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Old 01-03-2013, 03:47   #1
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Rocna sizing

I felt the breath of a thousand cruiser exhaling in exasperation as I typed the words "Rocna Sizing" but I just couldnt help it

Next season I'm planning on a fitting a Rocna or a Manson Supreme with 10mm all chain rode on my 44' 12 ton Moody 44. We cruise in Greece and anchor most of the time we are there. Currently summer only but hoping to extend the cruising season after retirement next year.

The Rocna is actually cheaper for me to buy in Greece but I just cant decide between the 20kg or 25kg.
I know that the concesus is that bigger is better but I dont want an elephant hanging off the bow and my windlass is elderly.

The Rocna sizing charts seem to put me between 20kg and 25kg but I know of several Moody44s which happily use a 20kg Manson

I think I'm slowing answering my own question but just wondered what others would do ? Is a 25KG OTT ?

BTW I have a vested interest in getting this right as I dragged my anchor past one of this forums moderators last year and I still wake up in a cold sweat thinkng about it .
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Old 01-03-2013, 04:22   #2
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Re: Rocna sizing

If you dragged before, seems like you have answered you own question. As the gals all say - "size does make a difference - bigger is better"

I'm putting a 33 kg on my (fully loaded)11 ton boat

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Old 01-03-2013, 05:30   #3
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Re: Rocna sizing

Quote:
Originally Posted by carstenb View Post
If you dragged before, seems like you have answered you own question. As the gals all say - "size does make a difference - bigger is better"

I'm putting a 33 kg on my (fully loaded)11 ton boat

carstenb
I guess I should explain that I dragged (on a CQR) through my own complacence.
I had just changed boats (to the M44 with a 45lb CQR) from a 34' boat with a Delta. With the Delta I was used to pretty much just dropping/setting the hook and forgetting about it. Having thought Id set the CQR properly it came as a rude awakening to find myself dragging after a few minutes having popped down below to grab a cold one.
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Old 01-03-2013, 06:12   #4
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Re: Rocna sizing

The 25kg would be the way to go for your Moody 44
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Old 01-03-2013, 06:32   #5
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Re: Rocna sizing

I used to have the 25kg on my Hunter 450. The anchor worked fine and wasn't too large. The boat weighed less than your Moody for sure. Even with the 25kg Rocna I dragged once in a 40-50k knot blow while anchored in grass. Bigger is better.
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Old 01-03-2013, 07:01   #6
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Re: Rocna sizing

I would go for the 25Kg

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BTW I have a vested interest in getting this right as I dragged my anchor past one of this forums moderators last year and I still wake up in a cold sweat thinkng about it .
My lips are sealed
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Old 01-03-2013, 08:16   #7
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Re: Rocna sizing

Go for the 25 kg or even bigger. When the guys at the dock laugh and point to your too big anchor, then you probably have a big enough one.

I had a 25 kg on a 35' catamaran and thought that it was just about right. Cats have more windage than monohulls of the same length, but your boat is probably equal or more and much more displacement. Go with BIG.

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Old 01-03-2013, 08:30   #8
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Re: Rocna sizing

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Originally Posted by djmarchand View Post
Go for the 25 kg or even bigger. When the guys at the dock laugh and point to your too big anchor, then you probably have a big enough one.

I had a 25 kg on a 35' catamaran and thought that it was just about right. Cats have more windage than monohulls of the same length, but your boat is probably equal or more and much more displacement. Go with BIG.

David
I agree. You always have to compensate for the extra windage on a cat.
The frontal area is larger.
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Old 01-03-2013, 08:48   #9
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Re: Rocna sizing

We have a 25 KG Rocna on our Catalina 470 with 5/16" all chian rode. The last haulout the boat weighted 36,000 lbs (18 tons).

We haven't slipped yet with 5 to 1 scope in winds up to 55 knots on a sand bottom.

Our last anchorage at Isla Providencia, Columbia, two boats draagged in the sand and grass bottom in 30 knots of wind... Both were using BRUCE anchors, which could not reset in the grass/sand and plowed along for over 1/2 mile on both boats before they got control.

I have yet to see a ROCNA drag, which is probably due to its ability to right and reset itself in short distances.

It is also the best "All Around" anchor I have ever owned... It sets in Mud, Sand, Grass, Coral and Rocks.
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Old 01-03-2013, 08:50   #10
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Re: Rocna sizing

No one lying in their berth at 2AM during a sudden squall thinks "I should have bought a smaller anchor"

You have a heavy boat. You never "round down" in an anchor size chart. The 20kg is small and will look small. Personally, I'd go for the 33kg. It really won't look too big..
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Old 01-03-2013, 08:59   #11
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Re: Rocna sizing

I use the 25 kg Rocna on a 46' monohull displacing 13 tons empty. All chain rode, of course. The only problem I ever have with it is that it occasionally digs itself in so deep I have to use the diesel to break it out.
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Old 01-03-2013, 09:19   #12
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Re: Rocna sizing

I've got the 27kilo / 60lb manson supreme on my 12 ton 36' hans christian. 300' of chain.

The heavy ones are nice because sometimes, from getting yanked out in tides, it's just resting on the sea floor with barely the tip dug in. When you put load on it, the bastard digs in like a gopher.
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Old 01-03-2013, 09:29   #13
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Re: Rocna sizing

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When you put load on it, the bastard digs in like a gopher.
That reminds me, how did your rodencia problema work out?
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Old 01-03-2013, 09:35   #14
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Re: Rocna sizing

We use the 25kg on our 18,000 boat. It does look to big but it isn't!
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Old 01-03-2013, 12:49   #15
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Re: Rocna sizing

IIRC, Rocna's website has a pretty good sizing chart or recommendations. We sized our anchoring SYSTEM this way, with these charts:

Ground Tackle & Anchor System Sizing TABLES & Swivels
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