anchoring in 120kn gusts - which anchor will hold that??

[jorapazu]

Originally Posted by Breaking Waves

this is a bit further south - note: if you look closely you will see there is both an anchor and a shore line from the bow - that's a 30 ton boat being heeled over

Attachment 201028

Too close to land for comfort. My opinion

[Ita]

Originally Posted by roscheetham

Rocna anchors were designed for use in extreme conditions and can be put in tandem if needed in those cases. Look up the Rocna anchor users guide on the internet and this article https://www.petersmith.net.nz/boat-a...-anchoring.php.

We have a rocna on our 44’ catamaran and are extremely pleased with it. We previously had a Beneteau 37 and our Rocna held in 70+ knots.

What’s the size of the Beneteau Rocna?

[Gerrit Coetzee]

Originally Posted by Nicholson58

You do know that most of us do anything to avoid the conditions you seek. I live in sandals and shorts. I own one pair of long pants, somewhere. This is supposed to be fun, not survival. We may not be the best source of advice.

I was caught in a 80,2kn apparent wind on my way to a marina on 24 Sept. The passenger arriving before me in the harbor turned around and fled off into deep sea. I did not know why, as nothing but rain was predicted. Then the squall and wind hit us.


At 80kn the wind would crush us into the marina, so i tried to turn around and follow the passenger ship who was out of sight by then.

In 80kn I could barely turn and had to venture with short bursts of SB throttle close and reverse to make the 44'-footer turn. Then painstakingly slow rode into the storm.

I cannot imagine what 120kn, 40kn more then what we survived at 80kn could be like. I pray that it never happens to me again.

Thus I side with others, we are in it for fun and safety (which includes avoiding storms), alternatively you did not experience the mild wrath of the seas yet..

[Icarus]

Originally Posted by Ibetitsthisway

Hi guys -

I am "the anchor" guy. I love the anchor manuever and I always trust my anchors to hold - which they always do perfectly.

well...sofar... in "normal" situations up to bf9.

But planing to go to the high latitudes and very remote and windy areas and trying to be prepared for the "unthinkable" - I see pulling forces of 24000 lbs for a boat of the size I want at windspeeds of 120kn.

The "wise" bobby schenk also runs a chain for 15000lbs pulling force for an 11m boat.


now... there are new researches showing that these "known" tables which state these forces are wrong and that forces are about 30% less.
I have read them, and I did understand their calcs.

anyway... chain or rope - all fine - but what about the anchor itself?

I do NOT FIND ANY numbers on the forces ankers can withstand.

a) I dont want to rip the anchor apart with my 24000lbs chain...(or 16000 or whatever)
b) the anchor needs to bring that pulling force into the ground.

there are some tests with 15kg anchors holding 2500-5000lbs. does that mean a 5 or 10 x15kg = 75kg-150kg anchor will do??

who tells me that my cleats will hold 12000-24000lbs??

somehow everybody talks about chains... but not about the rest

24000lbs? Thats about 12tons!
Depending on the grade you are looking at 5/8 to 3/4 diam chain! Shackles got to be 3/4to 1" pin size.
At 24000 bollard pull you going to rip you cleats off the bow on a plastic vessel.
Snubbing loads are about twice as much...so do the math
You really want to carry this sort of gear on a 38ft boat.?
I think your data concerning sustained bollard pull are questionable to say the least.
You really want to anchor in hurrican condition?

[Simi 60]

Originally Posted by Gerrit Coetzee

I was caught in a 80,2kn apparent wind on my way to a marina on 24 Sept. The passenger arriving before me in the harbor turned around and fled off into deep sea. I did not know why, as nothing but rain was predicted. Then the squall and wind hit us.


<snip>

Thus I side with others, we are in it for fun and safety (which includes avoiding storms), alternatively you did not experience the mild wrath of the seas yet..

And how do you propose to do that when you didn't know about the storm/wind that got you?
You can't just "magic" yourself away.

[s/v Jedi]

Originally Posted by Leighpilot

Don’t forget ,if your chain and anchor strength exceed the strength of your windlass mountings , you’re still going to drift downwind. But now you’ll have a hole in your foredeck where the windlass was. To visualize it, if you’ve got 15000lb chain , hanging a 7 1/2 ton weight from the windlass. Are those four 3/8 bolts and Lenny washers going to stop the windlass from ripping out

Seems you forgot to install the most important component: the chain stopper
It is the chain stopper that must take the load, never the windlass because it isn’t engineered to do that. My Maxwell 3500 windlass has a chain stopper lever integrated but still needs a separate stopper. The stopper must be mounted at a strongpoint off course
Much like here:

[s/v Jedi]

80,2kts of wind huh....

[a64pilot]

Not trying to say this is how it should be done, but this is my stopper.
It’s thru bolted through the sprit with the all thread cast in place with Epoxy and I used barrel nuts to secure it. The aluminum block is to get the stopper in line with the chain.

[AndyEss]

Originally Posted by Nicholson58

You do know that most of us do anything to avoid the conditions you seek. I live in sandals and shorts. I own one pair of long pants, somewhere. This is supposed to be fun, not survival. We may not be the best source of advice.

I have several pairs of slacks for going dancing when I’m in La Paz. I even have a kick as$ pair of low cut boots with embroidered dragons. The Mexican ladies love them.
As for going out of my way to find a place that has 120 knt winds just so I can test ground tackle with my own life and property, I believe a good life philosophy is to stay as far away as possible from people with a death wish.

[Simi 60]

We simply do not have the space for a chain stopper.

Anchor shackle stops 50mm from a heavy welded down grooved roller for keeping chain angle low before going onto horizontal chain wheel set 300mm aft of the roller.

Best solution to date is a horizontal bolt that just fits through the chain link aft of the roller.

[Psy at SEA]

I'm reading between the 'links' ..... bigger is better.

Dankie Jedi Kaptein

[Gerrit Coetzee]

I don't know but I am open for suggestions. As in seriously, because I would appreciate staying out of its way. (Radar was not on , we were so close to the Marina and the storm that was driven South by NE wind, turned at that moment and hit us on Port side out of the West)

[contrail]

Originally Posted by s/v Jedi

Right now Florida & Bahamas. Before that West Caribbean, then East Caribbean, then before retirement 30 years Dutch inland waters and North Sea. Won’t see me sailing in the North Sea again



I actually left some items out because of controversy or weird sounding

Out of curiosity,where exactly were you in Dorian?

[Streetcar]

Never done 120kts of wind but what experience I do have of hurricanes and cyclones tells me it would be a miracle to get through a genuine 'deck level' 120kts hanging on an anchor... or anchors.

I spoke to one captain who survived an estimated 'deck level' 90 kts on anchor. Luckily his anchor had hung up on a bommie on his way onto the beach. He then spent several hours capsizing each time the boat swung and yawed across the wind. He said that anything that can reduce the yawing would make a huge difference.

Don Street once estimated that the load on the chain of an average yacht in 120 kts of wind could be similar to that if the yacht was hung by its chain from a crane. Can't think of any strong points on my boat that would take that load. Perhaps all the winches, the mast and the cleats webbed together might do it. I would expect to be replacing all this bent gear tho,... if I survived.

If it was me and there was a genuine 120kts (deck-level) forecast, I'd be somewhere else.

[Simi 60]

Originally Posted by Streetcar

I spoke to one captain who survived an estimated 'deck level' 90 kts on anchor. Luckily his anchor had hung up on a bommie on his way onto the beach. He then spent several hours capsizing each time the boat swung and yawed across the wind.

Capsizing eh?

Don Street once estimated that the load on the chain of an average yacht in 120 kts of wind could be similar to that if the yacht was hung by its chain from a crane

.
I don't know who Don Street is but it sounds like he has no idea.
Think about it

If it was me and there was a genuine 120kts (deck-level) forecast, I'd be somewhere else.

Are you just going to "magic" yourself out?