Sailing through overfalls: how to sail safely through them.... Or go around?

[tom3987]

Hi Everyone,

I seem to get caught out with overfalls or underestimate how bad they can be which is why im doing my homework on them.

Just some cases- back in April i was sailing around the isle of man, We took Chicken Rock - about 1 mils outside the overfalls on the chart but they was still rough

Just before Christmas we was heading down from Caernarfon to Pwllheli stayed on the outside on The Tripods - about 1 mile again and was rough.

Both these times was with tide heading in the direction we was sailing and light winds - They was doable and not to bad but was rough for 20/30 minutes. - Devils ridge was flat.

We have just left Fisgard (17th Jan) to Milford Marina. Winds about 13kts to 18kts southerly, spring tide. Everything was great, really good sail up to St David's, we went through St Georges Channel which i was aware of and knew it was going to get choppy but choppy was an understatement. We was motor sailing and it was that rough the engine failed which I'm assuming was a fuel issue. it came back on shortly after with no issues.

We crosses the bay, motor sailing, and tide pushing us. I was going to go through Jack sound as we should have hit their at low water slack, but the wind was a bit high and the conditions we just had i changed my mind to go around Skomer and go through Broad Sound, Again i took this wide, about 1-2 miles outside the overfalls on the charts. It looks choppy so i decided to go around Stockholm (Wild goose race). This was a disaster. We get F***ed. Massive waves easily 4-5m. Towering. Engine failed multiple times as i tried to hit them on the shoulder. Was a sh*t show. Completely my fault for under estimating them. But this is the first time i feel like i badly messed up and put us in danger. Jack sound should have been low water slack but i was going at 11.8kts at this point. The tide was ripping. I had an anchorage on the north side on Skomer which at this point was only 1.5miles away so we tried to turn back, i was doing 1kt with engine at full speed. We had to turn into it. I decided to head out further to hopefully get out the overfalls. 20,30 minutes of slamming and battling the waves they finally settled down. Luckily i had the sail out reefed which kept steering when the engine failed.

Luckily we are all good and no damage to the boat, the inside was a mess with a few things broken that got flung about.

I don't want to make this mistake again. I wanted to see what yous do, do you avoid overfalls, do you time them for slack water? My thoughts at the moment is to go miles (3/4 if not more) around them. I need to know what's the best approach to these as i can see im going to encounter a lot around the Bristol Channel and south of the UK.

Also, just FYI, we both had a PLB on us and both Harnesses in. But i hope to never get to the point where im thinking we need to use it. Also when i say caught out on overfalls - I mean it like understate them. I am fully aware of them on the charts when i do my planning.

Thanks in advanced.

 

[RunAgroundHard]

I sail around them. Over the years I have sailed through them, some no probs, some big issues with slamming, sudden stopping, dousing.

If planned for, usually they are easy to sail around and avoid. There are times that they can be benign.

 

[wingcommander]

Did you have your slack water timings correct. Wind opposing tide will chuck up some fairly big seas, especially with a spring flow

 

[vyv_cox]

In Irish Sea there is considerable tidal range, so a lot of water moving about. I think you should consider giving overalls a wider berth, for example advice for South Stack is five miles in Ralph's pilot.

The Tripods are always quite bad, I have gone through on a beautiful day in nearly no wind and been thrown about a good deal. I usually keep well inside there, which is quiet.

Having said that I think the biggest seas I have been in were off Dover port, gale behind us and full flow against. Always better if wind and tide are with you.

 

[tom3987]

I sail around them. Over the years I have sailed through them, some no probs, some big issues with slamming, sudden stopping, dousing.

If planned for, usually they are easy to sail around and avoid. There are times that they can be benign.

How wide of a berth do you give when going around?

 

[tom3987]

Did you have your slack water timings correct. Wind opposing tide will chuck up some fairly big seas, especially with a spring flow

Low water at Jack sound shoudl have been about 3pm. We hit the goose race about 3pm so i assumed it would be nearing slack but i could have been wrong.

 

[rotrax]

We always give Portland 6 miles offing. 4 for St Albans unless benign. Looe Channel can be grim W over T. The Needles Channel can be interesting too.

Took a look at Fair Head once. Decided I had got the timings wrong, it was bloody awful! Went back to Glenarm. Next day, better timing, all was OK.

Went into Portsmouth Harbour once. A big - 50 footish - Trawler Yacht showed both his props by Blockhouse. He nosedived into a big W over T hole.

I moved centre channel, got shouted at by the Volunteer Harbour Patrol.

I shouted back...............................

 

[RunAgroundHard]

How wide of a berth do you give when going around?

Well that depends on the pilot book and the chart overfall symbols. In some places, WCoS, you can be 50 feet away from overfalls in very calm water, in other places about 3 miles offshore. You just have to plan the passage using all of the available information.

 

[RunAgroundHard]

Low water at Jack sound shoudl have been about 3pm. We hit the goose race about 3pm so i assumed it would be nearing slack but i could have been wrong. ..

There have been posts in YBW about the inaccuracy of times on digital Apps, compared to Hydrographic Office tide data. Also slack water time duration can be very short and also impacted by atmospheric pressure, wind direction and wind strength. You need to consult pilot information (books, Apps) for the concerned area to get useful insights. Local knowledge from sailors, divers, clubs, fisherman, lifeboatmen, pilots et cetera can be invaluable and very accurate.

 

[Ammonite]

Did you check the tidal stream atlas or did you just assume slack would be at low water? It isn't. See here

Skomer Tides

 

[Telstar26]

Going south through Ramsey then Jack Sound is not a good idea in a moderate to strong southerly. If you go through Ramsey at slack, Jack will be running hard by the time you get there.

In those conditions I'll stop at Solva and wait. But I have a lift keel.

But the big mistake was thinking slack is at low/high water. It ain't!

There are passage notes here: Visiting Yachts – Fishguard Bay Yacht Club – Clwb Hwylio Bae Abergwaun and in the Sea Guide to Pembrokeshire

But I agree with you about Wild Goose race; I made the mistake of going through it once!

 

[TSB240]

There is ýour first mistake you should never use local high or low water as a Guarantee of tidal slack period.

The best advice for Jack sound is slack water is 2 to 2 1/2 hours after Milford High or Low water depending on spring or neap. I have been through both Jack and Ramsey sound at slack water with a good force 5 blowing. It wasn't for the feint hearted but at least we were not fighting any additional tidal driven waves.

You cant just use any tidal height tables to guess the slack period. This applies to most of the tidal gates you mention getting into trouble around Wales. High water at Menai Bridge is 2 hours after the slack period and makes any transit of the swellies either impossible without a planing hull and 50 hp or very quick without either.

The same applies for Bardsey so no wonder you are experiencing problems with recent overfall passages.

 

[oldbloke]

Did you check the tidal stream atlas or did you just assume slack would be at low water? It isn't. See here

Skomer Tides

Yes, South Devon also, slack, water at Start Point is about 2 1/2 hrs before high and low water. Thigh and low water the stream is at full chat

 

[Supertramp]

I sail the areas you mention and a further factor is the swell. Make a passage in light winds the day after a howling southwesterly and waves appear out of nowhere. Bardsey Sound and South Stack can be very uncomfortable even at slack water, sometimes worse than during the flow. And the difference between spring and neap tides is significant. As others have said, slack is not HW/LW and worth reading pilot guides for details of eddies and counter flows.

I try to choose my weather and timing carefully and avoid wind over tide.