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Old 28-12-2012, 19:00   #61
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Re: Manson Supreme in Weed

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My point was cats have more windage so that is why everyone recommends going up one size for a cat verses a monohull

Just goes to prove how good some anchors are

But interesting point on windage.

Multis in full crusing mode have much the same windage as when 'new' (becuase anything we add is stuck to cabin roof or below roof level and between the transoms). Mono hulls in full cruising mode often have biminis, dodgers high rise developments with davits, solar panels and a dinghy hanging well beyond the transom. Not sure how to cmpare windage, really?
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Old 28-12-2012, 19:23   #62
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Re: Manson Supreme in Weed

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Not sure how to cmpare windage, really?
As you point out, it is not easy to compare, but I would say in general cats have a lot more windage than monos of a similar length. My 32-foot cat, relatively sleek compared to many more modern designs, pulled a lot harder on the anchor rode than does my 38-foot pilothouse mono motorsailor. I know because I try to pull in the anchor by hand until directly over the anchor. I think most who have sailed both cats and monos of similar sizes agree on this. However, a cat using a bridle can avoid the peak loads that a mono can generate by yawing back and forth at anchor.
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Old 28-12-2012, 20:25   #63
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Re: Manson Supreme in Weed

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My point was cats have more windage so that is why everyone recommends going up one size for a cat verses a monohull

We hear you.
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Old 28-12-2012, 20:30   #64
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Re: Manson Supreme in Weed

OK,
Here is a Catalina 50 footer monohull
Here is a Lagoon 50 cat
Which one would you you upsize the anchor on because of windage.
This is not hard math at this point it's all in the eyes of the beholder.

The cat has two hulls and 24 feet of vertical windows and extra freeboard with everything above the waterline
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Old 28-12-2012, 20:38   #65
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We are about to anchor our 45 foot cat at Emu Bay, Kangaroo Island with our 60lb Manson Supreme. Weedy bottom. Will let you know if we are still stuck in the morning. 20 knots of wind.
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Old 28-12-2012, 21:01   #66
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Re: Manson Supreme in Weed

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Originally Posted by Cotemar View Post
OK,
Here is a Catalina 50 footer monohull
Here is a Lagoon 50 cat
Which one would you you upsize the anchor on because of windage.
This is not hard math at this point it's all in the eyes of the beholder.

The cat has two hulls and 24 feet of vertical windows and extra freeboard with everything above the waterline
With no disrespect to Lagoon (and their owners), windage looks to have been very low on the design priority list. I am sure there are 50' yachts with higher windage than the example you post, as there are multihulls with lower windage than a Lagoon.

We've done the measurements, our 38' cat has the same windage as a, 2008 model, Bav 45 and this is about 30% more than a Bav 35. This is taking full frontal and full side cross sectional areas. It excludes the new real estate the owner of the mono might instal to convert the factory model into a cruising yacht. Windage is only part of the issue. The loads on an anchor are not caused by the wind steadily blowing in one direction onto the cross sectional area of a yacht. The loads are caused by the yacht veering, or if you like, sailing at anchor. The loads develop from a variety of causes and effects, surface area being one, underwater profile another - but momentum is also a function of weight. An ability to minimise 'sailing at anchor', minimises the actual snatch loads if they develop. By using 14m snubbers with 30% elasticity, using a bridle, using 2 anchors when necessary. I wonder how many monos use 13m snubbers? We have also measured the actual loads on our anchor under different wind speeds and at different scope ratios. We've done the maths and then checked it in practice and have not found the need to increase anchor size.

As mentioned its a good anchor, just a pity the sceptics are unable to try it, or even see itm before damning the practice
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Old 28-12-2012, 21:25   #67
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Re: Manson Supreme in Weed

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Originally Posted by Teeto View Post
We are about to anchor our 45 foot cat at Emu Bay, Kangaroo Island with our 60lb Manson Supreme. Weedy bottom. Will let you know if we are still stuck in the morning. 20 knots of wind.
Teeto,

If you are not using them, really long (boat length+) nylon snubbers will make a world of difference. I do not know why but had not realised you were on a cat. But I'd downplay the size of your anchor the 'big is better' anchor police will have you in their sights as well!

Have a quiet time.
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Old 28-12-2012, 21:39   #68
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Thanks Jonjo. We think the size of our anchor is just fine for us. We only weigh 8-9 tons and quite streamlined compared to a Lagoon shape. It's just this weed business that is the unknown.
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Old 28-12-2012, 21:41   #69
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Re: Manson Supreme in Weed

Wow how the tide turns, cat vs. mono, thats new. I'm all for crazy overkill. right now I run a 66 lewmar claw, for lunch. If I'm gonna stay for a week, I put a 44 claw on 40' of 5/16" chain and shackle that to the end of my 66 claw. Both are on the bow in anchor rollers, let the 44 fly, as I back down I pay out the 66 on the same rode (200 of 3/8"). My scope is figured from the 2nd anchor (66 lb claw). Then I can put a ball on the chain end and add 2-30' 3/4" pennants as snubber for huricane stuff. This is my audi quattro of anchoring systems. I sleep well. If I had a Lagoon anything I would fly a 100 lb whatever. I do intend to get Ronca this summer when I return to VT, at least 70lbs as I've been going up 10lb a year since I begain this cruising thing.
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Old 29-12-2012, 01:59   #70
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Re: Manson Supreme in Weed

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Originally Posted by Teeto View Post
We are about to anchor our 45 foot cat at Emu Bay, Kangaroo Island with our 60lb Manson Supreme. Weedy bottom. Will let you know if we are still stuck in the morning. 20 knots of wind.
Hope you are still there

You will generally find with only an average of 20 knots wind there will be no force on the anchor. If you leave a loose loop of chain near the anchor it will not straighten out until you hit an average wind strength of 20-25 knots. Weed is actually much better in this regard. In light winds, when the chain is still on the bottom it provides considerable holding. I have dived to observe and still had a loop in the chain in average wind in the low 30s in weedy anchorages.

One difficulty in evaluating anchors is owners are often praise anchors for holding in 20-25 knots of wind with gusts to say 35knots. At this level of wind anchors are doing very little work and will often hold if not set at all.
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Old 29-12-2012, 03:00   #71
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Re: Manson Supreme in Weed

Noelex,

Really interesting comment, does it depend on the amount of chain and the depth/chain length ratio? Is this a valid comment for Kangaroo Island? Is this a comment valid for all situations?

Our Bureau Of Meteorology (BOM) here, Australia, clearly states 'that wind gusts can be 40% stronger than the averages given here'. So averages of the low 30s, here in Oz, would normally enjoy wind gusts of +42 knots. I've just read in the Jan issue of YM, page 38, 'and on a 'normal' day, you can expect gusts to be one third stronger than the average wind speed.' in the low 30s, your figure again, that would mean wind gusts of 39 knots. There is some consistency between wind gusts of 40% and 1/3 - given the problems of forecasting and the differences in geography.

Can you re-confirm that you have dived on an anchor in average low 30s knots (when gusts in the UK and Oz would be 39 and 42 knots respectively) and you still have a loose loop of chain on the seabed.
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Old 29-12-2012, 03:24   #72
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Excellent point Noelex, I guess the variables of weed density, depth and amount of chain all play a part. Sitting here fine so far. MS set well.
Thanks for the thoughts.
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Old 29-12-2012, 04:19   #73
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Re: Manson Supreme in Weed

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Originally Posted by noelex 77 View Post
Hope you are still there

You will generally find with only an average of 20 knots wind there will be no force on the anchor. If you leave a loose loop of chain near the anchor it will not straighten out until you hit an average wind strength of 20-25 knots. Weed is actually much better in this regard. In light winds, when the chain is still on the bottom it provides considerable holding. I have dived to observe and still had a loop in the chain in average wind in the low 30s in weedy anchorages.

One difficulty in evaluating anchors is owners are often praise anchors for holding in 20-25 knots of wind with gusts to say 35knots. At this level of wind anchors are doing very little work and will often hold if not set at all.
Absolutely right, and especially if you have fairly heavy chain. I am often surprised when anchoring in a place with a tidal stream which changes every 6 hours, that when I let out say 50 meters of chain, my position doesn't change by 100 meters when the tide changes, even if the tidal stream is strong. Often my boat just turns around in place. Most of us are held by our chains on the bottom probably most of the time, and not by the anchor at all. Thus many opinions about anchors relate to setting behavior, not holding ability.

My individual, subjective observations on the subjects under discussion:

1. Bigger is definitely better where anchors are concerned, seemingly disproportionately. As Noelex says, however, you need to anchor in some tough weather to find out about this. I think there is a question of soil mechanics involved -- anchors of different sizes don't interact with the sea bed the same way, even if they are otherwise identical.

2. Sharper is definitely better, where setting is concerned. One reason why Fortresses work so well -- very sharp flukes.

3. Denser is definitely better, where setting is concerned, especially in mud, weed, etc., so lead is good vs. steel, as is steel vs. aluminum. Remember that under water, the difference in density between steel and lead is exaggerated - hence the significant difference in performance of lead vs. iron keels.

4. "Using your storm anchor all the time" is a good policy, in my opinion. You can't always predict what will blow up overnight. Anyway, the biggest anchor you can handle easily (assuming you have an electric windlass) is likely to be as big or bigger than anything you could easily find a place to store elsewhere, as a storm anchor. Certainly it is on our boat. I keep a big Fortress in reserve (ready to launch, in the anchor locker with rode attached), but don't think I could find a place to store something bigger than our 100 pound Spade bower anchor, unless it were maybe one of those knock-down aluminum Spades.
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Old 29-12-2012, 05:07   #74
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Re: Manson Supreme in Weed

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Noelex,

Really interesting comment, does it depend on the amount of chain and the depth/chain length ratio? Is this a valid comment for Kangaroo Island? Is this a comment valid for all situations?
.
My comments are generalities and one of of the problems is bottom conditions do vary considerably. Terms like "thick weed" have very different conitations depending on your background. Scope, water depth etc will all make a difference.
I almost went to Kangaroo island a few times, but in end despite looking like a great cruising ground the risk of sharks put me off. I am happy to dive with reef sharks, but I get nervous in areas where there are white pointers and I love swimming / diving.


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Our Bureau Of Meteorology (BOM) here, Australia, clearly states 'that wind gusts can be 40% stronger than the averages given here'. So averages of the low 30s, here in Oz, would normally enjoy wind gusts of +42 knots. I've just read in the Jan issue of YM, page 38, 'and on a 'normal' day, you can expect gusts to be one third stronger than the average wind speed.' in the low 30s, your figure again, that would mean wind gusts of 39 knots. There is some consistency between wind gusts of 40% and 1/3 - given the problems of forecasting and the differences in geography.

Can you re-confirm that you have dived on an anchor in average low 30s knots (when gusts in the UK and Oz would be 39 and 42 knots respectively) and you still have a loose loop of chain on the seabed.
To give you one example I anchored a few months ago at Skantzoura island. I had to move and reanchor at about 3am due to a silly charter boat. The anchorage has some clear patches of sand, but of course these cannot be seen at 3am. The rest is weedy.

I anchored in about 13m at 6:1. The forecast was 35knots, but it was only averaging low 30s maybe 31-32. Peak wnds were high 30s maybe 38. There was - gradual 30 degree shift in wind direction.

In the morning my brave wife dived on the anchor (it was too cold for me) and reported still loose chain near the anchor.
This is not typical, normally I would expect the chain to straightened out at this wind strength, but I have noticed this before in weedy anchorages. It's also difficult to separate how much the chain was being held by weed itself and how much was held by rock which is often found in weedy anchorages. Nevertheless there was very little force on the anchor and, for this occasion, anchor design and size was playing little role in holding us.

For most anchorages an average about 20-25 knots ( generally closer to 25) is a real transition point. Below his level boats with unset (or very minimally set) anchors will stay put. If you dive on the anchor the next day it remains unchanged. Above this level boats with unset anchors will drag, or if you dive on their anchor it will have set properly with the force of the wind.
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Old 29-12-2012, 05:21   #75
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Re: Manson Supreme in Weed

This is one of our "off the beaten path" anchorages we frequent. The eel grass is about 5-6' tall and comes up to the keel & rudder. We've anchored here reliably with the Spade, Manson Supreme and Rocna. We were swinging to our Rocna when this shot was taken.

To set here I usually set it gradually, a bit at a time, before a full throttle back down. I then re-test with full throttle reverse before bed and upon waking in the morning. Not yet had our Manson or Rocna fail us here but did have a large root ball give on one back down requiring a second try.

Of the three reliable anchors in this bottom, the Spade is the only new gen we've had trouble with setting there and even then it only took three tries.. Our genuine CQR will not set here no matter how many attempts are made. We had written this spot off for many years when using our CQR thanks to the newer designs we can now stay here again...

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