Leaving Your Boat at Anchor on a Windy Day

[colemj]

Originally Posted by Jim Cate

Uhh, Mark,

There you are backing down on your rope rode. The 5/8 inch nylon has stretched so much that it is down to 1/4 inch diameter (not bloody likely, BTW). What is that nylon attached to that provides the resistance that you are pulling against? Well, the only thing out there is the anchor, so it must feel the full tension that you are putting on the upper end.

I won't argue about how much pull the average yacht can exert, but if you continue to pull until the rode stops stretching, the anchor will have all that pull exerted on it. It may or may not dig in, but it will have the full load applied.

And I agree that setting was not likely the culprit in the OP's situation.

Cheers,

Jim

I think we are mostly agreeing with each other Jim. 5/8 to 1/4" would be bar tight, and there is no boat that is going to accomplish that. So no reasonable boat can pull until the rope stops stretching - it can only pull until the stretch resists it.

The anchor will feel any force the nylon transfers to it, but until the nylon is bar tight (1/4"), a proportion of the applied force will still be lost in the stretch. Of course, if the boat has enough pull, then the proportion of the force the anchor sees becomes a large majority of the force applied as the rode gets stretched more.

But the largest problem is "rubber banding", where the boat applies a stretching force to the nylon, but cannot maintain it, so the boat surges forward and then back, and then forward, etc. Much less force is going to the anchor with nylon than with chain for this.

Chain doesn't have this problem, or at least it exists only in the cantenary, which is much less than the nylon stretch and robs a proportionally smaller amount of force.

Mark

[capngeo]

Back in my commercial days. I stretched a lot of nylon lines to the breaking point. Can't ever say I saw ANY line loose 50% of it's diameter under tension. I've parted many and pulled a lot until they melted. The biggest tug I worked had 3" WIRE rope on the towing engine... yup, broke that too once.

[rtbates]

[QUOTE=jacob30;1223935] He reported that the anchor was fouled with oyster shells.

Jacob[/QUOTThat's one of the many reasons why I took all my danforth anchors off my boat. Pulling out in a wind shift and putting me on a beach TWICE was another. I now use a 22kg Bruce and a 16 lb Bruce. If needed they can be shackled in line. Lots of holding for a 25 foot, low freeboard, 6k lb boat.

I must have missed the part where you learned that danforth type anchors suck!, haha

[Fortress]

I think GordMay simply picked up his anodizing (anodising) description directly from us, so its our error if the wording wasn't accurate enough for all readers.

Originally Posted by endoftheroad

When I see a heavy cruising boat with a danforth hanging on the bowsprit I start looking for the captain to be wearing clean fashionable weather gear">foul weather gear and maybe a couple yapping poodles.

Here's a very heavy patrol boat with one on the bow, the USCG's new 154-ft Fast Response Cutter (FRC) which displaces 353 long tons (790,000 lbs). The anchor pictured is the 70 lb Fortress FX-125.

The ladies & gents aboard will definitely be in clean fashionable gear, but no yapping poodles, although maybe other drug-sniffing dogs.

Your local USCG station in Key West should get one of these new patrol boats sometime this year.

[zeehag]

speaking of leaving boat on a windy day----back to subject matter, btw--rodlmao----
some folks have tried to tell me boats do not drag in wind alone--i beg to differ----we had a catamaran drag in only 15 kts wind the other day--we get wind un afternoons--sometimes only 5 kts, but more often is over 15-20, frequently is 30 or so .....he dragged in 15 kts...

make sure your tackle is secure before leaving boat. i usually remain on board when i now winds will rise---and if i dont ned provisions.....i try to project my provisioning in for days with predicted less wind, per my satellite and passage weather and such sites.
is a good thing i was home the day of the cat dragging--i called out the boys with motorized dinghies and all was secure in about an hour and half. as the boat had not the key in ignition, it called for 2 dinghies, one either side of cat to propel it into a safe and secure anchoring.
you folks who leave in winds need to know what happens while you are not at your boat. please take care of business before leaving so others donot have to do your business for you. and so you donot lose your boat. had someone not been watching out, the owner would have had to unstick his boat from the thank goodness muck(isnt too rocky here--is a lagoon with much and some rocks).
it seems many of the west coast cruisers do not study anchoring 101.

it matters not what kind of anchor and rode you have if you do not use it correctly.

please take care of your stuff---not always is someone watching out....

[Fuss]

Originally Posted by zeehag

speaking of leaving boat on a windy day----back to subject matter, btw--rodlmao----
some folks have tried to tell me boats do not drag in wind alone--i beg to differ----we had a catamaran drag in only 15 kts wind the other day--we get wind un afternoons--sometimes only 5 kts, but more often is over 15-20, frequently is 30 or so .....he dragged in 15 kts...

make sure your tackle is secure before leaving boat. i usually remain on board when i now winds will rise---and if i dont ned provisions.....i try to project my provisioning in for days with predicted less wind, per my satellite and passage weather and such sites.
is a good thing i was home the day of the cat dragging--i called out the boys with motorized dinghies and all was secure in about an hour and half. as the boat had not the key in ignition, it called for 2 dinghies, one either side of cat to propel it into a safe and secure anchoring.
you folks who leave in winds need to know what happens while you are not at your boat. please take care of business before leaving so others donot have to do your business for you. and so you donot lose your boat. had someone not been watching out, the owner would have had to unstick his boat from the thank goodness muck(isnt too rocky here--is a lagoon with much and some rocks).
it seems many of the west coast cruisers do not study anchoring 101.

it matters not what kind of anchor and rode you have if you do not use it correctly.

please take care of your stuff---not always is someone watching out....

Hmm, dragged in 15kts of wind.
Either, they did not have enough scope or they did not have an all chain rode.
My anchor chain would hardly know there was an anchor on the end of it in 15kts of wind.

[sailorboy1]

crap happens, and in an anchor thread there is lots of crap!

[alan_za]

Originally Posted by Fortress

Here's a very heavy patrol boat with one on the bow, the USCG's new 154-ft Fast Response Cutter (FRC) which displaces 353 long tons (790,000 lbs). The anchor pictured is the 70 lb Fortress FX-125.

The ladies & gents aboard will definitely be in clean fashionable gear, but no yapping poodles, although maybe other drug-sniffing dogs.

Your local USCG station in Key West should get one of these new patrol boats sometime this year.

When does the USCG ever spend a night out under anchor? Looks pretty though.

[Fortress]

Originally Posted by alan_za

When does the USCG ever spend a night out under anchor? Looks pretty though.

I didn't think ever, until a Coastie aboard their 87-ft patrol boat called in from a USCG station on the Gulf of Mexico to order an anchor. He said that the seas were too rough for their routine patrols, so they hung on the anchor for three days.

When it came time to pull the anchor up (47 lb FX-85), he said they couldn't retrieve it and they had to cut it loose, so he was calling to buy another.

[Andrew Troup]

Originally Posted by Kettlewell

....
This ooze also does a number on your scope. Your depth sounder reads 10 feet and you add 5 feet for the bow, so you put out 75 feet of rode to get 5:1. But, that 10-foot reading is just the top of the ooze. The real holding ground is probably another 10 feet down, so to reach that you need to put out 125 feet of rode to maintain your 5:1. The moral of the story is to use a lot of anchor rode in the Chesapeake.

Kettlewell, that's something I've never considered, nor heard (or read) anyone raise.

I'll certainly be rowing across with a bottle of something palatable if I spot your boat at some future date ...

[Andrew Troup]

I've possibly said this before, but it bears repetition: I think Brian from Fortress is the absolute model for a commercial member.

I don't think I've ever seen a post from him which gave me the feeling my perceptions were being massaged or manipulated in some undeclared way.

What's more, he never makes a secret of the fact that his products have specific limitations to balance their considerable and evident virtues.

Honour where honour is due...

[Fortress]

Kettlewell, that is a very strong point and it reminded me of a story about the US Navy. Since WW II, they've conducted anchor holding tests in the soft mud off of Hunter's Point in San Francisco Bay. In the mid-80s they wanted to mark the area by driving in a 65-ft steel piling.

The depth of the water was 18-ft, and they expected to hammer the piling into the bottom, however when they dropped it into the water....all 65-ft disappeared. The piling had sank completely under its own weight. That's SOFT mud!

Andrew, many thanks for your kind words.

Much appreciated,
Brian

[Andrew Troup]

On the topic of dragging in lightish winds: I have a feeling that this is rather more common than anchoring threads would have us believe.

In my experience, those who know their way around anchoring rarely drag in strong winds: they do whatever it takes to make sure they don't, including going somewhere else before it gets to that stage, putting out shorelines and/or extra anchors, stripping windage off, and CERTAINLY digging the anchor in to the extent required, by whatever means prove necessary.

And if they do drag, they've already got a plan B, the engine is already warmed up or running, the course to another anchorage is plotted ...

They're certainly not all down belowdecks, having thoroughly explored the bottoms of several bottles, snoring swinishly while sleeping on both ears.

The sort of situations which can catch us unawares include settled conditions, where we never expect to stay the night but get enchanted into doing so, and forget that we didn't do the full nine yard drill when we ... say ...

"dropped an anchor for a quick cup of tea for the grownups and a bit of a run ashore for a couple of frisky younguns .... "

The wind comes up gently overnight, never enough to wake us... but in conjuction with a tidal eddy, or an increased flow from a river fed from a rainy catchment far away, and the fact that we inadvertently dropped on top of a hillock, it's enough to waft us onto a bank....

where we wake at 2am to a gentle-sounding gust which nevertheless, disproportionately and puzzlingly, lays the boat over ten degrees... but it doesn't come back upright .... What the .... ?

And that's just one of a bunch of reasons I like heavy chain: it does a great job of stopping dragging when I would least expect to drag and am consequently most likely to, in lighter winds.

And heavy chain greatly assists an anchor to 'self-set' if conditions gradually put bigger demands on it - another 'trap for the unwary' situation which can lead to dragging.

I hate having to start the engine just to set the anchor unless it's an overnight stop, (and even then it rankles), so for me at least this is a welcome feature.

And possibly helps explain why heavy chain in combination with smaller anchors was such a popular combination before the advent of powerful engines on sailing vessels, together with props which provide a decent amount of reverse thrust.

[Kettlewell]

And possibly helps explain why heavy chain in combination with smaller anchors was such a popular combination before the advent of powerful engines on sailing vessels

Not sure what era you are referring to, but "back in the day" here in the USA ('50s-'60s) the popular set up was mostly nylon or hemp before that, with a short length of chain, because nobody had a windlass either! A very nice wooden 37-foot boat custom built in the 1960s (in Denmark) I owned had the typical bow arrangement for the era--a couple of chocks, one central cleat, and a tiny deck pipe that would only fit rope down into the anchor locker. Maybe 6 feet of chain would reside on deck, most likely connected to something like a 20H or 35H Danforth anchor. Take a look at any oldies from that era, like the original Block Island 40 in the photo. Somebody added an anchor roller and windlass later, but it wouldn't have been standard, and they did come with double cleats too.

I sailed on a boat to Labrador with such a rig, only the owner made us remove the Danforth and chain and stow them after each use! Anchored all over the place with no major issues.

[engele]

I have no idea why anyone would knock Fortress anchors. Our Fortress is the single most awesome at anchor I've ever used. Combined with a nice alternate (like say a Manson), you can cover just about any condition, but in my mind, I am not sure that a Fortress wouldn't be a great primary (I've been tempted to put it on my roller as our primary).

Our Fortress has never fouled or unset even when set from the dinghy as our secondary, unlike our very oversized CQR with all chain set at full power in reverse with 7:1 (which I normally trust absolutely). I am opening myself up to criticism here by saying two un-cool things, I have a CQR and I like a Danforth style anchor, but the fact is opinion runs rampant around here, and not everyone here really actually has experience with the things they comment on.