Research on anchor chain and rope

[nealeboy]

I need help!! I cant seem to get my boat to anchor "quickly". I have a 16' Fibreglass half cab, currently i have 12mm anchor rope with about 4 metres of 12mm chain, (i think quite heavy). whether i use a sand anchor or my reef anchor (12mm rods), i always seem to drift a while befor it graps and i lose my spot. what can i do to get a quicker grab?

Nealeboy

[Vitamin Sea]

What depth are you tryjng to anchor in and are you going far enough up current before you deploy? you want about 11/2 to 2x the depth.
I would prefer longer chain in a smaller size as well, say 5m x 8mm chain, make sure that its laid out and not just thown over as well.
cheers

[robfish 1]

Hey Nealeboy...I've ALWAYS had the same trouble with a sand anchor-(danforth pattern). The only time they seem to grab is on reef, just where you don't want them to grab!
I've now been using a 'fisherman' style anchor on my boats for the past 15-20 years without issue. The flukes point away from each other, rather than towards each other, and provide a quicker, more secure bite. They're also called a slip ring anchor, and are VERY snag-resistant, and cheap to buy. I'm sure some others will undoubtedly suggest other patterns as well, and all are pretty effective, I just chose the slip ring style for its low cost, bite and snag-proofing capabilities, and have never needed to change.

Depending on the depth you're anchoring in, I'd say that your 4m of chain would be sufficient, but if it's usually in excess of 20 metres, I'd opt for a longer, lighter chain, and possibly letting out more rope. The scope needs to be around 1 in 3, or 1 in 4. For every metre of depth, around 3-4 metres of anchor warp.
In PPB, with a hull length of 16ft, my half cab needs around 50m of anchor warp out in 15-18m of bumpy water, less if it's smooth. I use around 6m of 8mm chain, and do not experience any issues. It seems to me that the longer the chain, the more secure the anchor will hold, rather than the chain's weight. This longer chain will help your rock pick grab, too.
Hope all this helps.

[sharkymark2]

Yes I have the slip ring style as well. I have lost a heap of anchors fishing in rocky areas and even a few reef anchors. After using the slip ring and attaching the chain to the base and tying the top of the anchor with a zip tie to the chain i don't have any more problems. This style of anchor rapidly digs in and has been the best I have ever used.

[Noelm]

There is a few things at play when trying to anchor in an exact spot, if you stop the boat, then lower the anchor to the bottom, then reverse, you will take ages to get a "bite" because the rope will have a big "belly" in it from you being above it, then reversing away from it, get the picture? You need to select the right anchor to suit the bottom, a reef pick is fine, on reef, useless in gravel and soft bottoms, the prongs need to be short, not long dangly things, and some decent chain, and you will have no problems on hard reef bottoms, drive to your spot, start to reverse and LOWER your anchor and rope, do not just toss the lot over the side. Sandy bottoms require a lot longer drift to get the anchor into the sand, they do not "hook" like in rocks, you need long chain, lots of rope out, and going astern to drag in into the sand.

[nealeboy]

Thanks Vitamin Sea. 2 main depths are 6metre and 12metres. i fished in 20metres yesterday and the same thing. i can feel the anchor dragging across the bottom for a while before it grabs. i usually use a sand anchor on either sand, mud or coffee rock but yesterday tried the reef anchor on the coffee rock areas.

[nealeboy]

Thanks Robfish. do you use the slip ring on all bottom conditions, sandy-reefy?

Sharkymark2, why do you zip tie the chain to the topof the anchor?

[Crunchy]

4M not really long enough when the current is running hard IMO. I use about 10M which is overkill but if I leave my boat our all night good to know it will be there in the morning.

[Vitamin Sea]

general rule of thumb, chain as long as the boat.

[scottar]

It will also depend on the areas you are trying to anchor. One area we fish on occasion has a bottom that is made up almost entirely of broken coral. We know this because we have dived on it. The only way I have successfully anchored on this is with a rig made from two anchors and twelve metres of chain - for a 4.5m tinnie. Anything less that we have tried has simply dragged through the rubble under influence of tide and wave action. As a standard on that tinne we used to run whatever anchor plus about 5-6 metres of 10mm chain - heavy and a PIA to retrieve but it didn't pull too often. In anything over about 5 metres we simply used a retrieval ball.

[Vitamin Sea]

general rule of thumb, chain as long as the boat.

[robfish 1]

Thanks Robfish. do you use the slip ring on all bottom conditions, sandy-reefy?

Sharkymark2, why do you zip tie the chain to the topof the anchor?

Mate, I think it all depends on how bad the reef is. I use the slip ring on all bottom conditions down here, as we very rarely have snaggy-type reef - it's all hard rock with little to catch an anchor really badly. I'd be inclined to use a rock pick on bad reef though, and as stated in an earlier post by NoelM, make sure the prongs are short - only about 20cms for your hull. If you know the reef well, and it's not too bad, you may get by with the slip ring, as they are VERY snag-proof - google them and you'll see why. For my 16ft half cab, I successfully use one of 6lbs, with around 5-6m of 8mm chain - and PPB can get up a nasty chop at times. I reckon that with the flukes pointing away from each other, they tend to offer a higher grip than the danforth style, too.
I've also recently invested in a 'Cooper' aluminium anchor for my 3m punt - and with 2m of 4mm chain, it's holding power is phenomenal!
I'm seriously debating getting a larger version for the half cab as well - although that would mean carrying more anchors than I have room for! Wonder how the Missus would come at a bigger boat?

[Dignity]

nealeboy, I found I improved my anchoring on my 6m boat by having about 5m of 6 mm chain on the anchor followed by about 2 metres of 12 mm chain. I used to run 10 m of 6 mm but still had difficulties on a regular basis but the above modification works so much better. It was only because I lost an anchor and was a bit short on chain at the time that I did this but now it is the norm for me.

[sharkymark2]

Nealeboy the reason I do that is when it does get snagged the thick tie snaps and the anchor is pulled out backwards releasing the snag. No more lost anchors and no more doing a squat on the front deck to pull up a snagged anchor.

[TheRealAndy]

There is no substitute for weight on coffee rock. If its a big area, you either need heaps of rode and drop your pick off the rock, or you need a 200hp merc on the end :P

FWIW, I reckon half of moreton bay is perfectly screeded coffee rock covered by 4 foot of the worlds softest mud. There is some spots where you need a half ton concrete block to hold anchor.

[scottar]

It is actually quite surprising just how much weight can be dragged across the bottom. I work for a tug company. On the project we are on currently the anchors in use for the moorings are either 3 or 5 tonne units. If these foul in the chain during deployment and a tug is moored to them (admittedly a 400 tonne tug) they will quite happily move across the bottom in as little as a metre of swell.

[littlejim]

Neale,
join the club. It's not a precise science, depth, wind tide direction make it tough. Takes a while for the thing to get to the bottom and then dig in.
When it digs in your swing round distance varies with the amount of rope out.
All you (I) can hope for is that by go #10 you (I) are a bit better than on go #1. By then eyeballing how far upwind/tide to chuck it out should be a bit better.
Might have to chuck two out if you want to hold a spot without the swing.
I've left a couple behind on the bottom.
Soon learnt that one of the so called guru's espoused method pulling the anchor up from the back of the boat was a good way to sink the boat motor first.
Now only pull from the front and cut the rope if nothing gives. Usually a prong straightens out and up it comes. Go for the thinnest prongs that will hold the boat.

[bigjimg]

I use a simple rule. My chain is 8mm @ 7m long and warp is 12mm attached to a Lewmar 6Kg plough. I have 10m increments marked on the warp with spay ink. If for instance I am in 15m of water I will move off the mark a known distance, in this case .025 of a Nm or 46 meters.
So 15m squared =225 and 46 meters squared = 2116. 225 + 2116 = 2341. Square root of 2341 = 48.383 meters of rope +/- depending on conditions. Using these sums and with my setup I have never dragged anchor. Once you get to know rate of drift you should be able to set your anchor positively by backing it in. Jim.

[wayno60]

just on all things anchored, does any one use this hole for what it was intended?
103485

[scottar]

That's there so you set the anchor up to trip in snaggy areas. The chain is shackled to that hole and then layed along the anchor and either cable tied as previously mentioned or attached with cord or wire that will break if required so the anchor will come out backwards.

[nealeboy]

thanks all. before i buy a new anchor, i will try lengthening the chain with a smaller diametre as Dignity mentioned and shorten the prongs to 20cms and give that a shot.

[wayno60]

Very good scott. I knew what it was for but wondered how many others knew. Getting the right length of chain between the 1st and 2nd holes in the secrete. I made one up with to much chain between the holes and if landed the wrong way would not open the flukes because the chain got in the way...I use a stainless key ring instead of cable ties.

[scottar]

thanks all. before i buy a new anchor, i will try lengthening the chain with a smaller diametre as Dignity mentioned and shorten the prongs to 20cms and give that a shot.

What you are trying to achieve with the chain is enough weight/length so that there is always a belly in it. Having enough rope in the water helps but if you have enough length of heavy chain you can generally keep ropes fairly short. If the chain is pulling perfectly straight in any sort of wave action or current the snatching or jerking action of the boat against the anchor will pull it out of the bottom or prevent it getting a hold. You can use a surprisingly small anchor if you have sufficent chain to achieve this.

[ranga7]

Had the same problem and easy fix. I don't like the idea of long chain as it can easily get caught on, in, or around reef and bye bye anchor or worse tip your boat when trying to retrieve. 2 mtrs is plenty. What you need is a heavy as anchor, i got a welder to make me some using solid rod about 3 foot long with reo prongs. Also 12mm rope is to much, i use 8mm on a 6.2m platey. Rope floats so the thicker the rope the more it will float which isn't what u want when your trying to keep your anchor down.

[Dignity]

I use a simple rule. My chain is 8mm @ 7m long and warp is 12mm attached to a Lewmar 6Kg plough. I have 10m increments marked on the warp with spay ink. If for instance I am in 15m of water I will move off the mark a known distance, in this case .025 of a Nm or 46 meters.
So 15m squared =225 and 46 meters squared = 2116. 225 + 2116 = 2341. Square root of 2341 = 48.383 meters of rope +/- depending on conditions. Using these sums and with my setup I have never dragged anchor. Once you get to know rate of drift you should be able to set your anchor positively by backing it in. Jim.

I guess I had better start eating my cornflakes again so that I can get my Kelloggs degree in maths.

[scottar]

I guess I had better start eating my cornflakes again so that I can get my Kelloggs degree in maths.

Oh come on Dignity - The square of the hypotenouse of a right angle triangle is equal to the sum of the square of the other two sides. On second thoughts - My calculator's sh*t itself - just drop the heavy bit and let out some rope. LOL

[Dignity]

I knew it was too simple, the first part I couldn't get as I had no idea what hippo's had to do with anchoring but the second part is what I do, I usually find a mark, let the boat drift a little to work out which way the wind and tide might be pushing me, head back over the mark and whatever the depth is I go twice the distance and drop the pick with 3 times the depth of water (more in rougher conditions). Works most times and is simple enough for me to work out, my line has coloured twine spliced at 20 m intervals so I can tell at a glance what amount of rope is out there.