An unlucky Vulcan

[carstenb]

Originally Posted by qwerme

Yes, I understand plenty of people don't know how to anchor.

Bot Boatman and Lodesman are very competent sailors - I would not have any problems relying on their anchoring techniques

[qwerme]

Originally Posted by carstenb

Bot Boatman and Lodesman are very competent sailors - I would not have any problems relying on their anchoring techniques

I don't doubt it.

[Anders]

Originally Posted by s/v Jedi

Anchor rode chain is selected based on strength, not wire diameter.

I believe in an anchoring system. I also believe an extra kilo is better used in the anchor rather than the chain. Within reason.
For the OPs boat Rocna recommends a 33kg Vulcan with a 10mm chain. His anchoring system are way below what they recommend with his tiny 8mm chain.
If it was my boat I would start thinking about 12mm chain and an oversize anchor.
Alternatively I would consider 10mm G70 and a very oversized anchor.
8mm? No way I would do that.

[rslifkin]

Originally Posted by Anders

I believe in an anchoring system. I also believe an extra kilo is better used in the anchor rather than the chain. Within reason.
For the OPs boat Rocna recommends a 33kg Vulcan with a 10mm chain. His anchoring system are way below what they recommend with his tiny 8mm chain.
If it was my boat I would start thinking about 12mm chain and an oversize anchor.
Alternatively I would consider 10mm G70 and a very oversized anchor.
8mm? No way I would do that.

Rocna is spec-ing chain size not for better holding power, but because of the loads the anchor could potentially hold in a good bottom stressing the chain. In my mind, sizing that based on the anchor is pointless. Chain loads are sized based on the boat, as that's what's applying force to the chain.

Working load on 5/16" (8mm) G43 chain is 3900 lbs, for example. That should cover well over 60 kts of wind on most 43 foot cats, so I'd consider it adequate. Given a bigger (higher windage) boat, it would be time for bigger chain. An upgrade to 5/16" G70 would only raise the working load slightly (to 4230 lbs), but it wouldn't hurt as a conservative step if the windlass can accept it.

There's also the issue that smaller cats are often limited in weight capacity. As long as the chain is strong enough, I'd rather have more chain than heavier chain. If we look at 5/16" / 8mm chain, 300 feet is about 310 lbs. For 3/8" / 10mm chain, 300 feet is about 450 lbs. 300 feet of 1/2" (slightly bigger than 12mm) would weigh a whopping 760 lbs.

In this specific situation, I'd probably want the 40kg / 88lb Vulcan for some extra safety margin, but I'd be inclined to stick with 5/16" chain unless the boat had plenty of weight capacity to spare, then I might go for 3/8" G43 (but definitely no bigger).

[ThereAndBack]

Originally Posted by rslifkin

In this specific situation, I'd probably want the 40kg / 88lb Vulcan for some extra safety margin, but I'd be inclined to stick with 5/16" chain unless the boat had plenty of weight capacity to spare, then I might go for 3/8" G43 (but definitely no bigger).

Unfortunately, I don't have weight to spare and as you rightly pointed out, I took length over size. Also, the fact that his boat has been in near constant use for 20+ years in hurricane alleys using 8mm chain all that time tells a tale. I spend money/resources/weight where I think it counts and the chain has been good enough all this time.



I agree, I wish they'd had a 40kg anchor in stock when I bought, but I was in a bad way and took what I could get at the time. When I return to the states I'll probably switch back to a 40kg-ish roll bar anchor.

[Lodesman]

Originally Posted by qwerme

Yes, I understand plenty of people don't know how to anchor.

And there are plenty of people who think they know how to anchor, but haven't actually put any thought into it, and just blindly use simplistic ratios.

[Chotu]

Originally Posted by Lodesman

And there are plenty of people who think they know how to anchor, but haven't actually put any thought into it, and just blindly use simplistic ratios.

that’s me!

in any typical harbor I’m 10:1. Set it and forget it.

Of course there are some strange exceptions like really deep water anchorages. I actually don’t really visit these. and every once in a while a place is crowded and kind of deep.

For instance Block Island great salt pond. that one tends to be pretty deep and also really crowded. You are in 30ft of water rubbing rubrails with 15,000 other boats. So you end up with 5:1 or 7:1 and pray the afternoon squalls are kind to you as you nearly touch all the boats around you.

but that’s not very common. I just do 10:1 and forget it wherever I am for the most part.

[sv_pelagia]

Originally Posted by Chotu

that’s me!

in any typical harbor I’m 10:1. Set it and forget it.

Of course there are some strange exceptions like really deep water anchorages. I actually don’t really visit these. and every once in a while a place is crowded and kind of deep.

For instance Block Island great salt pond. that one tends to be pretty deep and also really crowded. You are in 30ft of water rubbing rubrails with 15,000 other boats. So you end up with 5:1 or 7:1 and pray the afternoon squalls are kind to you as you nearly touch all the boats around you.

but that’s not very common. I just do 10:1 and forget it wherever I am for the most part.

routinely 10:1? Such an approach would not go over "very well" here in British Columbia. (Cue unpleasant interactions....)

3:1 or 4:1 certainly... 5:1 hmmm... 6:1+: there better be a big blow forecast.

Our anchorages are typically 25+ ft (to 60-70+ ft) at low tide, then add 10-18 ft for high tide.

[Chotu]

Originally Posted by sv_pelagia

routinely 10:1? Such an approach would not go over "very well" here in British Columbia. (Cue unpleasant interactions....)

3:1 or 4:1 certainly... 5:1 hmmm... 6:1+: there better be a big blow forecast.

Our anchorages are typically 25+ ft (to 60-70+ ft) at low tide, then add 10-18 ft for high tide.

and that’s exactly what the rest of my post said after the second line. I don’t typically visit places that deep. But I think if I go up to Canada in the summer, I’m going to be hitting places like that. So I had better practice these skinny scope techniques

i’m 10:1 right now. In 6ft of water. Been here for about a month with not a thought of my anchor.

[Anders]

Originally Posted by sv_pelagia

routinely 10:1? Such an approach would not go over "very well" here in British Columbia. (Cue unpleasant interactions....)

3:1 or 4:1 certainly... 5:1 hmmm... 6:1+: there better be a big blow forecast.

Our anchorages are typically 25+ ft (to 60-70+ ft) at low tide, then add 10-18 ft for high tide.

The same scopes are used were we sail but from late spring to early autumn there will be a few gales but usually nothing bigger. In the winter the weather can be nasty but by then you have the whole anchorage to yourself. Still can't see any need for more than 5:1 with a properly sized anchoring system.

[sv_pelagia]

Originally Posted by Anders

The same scopes are used were we sail but from late spring to early autumn there will be a few gales but usually nothing bigger. In the winter the weather can be nasty but by then you have the whole anchorage to yourself. Still can't see any need for more than 5:1 with a properly sized anchoring system.

We saw too many gales in Northern BC last summer. Had to hide out several times for 2-3 days each time. In places where 5:1 would have us on the rocks. (Thankfully decent protection.)

[Ballsnall]

Your dragging in 20kts, lot of discussion on technique and scope, but if your anchor is not holding in lightish conditions get a decent anchor. 3:1 scope should hold easily. I can hold in 35kts at 5:1 with a CQR.
Get a decent anchor and sleep easy.

[SV Confianza]

This doesn’t sound like what we experience with the Vulcan. We have only dragged twice on our Rocna Vulcan. We also use a 33 on a 44ft cat.

I’ve only dragged twice in two years. Once we anchored in a spot that had shifting grounds, and the second, the shackle attaching the anchor got weirdly wedged sideways in the attachment point and kept the anchor from righting itself like it should.

[noelex 77]

Originally Posted by SV Confianza

the second, the shackle attaching the anchor got weirdly wedged sideways in the attachment point and kept the anchor from righting itself like it should.

This is good point that is often overlooked. This problem causes some unexplained instances of poor anchor performance.

The anchor attachment point (shackle or swivel) can in some circumstances be jammed and locked in an unfair position in the slot or hole where it attaches to the anchor. This problem occurs usually during a wind shift. It produces an unbalance in direction of pull and can lead to very poor anchor performance. Sometimes this is obvious, as it stays during the anchor retrieval, at other time lifting the anchor shakes out the jam.

The remedy is to test the attachment point on dry land by dragging and jerking the chain from different angles in an attempt to make it lock up. If this happens, you need a different attachment method. Often just changing the shackle to another brand with a slightly different shape will eliminate the problem.

The second related problem is using multiple shackles and paraphernalia such as anchor straighteners. This extra hardware can jam on other parts of the anchor and create a similar issue. The remedy is just to remove the extra devices.

This photo of a Mantus M1 shows how a wind direction change in light or even moderate wind does not always result in the anchor moving. In these situations the chain attachment point is forced backwards. Make sure the chain attachment point cannot jam or bind in this position:

[Sonosailor]

This idea of setting the anchor with 3:1 or less (from the roller): Draw it out to scale, and then look at the angle at the anchor. You are still pulling up on the anchor shaft and thereby pulling the fluke(s) in at a more shallow angle. It will be an inferior set! Then, leaving it at 3:1 while gusts pull and waves lift the bow may cause the anchor to ratchet back. This is what I mean by visualizing what you are doing.