Reply
 
Thread Tools Search this Thread
 
Old 12 November 2013, 17:35   #1
Member
 
Country: UK - England
Make: Gemini Waverider 600
Length: 6m +
Engine: 2 x Yamaha 90 2S
Join Date: Nov 2013
Posts: 30
Perhaps I need a speed log!?

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!?"
__________________

__________________
Fizzwizz is offline   Reply With Quote
Old 12 November 2013, 17:56   #2
Member
 
Country: UK - England
Length: 3m +
Join Date: Sep 2008
Posts: 2,583
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 ;-)
__________________

__________________
ShinyShoe is offline   Reply With Quote
Old 12 November 2013, 17:59   #3
Member
 
Burtox's Avatar
 
Country: UK - England
Town: Christchurch
Boat name: Sweet Chilli
Make: Ribcraft 585/Wetline
Length: 6m +
Engine: Honda 90HP Yam 4HP
MMSI: 235084532
Join Date: Jan 2011
Posts: 161
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.
__________________
Is it Friday yet????
Burtox is offline   Reply With Quote
Old 12 November 2013, 18:00   #4
RIBnet admin team
 
Poly's Avatar
 
Country: UK - Scotland
Boat name: imposter
Make: FunYak
Length: 3m +
Engine: Tohatsu 30HP
MMSI: 235089819
Join Date: Sep 2005
Posts: 11,121
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.
__________________
Poly is offline   Reply With Quote
Old 12 November 2013, 18:01   #5
Member
 
Country: UK - England
Make: Gemini Waverider 600
Length: 6m +
Engine: 2 x Yamaha 90 2S
Join Date: Nov 2013
Posts: 30
Quote:
Originally Posted by ShinyShoe View Post
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 is offline   Reply With Quote
Old 12 November 2013, 18:04   #6
Member
 
Country: UK - England
Make: Gemini Waverider 600
Length: 6m +
Engine: 2 x Yamaha 90 2S
Join Date: Nov 2013
Posts: 30
Quote:
Originally Posted by Poly View Post
Speed limit is 'over ground'
Better not go out during Springs then else I might have to put it in reverse!
__________________
Fizzwizz is offline   Reply With Quote
Old 12 November 2013, 18:08   #7
Dhf
Member
 
Dhf's Avatar
 
Country: UK - Wales
Length: no boat
Join Date: Jan 2012
Posts: 1,012
Quote:
Originally Posted by Fizzwizz View Post
"Perhaps I need a speed log!?"
No! You need a bigger engine, he won't catch you then
__________________
Dhf is offline   Reply With Quote
Old 12 November 2013, 18:09   #8
Member
 
Country: UK - England
Length: 3m +
Join Date: Sep 2008
Posts: 2,583
Quote:
Originally Posted by Burtox View Post
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:

Quote:
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 is offline   Reply With Quote
Old 12 November 2013, 18:12   #9
Member
 
Country: UK - England
Length: 3m +
Join Date: Sep 2008
Posts: 2,583
Quote:
Originally Posted by Fizzwizz View Post
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?
__________________
ShinyShoe is offline   Reply With Quote
Old 12 November 2013, 18:22   #10
Member
 
Country: UK - England
Make: Gemini Waverider 600
Length: 6m +
Engine: 2 x Yamaha 90 2S
Join Date: Nov 2013
Posts: 30
Quote:
Originally Posted by ShinyShoe View Post
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!
__________________
Fizzwizz is offline   Reply With Quote
Old 12 November 2013, 18:40   #11
Member
 
Country: UK - England
Length: 3m +
Join Date: Sep 2008
Posts: 2,583
Quote:
Originally Posted by Fizzwizz View Post
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.

Quote:
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.
__________________
ShinyShoe is offline   Reply With Quote
Old 12 November 2013, 18:54   #12
Member
 
Country: UK - England
Make: Gemini Waverider 600
Length: 6m +
Engine: 2 x Yamaha 90 2S
Join Date: Nov 2013
Posts: 30
Quote:
Originally Posted by ShinyShoe View Post
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!
__________________
Fizzwizz is offline   Reply With Quote
Old 12 November 2013, 21:28   #13
RIBnet admin team
 
Nos4r2's Avatar
 
Country: UK - England
Town: The wilds of Wiltshire
Boat name: Dominator
Make: SR5.4
Length: 7m +
Engine: Yam 85
MMSI: 235055163
Join Date: Jul 2005
Posts: 12,898
RIBase
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.
__________________
Need spares,consoles,consumables,hire,training or even a new boat?

Please click HERE and HERE and support our Trade Members.

Join up as a Trade member or Supporter HERE
Nos4r2 is offline   Reply With Quote
Old 13 November 2013, 01:36   #14
Member
 
Pikey Dave's Avatar
 
Country: UK - England
Town: South Yorks
Boat name: Black Pig
Make: Ribcraft
Length: 5m +
Engine: DF140a
MMSI: 235111389
Join Date: Feb 2008
Posts: 9,771
RIBase
Quote:
Originally Posted by Nos4r2 View Post
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.
__________________
Rule#2: Never argue with an idiot. He'll drag you down to his level & then beat you with experience.
Rule#3: Tha' can't educate pork.
Rule#4:https://www.youtube.com/watch?v=unkIVvjZc9Y
Pikey Dave is offline   Reply With Quote
Old 13 November 2013, 06:22   #15
Member
 
HughN's Avatar
 
Country: UK - England
Town: Littlehampton, W Sx
Length: no boat
MMSI: 235101591
Join Date: Jan 2012
Posts: 732
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!)
__________________
"Can ye model it? For if ye can, ye understand it, and if ye canna, ye dinna!" - Lord kelvin
HughN is offline   Reply With Quote
Old 13 November 2013, 06:34   #16
Member
 
Country: UK - England
Make: Gemini Waverider 600
Length: 6m +
Engine: 2 x Yamaha 90 2S
Join Date: Nov 2013
Posts: 30
Quote:
Originally Posted by HughN View Post
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.
__________________
Fizzwizz is offline   Reply With Quote
Old 13 November 2013, 07:34   #17
Member
 
biffer's Avatar
 
Country: UK - England
Town: swanwick/hamble
Boat name: stormchaser
Make: custom rib
Length: 8m +
Engine: inboard/diesel
Join Date: Aug 2007
Posts: 3,848
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
__________________
biffer is offline   Reply With Quote
Old 13 November 2013, 08:07   #18
nik
Member
 
Country: UK - England
Town: east cowes
Make: academic
Length: no boat
Engine: fresh air
MMSI: N/A
Join Date: Sep 2003
Posts: 543
Its 6 Knots and no wake.
Some of these gin palaces can create significant wake at 5 knots or less.
__________________
nik is offline   Reply With Quote
Old 13 November 2013, 08:14   #19
Member
 
Hightower's Avatar
 
Country: UK - England
Town: Fareham
Length: 6m +
Join Date: Sep 2003
Posts: 7,855
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?
__________________
Andy

Looks Slow but is Fast
Member of the ebay Blue RIB cover club.
Hightower is offline   Reply With Quote
Old 13 November 2013, 09:31   #20
Member
 
Huib1965's Avatar
 
Country: UK - England
Town: Southsea
Boat name: RIB GLADYS
Make: AVON
Length: 4m +
Engine: Mariner 60HP EFI
Join Date: Aug 2013
Posts: 117
RIBase
Get a "speed in knots" on your Android or Apple Smart phone.... Its free and accurate
__________________

__________________
Huib1965 is offline   Reply With Quote
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off




All times are GMT -5. The time now is 23:22.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2020, vBulletin Solutions, Inc.