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Old 01 August 2016, 10:47   #1
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Which Anchor

So, just how long is a piece of string

Seriously, I realise that there are many variables but what would be considered the better choice for a 2.7m SIB anchored in 5 to 10 meters with a considerable flow over a mainly sand but sometimes broken bottom?

Bruce or Danforth and what respective weights? Would 2Kg suffice?
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Old 01 August 2016, 11:16   #2
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I'd say either. A 2kg Danforth (or quality knockoff) will hold your boat without a problem. Bruce tends to need a bit more mass than the Danforth types for a given anchor weight (not sure how small they come, but for a boat that small, I'd think you'd be fine.) Bruce will store easier, and won't pinch fingers.

I use an 8lb Danforth clone for my primary anchor (18' aluminum hull RIB), with a 5 or 6lb Bruce knockoff as a backup. Both have about 20' of chain (I think 1/4" on the backup, and 5/16" on the primary, but I could be off on both sizes.)

Important to have enough chain and scope out a bit so as to keep the pull on the anchor horizontal(ish).

jky
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Old 01 August 2016, 11:24   #3
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Bruce or Danforth and what respective weights? Would 2Kg suffice?
Yes, they'll be fine. I use a 2.5kg Bruce on 3.9m boat and never had a problem. I have a Danforth "style" too of similar weight and its rock solid, but as JKY says not so easy to store.

Make sure to add some chain - on a wee sib with enough chain even the much maligned grapnel will hold you in normal conditions.
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Old 01 August 2016, 11:53   #4
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Thanks both.

Tried a small grapnel with 3m chain in around 5m water yesterday and its effect was non-existent even with 18m of warp out. Am I correct in thinking 2.5 – 3 x depth should be enough warp?
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Old 01 August 2016, 14:42   #5
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Thanks both.

Tried a small grapnel with 3m chain in around 5m water yesterday and its effect was non-existent even with 18m of warp out. Am I correct in thinking 2.5 – 3 x depth should be enough warp?
No, most yachties would only anchor with 3x depth if the whole of the anchor rode was chain. As a rule they would be 5x depth using a mostly rope rode. Some go as far as 7x if there is enough swing room.

Whilst you might have less windage than a yacht you also are a lot lighter so I think their rules of thumb are sensible.
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Old 01 August 2016, 14:50   #6
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Nylon Cooper Anchor - Cooper Anchors for jetskis, Kayaks, boats

Brilliant little anchor, worlds apart from a grapple
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Old 01 August 2016, 17:27   #7
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No, most yachties would only anchor with 3x depth if the whole of the anchor rode was chain. As a rule they would be 5x depth using a mostly rope rode. Some go as far as 7x if there is enough swing room.

Whilst you might have less windage than a yacht you also are a lot lighter so I think their rules of thumb are sensible.
Thanks Poly, will try a longer rope next time out.

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Nylon Cooper Anchor - Cooper Anchors for jetskis, Kayaks, boats

Brilliant little anchor, worlds apart from a grapple
Thanks Lee, looks great but that price point is bit high for my occasional needs.
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Old 02 August 2016, 19:10   #8
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No, most yachties would only anchor with 3x depth if the whole of the anchor rode was chain. As a rule they would be 5x depth using a mostly rope rode. Some go as far as 7x if there is enough swing room.
I don't disagree, but those rules (guidelines, whatever) are for large boats overnighting where there's a chance that weather can turn.

For anchoring someplace where you're staying on the boat, or at worst not being far away, 2-4x depth is generally sufficient. Add more scope for rough water, high winds and/or heavy tidal or current flows.

jky
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Old 02 August 2016, 19:37   #9
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Ive used just about every style on the market over the years, these days where I often anchor on reefs, shingle and sand all in one day and use sarca anchors. With these I can get away with double the holding power for half the weight, only problem is they can be a little expensive.Super SARCA Anchor - anchorright.com.au

Jon
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Old 03 August 2016, 04:06   #10
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I don't disagree, but those rules (guidelines, whatever) are for large boats overnighting where there's a chance that weather can turn.

For anchoring someplace where you're staying on the boat, or at worst not being far away, 2-4x depth is generally sufficient. Add more scope for rough water, high winds and/or heavy tidal or current flows.

jky
Thanks, with the 2nd or 3rd highest tidal range in the world (changes from year to year) the flow in theses parts is considerable so I probably need the upper end of 2-4x depth. But as an occasional, fair-weather, novice, in a 2.7m SIB, I won't be test an anchor in rough water or high winds.

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Ive used just about every style on the market over the years, these days where I often anchor on reefs, shingle and sand all in one day and use sarca anchors. With these I can get away with double the holding power for half the weight, only problem is they can be a little expensive.Super SARCA Anchor - anchorright.com.au

Jon
Thanks but a bit of overkill for my requirements I think.
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