Perhaps I need a speed log!?

[Fizzwizz]

I set off down the Medina at about 4pm, thinking if I'm quick I can get out into the solent for a quick sea trial after a few RIB improvements. I didn't need to read the channel buoy to know the speed limit in this part of the world is 6 knots. I've sailed this stretch in my yacht numerous times without incident. Setting the throttle to a speed that felt very much like 6 knots I ambled up the river against the tide. To my amusement a blue flashing light made its way towards me. After a reasonably polite warning from the harbourmaster I reduced the throttle to an almost snails pace. It felt like 3 knots.

Once out to sea I managed 5 minutes of solent fun before turning back to beat the setting sun (Nav lights disconnected presently). I was almost near the chain ferry doing what seemed like less than 6 knots when, again, I was met by flashing blue lights and, to the amusement of my kids, a siren. Albeit a different harbourmaster the warning this time had a more serious tone to it.

Crawling back to my berth at a pace that seemed slower than I can swim I couldn't help thinking ... "Perhaps I need a speed log!?"

[ShinyShoe]

Shouldn't be that tricky, you just need to be in displacement mode, so tubes in the water?

HullSpeed[kts] = 1.34 * SQRT( Lwl [ft])

for a 21ft boat thats 6.14kts

However, a GPS would be mighty useful for you for a number of reasons, including SOG. I think technically you are supposed to be Speed Thru' Water at the Medina.

If in doubt try swimming it ;-)

[Burtox]

I've seen them pull loads of people in the past. The speed limit is not against the water I guess it's against the land.

[Poly]

Speed limit is 'over ground' isn't it? So you don't want a log (which is through the water - and notoriously unreliable at low speed on a rib anyway). Any GPS will provide what you want [or a smartphone in appropriate wrapper].

Speed overground means if you are travelling against the tide, the speed through the water could be much lower.

[Fizzwizz]

Originally Posted by ShinyShoe

Shouldn't be that tricky, you just need to be in displacement mode, so tubes in the water?

HullSpeed[kts] = 1.34 * SQRT( Lwl [ft])

for a 21ft boat thats 6.14kts

However, a GPS would be mighty useful for you for a number of reasons, including SOG. I think technically you are supposed to be Speed Thru' Water at the Medina.

If in doubt try swimming it ;-)

I bloody knew it, this was my retort exactly (without the calcs). I was completely at displacement speed. The bow rises very quickly once she starts to lift off the tubes. I wasn't sure how fast this occurs, but I'm not arguing with those calculations!!

[Fizzwizz]

Originally Posted by Poly

Speed limit is 'over ground'

Better not go out during Springs then else I might have to put it in reverse!

[Dhf]

Originally Posted by Fizzwizz

"Perhaps I need a speed log!?"

No! You need a bigger engine, he won't catch you then

[ShinyShoe]

Originally Posted by Burtox

I've seen them pull loads of people in the past. The speed limit is not against the water I guess it's against the land.

Cowes Harbour is Speed through the Water since late last year / earlier this year:

Originally Posted by cowesharbourcommission.co.uk

3.2.1 Every vessel navigating the Inner Harbour of Cowes or within 100 metres of the Mean High Water Mark shall unless otherwise authorised by the Harbour Master in writing, subject to the requirements of maintaining adequate steerage way and control, be navigated at a speed not exceeding 6 knots through the water.

Are they being stricter in view of NTM30?

[ShinyShoe]

Originally Posted by Fizzwizz

I bloody knew it, this was my retort exactly (without the calcs). I was completely at displacement speed. The bow rises very quickly once she starts to lift off the tubes. I wasn't sure how fast this occurs, but I'm not arguing with those calculations!!

Did they say you were speeding? Or creating too much wake?
Did they mention the conditions imposed by NTM30?

[Fizzwizz]

Originally Posted by ShinyShoe

Did they say you were speeding? Or creating too much wake?
Did they mention the conditions imposed by NTM30?

They said I was speeding, but they did refer to my wake too. I did keep checking my wake wasn't washing up onto shore. I think for the speed my RIB creates more wash than my yacht, and I guess they were probably judging my speed by my wake.

NTM30 wasn't mentioned.

To be honest, the second guy was quite stern, but when he realised I wasn't apathetic and wasn't purposely ignoring the rules he was quite polite. I think I opened the throttle a buoy too early too on the way out (by mistake), luckily he didn't see that or I would have been for it!

[ShinyShoe]

Originally Posted by Fizzwizz

They said I was speeding, but they did refer to my wake too. I did keep checking my wake wasn't washing up onto shore. I think for the speed my RIB creates more wash than my yacht, and I guess they were probably judging my speed by my wake.

NTM30 wasn't mentioned.

I guess if they were busy with the salvage operation I'd be stressed at having 8000 litres of diesel that might be leaking and then some ribnobber comes by and might slosh some over the booms.

I think I opened the throttle a buoy too early too on the way out (by mistake), luckily he didn't see that or I would have been for it!

Limit applies to a transit basically between No 1 and No 2 to both shores.

[Fizzwizz]

Originally Posted by ShinyShoe

I guess if they were busy with the salvage operation I'd be stressed at having 8000 litres of diesel that might be leaking and then some ribnobber comes by and might slosh some over the booms.

Limit applies to a transit basically between No 1 and No 2 to both shores.

My wake barely touched the salvage booms.

Ha, I love the phrase Ribnobber. Christ I hope my wife doesn't hear that one I'll never hear the end of it!

I was definitely past the line between 1 and 2 so maybe I was OK. Bloody hard work this going fast malarky. I never had these concerns when sailing. With speed comes much responsibility!

[Nos4r2]

You shouldn't have been making a wake at all. That's what gets the WAFIs riled and on the blower to the harbour master.

[Pikey Dave]

Originally Posted by Nos4r2

You shouldn't have been making a wake at all. That's what gets the WAFIs riled and on the blower to the harbour master.

If I'm moving, I'm making a wake. At displacement speeds it's worse than on the plane. This is the problem on the Thames with the 12kn limit, at 10-12kn my wake is about as bad as it gets, let met go another 3-5kn faster (through water) to 15-18kn to get on the plane & my wake virtually disappears.

[HughN]

Unless they had a radar gun, etc., how could they determine what your speed was to an accuracy that justified stopping you?

(Everybody needs a plug-in box connected to the GPS that gives alerts for speed / locations!)

[Fizzwizz]

Originally Posted by HughN

Unless they had a radar gun, etc., how could they determine what your speed was to an accuracy that justified stopping you?

(Everybody needs a plug-in box connected to the GPS that gives alerts for speed / locations!)

I was told they take photos of your wake and issue fines based on that. I'm wearing a balaclava next time.

[biffer]

What a load of bollox, they can't tell the speed by the wake, mine creates more wake the slower I get, short of nearly stop, I'd like to see them get that to court

[nik]

Its 6 Knots and no wake.
Some of these gin palaces can create significant wake at 5 knots or less.

[Hightower]

So when the water current reaches 6knots which it can do down the Madina and your punching tide your supposed to go no where are you?

[Huib1965]

Get a "speed in knots" on your Android or Apple Smart phone.... Its free and accurate