Reply
 
Thread Tools Search this Thread
 
Old 05 August 2009, 16:13   #11
JSP
Member
 
Country: UK - England
Town: Southport
Boat name: Qudos
Make: 5.4 Searider
Length: 5m +
Engine: Yam 115 V4
MMSI: 235068784
Join Date: Sep 2008
Posts: 3,930
Quote:
Originally Posted by m chappelow View Post
only problem with using a sand bag anchor is that it wont dig in to the bottom and the other reason is that sand will lose a third of its weight when submerged ,something like any of thesein the photo will be ok .
Could use rocks if sands no good?
__________________

__________________
JSP is offline   Reply With Quote
Old 05 August 2009, 17:14   #12
Member
 
m chappelow's Avatar
 
Country: UK - England
Town: yorkshire
Boat name: little vicky
Make: avon ex RNLI
Length: 3m +
Engine: tohatsu
Join Date: Mar 2008
Posts: 2,310
Quote:
Originally Posted by JSP View Post
Could use rocks if sands no good?
problem is rocks and concrete are just about the same ,
__________________

__________________
m chappelow is offline   Reply With Quote
Old 05 August 2009, 17:21   #13
Member
 
Country: UK - Wales
Town: swansea
Boat name: Too Blue
Make: BLANK
Length: 8m +
Engine: Suzuki DT225
Join Date: Mar 2004
Posts: 12,791
Quote:
Originally Posted by jyasaki View Post
Not for sand, it's not. I'd suggest a smallish Bruce knockoff or a small Danforth type.

I agree with the amount of rode, and you should also add 10 feet of fairly hefty chain. Keep the bitter end of the rode attached to the boat (having a float on it makes for a quick getaway.) And wire any shackles so they can't come undone.

jky
I agree but not with the chain. A small bruce or similar holds my 9m RIB very well without the chain - on a sib it should be fine!!!

The grapnels are great in rock - useless anywhere else - even a 7.5kg grapnel caqn be pulled through sand with 1 hand!!!
__________________
codprawn is offline   Reply With Quote
Old 05 August 2009, 17:36   #14
JSP
Member
 
Country: UK - England
Town: Southport
Boat name: Qudos
Make: 5.4 Searider
Length: 5m +
Engine: Yam 115 V4
MMSI: 235068784
Join Date: Sep 2008
Posts: 3,930
Quote:
Originally Posted by m chappelow View Post
problem is rocks and concrete are just about the same ,
I don't get ya mate.
__________________
JSP is offline   Reply With Quote
Old 05 August 2009, 18:05   #15
Member
 
m chappelow's Avatar
 
Country: UK - England
Town: yorkshire
Boat name: little vicky
Make: avon ex RNLI
Length: 3m +
Engine: tohatsu
Join Date: Mar 2008
Posts: 2,310
Quote:
Originally Posted by JSP View Post
I don't get ya mate.
things in sea water dont weigh as much as they do on land ,even solid objects such as a block of concrete ,,,next time you are wading in the sea try picking up a large boulder you will find its a easier to lift until you try get it out of the water ,,,i have a commercial diving book some where that tells the difference of weights of things like sand /concrete / stones/blocks of metal in sea water ,,,cant remember the exact ratio but for sand its something like a third weght lost in water ......thing is for all the exra weight of carrying a bag of sand or boulder of some sort ,compared to a small anchor its not worth the effort . regards mart
__________________
m chappelow is offline   Reply With Quote
Old 05 August 2009, 18:40   #16
JSP
Member
 
Country: UK - England
Town: Southport
Boat name: Qudos
Make: 5.4 Searider
Length: 5m +
Engine: Yam 115 V4
MMSI: 235068784
Join Date: Sep 2008
Posts: 3,930
Quote:
Originally Posted by m chappelow View Post
things in sea water dont weigh as much as they do on land ,even solid objects such as a block of concrete ,,,next time you are wading in the sea try picking up a large boulder you will find its a easier to lift until you try get it out of the water ,,,i have a commercial diving book some where that tells the difference of weights of things like sand /concrete / stones/blocks of metal in sea water ,,,cant remember the exact ratio but for sand its something like a third weght lost in water ......thing is for all the exra weight of carrying a bag of sand or boulder of some sort ,compared to a small anchor its not worth the effort . regards mart

Now you mention it I had noticed that in the past.
__________________
JSP is offline   Reply With Quote
Old 05 August 2009, 18:42   #17
Member
 
Country: UK - England
Town: Bristol
Boat name: Happy Days
Make: Zodiac
Length: 3m +
Engine: Mariner 4St/4HP
Join Date: Jul 2009
Posts: 83
Send a message via Skype™ to MikeP
Here's a noddy question then: why is the length of chain important ? I've read a couple of times about having an anchor at the end of chain and then rope, but no explanation as to why...
__________________
MikeP is offline   Reply With Quote
Old 05 August 2009, 18:50   #18
RIBnet admin team
 
Poly's Avatar
 
Country: UK - Scotland
Boat name: imposter
Make: FunYak
Length: 3m +
Engine: 2 stroke YAM 20 HP
MMSI: 235089819
Join Date: Sep 2005
Posts: 10,114
Quote:
Originally Posted by MikeP View Post
Here's a noddy question then: why is the length of chain important ? I've read a couple of times about having an anchor at the end of chain and then rope, but no explanation as to why...
chain helps in a couple of ways:

1. it means the pull on anchor is more horizontal (along sea bed) helping it dig in.
2. it wears much better than rope on a rough bottom so means you are more likely to stay connected to the anchor.

To get the same "direction"/angle of pull you need less scope (total rope/chain) if you use some or all chain. The downsides of all chain are - no stretchiness (thats a technical term!) and the weight penalty.
__________________
Poly is offline   Reply With Quote
Old 05 August 2009, 18:55   #19
RIBnet admin team
 
Poly's Avatar
 
Country: UK - Scotland
Boat name: imposter
Make: FunYak
Length: 3m +
Engine: 2 stroke YAM 20 HP
MMSI: 235089819
Join Date: Sep 2005
Posts: 10,114
Quote:
Originally Posted by m chappelow View Post
thing is for all the exra weight of carrying a bag of sand or boulder of some sort ,compared to a small anchor its not worth the effort . regards mart
yes might be useful approach if e.g. you arrive at a beach and want to keep your boat afloat... or even if you want to beach the boat with a flooding tide and stop it drifting away. And I guess has advantages if you fold up and carry all your gear at some point - but would you want to rely on it to stop you getting washed out to sea in nasty conditions?
__________________
Poly is offline   Reply With Quote
Old 05 August 2009, 19:08   #20
JSP
Member
 
Country: UK - England
Town: Southport
Boat name: Qudos
Make: 5.4 Searider
Length: 5m +
Engine: Yam 115 V4
MMSI: 235068784
Join Date: Sep 2008
Posts: 3,930
Quote:
Originally Posted by MikeP View Post
Here's a noddy question then: why is the length of chain important ? I've read a couple of times about having an anchor at the end of chain and then rope, but no explanation as to why...
What Polwart said plus you can cut the rope at the end of the line if you can't free the anchor off the seabed.
__________________

__________________
JSP is offline   Reply With Quote
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search

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





Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -5. The time now is 22:29.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.