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Old 22-08-2007, 13:35   #61
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G'day nalani

Heavy is good in no weather, they just sit there doing not much. When the weather goes bad they work the gear harder. Momentum is what it's all about. The bigger the potential momentum the bigger the gear is needed to stop it. So when the brown stuff is hitting the fan heavier boats need bigger gear than lighter boats.

Anchor systems work in such a variable environment nobody can give you a direct size guide as such.

1lb a foot is a starting point and not to bad a one but only a guide. I'd say a average 40fter odd doing in-shore stuff use a 40lb anchor. From there you adjust for the boat, the user and the required safety margin you want, type of anchor and etc. If you are big, heavy and planning on extended cruising go up in size. The 1lb thing refers to older anchor more than some of the new ones. Whether you adjust for the newer designs or just take the extra safety margin is up to you, most take the enhanced margin.

So if you and/or your boat are -
Heavy, wide, has big windage, blunt bowed, cruising offshore or extended coastal, in fast changing weather zones, nervous, sleep like the dead when your head is on the pillow and things like that go up some sizes.

If you are -
A Nana boater (flat water, less 10kts wind and only in full sun), know the seabed you'll be in all the time (note 'all'), skinny, light, a loose unit and the like you can downsize a bit.

In that calc you also have to take the rode behind the anchor into account. Specing an anchor without taking the rode into account is silly and could very easily cost you something be it money, weight, a few things really.

Generally it is a lot easier to go down sizes with the smaller boats than the bigger. Most small boats, approx 30-32ft and down are over anchored. On the same scale as that many 50-60fters are under anchored.

Generally a cruising yacht is the best anchored, the owners have to take more care obviously.

I've used a lb/ft for many many years and if you look at 100 assorted boats you'll find it is pretty damn close as an average. That also means assorted anchoras as well, not just one particular type.

Looking at others is a good idea but make sure they do actually have a decent set-up first. I see many using gear that makes me quite nervous. It's quite surprising what some people get away with.

Hope that helps rather than confuses.

Give us a bit more of you're boats details and we can all have a go at saying what we would use.

Apologies to all Nana's, it is meant in a loving way

Steve - I'm in NZ. You're in the North of ??
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Old 23-08-2007, 01:55   #62
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Hi Gmac, I'm In Maungaturoto, with a name like that it has to be NZ, yacht is in Tutukaka, alloy Trismus 37 twin centre boarder.
Steve.
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Old 24-08-2007, 00:55   #63
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Quote:
Originally Posted by Steve Pope
Hi Gmac, I'm In Maungaturoto, with a name like that it has to be NZ, yacht is in Tutukaka, alloy Trismus 37 twin centre boarder.
Steve.
A ha... That's why the name rang a bell. I do believe you are up north of me, not that far though. I'm in Ranfurly Sheid territory the mighty Nth Shore, the road works captial of NZ.

We do Spades (and most others) but are struggling to get enough currently. Strange as it may seem we think all of Craigs good Rocna work is lifting the profile of all the newer designs, not that the Spade is actually that new. While he might not like the idea of that particular bit at least he is improving the safety of anchoring overall. That's not a bad thing.

Have a pile more on the water though, I hope. As this is not a commercial forum I'll not spill my guts here as they say. PM coming.
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Old 24-08-2007, 09:50   #64
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GMAC - hi there from hurricane central (south florida)!
So yes, changing conditions/heavy winds is something we have to think about quite frequently - thank god that Dean missed us.

we are doing mostly coastal cruising now, with trips to the bahamas, but plan on doing extended offshore cruising starting next year. so different conditions are going to have to be addressed.

just some spec's on our boat:
46'
beam: 14'
displacement: 29,700
tonage: 29,000
center cockpit
cutter rigged
in boom furling.
5'3 draft with bulb keel

I definitely realize that the amount of rode is a key factor - we have about 150' of chain on the boat now and i expect we need more.

here is a picture

i know you have an opinion!
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Old 26-08-2007, 09:09   #65
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Quote:
Originally Posted by craigsmith
No, a heavier boat can expect to generate higher shock loads than a light boat (not always, depends on the circumstances, but over time the heavier boat will prove it needs a larger anchor).


No, it isn't.
craig - i just went on your website to determine anchor sizing and it is really confusing. how do i determine which anchor is the correct anchor in my size range - you state to take into account displacement yet you don't match the displacement to your sizing - you just give me four anchor sizes. i need your help. see further down this email string to find my specific info.
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Old 26-08-2007, 10:18   #66
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Quote:
Originally Posted by nalani
craig - how do i determine which anchor is the correct anchor in my size range - .
nalini:
Read THis SetSail.com - the serious cruising sailor's website


IMHO you should err on the higher end of the range that Craigs chart suggests. THis will allow for shorter scope anchoring in a pinch and you will get much more sleep at night in a blow.

Keegan
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Old 26-08-2007, 10:44   #67
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hi keegan - according to rocna we would need an 88lb anchor since we would have to go up to the closest desplacement of 40T - is this really right? or am i misreading?
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Old 26-08-2007, 12:19   #68
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Quote:
Originally Posted by nalani
hi keegan - according to rocna we would need an 88lb anchor since we would have to go up to the closest desplacement of 40T - is this really right? or am i misreading?
I thought your boat was about 30,000 lbs? I would go with the Rocna 33 but you can certainly rationalize the 88lb'er. Steve Dashew would tell you to go with the 88lb'er or bigger. For my cat, which has much more windage than your mono, I chose a 73lb, Rocna 33 and that was "conservative" in Craigs view.

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Old 26-08-2007, 13:35   #69
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i think i am totally confused with using the rocna website. for example - i select my boat length - in the left column. If i scroll over -what does the "20T" mean for example - is that the weight? if so why would you select the 33 when our's is 30,000 lbs? thanks so much for having the patience for a newbie!
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Old 26-08-2007, 13:51   #70
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Quote:
Originally Posted by nalani
i think i am totally confused with using the rocna website. for example - i select my boat length - in the left column. If i scroll over -what does the "20T" mean for example - is that the weight? if so why would you select the 33 when our's is 30,000 lbs? thanks so much for having the patience for a newbie!
20T (tons) is 44,000lbs. Your boat weighs greater than 12T and less than 20T, therefore, according to the Rocna chart you should go with a Rocna 33. Also, email Craig directly and discuss this with him.

Keegan
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Old 26-08-2007, 13:57   #71
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Quote:
Originally Posted by Keegan
20T (tons) is 44,000lbs. Your boat weighs greater than 12T and less than 20T, therefore, according to the Rocna chart you should go with a Rocna 33. Also, email Craig directly and discuss this with him.

Keegan
Oops, I meant 20T equals 40,000lbs. , so you still fall within the Rocna 33 zone.

Keegean
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Old 26-08-2007, 18:35   #72
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Quote:
Originally Posted by Keegan
I thought your boat was about 30,000 lbs? I would go with the Rocna 33 but you can certainly rationalize the 88lb'er. Steve Dashew would tell you to go with the 88lb'er or bigger. For my cat, which has much more windage than your mono, I chose a 73lb, Rocna 33 and that was "conservative" in Craigs view.

Keegan
Thats interesting, my reply from Craig for my 50 footer at 8500Kg full displacement was:


"I think we'd recommend a Rocna 25 (55lb) for your cat. Our sizing is conservative and this will be adequate in all conditions. Please take a look at the note concerning sizing on our website (under "sizing recommendations"). You can downgrade to the 20 (44lbs) if you wish but this is getting very marginal for a 50' cat, no matter the displacement."

Dave
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Old 26-08-2007, 21:10   #73
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Quote:
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Thats interesting, my reply from Craig for my 50 footer at 8500Kg full displacement was:

"I think we'd recommend a Rocna 25 (55lb) for your cat.

Dave

Dave:

The way the conversation went with Craig when I chose my Rocna was I emailed him the suggestion that I go with the Rocna 33 and he wrote back and said that would be fine, but "conservative" BTW, your cat is longer than mine by four feet but mine will weigh in substantially heavier than the 8500kg that yours is. It makes more since for me to go up a size from your. Anyway, as you know there is no perfect anchor size. They are either too big or too small.

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Old 27-08-2007, 01:14   #74
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Quote:
Originally Posted by Keegan
Oops, I meant 20T equals 40,000lbs. , so you still fall within the Rocna 33 zone.

Keegean
You were right the 1st time.
20t is 20,000 kilos is 44,000lb. Think metric chaps, we chucked that bloody awful Imperial measurements long ago. The US using 'Imperial', sort of ironic a bit don't ya think

Anywho - Nalani
33kg Rocna should do you well as a good all round sort of a size. If you're a real nervous sleeper or expecting lots of real nasty weather go up to a 40. If you're going Race mode drop to a 25. Same anchor sizing if a Supreme or Spade.

The 33 is a good bloke sized beast. If you're thinking of a 40 make sure it will fit, it is a quite a monster size wise.

That would be my cruising anchor size. Just costal and things like that I'd run a 25 but if you're thinking about offshore go straight to the 33 now, no having to swap later.

3/8" HT chain or a 10mm Grade 40 if you buy outside the US, it's the same thing. Just jake sure it fits your gypsy 1st.

Nice long (20-30ft) Snubber out of a 5/8" nylon, mutliplait is nicer to use and works better than a 3 strand. An 8 Brait. Some hook or a rolling hitch to attach to chain.

A bit generic but a good place to start and tune from.

Easy really.
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Old 27-08-2007, 01:34   #75
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[quote=GMac]The US using 'Imperial', sort of ironic a bit don't ya think

quote]

Yeah, we have become quite the imperialists of late, unfortunatly.

Keegan
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