar, but perform differently or so I am told.

[danielamartindm]

The only time you can have too much rode out is in a crowded anchorage, when using so much more than your neighbors can cause swinging issues. The rest of the time, more rode=more security and better sleep.

[zboss]

So... mud. The problem with mud is that it was a often very thin at he top but just thick enough that it returns a depth that is less than the depth that can hold an anchor. So, while you think you might be in 10 feet of water you could be in an effective 13-15 feet of water, as far as your anchor is concerned. The best bet for mud is to drop the anchor and let it sit for an hour or two before even attempting to back down on it. Let the wind do the backing down.

[thinwater]

Originally Posted by zboss

So... mud. The problem with mud is that it was a often very thin at he top but just thick enough that it returns a depth that is less than the depth that can hold an anchor. So, while you think you might be in 10 feet of water you could be in an effective 13-15 feet of water, as far as your anchor is concerned....

This is a subtle point that is easy to miss. In really soft mud, your anchor is at least 2 feet down and perhaps 3-4. In the case of 8' of water, you need to remember to add 3' for freeboard and 3 feet for dive, making it 14 feet. Suddenly 100 feet (7:1) is not extreme at all. It's not quite that simple, since the chain takes on a reverse curve, but there are also other factors, so this is close enough for a forum post.

Another interesting thing about chain cateneray and shock absorption. If you look at the math, it isn't so much about the scope or the depth of the water, but in having enough chain out. It is the weight of chain you are lifting. Less than 100 feet is nearly always questionable if the bottom is questionable. Over 250 feet will always give a nice cushion and keep the chain down. Heavier chain will reduce this a little, but not quite in proportion. If you don't want to put out 250 feet, you are going to need a snubber if it actually blows (25 knots is not blowing). Again, I have over simplified on purpose.

[Dave_S]

Originally Posted by a64pilot

Still waiting on Space-X launch, but I bet not today, not in this wind.
What are a rockets wind limitations?

Really - So jealous, how far from it are you ?

[Mithril Bham]

Should be no need to back down that hard. Anchor will set itself. Backing down too hard can stress tackle. Sounds like you were anchored in the wrong place.

[valhalla360]

Originally Posted by 44'cruisingcat

And do you really think a light boat makes it's anchor work harder than a heavy one?

Actually, it's quite possible.

The force on the anchor line is a function of both the weight and the speed of the boat when the anchor line pulls it to a stop.

Assuming no current or other confounding complications:
- A heavy full keel boat sitting deep in the water will have less windage and more water resistance limiting the boat speed when the rode stops the boat.
- A light boat (like a catamaran) that sits mostly above the water line, will have lots of windage and very little below the water to slow it down.

So if you have:
- A 10,000kg deep keel boat that reaches a peak speed of 0.25m/s...total momentum is 2500kg-m/s
- A 5,000kg catamaran that reaches 1.0m/s...total momentum 5000kg-m/s

Actual force depends on the "stretch" in the anchor chain/rode but it generally correlates pretty well to the momentum. (I exaggerated the figures to make the math clear but it is definitely possible for a lighter boat to have higher loads)

[Fuss]

Look at all these posts over the history of cruisers forum, it's so overthought that the very basics are lost in the confusion.

Then complex anchoring strategies are added to the mix to confuse even more.

No boat should ever drag in 25-30 kts of wind. If you think you can stress your ground tackle by backing down on it , then it's too small.
If you think that you have to let your anchor settle before backing down on it, how is it ever going to work in an emergency.

Just back down on it and work up to full power while ensuring it's not dragging. If it's dragging, then pull it up and re anchor with more scope.....repeat until not dragging.... or change location.....after a few weeks you will always anchor with enough scope out and you will not be dragging in 25-30kts.

If you are still complaining that its not working and full revs causes dragging then get a bigger anchor and repeat.

It really is that simple.

[44'cruisingcat]

Originally Posted by valhalla360

Actually, it's quite possible.

The force on the anchor line is a function of both the weight and the speed of the boat when the anchor line pulls it to a stop.

Assuming no current or other confounding complications:
- A heavy full keel boat sitting deep in the water will have less windage and more water resistance limiting the boat speed when the rode stops the boat.
- A light boat (like a catamaran) that sits mostly above the water line, will have lots of windage and very little below the water to slow it down.

So if you have:
- A 10,000kg deep keel boat that reaches a peak speed of 0.25m/s...total momentum is 2500kg-m/s
- A 5,000kg catamaran that reaches 1.0m/s...total momentum 5000kg-m/s

Actual force depends on the "stretch" in the anchor chain/rode but it generally correlates pretty well to the momentum. (I exaggerated the figures to make the math clear but it is definitely possible for a lighter boat to have higher loads)

Guess the guys at Rocna got it wrong then...

Anyway we weren't talking about two massively different boats. We were talking about making the same boat a little lighter.

And yes you certainly did exaggerate the figures. The cat supposedly got up to 3.6 knots while anchored? I guess if you're willing to invent ridiculous enough numbers you could "prove" anything.

[zboss]

Originally Posted by Fuss

If you think that you have to let your anchor settle before backing down on it, how is it ever going to work in an emergency.

Very much disagree with this. There are often many types and layers to mud, with only the bottom most layer containing silt with enough tenacity to hold any anchor.

We have a lot of experience with this having anchored out in areas with muddy bottoms perhaps 400 or so days in the last 2 or 3 years.

Especially in areas that are near paper mills and in areas that are in areas surrounded by large amounts of foliage and don’t experience heavy current, you will be challenged to find a spot suitable to anchor without waiting for your anchor to settle.

If you are in an emergency you can reduce the time needed to back down but if you don’t wait you are experiencing false economy of your method.

[valhalla360]

Originally Posted by 44'cruisingcat

Guess the guys at Rocna got it wrong then...

Anyway we weren't talking about two massively different boats. We were talking about making the same boat a little lighter.

And yes you certainly did exaggerate the figures. The cat supposedly got up to 3.6 knots while anchored? I guess if you're willing to invent ridiculous enough numbers you could "prove" anything.

I exaggerated to demonstrate a principal and clarified that in the original post. If you want to play with the numbers you can do a 10,000 vs 8,000kg boat and lower speeds and come to the same conclusion that yes, a lighter boat definitely can have higher loads and this is supported by the fact that light boats often complain of dancing around on the anchor in windy conditions while heavy boats don't move around nearly as much.

You on the other hand implied a fraction of a percent difference in the weight of a boat will make a measurable difference the loads on the anchor.

Now who's inventing ridiculous stuff?

[Tortuga's Lie]

I agree with Jim and others: you need a wide Danforth style anchor in that soup-mud like a Fortress, the Rocna is plowing through it and not getting down to the hardpan underneath the mud. If you can, as others have suggested, use a tandem set up with the danforth/fortress ahead of the Rocna attached with maybe 10 feet of chain connecting the two.
Rocnas and other next-gen anchors are great all-purpose anchors but they do have their Achilles heel: really soft mud. I use a Mantus as my primary but keep a Fortress for situations as you are describing.

[sailorboy1]

Originally Posted by a64pilot

Well whatever my Brit neighbor is using for an anchor isn’t holding either, they just moved and reset theirs too.
I’m leaning towards a poor holding bottom, although I’m still holding now, fingers crossed, cause I don’t want to do the anchor drill at 3 am.

maybe time to just move to somewhere else

[Jason Flare]

Originally Posted by sailorboy1

maybe time to just move to somewhere else

Maybe a basement in Missouri?