Lesson Learned: When a Squall Comes Into an Anchorage

[impi]

Originally Posted by callmecrazy

I'm no expert, but I don't think the scope was the issue. Considering the multitude of other boats in the anchorage with similar scope. I find it very hard to believe that 4 more feet of scope would prevent the boat from dragging across the entire anchorage....

Sounds more like a fouled anchor, wind/current shift 180 degrees, boat drifts over anchor pulling it out (the OP's original conclusion, except it didn't matter that he let out more scope), anchor doesn't reset itself. Sounds very typical to me.

Makes sense!

[SailPenelope]

Related story here:

We were anchored at Santa Barbara island, here in So Cal. We were the last boat to arrive, we found the most open spot, anchored, and miraculously, ended up exactly where we wanted to be, no close neighbors. We have all chain, I think we did 4:1 scope, maybe more. I think once you've backed down and it's set (plow anchor), with chain, it runs along the bottom and comes straight up. I've found we can turn around completely at night, and still have not moved. I think we just rotate on it.

Anyway, as we went to bed, I noticed a boat moving around a bit.....wasn't surprised later that night to wake up with the boat thumping alongside. We pushed it off (apparently no one aboard) and it moved off. Went back to bed, and it happened again in the morning, so we left.

No storm conditions, no harm done. No one did anything wrong here. The other boat had rode with a lot of scope.....and as the conditions changed (wind died), the boat started wandering on slack line. We stayed put on our chain. But we were the last to arrive, were afraid we would be blamed, so we did leave. I think there can be such a thing as too much scope.

[callmecrazy]

More info about slack lines in the rode (ie: drifing over anchor) read here.

Obviously you can't always use a bahamiam moor. but I think it's a good enough cause to upgrade to a modern anchor (manson/rocna) that resets itself easily.

Also, obviously, heavier chain rode will help compared to lighter rope. Many anchors will stay set within a 180 degree turn only because the chain is doing more work than the anchor.

[engele]

Ganges can be crowded, but there is always room on the outside. We have always had excellent luck there. I think the scope criticisms are a bit unrealistic. In the gulf islands in general there are far too many people to put out 7:1 in many cases. It might be time to consider upsizing your anchor though and going to all chain. You probably also want to make sure you are not unsetting your anchor when you let more out (so slows good, and maybe a test tug after to check the set). Best of luck in the future and Im glad to hear it all worked out okay.

[SailPenelope]

Clarification, if needed....in the story I posted about the situation at Santa Barbara island....I think the other boats anchor never dragged.....it's just that the rode went slack.

[SailPenelope]

Thank you Callmecrazy! Great site, good read. Adding to my bookmarks.

[cwyckham]

Isn't the dock in Ganges free for short stays? Then you can get the heck out of dodge and anchor in Glenthorne Passage overnight.

[Elysium]

Thanks for the web link Crazy...that's awesome. As always I am just so grateful for all the knowledge that people are willing to share on this forum. I have (only) been sailing for 16 years and I honestly think that since joining this forum I have learned more in the past year than all previous years. Textbooks are one thing, but the huge range of perspective you get here is what's really key.

Many of you will be familiar with Mainsail and his extremely knowledgeable posts on this and other forums. Here is his link to his info on anchoring and scope. It's very thorough. He also has some posts out there regarding anchor selection.
I'm solidified in switching to the Manson Supreme (25# galvanised). I know there are plenty of Bruce haters out there, but they do work well in BC waters. In my 16 years, this is the first time I have dragged it. And I've watched plenty of boats ghost past me in those middle-of-the-night blows. However - bring on the new technology!!!!!

[Elysium]

Originally Posted by cwyckham

Isn't the dock in Ganges free for short stays? Then you can get the heck out of dodge and anchor in Glenthorne Passage overnight.

Another great point. Especially with guests on board. I didn't know that about Ganges....but it is certainly true at other locations in the Gulf Islands. (Poet's Cove, etc.) A lot has changed in Ganges over the past few years, but it never hurts to ask.

[capn_billl]

Reset anchor after making a rode change, check! Check rode tension after major wind shift, check!

I use a Bruce in mud, you can't blame the anchor. Back down hard with lots of scope to bury it. I have a relativly oversized chain, 20ft 3/8 HD, I use a thimble from chain to rode to eliminate abrasion issues.

[s/v Jedi]

With an original Bruce, you should set it at 5:1, not more scope as that will not work as well.

cheers,
Nick.

[foggysail]

Originally Posted by Nicholson58

Better tune your rule of thumb to the boat. We are 58 feet and 55,000 disp. Manson and Rocna both recommend anchors closer to 2 to 3 #/ft. My CQR 75 # is woefully too small. We carry 310 feet of 7/16 BBB. New anchor in the plan.

This is the first time I heard/read of that rule. I think it makes a lot of sense. I have an 80# Maxwell Supreme on my 40' Silerton. Before the Maxwell, I used an 88# Delta so I could sleep at night; I didn't!

Foggy

[s/v Jedi]

We have a 176lb Bruce on a 64' light displacement boat so the 3lb/foot is a good rule of thumb I guess.

But with a bit of Googling you can quickly find better formulas using length, freeboard, size of superstructure and weight as input.

cheers,
Nick.

[Stumble]

Frankly I think almost everyone has a too small of an anchor. Most manufacturers recomendations are made at 35-40kn not the conditions when you really need an anchor to set. Instead most people upsize the chain, but the numbers show that that doesn't really work. Weight of the anchor matters much more, than weight of the chain, so stick with a normal sized chain or go all rope, and get a 150lb anchor. It almost doesn't matter which one, it will hold better, and likely still take weight off the bow.

[zeehag]

all rope will guarantee a good and entertaining evening for the other anchorers in a cove as you start to speed away at wind speed from the safety of the anchorage into oblivion. this month there were 4 walkabouts due to rope rode. have a good sail --figger out where to stash your chain so you have it to anchor with. you WILL need it.