Anchor rope / painter

ajstars · 22 July 2012, 00:47

I have a 5.5m (18ft) Humber Attack RIB and need some advice as to what weight anchor I should use and what diameter of rope/painter line I should use. Advice welcomed.
Thanks

thomas · 22 July 2012, 07:37

anchor rope length - Google Search

Keep the painter shorter than the boat so it can't reach the prop

Channel Ribs · 22 July 2012, 07:40

It is quite an emotive topic, so brace yourself. At least you didn't ask this on a yachty forum!

You will want a fair bit of chain, it is the chain that does the work. Your not just heaving a dead weight over the front.

Pikey Dave · 22 July 2012, 09:20

Quote:

Originally Posted by ajstars

I have a 5.5m (18ft) Humber Attack RIB and need some advice as to what weight anchor I should use and what diameter of rope/painter line I should use. Advice welcomed.
Thanks

Re. anchor, chain, rope. Generally, heavier, longer & thicker is best. But then you get to the practicalities of handling & storage. On my 6.4 I have a 7.5kg CQR with 8m of 10mm chain, (the chain is way ott, but it was left over from a job

) All fastened to 60m of 12mm Anchorplait. Any heavier & I'd stuggle to pull it all in, but the combination has good holding power. Anchors are critical safety items that oft get overlooked, especially as they are usually out of sight. Peeps will happily spend hundreds on shiny, VHFs, PLB, flares, lifejackets etc, but when that engine fails by a lee shore...........................

Mollers · 22 July 2012, 09:32

Agree with Pikey re. safety a lee shores. Further to that, don't be tempted with a cheap nylon type anchor line, It'll twist and turn a generally do it's own thing which often results in tangles.
I use a good quality 8 strand plait. I flake it into the anchor locker rather than attempt to coil it. It would deploy in seconds without fear of a tangle.

BogMonster · 22 July 2012, 10:02

Quote:

Originally Posted by Pikey Dave

Peeps will happily spend hundreds on shiny, VHFs, PLB, flares, lifejackets etc, but when that engine fails by a lee shore...........................

I thought that was why you had two

I use 10mm three strand white nylon for my anchor line but mainly due to a lack of other locally available options (apart from 24mm, and that was a bit big!). I don't recommend it, as it does tangle easily.

Pikey Dave · 22 July 2012, 12:16

Quote:

Originally Posted by BogMonster

I thought that was why you had two

it is

spartacus · 22 July 2012, 15:51

Quote:

Originally Posted by Pikey Dave

Anchors are critical safety items that oft get overlooked, especially as they are usually out of sight. Peeps will happily spend hundreds on shiny, VHFs, PLB, flares, lifejackets etc, but when that engine fails by a lee shore...........................

Agreed +1

You just have to look at the North Star rib incident this week. Don't know specifics yet - apart from the rib had engine trouble and drifted onto rocks. Early deployment of an anchor could have saved the situation.

BogMonster · 22 July 2012, 20:55

Quote:

Originally Posted by spartacus

You just have to look at the North Star rib incident this week. Don't know specifics yet - apart from the rib had engine trouble and drifted onto rocks. Early deployment of an anchor could have saved the situation.

Indeed. The excuse for parking the other one next to is probably needs to be different though

jyasaki · 23 July 2012, 00:31

Quote:

Originally Posted by Pikey Dave

Re. anchor, chain, rope. Generally, heavier, longer & thicker is best.

Disagree as far as the line goes. Assuming a reasonably sized nylon rode, the line should stretch as the boat surges in the swell. Use too large a line (or a low-stretch line of any size), and the boat will not generate the force to stretch the line, resulting in a lot of harsh snatch and jerk stuff as the boat rides on the hook. May or may not be really bad depending on conditions of seas and boat, but can be fairly destructive over time.

Chain, yes, bigger is better as long as it doesn't get cumbersome to the point of not wanting to deploy becuae of it.

Anchor: size ideally depends on the type, which ideally depends on the bottom structure and seas you'll be anchoring in.

jky

m chappelow · 23 July 2012, 08:05

Downside of using an anchor line too thick is that in really deep water and big waves and with a strong tide running the amount of drag acting on the line doesent always let the boat ride the waves proper to the point that some boats can start getting swamped .
Best rope for anchoring or veering is nylon as is has a high loading will stretch and reduces snatching action .
Another good thing about nylon is that if anchored up and veering or backing up to something Say a sheer cliff or lee shore to pick up someone , using the high elasticity of nylon if your engine then cuts out or the prop catches a rock the stretch of the line (up to 50%before parting ) ) will pull you back out into deeper safer water .
Nylon is ideal as an anchor line or tow line for a boat but it's not suitable and can be dangerous in long lengths for pulling boats on slipways with a vehicle or tractor especially if the trailer wheels get stuck or bogged down and the wheels then suddenly break out
and yes I have seen a I ton boat suddenly fly up the slipway

tonto · 23 July 2012, 13:36

Quote:

Originally Posted by m chappelow

Downside of using an anchor line too thick is that in really deep water and big waves and with a strong tide running the amount of drag acting on the line doesent always let the boat ride the waves proper to the point that some boats can start getting swamped .
Best rope for anchoring or veering is nylon as is has a high loading will stretch and reduces snatching action .
Another good thing about nylon is that if anchored up and veering or backing up to something Say a sheer cliff or lee shore to pick up someone , using the high elasticity of nylon if your engine then cuts out or the prop catches a rock the stretch of the line (up to 50%before parting ) ) will pull you back out into deeper safer water .
Nylon is ideal as an anchor line or tow line for a boat but it's not suitable and can be dangerous in long lengths for pulling boats on slipways with a vehicle or tractor especially if the trailer wheels get stuck or bogged down and the wheels then suddenly break out
and yes I have seen a I ton boat suddenly fly up the slipway

Nylon also looses a fair amount of its strength when wet, so needs to be a little bigger to cope with the loss of strength.

The problem of whiplash with nylon is very real, think elastic band breaking, and at the very least if you are in the way, it will sting, or worse.

jyasaki · 23 July 2012, 15:22

Quote:

Originally Posted by tonto

The problem of whiplash with nylon is very real, think elastic band breaking, and at the very least if you are in the way, it will sting, or worse.

Not really an issue with anchoring, as the water will dampen any backlash from a sub-surface failure and the above water length isn't long enough to be a major concern, but it is definitely something to watch for when towing.

jky

Pikey Dave · 23 July 2012, 15:22

Quote:

Originally Posted by jyasaki

Disagree as far as the line goes. Assuming a reasonably sized nylon rode, the line should stretch as the boat surges in the swell. Use too large a line (or a low-stretch line of any size), and the boat will not generate the force to stretch the line, resulting in a lot of harsh snatch and jerk stuff as the boat rides on the hook. May or may not be really bad depending on conditions of seas and boat, but can be fairly destructive over time.

Chain, yes, bigger is better as long as it doesn't get cumbersome to the point of not wanting to deploy becuae of it.

Anchor: size ideally depends on the type, which ideally depends on the bottom structure and seas you'll be anchoring in.

jky

I did say Generally(even underlined it)

The gear needs to be relatively matched, i.e. there's no point putting a 2kg folding grapnel on the end of a 20mm dia rope. Neither is there any point putting a 20kg plough on the end of a 6mm bootlace. I had credited the OP with some common sense

. The chain plays as large a part in acting as a shock absorber as the rope does, if not more so.

Channel Ribs · 23 July 2012, 15:33

Quote:

Originally Posted by Pikey Dave

The chain plays as large a part in acting as a shock absorber as the rope does, if not more so.

+1

I just had a look on Youtube to see if there is a nice animation of a chain laying on the seabed, showing the anchor as being nothing more than the machine hat holds the end steady. Having not found one, I might see if Brains' underwater camera is available to film some footage of just that.