Dense sand - mushroom anchors float on it - SailNet Community
 
LinkBack Thread Tools
post #1 of 2 Old 05-17-2009 Thread Starter
Glad I found Sailnet
 
Bene505's Avatar
 
Join Date: Jul 2008
Posts: 3,816
Thanks: 14
Thanked 51 Times in 50 Posts
Rep Power: 8
   
Dense sand - mushroom anchors float on it

I'm about to buy a 1,000 mushroom anchor for our Beneteau 50. Then I remembered the mushroom anchors I saw "floating" on the sand where we keep our boat. I even saw one whose shank eye had worn through and it was only 1/2 way into the sand. I don't have confidence that a mushroom will "set" and provide good holding power.

I think the same problem would exist with a pyramid anchor, since they are also made of steel and would have the same density. Here's an email from dor-mor about their pyramid anchor, from earlier this month. They were very responsive to my email questions.
Quote:
Based on the tables of American Boat and Yacht Council, the wind load on your vessel in winds of 64 knots would be 7250 lbs. and in wind speeds of 100 knots would be 16,000 lbs.

Our Anchors when fully imbeded using 3:1 scope achieve approx. 10 times their dry weight in holding power.

When you asked about the 1000 lb. anchor - if you are using 3:1 scope and have a penetrable bottom, then it should achieve approx. 10,000 lbs. in holding power...
There's the "when fully imbeded" condition again.

So now what? I'm thinking that I'm back to a 3-anchor system, like I was considering last summer.

With the philosophy that each of the 3 anchors should be able to hold our boat individually, we could use 33kg Rocna anchors. Our boat is 50 feet, 12.7 metric tons. The Rocna 33kg work for 52 foot 15 metric ton boats. See the sizing chart. From their website: "We base our calculations on 50 knots wind, associated surge, and soft moderate holding bottoms into which it is assumed the anchor has set. Adequate scope is assumed." The lake is 3 miles long, 8 feet deep, with few other boats anchored nearby. Adding some extra scope is not a problem. The Rocna will surely set in the hard sand.

Finally, I found no local rules about anchor size when I looked last summer. And I intend to call my insurance company to see if they have any requirements that I need to meet.

Any thoughts on all this? Am I missing something here?

.
.
Great minds discuss ideas;
Average minds discuss events;
Small minds discuss people.
.
The best minds discuss sailing (and a little bit of politics). I don't know why. It's a mystery!
.
Bene505 is offline  
Quote Quick Reply Share with Facebook
Sponsored Links
Advertisement
 
post #2 of 2 Old 05-17-2009
Telstar 28
 
sailingdog's Avatar
 
Join Date: Mar 2006
Location: New England
Posts: 43,290
Thanks: 0
Thanked 14 Times in 12 Posts
Rep Power: 14
         
Getting a properly installed helix mooring would probably make a lot more sense than getting and installing three 33 kg Rocnas...

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.
sailingdog is offline  
Quote Quick Reply Share with Facebook
Reply

Quick Reply
Message:
Options

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:
OR

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
Show Printable Version Show Printable Version
Email this Page Email this Page



Similar Threads
Thread Thread Starter Forum Replies Last Post
Using Two Anchors Tom Wood Seamanship Articles 0 01-19-2004 07:00 PM
Using Two Anchors Tom Wood Gear and Maintenance Articles 0 01-19-2004 07:00 PM
Choosing Anchors, Rodes, and Windlasses Liza Copeland Seamanship Articles 0 01-19-2003 07:00 PM
Choosing Anchors, Rodes, and Windlasses Liza Copeland Gear and Maintenance Articles 0 01-19-2003 07:00 PM
Choosing Anchors, Rodes, and Windlasses Liza Copeland Cruising Articles 0 01-19-2003 07:00 PM

Posting Rules  
You may post new threads
You may 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 On
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome