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Old 19-03-2011, 20:10   #1
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Anchor Sizing - Rocna 20 on 36ft boat

Hello:

It is not without tripidation that I dip my toe into the Anchor debate but I have a question about anchor sizing, specifically for the Rocna. This is not about comparing anchors so much as trying to determine the correct size of anchor.

To get to the point quickly, my question is if a Ronca 20 is sufficient for a 36ft LOA, 11.5' beam sloop with 15,500 lbs displacement in a "typical" East coast and Carribean anchorage? The 20KG is the rated size according to the Rocna charts.

Now the long winded explanation:
Currently, I have a 35lb Kingston Plow which has offered adequate, if not stellar service (we dragged last year in a 35 knot blow albeit in heavy weed after a wind shift). As I am making other changes to my ground tackle I am thinking of also upgrading my anchor and making the plow my backup (I also have a Fortress 16).

Being budget conscious, I am considering going with a Lewmar Delta 44 (which is oversize based on the charts that stipulate 35lb). I can get that locally for about $400. For about $650, I can get a Rocna 20, which is the same weight as the Delta. (BTW. Manson Supreme does not seem to be available in Canada so I would have to order it over the Internet (roughly $500 with shipping and duty from Defender) and I am hesitant to buy things without first seeing them.)

Delta would be more than adequate for the anchoring I that I currently do (inland Great Lakes, mud/sand bottoms, lots of weeds). However, I have (loose) long term plans to head south so I am trying implement solutions that support that goal.

My options are get a Delta now, and upgrade later if required. Or, go with a Rocna20 with the expectation that is a satisfactory for more challenging anchorages. However, I wonder if I should be oversizing it as I did with the Delta, which would put me into the 25KG or 33KG. Upsizing takes it out of my budget comfort zone and thus won't happen now. Which leaves me back with the Delta.

Comments anyone?

Andrew
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Old 19-03-2011, 21:06   #2
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Re: Anchor Sizing - Rocna 20 on 36ft boat

For 3 yrs in the Caribbean we have been delighted with our Rocna 55 on a 55ft, 33 ton boat and have never dragged when we set it with sufficient chain.

They are difficult to stow in the bow roller so going too big becomes a problem. We had to have extra 'cheeks' welded on the roller to stop it jumping the roller.

From my personal experience I would get the recommended size Rocna.
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Old 20-03-2011, 00:15   #3
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Re: Anchor Sizing - Rocna 20 on 36ft boat

We used a 45 pound CQR to anchor 24/7/365 for two years on a 32'/21,000# boat. Never dragged. Current boat is 35'/13,000# and am using a 15K/35# Manson Supreme which has worked fine in winds of up to 30mph in flat conditions though we'vr not been 24/7 on the hook. A 20k Rocna should be more than adequate for your boat.
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Old 20-03-2011, 00:31   #4
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Re: Anchor Sizing - Rocna 20 on 36ft boat

Andrew, just to check have you familiarized yourself with Rocna's outline of their sizing attitudes?
Rocna sizing recommendations (Rocna Knowledge Base)

Different manufacturers do not use the same criteria for their sizing so careful when comparing.
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Old 20-03-2011, 06:02   #5
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Re: Anchor Sizing - Rocna 20 on 36ft boat

For my money the Rocna 20 is the way I'd go. We had no problems with that same anchor on a 15K displacement cat. The 40lb CQRs that came with the boat were nothing but a way to lose sleep at night. I had a delta on a previous monohull and it too did not compare to the Rocna.

Others have said they sometimes do not fit the bow roller setup - and that is true. Make sure you won't need major mods up there before you buy.

Choosing anchors is almost like debating favorite colors.....
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Old 20-03-2011, 06:11   #6
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Re: Anchor Sizing - Rocna 20 on 36ft boat

I wouldn't bother with the Delta if I were you. A 25kg Delta came with our boat; we had lots of trouble with it. Trouble which disappeared when we fitted a (admittedly much larger) Rocna.

If I were you, I would scrape up and go one size bigger than what Rocna recommend, provided that size fits on your bow roller. Bigger is always better where anchors are concerned, and there's no such thing as too good holding.

Like Moondancer, we use a 55kg (121 pound) Rocna. It doesn't fit perfectly and it's not too easy to handle, but it is worth it in spades. The security is priceless.
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Old 20-03-2011, 06:31   #7
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Re: Anchor Sizing - Rocna 20 on 36ft boat

Quote:
Originally Posted by ADMPRTR View Post
Hello:

It is not without tripidation that I dip my toe into the Anchor debate but I have a question about anchor sizing, specifically for the Rocna. This is not about comparing anchors so much as trying to determine the correct size of anchor.

To get to the point quickly, my question is if a Ronca 20 is sufficient for a 36ft LOA, 11.5' beam sloop with 15,500 lbs displacement in a "typical" East coast and Carribean anchorage? The 20KG is the rated size according to the Rocna charts.

Now the long winded explanation:
Currently, I have a 35lb Kingston Plow which has offered adequate, if not stellar service (we dragged last year in a 35 knot blow albeit in heavy weed after a wind shift). As I am making other changes to my ground tackle I am thinking of also upgrading my anchor and making the plow my backup (I also have a Fortress 16).

Being budget conscious, I am considering going with a Lewmar Delta 44 (which is oversize based on the charts that stipulate 35lb). I can get that locally for about $400. For about $650, I can get a Rocna 20, which is the same weight as the Delta. (BTW. Manson Supreme does not seem to be available in Canada so I would have to order it over the Internet (roughly $500 with shipping and duty from Defender) and I am hesitant to buy things without first seeing them.)

Delta would be more than adequate for the anchoring I that I currently do (inland Great Lakes, mud/sand bottoms, lots of weeds). However, I have (loose) long term plans to head south so I am trying implement solutions that support that goal.

My options are get a Delta now, and upgrade later if required. Or, go with a Rocna20 with the expectation that is a satisfactory for more challenging anchorages. However, I wonder if I should be oversizing it as I did with the Delta, which would put me into the 25KG or 33KG. Upsizing takes it out of my budget comfort zone and thus won't happen now. Which leaves me back with the Delta.

Comments anyone?

Andrew
Andrew,

I too have a 36T and chose the Rocna 15. While a 20 is "optimal" I have purposely put my boat in a 55 knot blow to test it and the 15kg is more than adequate. Rocna is very conservative on sizing and a 20kg is a darn mooring for a 36T..

I rarely use my windlass so for 98% of the anchoring we do the 15kg has been spot on. It's a HUGE 15kg anchor, surface area wise, compared to the old school stuff. FWIW a good friend used my Manson 25 on his 36 footer for two years and weathered multiple storms before buying his own 35 pounder. He never once dragged an inch. If you use the windlass then the 20kg would be optimal but for up to 55-60 in fairly exposed conditions I have seen no need to go to a 20kg for our 36T. If heading off for extended cruising away from our home waters I would probably opt for the 20kg.

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Old 20-03-2011, 07:00   #8
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Re: Anchor Sizing - Rocna 20 on 36ft boat

Get the Rocna. The size seems pretty good - it would be nice if the link on the Rocna page worked craigsmith - it seems broken on the Rocna page today.

If for any reason you wanted a larger Rocna in the future, it would be much easier to sell your Rocna 20 (in my opinion) because it's highly desired. I have a feeling the 20 will provide plenty of security for you though.
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Old 20-03-2011, 07:48   #9
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Re: Anchor Sizing - Rocna 20 on 36ft boat

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Originally Posted by s/v Moondancer View Post
For 3 yrs in the Caribbean we have been delighted with our Rocna 55 on a 55ft, 33 ton boat and have never dragged when we set it with sufficient chain.

They are difficult to stow in the bow roller so going too big becomes a problem. We had to have extra 'cheeks' welded on the roller to stop it jumping the roller.

From my personal experience I would get the recommended size Rocna.
Thanks. Would you elaborate on what you mean by extra cheeks on the roller, please? I likely need to purchase a roller extension and was going to go for one designed for a Delta (e.g. a Lewmar). Would that be sufficient?

Andrew
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Old 20-03-2011, 07:54   #10
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Re: Anchor Sizing - Rocna 20 on 36ft boat

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Originally Posted by roverhi View Post
We used a 45 pound CQR to anchor 24/7/365 for two years on a 32'/21,000# boat. Never dragged. Current boat is 35'/13,000# and am using a 15K/35# Manson Supreme which has worked fine in winds of up to 30mph in flat conditions though we'vr not been 24/7 on the hook. A 20k Rocna should be more than adequate for your boat.
Thank you. In our case when we dragged on the plow it was after it held for 36 hours in a 35kt wind. When we pulled it up it was covered in weeds and I am not certain any anchor would have survived that. We also only had 25' of chain at the time. So the CQR is probably adequate but the experience did give me a moment to pause.

If you were buying a new anchor, would you still go with a roll bar type?

Andrew
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Old 20-03-2011, 08:04   #11
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Re: Anchor Sizing - Rocna 20 on 36ft boat

Quote:
Originally Posted by ADMPRTR View Post
Thanks. Would you elaborate on what you mean by extra cheeks on the roller, please? I likely need to purchase a roller extension and was going to go for one designed for a Delta (e.g. a Lewmar). Would that be sufficient?
As the roller sees things, the profiles of the Delta and Rocna are very similar, so a pre-fabricated roller assembly intended for a Delta is a good start. The Rocna shank has a cranked-back gusset which is designed to lock the roller in the shank as well as possible. This stops the anchor moving vertically as well as is possible when pulled home.

I think he means: ideally the cheek plates would extend to meet the upper surfaces of the anchor fluke, which then eliminates the anchor from rocking on the roller. A luxury that any prefab set-up cannot provide due to the exact dimensioning required.
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Old 20-03-2011, 08:24   #12
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Re: Anchor Sizing - Rocna 20 on 36ft boat

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Originally Posted by markpj23 View Post
For my money the Rocna 20 is the way I'd go. We had no problems with that same anchor on a 15K displacement cat. The 40lb CQRs that came with the boat were nothing but a way to lose sleep at night. I had a delta on a previous monohull and it too did not compare to the Rocna.

Others have said they sometimes do not fit the bow roller setup - and that is true. Make sure you won't need major mods up there before you buy.

Choosing anchors is almost like debating favorite colors.....
As you cat has more windage than my boat, that is a good testimonial. Taking a second look at the Rocna charts, my boat is just on the cuttoff for the 15KG anchor so in a way I would be oversized even with the 20.

Thanks,

Andrew
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Old 20-03-2011, 08:24   #13
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Re: Anchor Sizing - Rocna 20 on 36ft boat

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I can get A Delta locally for about $400. For about $650, I can get a Rocna 20, which is the same weight as the Delta.
Thats not a huge difference in price so I would be tempted to take the forums advice and go for the Rocna. We opted for the Delta because the Rocna is twice the Delta price in UK. Come on Craig, they are both made in China so sort your pricing out, you would sell a lot more and steal a lead on the competition.

Whilst we don't anchor if its going to be windy we have never had a problem with the Delta, although we always use lots of chain. 3 years on, the labels have faded but the galvanising is still very good. Might have to print up some new labels on a HP ink jet printer to replace them so it looks smart again, really don't like scruffy kit.

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Old 20-03-2011, 08:29   #14
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Re: Anchor Sizing - Rocna 20 on 36ft boat

The rocna has a deep stock and needs depth in the anchor roller or it slides off as it comes aboard and hangs over the side of the boat.

I don't have a working camera at the moment but the link shows a stowed rocna.

Customer Testimonials » Rocna Anchors

We raised the sides of the roller by 4 inches because as it came aboard it would rotate and on two occasions fell off the roller and hit the boat.

It is very hard to lift a 55 by hand while you are hanging over the side as your wife motors around a crowded anchorage. But since raising the sides of the roller it has not been a problem.

This is the reason I did not suggest an oversized rocna.

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Old 20-03-2011, 08:32   #15
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Re: Anchor Sizing - Rocna 20 on 36ft boat

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Andrew, just to check have you familiarized yourself with Rocna's outline of their sizing attitudes?
Rocna sizing recommendations (Rocna Knowledge Base)

Different manufacturers do not use the same criteria for their sizing so careful when comparing.
Yes, thanks Craig. It is one of the things I like about your product is the information that you provide and the explanations. And your products look well engineered. But, on the other hand, I also want real life recommendations.

I wonder if you could comment on the Practical Sailor tests, which while generally good, also had some negative comments regarding your product (e.g. short scope failing to set). I have also read that the roll bar can be a detriment to setting in soft mud.

Andrew
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