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Old 10-11-2015, 09:34 PM   #1
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High Hopes For The Rocna, Still Needed The Tandem.

Anchored in my favorite spot at Hilton Head for jumping off going outside to St Simons inlet. Bottom is hard mud and shell. With our new to me boat, I tried just the Rocna anchor with 6:1 scope of chain. But with 900 rpm I was slowly plowing the bottom. So after retrieving the Rocna, I teathered on to it, under the roll bar, eight feet of 3/4" line spliced to a Fortress FX-23. Dropped the Fortress over and while slowly backing down dropped the Rocna and 75' of chain over. Set the two tandem anchors with 1000 rpm and then went to bed and slept like a baby. Click image for larger version

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ID:	45406 we anchor just SE of the #4.
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Old 10-11-2015, 09:52 PM   #2
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Pgitug,
Is the Rocna small?
You mention it's one of your favorite spots. What history can you offer to this like old ______ anchor did this or that. Rocna didn't do well in the mud test reciently but that was very soft mud. The Rocna should do well at 6-1 scope.
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Old 10-11-2015, 11:56 PM   #3
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Anchored in my favorite spot at Hilton Head for jumping off going outside to St Simons inlet. Bottom is hard mud and shell. With our new to me boat, I tried just the Rocna anchor with 6:1 scope of chain. But with 900 rpm I was slowly plowing the bottom. So after retrieving the Rocna, I teathered on to it, under the roll bar, eight feet of 3/4" line spliced to a Fortress FX-23. Dropped the Fortress over and while slowly backing down dropped the Rocna and 75' of chain over. Set the two tandem anchors with 1000 rpm and then went to bed and slept like a baby. Attachment 45406 we anchor just SE of the #4.

That's in the entrance to Broad Creek, a pretty well used channel. Any problem with traffic?
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Old 10-12-2015, 12:11 AM   #4
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Criticizing Rocna?? There may be trouble ahead.
An anchor manufacturer recently told me a frequently used anchoring area can have compromised holding due to the surface being often disturbed. Could that be an issue, maybe not if it is a "well used channel" as described by Don.
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Old 10-12-2015, 12:17 AM   #5
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6:1 in 20' of water does not equal 75'.
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Old 10-12-2015, 12:17 AM   #6
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Hi I placed a Rocna for our trip to Tasmania last year on the bowsprit. I oversized it and we are 57 feet and I put a 110 kg size on the bow with 400 feet of 13 mm chain spliced to 100 feet of 20 mm nylon. We anchored on our cruise for 3 months and on some occasions experienced constant 35 knots and sometimes 50 knots for periods of time , mostly down on the South west coast.We mostly had a 6 to 1 scope and we never dragged or look like dragging. We were rock solid where as in one anchorage we had several boats drag one afternoon , flying past us in the strong gusts. Tassie is renown for its changeable and strong winds. We anchored with varying bottom make ups and some were soft mud, but the Rocna held firm. We have another backup system on 100 metres of 13 mm chain , but to date have never had to deploy it. Our vessel is 57 feet and weighs 36 tonnes.
Just wanted to get my experience out there on the Rocna, I did a lot of research on it before a I jumped in to purchase it for the trip.


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Old 10-12-2015, 12:23 AM   #7
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Criticizing Rocna?? There may be trouble ahead.
An anchor manufacturer recently told me a frequently used anchoring area can have compromised holding due to the surface being often disturbed. Could that be an issue, maybe not if it is a "well used channel" as described by Don.
Bruce, I have run that channel scores of times. There are 6 to 8' tides in that area, so the bottom is well scoured by current. The sides are soft grey muck that has very little holding power. The Haig Point ferries use the cut across break just north of that position. They run early to late. They should not be a bother there.,
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Old 10-12-2015, 06:30 AM   #8
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High Hopes For The Rocna, Still Needed The Tandem.

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6:1 in 20' of water does not equal 75'.
You are right. We were in 16 feet of water and my bow roller is five feet above the water line. We anchor north of the creek and SE of #4.
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Old 10-12-2015, 06:39 AM   #9
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Pgitug,
Is the Rocna small?
You mention it's one of your favorite spots. What history can you offer to this like old ______ anchor did this or that. Rocna didn't do well in the mud test reciently but that was very soft mud. The Rocna should do well at 6-1 scope.

We have anchored there before in our 41 foot sailboat using a tandem set up with our old Delta anchor and the Fortress. I have always used the tandem set up after our first of five trips up the east coast from Florida. It was the only method I found that never had the Delta drag even with 150' of chain out. I'll take a look at the model number of the Rocna at first light.
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Old 10-12-2015, 06:42 AM   #10
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That's in the entrance to Broad Creek, a pretty well used channel. Any problem with traffic?

We anchor closer to #4 than the creek. We are east of the channel, SE of #4, about 200 feet from the #4 marker in 15-17 feet of water. Few wakes because most boats and all ferries use the cut northwest of #4.
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Old 10-12-2015, 06:47 AM   #11
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6:1 in 20' of water does not equal 75'.

Well after review I think Capt Bill has a really valid point. I did not have out the proper scope. In hind sight I should have had a least 130' of chain/line out. Next time I will try more. My bad.
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Old 10-12-2015, 07:10 AM   #12
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Pgitug,
Is the Rocna small?
You mention it's one of your favorite spots. What history can you offer to this like old ______ anchor did this or that. Rocna didn't do well in the mud test reciently but that was very soft mud. The Rocna should do well at 6-1 scope.

My boat is a 37 Nordic Tug. The Rocna is a model 20 at 44#. It was on the boat when we bought it. Right size??
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Old 10-12-2015, 07:43 AM   #13
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We have anchored there before in our 41 foot sailboat using a tandem set up with our old Delta anchor and the Fortress. I have always used the tandem set up after our first of five trips up the east coast from Florida. It was the only method I found that never had the Delta drag even with 150' of chain out. I'll take a look at the model number of the Rocna at first light.
If you mean you had to use tandem anchors on a regular basis to get your anchor/s to set, something is wrong IMO.
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Old 10-12-2015, 09:01 AM   #14
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we are 57 feet and I put a 110 kg size on the bow ... Our vessel is 57 feet and weighs 36 tonnes.
Wow, you don't monkey around. Your anchor looks to be about two sizes larger and twice the weight as recommended. Coupled with the 1/2" chain, I doubt you would drag in a force 1 hurricane!
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Old 10-12-2015, 09:05 AM   #15
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If you mean you had to use tandem anchors on a regular basis to get your anchor/s to set, something is wrong IMO.

Yeh. What was wrong was my primary anchor was a Delta.
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Old 10-12-2015, 09:28 AM   #16
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Hard pan bottoms was the reason that I decided to go with the Sarca ExCel. Being in Florida since putting it on the boat there is not much of that stuff around here. When we go north the bottom problem will arise. I chose the ExCel because of the ballasted turned down point. I'm hoping it will grab and dig into those type bottoms.
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Old 10-12-2015, 10:40 AM   #17
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Well, I see two possible problems with the tandem rig that the OP used in addition to the lack of scope:

The Rocna has a hole near the bottom of the shank that is designed to be used in a tandem configuration. That is the only place where it is safe to tie on a tandem rig. Anyplace else and you upset its holding geometry.

That anchorage is a reversing current situation and pretty strong- a couple of knots at peak. When the current reverses after setting a tandem rig, the front anchor will rotate, partially pull out and then set after a few feet- if it is a Rocna ;-). Then you are on only the Rocna. If you need the additional resistance of the aft anchor and the Rocna drags, then the entire rig can get tangled up and be near worthless.

A tandem rig if rigged right can provide great holding but only if the wind/current is in a constant direction.

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Old 10-12-2015, 10:53 AM   #18
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Pgitug,
Yes 44lb is fine.
Looks like you had a scope of about 3.8-1. Unless I figured it wrong. In two or three anchor tests the Rocna did poorly in 3-1 scope but about 4-1 should have been OK. Close to 4-1 is not short scope. It's the middle ground for scope. But hard bottoms are a problem for many anchors.

Just a guess but there could have been a hard layer 6" or so under the surface. You mentioned different types of bottom in various places. That would limit penetration and the Fortress wouldn't suffer as moch as the Rocna in that scenario.

If the scope wasn't an issue my guess is penetration. The current mentioned several times here would be very likely to produce a layered bottom. As in sedimentary deposits on land. A shallow/loose top layer w a hard layer close would definitely be a great recipie for draging.

Perhaps you should try the Fortress alone.

FF has been a strong supporter of having several types of anchors for various conditions and your report strongly says that he is almost certianly right. You could consider making the Fortress your primary anchor and use the Rocna on rocky and weedy or bottoms. This experience of yours also brings to light something I have said many times .. that the biggest variable in anchoring is the sea floor .. not anchors.

I'd say this is not a problem w the anchor or scope but just a very difficult bottom.
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Old 10-12-2015, 11:40 AM   #19
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Pgitug,
I'd say this is not a problem w the anchor or scope but just a very difficult bottom.
Eric, I didn't mention that the Ex-Cel is galvanized, but has a stainless steel point. It can be sharpened for better cutting into bottoms and grasses. Being stainless rust is not a problem with sharpening it. I have been looking for something to penetrate the hard packed silt clay called hard pan around the South. Hopefully, it will do the job. With currents running strongly the bottom of the channels near the ICW are usually scoured in Georgia, SC and southern NC.

I also carry a Danforth and a Delta as backups.
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Old 10-12-2015, 12:21 PM   #20
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Don,
Yes the Excel holds great promise well above the Delta I think. But I've never used a Delta.
You may need to sharpen the point (or toe as Rex called it) as stainless is not as hard as carbon steel but it depends on what alloy of each. My late XYZ came w a SS tip and was a special alloy .. not common SS.
I, along w probably many others are anxious to see the Excel perform in a good independant anchor test. In some ways it's similar to the SARCA for the obvious reasons and personally I suspect the Excell will be very similar. Both have bent down toes not unlike an Eagle's beak and that could be a big help in setting and/or penetrating hard bottoms. While the very tip of the Excell curves down the tip of the Rocna curves up. I've always thought that had a lot to do w the fact or great probability that the curved up tip is aimed at "hooking" the bottom laying on it's side where it does it's setting. Can't see it (curved up toe) as a pluss when digging down after setting.

If I miss it (new anchor test) let me/us know about it.
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