Freak Waves in the Solent

[Peppermint]

If you sail the length of Southampton Water you will be subject to various "wash effects" as you go. The Red Funnel's and the Red Jet's, various commercial vessels and powerboats.

You get used to it and it's rarely a problem so I was a bit surprised by an incident off Calshot.

I was, heading south, out of the channel in 3m of water near the top of the tide. Flat calm wind about zero. I watched a wash from Red Jet 3 coming towards me as usual. Next thing my daughter who was catching some rays on the port cockpit bench fly's across the cockpit and headbutts my knee. The boat had rolled about 70 degrees from the vertical, and a big dollop of Solent arrived in the cockpit.

The dynamics of waves running into shallows is well known but this is the first time I've experience such a marked effect in this area. In view of the falling over catamaran I found this quite interesting

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[qsiv]

I seem to remember a fatality on the East Coast attributed to a fast cat wake becoming lethal in shallow waters. You get all three nastys as the wave runs ashore, it gets bigger, steeper, and then it breaks.

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[MainlySteam]

Tom, I have experienced quite unpredictable wake effects from the large Incat ferry that operates across Cook Strait even in quite open and deep waters (is a 40 knot vessel). Can be quite away from it (mile or so) and suddenly the wake arrives and is very obvious and steep, but other times, nothing even though it is still at cruise speed and nothing else obviously different.

We are currently managing the design and construction of 3 smaller foil assisted catamarans (35 knots) for harbour use in a very high quality environment in another country, not in New Zealand, (the build is actually just getting underway with the same yard as built "Red Jet 4" recently delivered over your way). The particular design seems to a particularly low wake producing one and will be interesting to see how they go.

John

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[Peppermint]

I can confirm that Red Jet 4 generates much less wake than the older designs.

The large cats that Stena operate out of Harwich have been plagued by "freak wave effect". So much so that the first hour or more of departure is spent at the same speed as the conventional ferries that also ply this route.

Studland bay is another area where this effect, often some time after the Condor Cat has passed, causes much bumping and barging in the anchorage.

It appears that so many variables affect this phenomenon, depth, stream, sea bed shape, etc. that coming up with general operating rules that prevent it's damaging effects is almost impossible.

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[burgundyben]

Interesting, Red Jet 3 was the fastest and I am certain makes the biggest wake, take you point about the wake piling up over shallow ground, I've also noticed that sometimes there seems to be a greater series of waves in the wake, sometimes its crashity bang, once, sometimes crashity bang several times.

<hr width=100% size=1>Sod the Healey - I think I'll buy an E-Type.

 

[wrr]

For an analyis of fast craft and freak waves, see this MAIB report: www.dft.gov.uk/stellent/groups/dft_maritimesafety/documents/page/dft_masafety_508309.pdf

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[MainlySteam]

Thanks for the comment on Red Jet 4. I talk with the designers of her at least several times a week so I will pass the comment on to them. I am sure they would appreciate the feedback from another water user regarding its wake.

John


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[Paul_H]

Dont know if this post was triggered by "wave heights" thread in reader forum, but there I commented on the scary waves that develop over the shallows in Poole Harbour when the Barfleur ferry (or any other big ship) goes in and out. This is not due to wash but simply dispalacement of the water as the ferry fills the channel in both depth and width.
With regard to the Condor fastcat they've certainly slowed down a lot compared to a few years ago possibly cos there were incidents of small boats and bathers being up ended in studland/shell bay.

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[Neraida]

We sail down Southampton Water and into the Solent almost every day and have become used to the catamaran's presence. Generally they are very considerate, Red Jet 4's wake is nothing to worry about but the other 3 create monster crashy wakes. We always try to avoid the area inside the Calshot Spit bouy, you can see the wakes cresting around there and if not possible if there is a container ship or another big or fast vessel to worry about try to take the wake on the nose to avoid rolling around as well as crashing.

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[andrewbarker]

I agree with you. I moor at Town Quay just on the wave break & get the wash from all the Red Jets. RJ3 is definitely the worst & quite different in magnitude to the others. On on occasion the wash it pulled the stern cleat & half my transon capping off my boat.There must be a reason & it's not just speed because it produces excess wash at the same speeds as the others. RedJet 4 (the new one) is much larger but produces less wash than all the others.

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[MainlySteam]

The builders of Red Jet 4 tell me that during their shakedown voyages on the Solent, one yachtsman called them up on the radio to commend them on the reduced wake. If you who made that call are out there reading this I can tell you they appreciated the call.

John

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