Anchoring a Multihull / Hurricane Prepardness - SailNet Community

   Search Sailnet:

 forums  store  


Quick Menu
Forums           
Articles          
Galleries        
Boat Reviews  
Classifieds     
Search SailNet 
Boat Search (new)

Shop the
SailNet Store
Anchor Locker
Boatbuilding & Repair
Charts
Clothing
Electrical
Electronics
Engine
Hatches and Portlights
Interior And Galley
Maintenance
Marine Electronics
Navigation
Other Items
Plumbing and Pumps
Rigging
Safety
Sailing Hardware
Trailer & Watersports
Clearance Items

Advertise Here






Go Back   SailNet Community > General Interest > General Discussion (sailing related)
 Not a Member? 


Reply
 
LinkBack Thread Tools
  #1  
Old 07-11-2006
Junior Member
 
Join Date: Jul 2006
Posts: 13
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 0
surfnrg is on a distinguished road
Anchoring a Multihull / Hurricane Prepardness

Was looking for advice on the best way to anchor a 35 ft. Wildcat Sailing Catamaran. Beam is 21.5 feet. She weighs 11,000 lbs but has high freeboard. Is it best to use a bridle and if so where can I purchase one or learn how to make one? I've been running a single line (3/4 inch 3 strand nylon) through the anchor roller and securing to the windlass using chafing of course near the anchor roller. Also, was wondering how effective it would be to use a three point anchoring if a hurricane rolls through. thinking of using two danforths 180 degrees apart (a 15 lb. FX-23 Fortress along with a 20 lb steel Danforth) then with a 35 lb. CQR up the middle with longer scope as my primary. The bottom here in Central East Coast Florida is mud and sand mix. Any thoughts are greatly appreciated.
Reply With Quote Quick reply to this message Share with Facebook
  #2  
Old 07-11-2006
sailingdog's Avatar
Telstar 28
 
Join Date: Mar 2006
Location: New England
Posts: 43,291
Thanks: 0
Thanked 11 Times in 11 Posts
Rep Power: 13
sailingdog is just really nice sailingdog is just really nice sailingdog is just really nice sailingdog is just really nice sailingdog is just really nice
First problem I see is that you're probably a bit undersized on the anchors, especially for a hurricane type situation. While a FX-23, a 20 lb. Danforth, or a 35 lb. CQR may be a decent anchor for normal conditions, I seriously doubt that any of these is really suitably large for extreme weather conditions, especially given the fact that your boat has far more beam and significant freeboard than a comparably-sized monohull.

A good bridle will run from both bows to the anchor rode.

I would recommend that you get two fairly long lengths of 3/4" nylon rope—braided or three-strand—to use as the bridle lines. Eye splice each to a heavy thimble—at least if you're using an all-chain main anchor rode—then use a heavy shackle to connect both thimbles to a good chain hook, . If you're using a combination rode, then you should use rolling hitches to connect the two bridle lines to the main anchor rode. Both bridle lines should be fairly long and allow you to let out at least 30-50' of additional scope if it is necessary.
__________________
Sailingdog

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.

Telstar 28
New England

You know what the first rule of sailing is? ...Love. You can learn all the math in the 'verse, but you take
a boat to the sea you don't love, she'll shake you off just as sure as the turning of the worlds. Love keeps
her going when she oughta fall down, tells you she's hurting 'fore she keens. Makes her a home.

—Cpt. Mal Reynolds, Serenity (edited)

If you're new to the Sailnet Forums... please read this
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
.

Still—DON'T READ THAT POST AGAIN.

Last edited by sailingdog; 07-11-2006 at 06:31 PM.
Reply With Quote Quick reply to this message Share with Facebook
  #3  
Old 07-11-2006
Junior Member
 
Join Date: Jul 2006
Posts: 13
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 0
surfnrg is on a distinguished road
I thought I'd be hearing from you since you're a multi-hull sailor as well.

I was thinking of purchasing an FX-37 (next size up) but came across a used FX-23 which Chapmans Piloting claims is good for a Storm Anchor for a 36 to 40 ft vessel - granted not taking the extra beam and windage into consideration. Thought I'd at least give this anchor a try since I've never used a Fortress before. Some people don't like 'em, others sware by them. If I like this one I may purchase an FX-37 and utilize it as a storm anchor since I'll be in mostly mud and sand mix. Was also thinking of purchasing a 35 or 44 lb Delta - but how would that be in mud???

And what do you think about the 3 point storm anchoring system that I initially described but this time using a 44 lb Delta as the primary anchor out front 10.1 scope and having the danforths to port and starboard on shorter 7.1 scope? Just don't want the lines to tangle. FYI I have one chain/rope combo with 40 ft. of 3/8 HT to 200ft of 3/4 inch 3 strand nylon (for the Primary), a 2nd setup of 25 ft. 3/8 PC on 150 ft of 3/4 inch 3 strand nylon, and 3rd setup of 30 ft. 5/16 HT on 200 ft of 1/2 inch. All these anchoring theory's drive you nuts. But I'd like to hear your opinion.
Reply With Quote Quick reply to this message Share with Facebook
  #4  
Old 07-11-2006
sailingdog's Avatar
Telstar 28
 
Join Date: Mar 2006
Location: New England
Posts: 43,291
Thanks: 0
Thanked 11 Times in 11 Posts
Rep Power: 13
sailingdog is just really nice sailingdog is just really nice sailingdog is just really nice sailingdog is just really nice sailingdog is just really nice
Generally, I'm against a multiple anchor deployment, as if you start to drag, you can run into some serious complications, especially if the different rodes get twisted or fouled.

The real issue I have with the Fortress anchors, is that being made of a lightweight aluminum alloy, once they break free, they will plane and not reset if they have any momentum.

The first two anchor rodes sound quite sufficient, but the third one is a bit light. I use 30' of 5/16" G4 and 200' of 5/8" nylon for my primary rode, but my boat is both smaller, less massive (about a third the mass) and offers considerably less windage than yours.

The really important part of any storm survival setup is chafe protection and having it setup properly...even the heaviest anchor line will fail if it chafes. I recommend using something that absorbs water, rather than something that is waterproof for chafe protection. Heavy canvas, denim or something like that is very good chafe protection. The reason for this recommendation is that another source of failure in heavy storms is the nylon line failing due to melting from internal friction. Denim, canvas and the like, while heavy enough to give a lot of chafe protection, allow the nylon line to get soaked and helps prevent failure from internal friction.

As for the setup you've described... it would be very vulnerable if the wind shifts 180 degrees IMHO, as the rodes would almost inevitably wrap the rodes around each other. Also, it doesn't really make sense to have the two danforths on a shorter scope, unless it was all chain—which it isn't in your case.

You don't say what the draft on your boat is, or what area of the world you're sailing in. Most cats have a fairly shallow draft, like my trimaran, and a better idea for hurricane survival is to take advantage of the shallow draft and hide the boat in a shallow canal or river, and use lines tied to large trees, bridge abutments, and things like that...which are far more sturdy and reliable than any anchor planted in mud or sand.

The real advantage of using a shallow river, canal or bay as a hurricane refuge, is you can often find one where you can get a fair amount of protection from the wind, and limit the direction the wind has a open shot at your boat...and then are able to secure the boat to resist the limited wind approaches more strongly. Also, picking the location allows you to limit the storm surge and how much fetch the wind has to build wave height to throw at your boat.
__________________
Sailingdog

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.

Telstar 28
New England

You know what the first rule of sailing is? ...Love. You can learn all the math in the 'verse, but you take
a boat to the sea you don't love, she'll shake you off just as sure as the turning of the worlds. Love keeps
her going when she oughta fall down, tells you she's hurting 'fore she keens. Makes her a home.

—Cpt. Mal Reynolds, Serenity (edited)

If you're new to the Sailnet Forums... please read this
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
.

Still—DON'T READ THAT POST AGAIN.

Last edited by sailingdog; 07-11-2006 at 08:53 PM.
Reply With Quote Quick reply to this message Share with Facebook
  #5  
Old 07-12-2006
Rickm505's Avatar
Banned
 
Join Date: Sep 2005
Location: Central Florida
Posts: 770
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 0
Rickm505 is on a distinguished road
I use the 3 anchor system Kanter promotes, each set 120 degrees from each other and the rode to each led to one common point in the center of the 'star' they create. A 20 foot bridle from each bow is attached to this point. The boat is stable, and the anchors hold. I've used it with 3 Fortress and it's dependable when 50/50 chain and 5/8" 3 stand Nylon at 10:1 is shackled to each anchor, and run to the center of the star.

Rick in Florida
Reply With Quote Quick reply to this message Share with Facebook
  #6  
Old 07-12-2006
Omatako's Avatar
Senior Member
 
Join Date: Sep 2003
Location: Auckland New Zealand
Posts: 2,426
Thanks: 0
Thanked 28 Times in 25 Posts
Rep Power: 12
Omatako will become famous soon enough
Storm surge

"Also, picking the location allows you to limit the storm surge"

I'll be the first to acknowledge a limited understanding of storm surge so maybe this stab at logic is way off.

I would have tried to stay away from any small bays when there was a threat of storm surge thinking that the surge would be accentuated in confined space. The mass of water will head in a given direction and will push into a narrow space in similar volumes to a wide open space causing it to "bunch up" for want of a better expression.

I recall seeing some good footage of the Boxing Day tsunami which suggested that the areas in small bays suffered hugely more destruction than those on open coastline.

I'm probably completely wrong and I'm always careful to not question other points of view without an alternative suggestion and I don't have one because all of the other reasons for finding a quiet secluded little space are quite compelling.

Just a thought . . . .

I also again start to wonder about the benefit of tandem anchors on a common rode. I have used this in areas of strong tidal streams (7 - 8 knots) with great results. Should also work to combat storm surge.

Interesting debate. . . .
Reply With Quote Quick reply to this message Share with Facebook
  #7  
Old 07-12-2006
sailingdog's Avatar
Telstar 28
 
Join Date: Mar 2006
Location: New England
Posts: 43,291
Thanks: 0
Thanked 11 Times in 11 Posts
Rep Power: 13
sailingdog is just really nice sailingdog is just really nice sailingdog is just really nice sailingdog is just really nice sailingdog is just really nice
Quote:
Originally Posted by Rickm505
I use the 3 anchor system Kanter promotes, each set 120 degrees from each other and the rode to each led to one common point in the center of the 'star' they create. A 20 foot bridle from each bow is attached to this point. The boat is stable, and the anchors hold. I've used it with 3 Fortress and it's dependable when 50/50 chain and 5/8" 3 stand Nylon at 10:1 is shackled to each anchor, and run to the center of the star.

Rick in Florida
Hey Rick-

Unless I'm reading his post wrong, he is actually advocating two anchors at 180 degrees apart port and starboard with one perpendicular to it off the bow, not a star formation as you're proposing. He's also using three different rodes and a bridle to just the bow anchor from what I see, as well as different scopes on the anchors—7:1 for the port and starboard, and 10:1 for the bow.

So you're comparing apples to oranges. He's also using three different anchor types, not three matched ones.
__________________
Sailingdog

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.

Telstar 28
New England

You know what the first rule of sailing is? ...Love. You can learn all the math in the 'verse, but you take
a boat to the sea you don't love, she'll shake you off just as sure as the turning of the worlds. Love keeps
her going when she oughta fall down, tells you she's hurting 'fore she keens. Makes her a home.

—Cpt. Mal Reynolds, Serenity (edited)

If you're new to the Sailnet Forums... please read this
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
.

Still—DON'T READ THAT POST AGAIN.
Reply With Quote Quick reply to this message Share with Facebook
  #8  
Old 07-12-2006
sailingdog's Avatar
Telstar 28
 
Join Date: Mar 2006
Location: New England
Posts: 43,291
Thanks: 0
Thanked 11 Times in 11 Posts
Rep Power: 13
sailingdog is just really nice sailingdog is just really nice sailingdog is just really nice sailingdog is just really nice sailingdog is just really nice
Quote:
Originally Posted by Omatako
"Also, picking the location allows you to limit the storm surge"

I'll be the first to acknowledge a limited understanding of storm surge so maybe this stab at logic is way off.

I would have tried to stay away from any small bays when there was a threat of storm surge thinking that the surge would be accentuated in confined space. The mass of water will head in a given direction and will push into a narrow space in similar volumes to a wide open space causing it to "bunch up" for want of a better expression.

I recall seeing some good footage of the Boxing Day tsunami which suggested that the areas in small bays suffered hugely more destruction than those on open coastline.

I'm probably completely wrong and I'm always careful to not question other points of view without an alternative suggestion and I don't have one because all of the other reasons for finding a quiet secluded little space are quite compelling.

Just a thought . . . .

I also again start to wonder about the benefit of tandem anchors on a common rode. I have used this in areas of strong tidal streams (7 - 8 knots) with great results. Should also work to combat storm surge.

Interesting debate. . . .
Shallow areas can be safer, as it can limit the size of the waves that can batter your boat. The shallow areas I am thinking of have a very restricted, and generally fairly long distance to any open water of significant size.

For instance... if you anchor in a shallow oxbox, up a small creek, the amount of water that the hurricane or storm can push up the creek is relatively small, as the banks of the creek and the narrow and convoluted path of the creek tend to limit the amount of water that can come up with any force.

The same can be done with some of the smaller coastal bays that are located up estuaries. Bogs and swamps are also good choice—I know several sailors who head their boats for mangrove swamps and have never had any significant storm damage to their boats from doing so.

The real damage from storms is from either the waves bashing the boat around, or the winds pushing the boat around—either indirectly or directly. In some cases, the damage is done by the docks the boat is tied to, or other boats that weren't secured properly coming loose and acting as a battering ram.

By isolating your boat in a small, shallow area, and picking the terrain properly, you can limit the directions the wind can come at your boat from with any strength as well as reduce the amount of wave action that results from the storm.
__________________
Sailingdog

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.

Telstar 28
New England

You know what the first rule of sailing is? ...Love. You can learn all the math in the 'verse, but you take
a boat to the sea you don't love, she'll shake you off just as sure as the turning of the worlds. Love keeps
her going when she oughta fall down, tells you she's hurting 'fore she keens. Makes her a home.

—Cpt. Mal Reynolds, Serenity (edited)

If you're new to the Sailnet Forums... please read this
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
.

Still—DON'T READ THAT POST AGAIN.
Reply With Quote Quick reply to this message Share with Facebook
  #9  
Old 07-12-2006
Rickm505's Avatar
Banned
 
Join Date: Sep 2005
Location: Central Florida
Posts: 770
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 0
Rickm505 is on a distinguished road
yer right, I was just commenting on what works for me as he did ask for advice. This link explains what I use.

http://www.southwindssailing.com/art...ntHarbor.shtml

Rick in Florida
Reply With Quote Quick reply to this message Share with Facebook
  #10  
Old 07-13-2006
Junior Member
 
Join Date: Jul 2006
Posts: 13
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 0
surfnrg is on a distinguished road
Anchoring a Multihull /Hurricane Prepardness

Sailing Dog, What I originally meant was using the 120 degree circle - not the 180 degree with Fortress's and a CQR right up the middle. My bad.

Regarding your concern of dragging multiple anchors and having them trip up - what do you think of this product? All three lines would tie into this swivel.

http://colligonautique.com/Hurricane...r%20System.htm

And regarding CQR's verse Fortress's - the bottom in my area is mostly mud with some sand mix. I'm a bit concerned about the limited holding power of my 35 lb CQR verse the high holding power of a Danforth, namely the Fortress, in the muddy bottom of my local anchorage. I've seen some tests showing the Fortress being 5X more holding power verse the CQR..,

Thanks everyone for your insights. I'm feeling like I'm getting little closer to working out a final plan for my hurricane anchoring system.

Kevin
S/V Blade Runner
Reply With Quote Quick reply to this message Share with Facebook
Reply

Quick Reply
Message:
Options

By choosing to post the reply above you agree to the rules you agreed to when joining Sailnet.
Click Here to view those rules.

Register Now

In order to be able to post messages on the SailNet Community forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.
Please note: After entering 3 characters a list of Usernames already in use will appear and the list will disappear once a valid Username is entered.
User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.




Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools

 
Posting Rules
You may post new threads
You may post replies
You may post attachments
You may edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On



All times are GMT -4. The time now is 04:03 AM.

Add to My Yahoo!         
Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
SEO by vBSEO 3.6.1
(c) Marine.com LLC 2000-2012

The SailNet.com store is owned and operated by a company independent of the SailNet.com forum. You are now leaving the SailNet forum. Click OK to continue or Cancel to return to the SailNet forum.