New Cowes breakwater

[Twister_Ken]

YBW news has just published a bit on the new breakwater to be built at Cowes. Plan here:

Given that it's designed to protect from strong Northerlies, isn't it likely that waves will refract around either end, and end up creating a washing machine effect in the dayboat moorings?

 

[lw395]

It may have rock armour to absorb the wave energy?
I suspect it will change the silting around the Shrape and the moorings, and be interesting as the tide turns.
The dayboats on swinging moorings are generally OK, it is the rafts off the marinas that get bashed around in a northerly.

 

[prv]

it is the rafts off the marinas that get bashed around in a northerly.

And anyone foolish enough to try Trinity Landing, as I once discovered

Pete

 

[Seajet]

As far as I can see it the only use will be to actually give some shelter to the dayboat moorings, boats which just happen to belong to wealthy influential types !

I've never found it that lumpy going in or out of Cowes - though just off Egypt Point can require one's attention - and strong Northerlies are surely relatively rare ?

What used to be Groves & Gutteridge marina ( I've avoided the ' Haven ' since and go to East Cowes ) certainly requires some form of shelter, but from the wash of ferries and gin palaces.

 

[l'escargot]

The full report and benefits are all in this document http://www.cowesharbourcommission.co.uk/documents/ARUPBreakwaterbusinesscase.PDF there is also technical info here: http://www.cowesharbourcommission.co.uk/pages/outerharbourplan?id=793

It is going to provide shelter for the new marina development on the eastern side. Being constructed from rocks it should dissipate the waves and with tidal flows running east/west it shouldn't affect silting.

 

[Seven Spades]

Seajet ylu obviously have not been in Cowes ina strong northerly, trust me this will make a huge difference. It won't cure the problem, but it will make a huge difference. I am please to see some money being spent. I wish someone would invest some money on deep water harbours in North Cornwall and Devon.

 

[Twister_Ken]

Am I the only one to have heard of wave refraction?

 

[Keen_Ed]

I've never found it that lumpy going in or out of Cowes - though just off Egypt Point can require one's attention - and strong Northerlies are surely relatively rare ?

 

[JumbleDuck]

Am I the only one to have heard of wave refraction?

I've heard of it, but I'm not sure of the relevance here.

 

[mainsail1]

Am I the only one to have heard of wave refraction?

This is exactly what I thought but decided the experts must know better than me.
My suspicion is that a breakwater in this position will be pretty much a waste of money but who am I to question the experts? I also have unhappy thoughts about it's effect on the tide in the river but, again, I am no expert.

 

[john_morris_uk]

Quite! Not lumpy sometimes off Cowes - the picture says it all. Not necessarily dangerous, but certainly lumpy sometimes.

Its a sad picture as some of those day boats are beautifully maintained, but I expect they were raised and washed down very quickly and hopefully not too much harm done.

I hope that the breakwater works. I put a large (over 70') boat alongside a pontoon just N of the chain ferry earlier this year and had to leave within minutes as it was untenable. We were about to burst fenders it was so bad.

 

[Twister_Ken]

I've heard of it, but I'm not sure of the relevance here.

Refraction causes waves to change direction as they pass an obstruction to one side of the wave train - to swing inwards, if you like. It's what lets swell get into anchorages that look as if they should be as smooth as silk.

It occurred to me that the breakwater might well bend waves passing either end of the breakwater inwards, acting like a lens and focussing them at some point to the South, in amongst the small boat moorings, with a resulting rather unpleasant cross sea there.

Still I suppose the experts have worked out that it's not going to happen. Unless it does.

 

[alant]

Quite! Not lumpy of Cowes - the picture says it all.

Its a sad picture as some of those day boats are beautifully maintained, but I expect they were raised and washed down very quickly and hopefully not too much harm done.

I hope that the breakwater works. I put a large (over 70') boat alongside a pontoon just N of the chain ferry earlier this year and had to leave within minutes as it was untenable. We were about to burst fenders it was so bad.

Which one was that?

 

[savageseadog]

There would have to be large openings at both ends as it would silt the whole harbour up

 

[Seajet]

Actually I've been in and out of Cowes a lot since 1970, and it has never been a dangerous entrance.

Weren't those keelboats in Cowes sunk at the same time as the hopefully unusual October 1987 Hurricane which destroyed many boats on shore let alone afloat and even sank keelboats at Itchenor, the force was quite beyond the normal laws of physics - I took part in recovering boats and found strong tree branches had been cut clean off just by the wind, while the light bulb on my deck floodlight had been sheared in half !

I am familiar with wave refraction but surely big storms tend to come from the South West, which is why St Helens Roads to the East is a well known sanctuary for big ships to anchor in shelter...

I do however welcome any financial input for the sadly underused Isle Of Wight and its' people, skilled in everything from boatbuilding and hovercraft to aeronautics.

 

[prv]

Weren't those keelboats in Cowes sunk at the same time as the hopefully unusual October 1987 Hurricane

No, it was in the last two or three years or so.

Pete

 

[l'escargot]

...Weren't those keelboats in Cowes sunk at the same time as the hopefully unusual October 1987 Hurricane...

No, it was April last year: http://www.iwcp.co.uk/news/news/boats-sink-in-heavy-seas-44153.aspx & http://www.iwcp.co.uk/news/news/sunken-yachts-recovered-44195.aspx

 

[Dockhead]

As far as I can see it the only use will be to actually give some shelter to the dayboat moorings, boats which just happen to belong to wealthy influential types !

I've never found it that lumpy going in or out of Cowes - though just off Egypt Point can require one's attention - and strong Northerlies are surely relatively rare ?

What used to be Groves & Gutteridge marina ( I've avoided the ' Haven ' since and go to East Cowes ) certainly requires some form of shelter, but from the wash of ferries and gin palaces.

Boats in the marinas get a right bashing in a NE'er in the winter time. I kept my boat in Cowes Yacht Haven (great place!) over one winter, and had actual damage.

I am very happy they are putting in the breakwater.

 

[l'escargot]

Boats in the marinas get a right bashing in a NE'er in the winter time. I kept my boat in Cowes Yacht Haven (great place!) over one winter, and had actual damage.

I am very happy they are putting in the breakwater.

This was the Yacht Haven last October - you might also notice the J with a broken mast:

 

[jac]

Refraction causes waves to change direction as they pass an obstruction to one side of the wave train - to swing inwards, if you like. It's what lets swell get into anchorages that look as if they should be as smooth as silk.

It occurred to me that the breakwater might well bend waves passing either end of the breakwater inwards, acting like a lens and focussing them at some point to the South, in amongst the small boat moorings, with a resulting rather unpleasant cross sea there.

Still I suppose the experts have worked out that it's not going to happen. Unless it does.

Knowledge on this is sketchy I have to say but if the breakwater absorbs the energy won't the wave dissipate? I thought t was rock clad to do this. Ser some will refract but wouldn't that be the waves that were coming through the ends so would therefore be diffused?

As I said though, certainly not an expert on this (school boy physics) so let's hope the engineers didn't drop the subject after o level!!