Cruisers Forum
 


Join CruisersForum Today

Reply
 
Thread Tools Rate Thread Display Modes
Old 16-09-2003, 18:16   #1
Registered User
 
Setia's Avatar

Join Date: Jul 2003
Location: Gladstone
Posts: 25
Safe Reef Anchoring

G'day all,
As I may have previously mentioned, home Port Gladstone has several Great Barrier Reef anchorages within a radius of 50nm.
Most anchorages are orientated to the prevailing southerly conditions & in up to 20kts wind are reasonably comfortable & safe.
However conditions can rapidly change,especially around this time of the year, it is possible to have an afternoon change to Northerlies with overnite westerlies. This raises the question of safe anchoring practices which must also include minimising damage to the reef. Do you encounter these conditions in the offshore reefs in the more frequented areas in the USA? What are the most commonly used reef anchor types over there & the methods used in their deployment. An exchange of ideas may be helpfull here. So lets have some feedback.
Regards, Glen
__________________

__________________
Setia is offline   Reply With Quote
Old 17-09-2003, 05:01   #2
Moderator Emeritus
 
GordMay's Avatar

Join Date: Mar 2003
Location: Thunder Bay, Ontario - 48-29N x 89-20W
Boat: (Cruiser Living On Dirt)
Posts: 31,579
Images: 240
Reef Moorings

GLEN:
In many places, it is becoming common practice to only use a permanent reef mooring, and never anchor over coral.
In many other places it is mandatory.
Gord
__________________

__________________
Gord May
"If you didn't have the time or money to do it right in the first place, when will you get the time/$ to fix it?"



GordMay is offline   Reply With Quote
Old 17-09-2003, 18:42   #3
Registered User
 
Setia's Avatar

Join Date: Jul 2003
Location: Gladstone
Posts: 25
Gord,
Thanks for your reply, some of the more frequented areas on the GBR have perm. moorings. Due to the vastness of the reef anchoring goes mainly unsupervised. However, general rules are:
Dont anchor over coral, anchor on the edge: always anchor in the sandy patches. What I was really getting at was types of anchors & means of deploying them for minimal damage & easy release. eg. for 40ft. boat: 2" solid shaft, 2'-6" long with 4 triangles (flukes) welded to one end & solid eyes on both ends. Shackle chain to botton eye, attach chain to top eye with wire. Idea being that top wire will break leaving chain to pull the anchor out by the fluked end. Any advances on this in the good old USA?
Regards, Glen
__________________
Setia is offline   Reply With Quote
Old 31-10-2006, 04:40   #4
Moderator Emeritus
 
GordMay's Avatar

Join Date: Mar 2003
Location: Thunder Bay, Ontario - 48-29N x 89-20W
Boat: (Cruiser Living On Dirt)
Posts: 31,579
Images: 240
See the “Mooring Buoy Planning Guide”: http://www.projectaware.org/asiapac/...f/moorbuoy.pdf

Embedment Mooring Anchors

All mooring systems consist of three basic elements:
1. An attachment to the sea bottom
2. A floating buoy on the sea surface
3. An interconnecting (attachment to buoy) means

Embedment anchors provide the highest holding power of all mooring attachment types. These type of moorings also offer the advantage of reducing the swing radius of the vessel by lessening the amount of scope required.
Flotation can be added to keep the ground tackle off the bottom, causing far less damage than the conventional long scope chain.

BoatUS Foundation, MIT Sea Grant & Cruising World Magazine Tests:
A recent BoatU.S. test using a large tug, and several types of moorings, found that the moorings that are the least likely to be dragged are the "embedment" type anchors (a helical and an expanding fluke anchor) which are deliberately screwed or driven into the harbor bottom. Traditional moorings (mushroom anchor and dead-weight blocks) were far more likely to be dragged with relatively little effort. A mushroom anchor that isn't sufficiently buried has very little holding power. The holding power of a mushroom or deadweight anchor can be increased by extending the pennant's scope, but you also have to consider the proximity of other boats. Embedment anchors do not rely on scope to increase their holding power, but scope must be sufficient to allow for tidal surge.

Mooring Type ~ Resisting Force (Water Depth) ~ Scope ~ Est. Cost
Helix ~12,000 Lbs (20') ` 4:1 ~ $850
650 lb Dor-Mor anchor ~ 4,500 Lbs (18') ~ 3:1 ~ $1,125
500 lb mushroom~1,200 Lbs (15') ~ 3.5:1 ~ $1,100
2000 lb single block~ 800 Lbs (14') ~ 3:1 ~ $350
8000 lb double block ~ 4,000 Lbs (35') ~ 3:1 ~ $550

The Vineyard Haven Anchor Comparison Test:
This table compares the holding power of different traditional marine mooring anchors with that of a helix anchor. The Vineyard Haven, Mass. USA, harbormaster selected typical traditional anchors within his harbor for a comparative test. A 65-foot tug pulled laterally on each anchor until it failed, and the load at failure was recorded.
The helix anchor never failed. Rather, the 1-1/2” pulling hawser parted at 20,800 lbs. of load.

Mooring Type (Bottom Condition) = Breakout Force
350 Lb. Mushroom (5 Ft. Deep in Mud) = 2,000 lbs.
500 Lb. Mushroom (In Sand Bottom) = 1,700 lbs.
3000 Lb. Concrete USCG Block (Set in Mud) = 2,100 lbs.
6000 Lb. Cement Block (On Sand Bottom) = 3,200 lbs.
8/10 Helix ~(Soft Clay Mud) = 20,800 + lbs.
__________________
Gord May
"If you didn't have the time or money to do it right in the first place, when will you get the time/$ to fix it?"



GordMay is offline   Reply With Quote
Old 02-11-2006, 16:05   #5
Registered User
 
cat man do's Avatar

Join Date: Aug 2006
Location: Brisbane Australia [until the boats launched]
Boat: 50ft powercat, light,long and low powered
Posts: 4,409
Images: 36
G'day Setia, a couple of years ago we were cruising out around the top of the bunker group and had an idea that the weather you descrbed was coming in, so we asked Heron Is. resort if we could pick up an unused mooring so as not to damage the reef.

After many exuses as to why we could not, one including our boat was too heavy{we were about 2500kg lighter than the boat they usually had on it} we anchored of the back of another reef. Motored up into about 14 ft and hung back in about 170 ft.

The part we found funny [or not] was that a national parks and wildlife boat was at Heron at the time and had been speaking to the resort just before we got on, and again after we had finished , and at no time did they stick up for us when we mentioned safe anchoring practice amongst the Great Barrier Reef Marine Park and the use of moorings being prefered.

On the positive side , we caught some bloody nice Red throat and spangled emporer on that reef that night, could'nt sleep though.

Have fun in paradise

Dave
__________________
cat man do is offline   Reply With Quote
Old 02-11-2006, 19:04   #6
Eternal Member
 
Alain d'HYLAS's Avatar

Join Date: Feb 2005
Location: Piriapolis - URUGUAY
Posts: 64
Quote:
Originally Posted by GordMay

Embedment anchors provide the highest holding power of all mooring attachment types.
Perfectly right.. they are very efficient and cheap.. The only dificulty could be to instal them as you need a specific pneumatic tool..
__________________
No more anchors to manufacture and to sale..I'm enjoying travels around South America..
Alain d'HYLAS is offline   Reply With Quote
Old 02-11-2006, 21:59   #7
֍֎֍֎֍֎֍֎֍֎

Cruisers Forum Supporter

Join Date: Apr 2006
Posts: 13,033
Setia-
"in the offshore reefs in the more frequented areas in the USA? "

Reefs, as in coral reefs, are unknown in most of the US. Offhand I think we only have them in Florida, and heaven help you if you are caught anchoring or damaging a reef which is in a protected area.

Other than that we have "artificial reefs" which are usually collections of sunken ships & vehicles, and anything you hook into them with must be considered expendable since fouling is common, and unreliable. Most of our coastal anchorages are some mix of rock, mud, or sand, bare or covered in vegetation.
__________________
hellosailor is offline   Reply With Quote
Old 04-11-2006, 02:56   #8
Marine Service Provider
 
craigsmith's Avatar

Join Date: Jun 2005
Location: New Zealand
Posts: 404
Images: 4
Arrow

Quote:
Originally Posted by Setia
However, general rules are:
Dont anchor over coral, anchor on the edge: always anchor in the sandy patches. What I was really getting at was types of anchors & means of deploying them for minimal damage & easy release. eg. for 40ft. boat: 2" solid shaft, 2'-6" long with 4 triangles (flukes) welded to one end & solid eyes on both ends. Shackle chain to botton eye, attach chain to top eye with wire. Idea being that top wire will break leaving chain to pull the anchor out by the fluked end. Any advances on this in the good old USA?
Use a buoyed retrieval line separate to the main rode, tied to the appropriate point on the anchor (all good designs will have one - if they don't, get something that does).

Use an anchor that will set instantly so you can trust it will set where you want it to, in a small patch of sand.

The breaking-wire method is a tad less reliable with larger gear, and also can be defeated if the chain itself becomes fouled on coral.
craigsmith is online now   Reply With Quote
Old 04-11-2006, 08:50   #9
Registered User

Join Date: Nov 2006
Location: Côte de Provence
Posts: 8
Normally, anchoring behind a reef, you will have to leave so much space between the reef and your anchor, that the boat can turn around and even slip for a short distance, without coming close to the corals.
Anchoring on the rocks is very dangerous, even if you have enough depth below, you cannot leave quickly, because your anchor will get stuck in 90 % of your time to the rock.
__________________
Nebro is offline   Reply With Quote
Old 22-02-2007, 17:02   #10
Registered User

Join Date: Feb 2007
Location: Dominican Republic
Boat: Bayfield 40' Silent Running
Posts: 49
Bahamian moor

We used a Bahamian moor in the Bahamas we have the same problem not with wind but with tide change. Lots of locations are tight spots or many boats. We don’t have the luxury of swinging around. The Bahamian moor is two anchors in opposite directions connected to the bow. We would find a sandy area setting the primary anchor the second anchor was a danforth type with ten feet of chain and about 100 feet of rope. I would take the dinghy to set the second anchor. We used an old coke can filled with lead as a weight on the rode so it did not catch the keel when the boat changed directions. Hope this suggestion helps.
__________________
d0ug is offline   Reply With Quote
Old 22-02-2007, 20:04   #11
Registered User
 
SydneyTim's Avatar

Join Date: May 2006
Location: Cruising USA & Caribbean
Boat: Passport 51 - Matsu
Posts: 56
Like all things depends on the reef. Out of Gladstone the ones I know are Lady Musgrave and Fitzroy in the lagoons and Wistari reef as a roadstead.

We heard lot's of stuff about the two lagoons from yachties, (most of whom hadn't been there) and the general gist was be careful of this and that, don't go if there's any wind etc, etc.. We spent 2 weeks in Fitzroy with a 20-30 knot northerly all day and night and it was paradise, would do it again. 2 nights at LM in the same 20-30 northerlies, plus we had 40+ knots for about half an hour from the south during a thunderstorm which showed the benefits of a lagoon if you're anchored well, we were still protected from the swells (Actually had a 68 knot max gust!) even though the wind had done a 180.

Basically you need to follow the same simple rules of anchoring anywhere, it's just very important in a lagoon because you are always on a lee shore, but you can't walk to hospital from it should the worst happen!

Entrance to both is on north side so in anything from the south it's easy to get in, but even in a nrtherly you can see the reef fine despite the waves. Anchoring is on sand, in a bout 10 metres not many bommies at Fitzroy a few more at LM. The secret is to find a spot where you can let out plenty of chain and swing free of the bommies and other boats, this is very easy at Fitzroy, can be more problematic at LM. Fitzroy just come in through the entrance and turn left, there's a massive anchorage almost completely free of bommies, if you go right to where the commercial moorings are there are many more bommies.

Best advice, get there early, get a spot, get the anchor well in, snorkel it to check it's well and truly buried, then sit back and relax. If you can't find a spot to swing or you are worried you might drag, you have time to get out and sail home. I think you would most likely get into trouble by arriving late, anchoring marginally and staying because it's now too dark to get out.

Hope this helps
__________________
SydneyTim is offline   Reply With Quote
Old 23-02-2007, 08:41   #12
Registered User
 
Amgine's Avatar

Join Date: Dec 2004
Location: Vancouver BC
Posts: 1,384
Images: 1
Great comments Sydney Tim

It's always nice to have the story from the person who's been there!

One question I've thought on is what are some of the ways to reduce swinging radius which are quick and easy. I'm really lazy, at heart, and I tend to not do the things I know I ought unless there's a specific threat. Especially when I'm cold/tired/wet/hungry.

Getting my gear set up so it's easy to deploy is a huge help. I had a bahamian moor setup and used it religiously, but then I moved boats... and haven't rigged one on the new boat. Another is to practice setting the gear so I'm familiar with all the steps, and make it a habit so I'm not really thinking about each step.

I think a safe reef rig for my boat would be a 75-100m rode with good anchors for the bottom, a large ring cow-hitched or heavily shackled in the middle with a good swivel attached to that. From the swivel to the surface can be whatever works for me at the time; I'd probably choose a fathom of heavy chain with a ring and a 10-15m length of nylon set up so I can put a mooring buoy on it, or adjust the length as needed.

__________________

__________________
Amgine
Blog

On the internet, nobody knows you're a dog anchored in a coral atoll.
Amgine is offline   Reply With Quote
Reply

Tags
anchor, anchoring, reefs

Thread Tools
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
Heavy weather anchoring, Stede General Sailing Forum 105 10-12-2008 11:11
are cats safe cruisers? sneuman Multihull Sailboats 50 12-11-2006 18:17
Anchors and Anchoring Sonosailor Anchoring & Mooring 3 17-03-2004 11:25



Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 06:35.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.