Bill Corten & offshore anchoring (B&B)

[Tony_N]

Just got my march edition of B&B and read with interest Bill Cortens article on offshore anchoring. He talks about leaving out anchor line/water depth of 4/1 to 7/1 depending on the roughness of the weather. However he says that this is only necessary on a sandy or muddy bottom. On a reef (he doesnt mean a coral reef which is protected from the open ocean) he maintains that you only need to put out enough line to hit the bottom and a few extra metres to accommodate the swell.

Now I know that Bill Corten is a guru whose experienced opinions should be respected without question, but I've always worked under the rule that you put out a minimum of 3/1 whatever the bottom. and I thought this was for safety reasons.

He doesn't spell it out, but it seems that it just has to do with making the anchor hold, and when there is marine growth on rocks/reef the shorter rope is fine.

Anchoring on a shorter rope would be more accurate and since we hardly ever anchor on sand, I'm keen to give it a run, but need it explained to me a bit more first. Can someone please help me out?


thanks

Tony

[bidkev]

Tony, I'm with you on the 3/1 although I do go shorter on flatter seas/less run.

The way I read it is that the shorter the rope, the steeper the angle to your bowsprit and therefore the easier to lift/break the achor. A longer rope means a lesser angle leading to a better grip/bite. It is also more beneficial in that even if the anchor does trip, it is more likely to rebite even if you drift into deeper water. The steeper angle on a shorter rope means that if your anchor trips it is likely to simply skip along the bottom and not re-grab unless you drifted into shallower water.......deeper water, and it would never re-bite.

kev

Fighting for peace is a contradiction in terms.

[dfox]

Ive done alot of anchoring in what i class deep water over the years (120 meters - 150 meters) chasing gold bands and this is how i see it. In shallow water 50-80meters, work on your theories, but in deep water its totally inpractical to say put out close to half a kilometer of rope to hold in 150. The drag on the rope alone will cause problems, let alone judging distances to drop the anchor from the fish. I use a bit more chain in the deep and in 150 about 200 plus meters of rope.
Now this may seem extreme but back in at 100meters the same principles work. Its silly to use 3 times the depth in rope in these areas even when the bottom is sand or mud, bills correct in his statement.
Carry a number of different anchors for various bottoms if need be, a reef pick will drag no mater what on soft bottom so a sand anchor is required in some areas.
Of course if the currents running forget all of the above...foxy

[whiteman]

I rarely use more than double the depth when anchoring over reef, more like 1.5x. Once the pick has a hold you can use as little as 1.2x although there will be extra rope backlash in swell.

[Tony_N]

Yep - that makes sense Foxy - thanks. For reasons of fuel economy/limited bank balance (1989 140 2stroke Evinrude - 2litres) we rarely fish much more than 40 metres and tops is 32 fathoms. So I'll keep to current practice. (though on a good day we often crib a lot on the 3X). anything over 2 metre swell makes me cautious enough to throw out a bit more rope, though. I keep remembering the story of the bloke locally who tried to use the swell to gain line to free a snagged anchor........

Tony

[snappa]

use a spear anchor to hold on the reef...


just enought rope to hold ....


because u are moving around a lot and makes for easy retrieve...

at nite i would use a reef anchor and plenty of chain .. i'm very sound sleeper ?

[Tony_N]

Snappa

I know of the anchors in the attached picture, I use a pick (or grapnel) and I've seen the sarca anchor - but don't know the "spear" anchor. Is that a local name for the plough, or another style of anchor altogether?

Tony

PS i sometimes go out with a friend who uses a sand (danforth) anchor for everything whether its soft or hard. Using a dan buoy he hardly ever gets it stuck, but I have seen him bend one rather badly - but he always carries a spare.

[Big_Ren]

Tony

I think I know the anchor that Snappa is talking about. We have one but I can't for the life of me remember it's name (not Spear). From memory, it's about 9lb (our boat is 19ft) with four flat bladed triangular prongs (my best description for it). The normal fastening eye i.e. at the end of the shaft at the opposite end to the prongs is held by a zip tie connecting chain to the eye. The working end (the prongs) also has an eye to which the end of the chain is d-shackled.

When driving off using an anchor buoy, the zip tie snaps and the prongs are pulled head first through the water column (if that makes sense). We have found it much easier to retrieve and no lost anchors compared to in the past when we have used more traditional set-ups.

Hope that all made sense.

Cheers
Paul

[banshee]

Mooloolabah pick?