Anchor for 7 metre RIB - Page 2

BogMonster · 15 June 2006, 15:56

Quote:

Originally Posted by codprawn

Sunlight is prob the worst killer of rope. If the rope looks fine with no nasty abrasions etc and hasn't been kept in the sun you should be fine.

Know what you mean about OTT mooring tackle. I have 2x50m lengths of 16mm rope - that's over 300' in real money - plus about 20' of stupidly heavy chain and a 14lb danforth. Plenty of room for it all.

For day to day stuff I have a big folding grapnel - yet to try it though. I know they are crap in sand but they are better than most in foul ground.

It looks like it might be nylon of some sort, very fine braided stuff (not 3 or 8 strand) probably 8mm or 10mm dia I think. 10mm 3 strand nylon that I use for mooring lines has a breaking strain of about 2000kg so hopefully this should be ok for a rarely used anchor on a 600kg rib

The rope isn't hard or brittle like nylon goes when exposed to sunlight and it is fairly well out of the way down in the bow though it would get some sunlight on it. I think the boat normally used to be kept in a warehouse anyway until I got it. Some way of covering the bow compartment up is on the "to do list" anyway so I can close the drain hole into the underfloor compartment and stop the damn thing filling up with water as soon as it rains

Jelly .... pickup buoy .... thanks for the idea. Never thought of that, will get one just in case

Searider · 15 June 2006, 16:38

Quote:

Originally Posted by Richard B

A quick point here about the theoretical "scope" (ie how much anchor line to put out)....

If you are anchoring amongst other boats, put out a similar scope to everyone else, regardless of the theoretical calculation. If you put out much more, when the tide turns you'll swing around in a greater arc to everyone else and very likely either hit the other boats or tangle your lines.

So how do you know how much everyone else has put out.
How do they know how much they have put out - hardly anyone bothers to mark their cable.
How do you know when they will be leaving - they should have put out enough for the deepest water they expect for their duration.

What you say is a great idea but impossible to achieve.

randski · 15 June 2006, 16:49

Quote:

Originally Posted by Alice

Last seen flyin' around the Penryn area!!

Sorry Bob, are you on the water on Sat or Sun? If not I'll drop them up to your place.

Hope to be out over the weekend. If not don't worry I'm sure I'll catch up with you soon.

Richard B · 15 June 2006, 16:56

Quote:

Originally Posted by Searider

So how do you know how much everyone else has put out.

Good question! You'll know once you swing a bit. Just don't put 7x the depth out expecting everyone else to do the same, and then insist that you know best!

jyasaki · 15 June 2006, 17:19

Quote:

Originally Posted by BogMonster

I haven't used it yet but I looked at the anchor on mine and thought it was a bit small, its a Danforth type not sure of the weight but prob about 8-10kg.
Can I hijack the thread slightly; how often do folks think you should change the rope on the anchor? Deterioration of the chain is fairly obvious but rope....? It's probably the original one so about 6-7 years old.

A 20 lb Danforth anchor is huge. I have an 18' or so aluminum RIB, and I use an 8 lb Danforth clone. Fluke anchors have a very large surface area for their weight, so they don't have to be heavy unless you primarily anchor in compacted mud.

Anchor line should be replaced when the rope starts going off (chalky, brittle, stiff, picking threads, abraded, etc.) A decent line that is not abused should last at least several years. It is, however, a last ditch piece of emergency equipment, so a little conservatism on use may be called for.

The grapnel anchors (going back to a different reply; sorry, Stephen) are, IMO, pretty much useless. They won't hold in sand, usually won't hold in mud, and hang up in rock (not to mention hanging up on everything inside the boat while you're trying to deploy it.) They do, however, make great gifts for boaters that you don't like.

jky

BogMonster · 15 June 2006, 17:29

Interesting web page about anchors here

Paul · 15 June 2006, 17:30

Thanks for the replies. Does anyone leave teir boat unattended at anchor or is this a real no no.

mark-f · 15 June 2006, 18:01

Quote:

Originally Posted by Paul

Thanks for the replies. Does anyone leave teir boat unattended at anchor or is this a real no no.

If its anchored properly it is not a problem, i regularly leave my rib anchored overnight.

Mark

Dino · 15 June 2006, 18:10

Quote:

Originally Posted by Paul

Thanks for the replies. Does anyone leave teir boat unattended at anchor or is this a real no no.

As an ex yottie i'd say this is an enormous no no,i was always taught that one crew stays behind as anchor watch and having had mine drag(again on the yacht not the rib)i wouldn't leave her out of sight with the anchor set.

Neal · 15 June 2006, 20:10

Quote:

Originally Posted by Paul

Thanks for the replies. Does anyone leave teir boat unattended at anchor or is this a real no no.

Some insurance quotes i had said this was a real no no

ADS · 15 June 2006, 22:26

Quote:

Originally Posted by Neal

Some insurance quotes i had said this was a real no no

Especially if your using Hugh Jardon's grapnel anchor

Alice · 15 June 2006, 22:29

Quote:

Originally Posted by ADS

Especially if your using Hugh Jardon's grapnel anchor

It would have been more effective putting a line around his Stereo and bunging that over the side!

Limey Linda · 16 June 2006, 00:36

A point which has not been mentioned is that you should not just bung it over the side. An anchor needs to be set by paying out approx. 3x and backing down under low power, down wind, until it holds firmly, then pay out the remaining scope. Also, there is no such thing as too much chain and always use twisted nylon. Personally I always carry a spare second anchor and have had need to use it many times. You can buy aluminioum achors also, but they are expensive. It is not the weight that does the work but the shape/surface area.

Hugh Jardon · 16 June 2006, 07:15

Quote:

Originally Posted by Alice

It would have been more effective putting a line around his Stereo and bunging that over the side!

stereo is not that big but i think the amp would have held us both!!

Andy Gee · 16 June 2006, 09:17

Quote:

Originally Posted by Hugh Jardon

under water?

It just melts underwater........honestly!!
Andy

Paul · 16 June 2006, 20:26

Quote:

Originally Posted by Limey Linda

A point which has not been mentioned is that you should not just bung it over the side. An anchor needs to be set by paying out approx. 3x and backing down under low power, down wind, until it holds firmly, then pay out the remaining scope. Also, there is no such thing as too much chain and always use twisted nylon. Personally I always carry a spare second anchor and have had need to use it many times. You can buy aluminioum achors also, but they are expensive. It is not the weight that does the work but the shape/surface area.

Thanks, what do you mean by twisted nylon.

Alice · 16 June 2006, 20:29

Quote:

Originally Posted by Paul

Thanks, what do you mean by twisted nylon.

I think that they're a New York punk outfit.

Alice · 16 June 2006, 20:33

I use multi-plat, it lies nice and flat in the anchor locker.

codprawn · 16 June 2006, 20:45

And multiplait has shock absobtion built in - less likely to jerk out the anchor - or your bollards!!!