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14 May 2013, 16:12
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#1
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Member
Country: UK - England
Length: 5m +
Join Date: May 2012
Posts: 59
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Towing behind a RIB
I'm doing a sailing event in the summer and we're planning to tow the boat from Hamble to Cowes behind our 5.2m Valiant rib, provided it's not too rough.
The rib has a 75hp 2 stroke Mariner engine on the back, and it usually drinks about 12 litres of fuel getting across the Solent to the IOW.
The boat we're going to be towing is about 8 metres long and weighs about 1500kg. It will start planing if we tow it at 10 knots or faster.
So my question is, how much fuel should we expect to use and would do you reckon the most fuel efficient speed to tow the boat at is? We've got a 25 litre tank but we don't really want to get halfway across the Solent and run out of juice. Thanks guys.
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14 May 2013, 16:21
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#2
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Member
Country: UK - England
Town: LONDON
Make: SR4/ZODIAC/3D
Length: 4m +
Engine: 30T/40T
Join Date: Oct 2011
Posts: 1,433
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You need at least 50 litres.
You'll need to lash up alongside and to the stern rather than tow.
And don't plane.
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14 May 2013, 16:24
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#3
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Member
Country: UK - England
Town: N. Devon
Boat name: (Not Another) Nutkin
Make: Highfield
Length: 6m +
Engine: Outboard, Honda 135
MMSI: 232036183
Join Date: Dec 2008
Posts: 2,037
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Quote:
Originally Posted by mister p
You'll need to lash up alongside and to the stern rather than tow.
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You do when taking out to sea and when moving around at berth but I'd be happy on a tow astern when crossing the open water.
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14 May 2013, 16:30
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#4
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Member
Country: UK - England
Town: LONDON
Make: SR4/ZODIAC/3D
Length: 4m +
Engine: 30T/40T
Join Date: Oct 2011
Posts: 1,433
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Just thinking about controlling a stop or turn on a busy waterway and then the control in Cowes. No mention of whether the sailer has an engine.
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14 May 2013, 16:37
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#5
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Member
Country: UK - England
Length: 5m +
Join Date: May 2012
Posts: 59
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Quote:
Originally Posted by mister p
Just thinking about controlling a stop or turn on a busy waterway and then the control in Cowes. No mention of whether the sailer has an engine.
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The boat will come out of the marina and out of Hamble under it's own steam, and it will motor into the marina in Cowes itself too. I'd imagine we'll be fine once in open water, we've got people with us who know the Solent extremely well and have a lot of experience so we should be okay in that respect. It's a very light boat for it's size so as soon as you take the power off the RIB the boat will slow right down pretty quickly.
We just don't really fancy motoring all the way to Cowes with a piddly little 2hp engine. Even if the water is perfectly flat it will take literally hours. We've done it before and it was an absolute nightmare, we simply haven't got the time this time round.
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14 May 2013, 16:44
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#6
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Member
Country: UK - England
Town: N. Devon
Boat name: (Not Another) Nutkin
Make: Highfield
Length: 6m +
Engine: Outboard, Honda 135
MMSI: 232036183
Join Date: Dec 2008
Posts: 2,037
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Quote:
Originally Posted by bad_moose
The boat will come out of the marina and out of Hamble under it's own steam, and it will motor into the marina in Cowes itself too. .
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Don't blame you 2hp would be nasty. I'd be going for astern tow
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14 May 2013, 16:46
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#7
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Member
Country: UK - England
Town: LONDON
Make: SR4/ZODIAC/3D
Length: 4m +
Engine: 30T/40T
Join Date: Oct 2011
Posts: 1,433
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Should be fine then, keep the weight on the sail boat well back.
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14 May 2013, 16:56
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#8
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RIBnet admin team
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: 13,067
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I know it's a bit obvious, but....sail the yacht?
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14 May 2013, 16:58
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#9
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Member
Country: UK - England
Town: Surrey
Boat name: Fugly & Rokraider 1
Make: Pac 22 & Porter 6.5
Length: 6m +
Engine: Ford 250 & jet,DT140
Join Date: Jun 2008
Posts: 681
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I wouldn't think you will get a 1500 KG sailer planing behind the RIB. Personally I would tow it astern and vary your line length to try and match wave sets. I find when towing dinghies in that it devours fuel big time, especially if I am trying to coax 6 or 8 lasers to get up to 8-10 knots with my 140 Suzuki 2 stroke. I find there is a hump which is difficult to get over when towing. The RIB doesn't really start planing until 14 knots. Towing up to 6 or so isn't too bad. Trying to get up to 14 requires a lot of power to achieve very little and I can see the fuel gauge moving. I don't bother going for the faster speeds now, it is better to travel at what is comfortable and save the fuel. Is it a keel boat? Will you have someone steering it?
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14 May 2013, 17:22
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#10
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Member
Country: UK - England
Length: 5m +
Join Date: May 2012
Posts: 59
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Quote:
Originally Posted by treerat
Don't blame you 2hp would be nasty. I'd be going for astern tow ![smilie](https://www.rib.net/forum/images/smilies/smile.gif)
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Awesome, thanks for the advice.
Quote:
Originally Posted by mister p
Should be fine then, keep the weight on the sail boat well back.
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Will do, thanks very much.
Quote:
Originally Posted by Nos4r2
I know it's a bit obvious, but....sail the yacht?
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We could do but there's only a very small wind range where that's really feasible. It's quite a sporty boat, if there's any real wind you need the weight of a full crew or it's very wet and slow. Plus we're going to have brand new sails for the event and we don't want to waste them on a delivery trip because they really don't last very long.
Quote:
Originally Posted by Rokraider
I wouldn't think you will get a 1500 KG sailer planing behind the RIB. Personally I would tow it astern and vary your line length to try and match wave sets. I find when towing dinghies in that it devours fuel big time, especially if I am trying to coax 6 or 8 lasers to get up to 8-10 knots with my 140 Suzuki 2 stroke. I find there is a hump which is difficult to get over when towing. The RIB doesn't really start planing until 14 knots. Towing up to 6 or so isn't too bad. Trying to get up to 14 requires a lot of power to achieve very little and I can see the fuel gauge moving. I don't bother going for the faster speeds now, it is better to travel at what is comfortable and save the fuel. Is it a keel boat? Will you have someone steering it?
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Yeah I can imagine it's quite hard work for the RIB. Maybe we won't be going for planing speeds then. ![lol](https://www.rib.net/forum/images/smilies/lol.gif) We definitely want to go for fuel efficiency rather than speed, as long as it gets the boat there faster than the 2hp we'll be happy. Yeah, it's a small keelboat. I think someone will need to steer it yeah, otherwise the rudder will be flapping about all over the place.
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14 May 2013, 18:49
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#11
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Member
Country: UK - England
Boat name: llyn raider
Make: xs
Length: 7m +
Engine: 1 200hp merc
Join Date: Nov 2006
Posts: 211
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I was in a rib when we towed a 1720 across from pwllheli to abersoch behind a 5mt humber with a 60hp, that got on the plane and was fine, but then it was suited for it! Just get a long stretchy rope and plan for the weather.
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14 May 2013, 19:25
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#12
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Member
Country: USA
Town: Seattle
Boat name: Water Dog
Make: Polaris
Length: 4m +
Engine: Yamaha 60hp
Join Date: Apr 2007
Posts: 1,152
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Lash the helm on the sailboat. Have an adjustable to tow line so you can try to match the wave sets; I wouldn't plan on planing anything.
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14 May 2013, 21:42
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#13
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Member
Country: UK - N Ireland
Town: Bangor
Boat name: Mitigator
Make: XS
Length: 7m +
Engine: Mercury Verado 250
Join Date: Jun 2008
Posts: 72
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And don't tow alongside!! You will be slower, wetter, use more fuel and add to wear and tear on both boats....
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15 May 2013, 07:27
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#14
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Member
Country: UK - England
Town: yorkshire
Boat name: little vicky
Make: avon ex RNLI
Length: 3m +
Engine: tohatsu
Join Date: Mar 2008
Posts: 2,310
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When you start to get into to the confines of a harbour or it starts to get busy with other boats & you don't want to lash alongside
towing a drouge or an old car tyre on a short line behind the sailing boat helps stop the it from overtaking you or crashing into the back of your own boat if you have to stop or slow down quick
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15 May 2013, 08:14
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#15
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Member
Country: UK - England
Town: Cambs
Make: Scorpion
Length: 8m +
Engine: 225 Opti
Join Date: Sep 2010
Posts: 356
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Definitely tow! Motored an SB3 from hamble to Cowes for the RTI race. It took an incredibly longtime!
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15 May 2013, 08:39
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#16
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Member
Country: UK - Scotland
Boat name: Wildheart
Make: Humber/Delta Seasafe
Length: 5m +
Engine: Merc 60 Clamshell
MMSI: 235068449
Join Date: Apr 2007
Posts: 4,671
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Silly Q - what speed does the yacht start to plane at? I've towed 420s on the plane with the SR4 still digging holes in the water....
Personally I'd rather have someone aboard the yacht on the helm - that way if it does overtake you can guarantee it will miss you!
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15 May 2013, 09:01
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#17
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Member
Country: UK - England
Boat name: llyn raider
Make: xs
Length: 7m +
Engine: 1 200hp merc
Join Date: Nov 2006
Posts: 211
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the one thing to watch out for is the plugs oiling up, not sure how suceptable the mariners are to that but lots of medium/low revs running might clog them up a bit.
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15 May 2013, 09:59
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#18
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Member
Country: UK - England
Length: 5m +
Join Date: May 2012
Posts: 59
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Quote:
Originally Posted by captnjack
Lash the helm on the sailboat. Have an adjustable to tow line so you can try to match the wave sets; I wouldn't plan on planing anything.
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I'd much rather have someone steering the yacht, I think it'll be much safer that way if something goes wrong. I'm planning to take the line through a cleat and onto a winch onboard the yacht so we can adjust the length of the tow.
Quote:
Originally Posted by mike-m
And don't tow alongside!! You will be slower, wetter, use more fuel and add to wear and tear on both boats....
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That's what I thought would happen, I can just imagine big jets of water shooting up between the two boats. :S It'll only come alongside when we're switching people between the boats and getting the boat through tricky spaces etc.
Quote:
Originally Posted by m chappelow
When you start to get into to the confines of a harbour or it starts to get busy with other boats & you don't want to lash alongside
towing a drouge or an old car tyre on a short line behind the sailing boat helps stop the it from overtaking you or crashing into the back of your own boat if you have to stop or slow down quick
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Ah thank you for the tip. I'll try and get hold of something like that, although I imagine we'll have to take the boat alongside so we can get someone onboard to get docklines out etc.
Quote:
Originally Posted by Portholme
Definitely tow! Motored an SB3 from hamble to Cowes for the RTI race. It took an incredibly longtime!
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On an SB3 that must have been horrendous! Our boat is bigger and a bit more enclosed than an SB and it's still not fun.
Quote:
Originally Posted by 9D280
Silly Q - what speed does the yacht start to plane at? I've towed 420s on the plane with the SR4 still digging holes in the water....
Personally I'd rather have someone aboard the yacht on the helm - that way if it does overtake you can guarantee it will miss you! ![wink](https://www.rib.net/forum/images/smilies/wink.gif)
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It will get up on the plane at around 10 knots of boatspeed, it'll happily surf down any waves there are too. We don't have to tow it that fast but I just thought that getting the boat on the plane would reduce the loads in everything etc. I think having someone steering is the best way to do it, really don't fancy running it up the RIB's backside!
Quote:
Originally Posted by andyxs
the one thing to watch out for is the plugs oiling up, not sure how suceptable the mariners are to that but lots of medium/low revs running might clog them up a bit.
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Oh I hadn't thought of that. Thanks for the warning! I'll talk to the guy who looks after the engine for us and see if he thinks it'll be a problem.
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15 May 2013, 10:07
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#19
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Member
Country: UK - Scotland
Town: Glasgow
Boat name: Thunder
Make: Halmatic Arctic 22
Length: 6m +
Engine: 2 x 150 Etec
Join Date: Oct 2008
Posts: 523
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Towed a 1720 from Kip to Tarbert a few years ago, we averaged around 12 knots with the 1720 being towed astern, it was no bother at all. Cant remember exactly how much fuewas used, I do remember being surprised that I hadn't used more.
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15 May 2013, 13:34
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#20
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Member
Country: UK - Scotland
Boat name: Wildheart
Make: Humber/Delta Seasafe
Length: 5m +
Engine: Merc 60 Clamshell
MMSI: 235068449
Join Date: Apr 2007
Posts: 4,671
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Thing with yachts is they are designed to either slip through the water with minimal resistance or skite across the top.....
Yonks ago I once towed some ridiculous tonnage of classic 8m into Rhu from the patch with a 25 on an SR4. Took lots of throttle and f-o-r-e-v-e-r to get moving, but once on the go I throttled back & let momentum do it's thing.
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