Rocna 10 (22 lb.) anchor for RT-25SC.

F

fst415

Member
Joined
Feb 9, 2015
Messages
20
Fluid Motion Model
C-26
Hull Identification Number
FMLR2516K415
Vessel Name
Little Toot
I am planning to replace the factory-fitted 16 lb, claw anchor that comes standard with the RT-25SC with a Rocna 10 (22 lb.) anchor. From reading some of the posts by RT-25SC owners who have made this switch, it would seem that switching to the Ronca 10 anchor is possible. However, what is less clear to me is whether owners who have made this switch have had to modify their bow pulpit anchor roller setup to accommadate this switch, or whether the change was possible without any modifications. My hope is that the latter is the case. Any feedback from RT-25SC owners who have made this switch would be greatly appreciated.

Feroz
 
We recently put a Rocna 10 on our 2011 R27 and had to extend the anchor roller to accommodate the barrel swivel and a larger bow shackle. Simple to do. Just take out one transverse bolt and slide the roller piece to the next set of holes (4 to 6 inches as I recall), then reinsert the bolt. That also puts the anchor a little farther in front of the bow, which we hope will reduce banging on the bow on retrieval.
 
We just upgraded to a Rocna 15 on our R-25sc and it fits nicely. We bought the boat used with a Rocna 6 installed, and the bow pulpit had already been shifted forward to the second set of bolt holes as mentioned earlier. We are keeping the Rocna 6 as a spare, and the 15 fit in its place with no changes. You should have no problems fitting the Rocna 10.
The Rocna 15 does touch the bail slightly so I might wrap that in something to prevent wear, but I like that the bail holds it snugly in place.
There are pictures in our photo album of the Rocna 15 in place:

 
Rocna 15 on our 25SC also. I did change the bail for a larger one. No problems and I sleep better at night.
 
Thank you all for your responses. I will go ahead and upgrade my anchor to a Rocna 10 and make the anchor pulpit extension adjustment as suggested.
 
We LOVE our Rocna! Had to make a new fairlead. Works great!
 
Before we leave this Rocna discussion, I have a question about finishing the installation of our Rocna 10. When we bought our R27 a couple of months ago, the existing anchor was connected to the chain by a barrel swivel attached directly to the anchor. The surveyor told us that risked deformation of the swivel if it were subjected to significant side loading, e.g. when shifting wind or tide cause the boat to swing around. We're planning to attach a bow shackle to the anchor and then a new barrel swivel to the chain. There's just enough room between the anchor and the windlass to accommodate that set up.

The question: which end of the shackle should be attached to the anchor? The pin end or the bow end? A quick walk around our marina shows that folks here, with a variety of different anchors, are close to half and half, with slightly more attaching the bow end to the anchor. Does it make any difference?

Obviously, we want to get this one right!
 
smcavana:
I did a lot of research prior to my Rocna 15 install and this is what I found on Rocna's website:

"Your Rocna or Vulcan has a slotted attachment point, meaning that a
single shackle may be used. You should select the largest shackle size the
pin of which will fit through your chain end-link. Loop your shackle head
through the shank shackle attachment point, fastening the pin through
the end link in your chain.
We recommend the use of proof tested shackles, especially on anchor
sizes 15 kg (33 lb) and above. Stainless steel shackles are popular but care
should be taken. A forged type is preferable, and cast versions should
always be proof tested. Select the largest size possible given the maximum
pin diameter that the chain end link will accept. When using G40 or
stronger chain, appropriately rated high-strength alloy shackles should
be used."

I bought the best shackle I could find with the biggest pin I can fit through my chain end link. But you need to shop carefully! for example:
The Croby 209 series shackles are "Forged - Quenched and Tempered with alloy pins". WLL= 1 1/2 tonnes for a 7/16" shackle (Crosby P/N: 1018437).
The Crosby 209A series are "Forged Alloy Steel - Qenched and Tempered, with alloy pins". WLL = 2 2/3 tonnes for a 7/16" shackle (Crosby P/N: 1017472).
Big difference! The devil is in the details.

The specs on the Titan ISO High Test G43 5/16" Windless Chain give an inside link diameter of 0.51".
The specs on the Crosby 209A 7/16" shackle give a pin diameter of 0.50".
That definitely meets the "maximum pin diameter that the chain end link will accept" parameter! 🙂

As for swivels, I've seen evidence both ways, but to me the risks of it being the weakest link outweigh the benefits. I won't use one. I've never had my rode come up twisted. I've never anchored in one place long enough that I could swing around the anchor enough times to twist the rode hard enough to unset the anchor. Until I need a swivel, why tempt fate?

Personally, I enjoy doing the research and sorting the details. I sleep better knowing (or believing?) my ground tackle is the best it can be,
Good luck on your research. Hope this helps.
Ron
 
Some swivels are much better than others. I and a friend have had the Kong ones like this deform badly:

https://www.westmarine.com/buy/west-mar ... gLiD_D_BwE

Here's one I was OK with for 3-4 summers in SE Alaska on the 26-footer, with lots of anchoring:

Suncor universal swivel: https://www.defender.com/product.jsp?id=3428533

I think the Mantus swivel on my 28,000 lb 37 Nordic Tug with 5/16 chain is a superior design, and not too costly either:

https://www.mantusmarine.com/mantus-swivel/

The key thing is to avoid side loading where the swivel connects to the anchor, unless the swivel body there is really strong. You can do this by adding a shackle between swivel and anchor, with the bow end through the anchor, but a better swivel design would take care of it.
 
Thanks for everyone''s input. After doing the research, we chose the Mantus swivel with integrated stainless bow shackle. The recommended size feels a bit like overkill, but hey, it fits and we'd rather be certain the shackle and swivel are strong enough--and it was substantially less expensive than some alternatives that wouldn't accommodate a bow shackle with enough excess working load limit to make us comfortable. Thanks again. It's great to have an active owners' group!
 
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