Anchoring in strong tides

[Kailani]

Off to the Brittany coast at the weekend, which is a new cruising area for us. Thought about anchoring overnight but not sure if it is a good idea considering the tidal range. We have a Bavaria 44 which I guess is fairly big for this area, but wondering if the tidal strength will be too much for one anchor and maybe we should think about putting out a kedge as well. Let me know if I'm not explaining myself clearly - it's my first post!.

 

[John_Clarke]

Welcome to posting on the forum.

Large tidal ranges and strong tidal currents make anchoring much more challenging. If you have not a lot of experience of anchoring it could be a wise decision to leave anchoring overnight in Brittany for another visit. A great deal could be learnt by anchoring for lunch breaks. I always go astern against the anchor and gradually increase the revs to test how well it is holding by looking sideways at transits. I do this even for a short stop and it has taught me a lot.

The tidal strength should not be too much if your anchor is adequate and well laid. The load on the warp in a 4kt current would be considerable but should less than in a F6 without current. I would hope that anchorages would not have as strong a current as 4kt!

Laying a second anchor at 180 degress to the bower to hold the boat when the tide turns can be a good idea but adds to the complication of laying and retrieving the anchors particularly if the wind gets up. Also, if other boats close by have not anchored in the same way you might go bump in the night when the tide turns.

You would also need to get your tidal sums right to avoid going aground at low water and to ensure that the scope is sufficient at high water.

Have a great cruise and lots of anchoring!

 

[VicMallows]

Isn't there some confusion here between tidal range and tidal current?

The former is of no consequence as long as you have planned your anchor scope and swinging room correctly. Plenty of anchorages in Brittany have huge range but little tidal current.

If you are indeed anchored where there is a strong tidal current....well you will have to be happy that your anchor will reset if necessary at the turn of the tide.....the same as anywhere else.

 

[Searush]

I assume you are not planning to anchor in the Raz or similar?

Most anchorages are relatively sheltered & while the range may be significant, currents are generally not that great. I sail in 20-30' tidal range & the currents are only strong where narrow channels feed large estuaries or bays - and even then are usually only 2-3kts.

Make sure you are in water as shallow as possible without going aground at LW (unless you can safely take the ground in which case no probs!) Use at least 3x max depth if chain & add rope if you need more. Leave plenty of room for swinging at LW if you are on a long scope.

In my experience, using 2 anchors is usually a complication too many - unless you can connect the chains to a swivel below a riser to make up a mooring style set up. An anchor from the bow & another from the stern in strong tides will almost certainly drag the weaker anchor (usually the stern kedge) & will often end up as an almighty tangle to recover.

If you can stay aboard & awake for at least one change of tide, just in case. That should give you the confidence to sleep soundly then!

 

[savageseadog]

One piece of advice, it's very easy to get caught out with the anchor biting suddenly and unexpectedly when in current. Keep your fingers and hands well clear and make sure your installation can cope with the shock loads.

 

[Salty John]

In strong reversing currents I'd always use a Bahamian moor - one anchor upsream and one downstream. You need two good sets of ground tackle, though, not a main anchor and a little lunch hook because, although you have the security of two anchors down, you lie to one anchor at a time.

 

[guernseyman]

Other possibilities are buoys - visitor's, of course, but local ones are usable so long as you remain on board in case the owner returns.

And rivers usually offer good shelter, remembering you can get blown sideways near slack water or at neaps.

 

[Searush]

One piece of advice, it's very easy to get caught out with the anchor biting suddenly and unexpectedly when in current. Keep your fingers and hands well clear and make sure your installation can cope with the shock loads.

Good point that, do not think you can hold it yourself, or "just slip it round the cleat" - you will come home missing a few fingers if you try.

Cleat it firmly before it bites & stand clear, holding on. It will just seem to bob a bit down as it bites & the boat stops - but do not be lulled into thinking there is no force involved!

 

[SHUG]

One piece of advice, it's very easy to get caught out with the anchor biting suddenly and unexpectedly when in current. Keep your fingers and hands well clear and make sure your installation can cope with the shock loads.

In that event you may well have snagged on a rock and come adrift when the tidal flow reverses

 

[savageseadog]

In that event you may well have snagged on a rock and come adrift when the tidal flow reverses

It happens in sand and mud too

 

[stav]

Guess you will be just past neaps so should be OK. I carry 80 metres of chain on board for anchoring around the Channel Islands and N Brittany. Generally no problems should be encountered in the estuaries and around the coast. Other people anchoring for a short stop might veer less cable than you so be prepared to adjust the scope as the tide/day/night changes. Be more cautious around some of the Islands, Minquiers etc and be prepared to take some of the strain on the motor. Anchoring in the little pool just before the marina in Treguier is a delight and in Lezardriuer there are generally buoys you can pick up, again delightful.

Have a nice long weekend.

 

[alant]

Off to the Brittany coast at the weekend, which is a new cruising area for us. Thought about anchoring overnight but not sure if it is a good idea considering the tidal range. We have a Bavaria 44 which I guess is fairly big for this area, but wondering if the tidal strength will be too much for one anchor and maybe we should think about putting out a kedge as well. Let me know if I'm not explaining myself clearly - it's my first post!.

Take the 'weight' off your chain, using a bridle (rope from one bow cleat, through the chain to the other bow cleat, with load on this rope).

This will allow load to be on both the cleats as strongpoints, protecting your windlass from any sudden snubbing/snatch loads.

 

[guernseyman]

Take the 'weight' off your chain, using a bridle (rope from one bow cleat, through the chain to the other bow cleat, with load on this rope).

This will allow load to be on both the cleats as strongpoints, protecting your windlass from any sudden snubbing/snatch loads.

It should be pointed out that some windlasses are not designed as a strong point for the anchor cable. Best to use the Samson post.

 

[Csail]

Well here in the Bristol channel we have the second highest tides in the world (some say first) but loads of chain and a good anchor you will be fine , maybe a 45 cqr.

 

[chrisclin]

We found that we didn't do as much anchoring as we had anticipated. First, there are visitors buoys (or unused residents' buoys) everywhere. Secondly we had bilge keels so found we dried out more often than not. On those occasions we did anchor, we did have to haul and veer cable from time to time. With a 10 metre rise and fall we found that 3 or 4 times max depth allowed the boat to range all over the place at low tide, usually over the shallow bits with the oyster beds!
Finally, there are lots of marinas where you can easily get fresh croissants and the prices aren't too bad.
It's a wonderful sailing area - enjoy

 

[alant]

It should be pointed out that some windlasses are not designed as a strong point for the anchor cable. Best to use the Samson post.

yes, but assumes you have a samson post.

However, i still prefer to spread the load.

 

[webcraft]

.
If the current is going to reverse when you are asleep you need to be pretty confident your anchor will reset itself. 'Next Gen' anchors are generally a lot better at resetting quickly in these circumstances, but if you have any doubt then I would plan to be awake at the turn of the tide.


- W