Upgrading to a Smaller Anchor

[wingssail]

Originally Posted by Lemsteraak

Getting back to the initial question, opting to go down a size with a new generation anchor.

That might be fine for normal use. The old timers would recommend carrying a big assed Luke in the bilge for when you really need a serious anchor. I was gifted a big assed stockless anchor a very long time ago and it rides in the bilge of every serious boat I've owned. Only deployed it in anger once, glad to have it.

The big assed anchor in my bilge is a 66lb Bruce which we've used a couple of times when we were worried about the 44lb Bruce, which by the way wasn't dragging anyhow.

[Don C L]

Originally Posted by wingssail

The big assed anchor in my bilge is a 66lb Bruce which we've used a couple of times when we were worried about the 44lb Bruce, which by the way wasn't dragging anyhow.

The extra 22lb is the sleeping med... especially after you've wrestled it out of the bilge without banging up the boat!

[Michael Cobbe]

My view was always buy an anchor one size bigger than is recommened for the yacht.

[noelex 77]

I will still speak to you Don .

If you are going to undersize an anchor, the Danforth/Fortress is the best candidate. This design has such exceptionally high holding power in its preferred substrate (medium/soft mud and soft sand) that even a small model can hold a large boat in strong wind. On the hand, it tends to have very little holding power in the wrong substrate (hard substrates and weed). The holding power is often so poor in the wrong substrate that a large anchor (relative to boat size) may still will not have enough holding power. Therefore the practical difference between a smaller and larger example is not as significant as other designs.

If you do go down this route beware of the tendency of these models not to be as reliable as other designs with a significant change in direction of pull. It also tends to drag very rapidly if it does let go (particularly a small lightweight model) which reduces the time availble to correct the situation.

The strategy can be sensible, for example for boats with no anchor windlass, but unless you only cruising an area that has a suitable substrate you will need to carry different anchor designs to cover harder and weedier substrates. You will also need to consider deploying multiple anchors to minimise the situations where there is a significant change in the direction of pull. This adds weight (although not at the bow when sailing), complication, difficulty and room for error (if you misjudge the substrate).

Not all cruising boats have the same requirements. If your ambition is cruising long distance where you will experience many different substrates and you have an electric anchor windlass, for a typical cruising boat the simple and easy strategy of a good oversized modern new generation anchor that is suitable in wide range of substrates is tough to beat, in my opinion. The oversizing will help compensate for an substrates where the design may be slightly weaker, as well as providing other benefits such as the ability to use smaller scopes, if required, than would otherwise be needed with a smaller anchor of the same design.

However, if your plans, or boat design falls outside the above parameters it is worth considering the alternatives. There are many possibilities for reducing anchor and rode weight (rode is where most of the savings can be made) and these may be worth the drawbacks for some boats.

[kmacdonald]

Originally Posted by Don C L

I have a confession to make. I downsized this summer. OK, there, I said it. But in my case with Danforths, and probably true of Fortress, they don't drag, once set. OK I know, I know... someone will say they have, but I will bet good money that once set, in sand or mud anyway, with proper scope, and not fouled, a Danforth will break before it drags. I once had a 5lb buried so deep I could not retrieve it. In the process of trying to, it broke. I have a 20H for my boat and I am pretty sure the deck will rip off and the chain will part before that anchor drags. The 12H being a bit easier to manage, I used it all summer (bow and stern) but I keep the 20H at the ready.

OMG they are coming out in droves!!!!!! The 12H might be on the big side also.

When's the keel hauling?

[Pete7]

Originally Posted by Gerrit Coetzee

For the difference between 15kg and 10kg, you wish to put at risk your safety, and the safety of other vessels around you?

Those extra 5kg on the bow should produce an 76% increase in holding power. Not a bad return for the equivalent weight increase of a couple of diving weights and perhaps an extra $150 on the price.

There is a calculator on Alain's website if you wish to play around with your own numbers:

Anchor

[Don C L]

Sure, all true abut the Danforths, but can any anchor be trusted in a grassy bottom, hard substrate or when dropped on a loose mass of kelp? Maybe a new design with a razor sharp leading edge of the shank? Many times I have dropped the anchor around here and thought I had backed down on it well, but then after dropping the stern and pulling both anchors against each other I find one dragging slowly. Sure enough, start over, pull it up and it brings up a wad of kelp. The flukes were just deep enough apparently to dig into some sand and try to bury until more force was applied. We have a few places with patches of eel grass around here that on first bite an anchor will feel like it is set well, but if put the the test the anchor will start pulling them out by the roots. I think there are some shots of some new gen anchors diving well into a fairly weedy bottom somewhere, and when I set off for unknown shores and plan on using only one anchor, I'll get a new one... maybe a little oversized too...

[rslifkin]

I had my first experience dropping my (slightly oversized) Vulcan in heavy weeds a couple weeks ago. Weeds were heavy enough that I pulled a couple of medium size dogs worth off the chain and anchor on retrieval and my depthsounder was only periodically able to get a reading. Anchor set on the first attempt and held my normal amount of reverse power. On retrieval, it brought up a pretty good load of sandy mud on the fluke, which makes me think it pushed/dug/cut through the weeds just fine and dug into the bottom below. It took at least as much effort to break out as I'm used to in clean mud.

Weeds are probably one of those cases where a bigger anchor will do better. Likely to the point of an appropriately sized anchor for a smaller boat will be at a significant disadvantage. Because weight scales up faster than fluke area, the heavier anchor will have more contact pressure against the weeds, making it easier to push / cut through them and get to a better holding substrate below. Design plays a big role as well, of course. Anchors that have any features that could easily be clogged by weeds are more likely to have trouble regardless of size.

[noelex 77]

Weed is one of the few substrates that can challenge even the better new generation anchors. It is not difficult to grab the weed itself, and this will generally provide enough grip to hold the boat in moderate winds, say up to 30 knots or so, but to hold in stronger wind typically requires the anchor to dig past the weed into the substrate below.

I have been very impressed with my Mantus M1 in this regard. The long, thin, tapered fluke together with the high tip weight is excellent at slicing through the weed. It also help that my anchor is large. The weed roots effectively become far less significant to a large heavy anchor, so this is another reason to consider fitting the largest anchor you and the boat can comfortably manage.

Diving is the best way to judge the performance, but even here you need to feel down to determine how well the fluke has penetrated the substrate.

Without diving or having strong wind conditions, gauging the performance is difficult, but you can often get some idea by observing the anchor just as it is retrieved. You want to see some evidence of the underlying substrate over all or at least most of the fluke as it comes up. The other clue is performance while setting, the anchor should dig in very rapidly. A longer setting distance is typical of the fluke just gripping the weed itself. It is easier to perceive the difference on anchors that naturally set quickly. Designs that work like this also stand less chance of becoming caught up in the weed before the fluke has penetrated and so tend to be good weed anchors.

Here is my Mantus in moderate weed:

[Mike OReilly]

Originally Posted by Don C L

Sure, all true abut the Danforths, but can any anchor be trusted in a grassy bottom, hard substrate or when dropped on a loose mass of kelp?

I just want to echo Noelex's far more authoritative comments here. Challenging conditions like heavy weeds and hard bottoms will challenge all anchors, but a Danforth-style is probably the worst option for these conditions.

I said earlier that the focus on weight is misguided in this discussion because weight is really just a proxy for holding power. But in the cases you cite, initial weight does matter. A heavier anchor is better able to penetrate weeds or hard bottoms so as to make the initial set.

wingssail: there's nothing wrong with a Bruce. It's a fine anchor, as is the CQR. And if you know it well there's an excellent reason to stick with it. But multiple tests show it's generally not as good as most of the newer designs.

I still carry a Bruce. It has served me well. But I wouldn't buy one new today -- not when there are better options available today.

[Don C L]

I wasn't endorsing Danforths or their ilk for weeds, just saying I'd be suspicious of any anchor in weeds. That said I can see how the Mantus M1 design looks like it will be the most likely to dive and slice through the vegetation relatively unimpeded in a grassy bottom. I think though that the arc of the shank will collect wads of loose kelp.