Harbour speed limit question??

FL390

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Are speed limits based on SOG or speed through the water? I know some are enforced with radar gun (SOG) is there a reference for using this speed definition?
 

johnalison

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I only have direct knowledge of one, which is Brightlingsea. I have heard from the HM that it is based on SOG.
 

Leighb

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I don’t see how any authority could measure speed through the water accurately, except on a lake where there is no water movement?I would assume SOG, although I believe the regulations on the non tidal Thames refer to speed through the water.
 

LittleSister

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I think it will depend on the regulations in the specific harbour. Though some specify which it is, I I imagine that many do not.

I know some harbours have both speed limits and regulations requiring 'no wash' or wash to be minimised, which will affect the allowable speed through the water if there was a strong tide/current.

In some places, people might even travel at a modest speed simply as a matter of common courtesy/environmental care/safety!
 

Stemar

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QHM Portsmouth doesn't seem to specify which, but it's 10 knots, probably just enough for a big ship to have steerage way, but either too fast or too slow for a lot of the mobos that go by just off the plane, making more wake than if they were doing 20
 

PeterBoater

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QHM Portsmouth doesn't seem to specify which, but it's 10 knots, probably just enough for a big ship to have steerage way, but either too fast or too slow for a lot of the mobos that go by just off the plane, making more wake than if they were doing 20
QHM Portsmouth: "Within half a mile of the shore and inside the Harbour, the speed limit is 10 knots through the water but create minimum wash at all times"
 

FL390

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Thanks for the reply’s. Seems pragmatism, courtesy and safety are as usual the important bits.

I had always assumed it was referenced to speed through the water. I struggle to do 6 kts with the tide behind me anyway ?. I noticed navionics shows the speed in red if exceeding the SOG limit (which of course is all it can reference) that got me thinking about my assumption.
 

oldharry

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Chichester Harboiur regs say boats shall noit be "..... be navigated or driven in the harbour at a speed exceeding
eight knots through, on or over the water " So speed through the water. As the tide can run through the entrance in excess of 5kts, a boat can legally be doing up to 13kts over the ground. They are more concerned at wash, and you can be fined for creting excesisve wash even below the speed limit. They enforce the seed limit with radar, so unless it is GPS linked they cannot accurately measure SOG?
 

chrishscorp

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Chichester Harboiur regs say boats shall noit be "..... be navigated or driven in the harbour at a speed exceeding
eight knots through, on or over the water " So speed through the water. As the tide can run through the entrance in excess of 5kts, a boat can legally be doing up to 13kts over the ground. They are more concerned at wash, and you can be fined for creting excesisve wash even below the speed limit. They enforce the seed limit with radar, so unless it is GPS linked they cannot accurately measure SOG?

Chichester do enforce you are likely to get 1 warning then the next stop is the local Magistrates, one of the young lads at my old club was caught, he got the warning they took his dads boat name so he had to tell his dad, he did try to work out what would be worse, teling his dad or paying a fine
 

Capt Popeye

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QHM Portsmouth doesn't seem to specify which, but it's 10 knots, probably just enough for a big ship to have steerage way, but either too fast or too slow for a lot of the mobos that go by just off the plane, making more wake than if they were doing 20

SO, just expect them MOBOS to reduce their speeds so as not to cause undue Wash or Disturbace and endanger

As on our Roads the Maximum permited speed is the MAXIMUM not necessarily the cruising speed
 

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It really can only be speed through the water or you would have no steerage in some places. you can only measure dog if you have GPS and most regulation will have been laid down along time ago.
 

johnalison

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It really can only be speed through the water or you would have no steerage in some places. you can only measure dog if you have GPS and most regulation will have been laid down along time ago.
Although speed through the water makes sense to users, authorities are free to set rules as they wish. Most of the time there is little difference, but the 4kn limit in Brightlingsea can be awkward when the current is running at a couple of knots, as it sometimes does. On the whole, they are rally only interested in boats making a nuisance and won't be looking out for yachts straying by a knot or so.
 

lustyd

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I don’t see how any authority could measure speed through the water accurately, except on a lake where there is no water movement?I would assume SOG, although I believe the regulations on the non tidal Thames refer to speed through the water.
How would they measure your SOG from their boat? Far easier to measure STW since they can stop in the water and drift with it.
That's the bit those mobos miss
Which would you like, slow speed or small wash? With a lot of boats you can't have both!
 

INT QRK

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Although speed through the water makes sense to users, authorities are free to set rules as they wish. Most of the time there is little difference, but the 4kn limit in Brightlingsea can be awkward when the current is running at a couple of knots, as it sometimes does. On the whole, they are rally only interested in boats making a nuisance and won't be looking out for yachts straying by a knot or so.

Certainly true on the Hamble IME, motoring up or down river at 5.5 kt or so at the weekend one will almost always have sailing yachts under power shoving past.
 

RobbieW

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QHM Portsmouth: "Within half a mile of the shore and inside the Harbour, the speed limit is 10 knots through the water but create minimum wash at all times"
Similar on the Hamble, 6 knots/Minimum Wash. The emphasis is on the speed, my view is that should be reversed. Of those vessels actually looking at thier speed, most will be using SOG/GPS. With tide against, 6kts SOG can be about 9kts through the water with the corresponding wash in many cases
 

INT QRK

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Similar on the Hamble, 6 knots/Minimum Wash. The emphasis is on the speed, my view is that should be reversed. Of those vessels actually looking at thier speed, most will be using SOG/GPS. With tide against, 6kts SOG can be about 9kts through the water with the corresponding wash in many cases

True but not very easy to enforce, measurement to acceptable standards being the issue qv the calibration requited of police traffic speedos.

Look at this clip at about the 15 min mark from Chichester harbour a couple of weeks back, within the speed limit, but minimum wash? not in my opinion and no obvious fear of prosecution.

 
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