Cruisers Forum
 


Join CruisersForum Today

Reply
  This discussion is proudly sponsored by:
Please support our sponsors and let them know you heard about their products on Cruisers Forums. Advertise Here
 
Thread Tools Search this Thread Rate Thread Display Modes
Old 11-04-2016, 12:42   #1
Registered User

Join Date: Feb 2014
Location: richards Bay, South Africa
Boat: voyage Mayotte 50 ft cat
Posts: 141
Over-specifying a Rocna anchor on a cat

Greetings,
My boat is a 50 ft Voyage Mayotte Catamaran. I will soon be purchasing a new Rocna anchor. Based on 50 kts of wind, surge and poor holding conditions, the sizing guide on their web site recommends a 40 kg anchor. However, it is probable that my boat will be moored on the other side of the globe for extended periods of up to a year at a time. I need to be certain that the anchor will hold in the most extreme of conditions. However, I am also nervous of over specifying. I'm not certain but think that my windlass is a Lewmar 1000. I'm particularly anxious on overstraining my windlass. Has anyone out there ever fitted a 55kg Rocna onto their 50ft catamaran? What is the advice, Stay with the recommended 40kg or go for the 55kg?

Regards
Mike
__________________

YPSILANTI is offline   Reply With Quote
Old 11-04-2016, 13:06   #2
Senior Cruiser

Cruisers Forum Supporter

Join Date: Mar 2007
Location: Santa Cruz
Boat: Boatless Again
Posts: 4,591
Re: Over-specifying a Rocna anchor on a cat

The lewmar 1000 is recommended for boats up to 38 ft. What chain are you using? How much does your boat weigh?
__________________

donradcliffe is offline   Reply With Quote
Old 11-04-2016, 13:12   #3
Moderator
 
a64pilot's Avatar

Cruisers Forum Supporter

Join Date: Oct 2013
Location: Albany Ga.
Boat: Island Packet 38
Posts: 22,905
Re: Over-specifying a Rocna anchor on a cat

I cut this from Rocna's website, but I feel better with an oversized anchor myself

Many Rocna customers, in improving their anchor type by switching to a Rocna from an older anchor which they have learned to be unreliable, make doubly sure about their upgrade by also increasing the weight of their anchor. We see this tendency a lot, and try to discourage it. As above, our official sizing is very conservative, and in many cases it's a case of "don't over-size – we already did that for you!"




You sure you have a Lewmar 1000? If that is the windlass I think it is, that's not going to work I don't think.
What size chain do you have?
a64pilot is offline   Reply With Quote
Old 11-04-2016, 15:11   #4
Moderator
 
Jim Cate's Avatar

Join Date: May 2008
Location: cruising SW Pacific
Boat: Jon Sayer 1-off 46 ft fract rig sloop strip plank in W Red Cedar
Posts: 13,900
Re: Over-specifying a Rocna anchor on a cat

The only time I have ever wished that I had a smaller anchor was when lugging it down to the boat.

If you are using chain rode (as you should), the extra 15 kilos from the larger anchor will be a fairly small increment when anchored in deepish water. If your windlass won't handle that, get a bigger windlass... you will need it with either anchor!

Jim
__________________
Jim and Ann s/v Insatiable II lying Sandy Bay, Hobart,
Jim Cate is offline   Reply With Quote
Old 11-04-2016, 15:17   #5
Registered User

Join Date: Jun 2012
Location: Port Aransas, Texas
Boat: 2019 Seawind 1160 Lite, Previous 2002 Seawind 1000
Posts: 1,231
Re: Over-specifying a Rocna anchor on a cat

Hmm, that is an undersized windlass. I have a 33 ft cat, rocna 15 kg anchor, all 8 mm chain, and a Muir 1250 windlass. Have not dragged to date.
sailjumanji is offline   Reply With Quote
Old 11-04-2016, 15:28   #6
Registered User
 
leftbrainstuff's Avatar

Join Date: May 2011
Location: San Francisco and Australia
Boat: Liberty 458
Posts: 2,117
Re: Over-specifying a Rocna anchor on a cat

You need to consider several related parameters and ensure all elements are sized appropriately.

1) chain and shackle size
2) anchor size
3) windlass
4) vessel weight, windage and worst case wind, sea, current load
5) weight, polar moment and load carrying points

Rocna's sizing seems reasonable based on empirical data.

If can clarify the above then you'll probably get more targeted responses.

Sent from my SM-N900T using Cruisers Sailing Forum mobile app
leftbrainstuff is offline   Reply With Quote
Old 11-04-2016, 16:28   #7
Elvish meaning 'Far-Wanderer'
 
Palarran's Avatar

Cruisers Forum Supporter

Join Date: Jan 2008
Location: Boat - Bahamas and for SALE!!
Boat: 56' Fountaine Pajot Marquises FSBO
Posts: 2,923
Re: Over-specifying a Rocna anchor on a cat

Quote:
Originally Posted by YPSILANTI View Post
Greetings,
My boat is a 50 ft Voyage Mayotte Catamaran. I will soon be purchasing a new Rocna anchor. Based on 50 kts of wind, surge and poor holding conditions, the sizing guide on their web site recommends a 40 kg anchor. However, it is probable that my boat will be moored on the other side of the globe for extended periods of up to a year at a time. I need to be certain that the anchor will hold in the most extreme of conditions. However, I am also nervous of over specifying. I'm not certain but think that my windlass is a Lewmar 1000. I'm particularly anxious on overstraining my windlass. Has anyone out there ever fitted a 55kg Rocna onto their 50ft catamaran? What is the advice, Stay with the recommended 40kg or go for the 55kg?

Regards
Mike
Ypsilanti, I think the 40kg is the correct anchor for your cat and the 55 overkill. In the Med, the cost of a 55 over a 40 is nearly 100%! Save the money and get the better chain and possibly a stronger windlass.

I have a 55kg on a 56' cat with a fair amount of weight and windage. I'm using 120 meters of 10mm G7 chain and a Lofrens 1700 watt windlass.
__________________
Our course is set for an uncharted sea
Dante

http://www.cruisersforum.com/forums/...an-204234.html
Palarran is offline   Reply With Quote
Old 12-04-2016, 08:36   #8
Registered User

Join Date: Nov 2013
Location: On board
Boat: Knysna 480
Posts: 50
Re: Over-specifying a Rocna anchor on a cat

I have a Knysna 480 with 40kg Rocna.....I don't regret that. I sleep well at anchor.
Have a Tigress windless. All chain rode.
Sailingveterinarian is offline   Reply With Quote
Old 12-04-2016, 08:46   #9
Registered User

Join Date: Aug 2009
Location: Switzerland
Boat: Outbound 46 -Callisto
Posts: 205
Re: Over-specifying a Rocna anchor on a cat

My rule of thumb is that if the neighbors in the marina aren't giggling at how big your anchor is, you should go up a size. If the cost of the 55 vs. the 40 matters to you, then go with the 40. Otherwise, bigger is always better. 15 kg on the bow won't change anything about sailing performance or windlass sizing.

As an aside, we had a friend who proposed (I don't think ever executed) an April Fool's joke, cruising through the anchorage on a 45' boat with a dinghy-sized danforth on the bow, and a French flag. Sure to cause gasps among the cruisers. (I love French people, but I think their sailing education on anchoring leaves lots to be desired)

David
s/v Callisto
DMCantor is offline   Reply With Quote
Old 12-04-2016, 08:48   #10
Registered User

Join Date: Feb 2008
Boat: Quorning Dragonfly 1200
Posts: 2,264
Images: 1
Re: Over-specifying a Rocna anchor on a cat

I have a Rocna 20kg on a 12 meter trimaran. It happens to be the size they spec for the boat but it's also the largest I can fit on my bow roller because the hoop height would interfere with my sprit. I'd upsize if it was practical, and have occasionally considered the Manson Boss because it doesn't have the hoop.


The Rocna is a great anchor but it can drag in soft mud if I back down hard in a strong wind. (I think in certain situations the hoop can ball up the mud/vegetation and limit burying depth). There's no such thing as too much anchor at o-dark-hundred when a strong squall comes through.
SailFastTri is offline   Reply With Quote
Old 12-04-2016, 08:58   #11
Senior Cruiser

Cruisers Forum Supporter

Join Date: Dec 2010
Location: Cruising Indian Ocean / Red Sea - home is Zimbabwe
Boat: V45
Posts: 1,324
Re: Over-specifying a Rocna anchor on a cat

On our V45 we use a Mantus 85lb. The Mantus sizing chart suggests a 105lb for your boat. In my opinion there is little in the way of real difference between Mantus and Rocna. We upgraded our windlass to a Lofrans Tigress - which we have used on several boats and have had positive experience with. Following recent postings and lots of research we are also looking at purchasing 90 meters of new 10mm German made stainless anchor chain; this shall surely be criticised by many - but having done a heap of research this actually seems to be a very viable route to go. We are all taught not to buy stainless chain but the German chain is real quality and we have met several cruisers using it on heavy boats and with many years of success.
I dont think you'll regret going for the larger anchor as long as you ensure you have adequately sized/rated chain and a windlass powerful enough to retrieve the entire length.


YPSILANTI;2094895]Greetings,
My boat is a 50 ft Voyage Mayotte Catamaran. I will soon be purchasing a new Rocna anchor. Based on 50 kts of wind, surge and poor holding conditions, the sizing guide on their web site recommends a 40 kg anchor. However, it is probable that my boat will be moored on the other side of the globe for extended periods of up to a year at a time. I need to be certain that the anchor will hold in the most extreme of conditions. However, I am also nervous of over specifying. I'm not certain but think that my windlass is a Lewmar 1000. I'm particularly anxious on overstraining my windlass. Has anyone out there ever fitted a 55kg Rocna onto their 50ft catamaran? What is the advice, Stay with the recommended 40kg or go for the 55kg?

Regards
Mike[/QUOTE]
Bulawayo is offline   Reply With Quote
Old 12-04-2016, 10:24   #12
Marine Service Provider

Join Date: Sep 2012
Location: Virgin Islands
Boat: 1999 Leopard 45, 45 foot cat, 1980 Hunter 33, 33 foot monohull
Posts: 693
Re: Over-specifying a Rocna anchor on a cat

If you want a larger anchor, Spade make an aluminum version of their steel anchor, which is the same basic design and a precursor to the Rocna. For the last twelve years I have carried a Spade A200. It's the aluminum version (25 kilos) of their steel Spade (55kilos, which is huge). The two versions have the same surface area, thus the same holding power. The aluminum version, being lighter for the same size, can sometimes be a bit more difficult to set and get dug in, but it's not a big problem, and when it's set, it is set! We are a charter boat, so anchor a lot, and have never dragged, once set.

Not having the ring on top helps in some installations but the shank is also quite large, both vertically and horizontally, so the measurements need checking.

By the way, the Spade has most of it's weight concentrated in lead inside the tip, so it wants to be right side up. I have never seen it the anchor laying on its side and consider the roll bar on the Rocna to be superfluous on a Spade.

I use a Lofrans Tigress windlass, which is plenty, but the anchor is usually in so deep that, almost always, I have to use the weight of the boat and the engines to break it out.
contrail is offline   Reply With Quote
Old 12-04-2016, 10:35   #13
Senior Cruiser

Cruisers Forum Supporter

Join Date: Dec 2010
Location: Cruising Indian Ocean / Red Sea - home is Zimbabwe
Boat: V45
Posts: 1,324
Re: Over-specifying a Rocna anchor on a cat

Seems the Tigress is popular.......

Quote:
Originally Posted by contrail View Post
If you want a larger anchor, Spade make an aluminum version of their steel anchor, which is the same basic design and a precursor to the Rocna. For the last twelve years I have carried a Spade A200. It's the aluminum version (25 kilos) of their steel Spade (55kilos, which is huge). The two versions have the same surface area, thus the same holding power. The aluminum version, being lighter for the same size, can sometimes be a bit more difficult to set and get dug in, but it's not a big problem, and when it's set, it is set! We are a charter boat, so anchor a lot, and have never dragged, once set.

Not having the ring on top helps in some installations but the shank is also quite large, both vertically and horizontally, so the measurements need checking.

By the way, the Spade has most of it's weight concentrated in lead inside the tip, so it wants to be right side up. I have never seen it the anchor laying on its side and consider the roll bar on the Rocna to be superfluous on a Spade.

I use a Lofrans Tigress windlass, which is plenty, but the anchor is usually in so deep that, almost always, I have to use the weight of the boat and the engines to break it out.
Bulawayo is offline   Reply With Quote
Old 12-04-2016, 11:24   #14
Registered User

Join Date: Feb 2014
Location: richards Bay, South Africa
Boat: voyage Mayotte 50 ft cat
Posts: 141
Re: Over-specifying a Rocna anchor on a cat

Gosh folks. The immensely informative replies and information is much appreciated. What has been confirmed is that my windlass is under specified which is what I've always suspected. I will mull over the information and will make a final decision. The feedback from the cats of similar size is helpful too.
Regards
Mike
YPSILANTI is offline   Reply With Quote
Old 12-04-2016, 12:15   #15
Senior Cruiser

Cruisers Forum Supporter

Join Date: Dec 2010
Location: Cruising Indian Ocean / Red Sea - home is Zimbabwe
Boat: V45
Posts: 1,324
Re: Over-specifying a Rocna anchor on a cat

Was you boat built by Fred Scholtz or Voyage? Voyage are good quality byt Fred took quality to very new standard. I know some of 47's morphed into 50's.


Quote:
Originally Posted by YPSILANTI View Post
Gosh folks. The immensely informative replies and information is much appreciated. What has been confirmed is that my windlass is under specified which is what I've always suspected. I will mull over the information and will make a final decision. The feedback from the cats of similar size is helpful too.
Regards
Mike
__________________

Bulawayo is offline   Reply With Quote
Reply

Tags
anchor, rocna

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Send Over-Pressure Shore Water Over the Side with Pressure Valve ? sdowney717 Plumbing Systems and Fixtures 7 28-06-2018 18:45
Rocna's new anchor/ Hey, Anchor thread!!! goat Anchoring & Mooring 167 15-10-2015 21:57
Varnish over Polyurethane? And PU over Varnish? MarkJ Construction, Maintenance & Refit 8 06-08-2013 16:31
It's Never Over Until You Say It's Over maxingout General Sailing Forum 12 16-03-2009 17:32



Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 06:12.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2019, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2019, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.