FL390
Member
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?
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"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
That's the bit those mobos misscreate minimum wash at all times
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?
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
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.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.
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.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.
Which would you like, slow speed or small wash? With a lot of boats you can't have both!That's the bit those mobos miss
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.
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 casesQHM 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