Reply
 
Thread Tools Search this Thread
 
Old 23 July 2011, 16:45   #1
RIBnet supporter
 
Country: UK - England
Town: South Coast
Length: 7m +
Join Date: Apr 2008
Posts: 1,445
Towing - stupid question

Whilst refuelling today, we came across a family on a 6m Zodiac that had broken down. They needed to get back to the slipway at Swanage for their car and trailer. They offered an acceptable fee and we agreed to tow them round.

We put the family aboard the Parker, with the owner/skipper on the Zodiac and made up a bridle for the tow. In the harbour we had to stick to the 10kts limit and to be honest, it was hard to tell we were towing another RIB at all. Once clear of the speed limit, I pushed on to 14kts, the Parker still not planning and the Zodiac nice and stable in our wake (but did look like it was planning).

So whilst we didn't, it would have been so easy to have raised the speed a little more and had both boats planning at about 16-18kts. The sea state was smooth/slight. Has anybody towed at planning speeds, is it sensible/safe??

I dont expect to do this again, but it just set the mind off wondering about the subject. We had a huge surplus of power and the other boat looked very stable.

Steve
__________________
250kts is offline   Reply With Quote
Old 23 July 2011, 16:57   #2
Member
 
Country: UK - England
Town: Enfield/Switzerland
Boat name: Zonneschijn II/Vixen
Make: Shakespeare/Avon
Length: 7m +
Engine: Evin' 175 DI /Yam 90
MMSI: 235055605
Join Date: May 2006
Posts: 1,418
Steve,

Ask Trevor g for his BIBOA tow experiences, he's witnessed scorpions towing other boats at about 25 knots; I would have thought puts a lot of strain on the tow line and fittings, but maybe better on plane than at displacement; I also worry about snatching at speed in slightly rougher copnditions, but would also be interested in others opinions

All I really know is my fuel consumption goes through roof towing at dispacement speeds, how did you find that?

Neil
__________________

__________________
Neil Harvey is offline   Reply With Quote
Old 23 July 2011, 17:15   #3
Member
 
Crusher's Avatar
 
Country: UK - England
Town: Southampton
Boat name: Bubbas Bouy
Length: 7m +
Engine: Mercruiser
Join Date: Mar 2011
Posts: 626
RIBase
Hi,
I have towed a 7.8 Rib, with a 7.8 Rib, Both at planning speeds (18-20knts), both rock steady. Boat being towed with engine tilted right up (I have heard others try and keep them down a little to keep everyhing straight, but this just seems dopey amounts of drag to me)
Was absolutely no issue, and towed for about 5 or so miles.

I now wait for all the comments telling me how stupid this was......
__________________
Crusher is offline   Reply With Quote
Old 23 July 2011, 17:58   #4
RIBnet admin team
 
willk's Avatar
 
Country: Ireland
Make: Redbay Boats
Length: 9m +
Engine: 370hp
Join Date: Feb 2008
Posts: 12,924
RIBase
The secret is a VERY long tow rope and balls of steel...

Linky

I've been towed (onboard a 6.5m RIB) at over 25kts - it's OK, you need to have your comms worked out though
__________________
willk is offline   Reply With Quote
Old 23 July 2011, 18:27   #5
Member
 
Anchorhandler's Avatar
 
Country: France
Town: Huisnes sur Mer
Boat name: Raufoss
Make: Avon
Length: 4m +
Engine: Mercury 50
Join Date: Sep 2010
Posts: 789
Quote:
I now wait for all the comments telling me how stupid this was.....
No not stupid....its all about risk assesment...i wouldnt recomend towing another vessel at those speeds in somewhere busy like the solent as waves and wash from passing commercial traffic will put a much increased strain on the bow eye of the vessel being towed. (especially if it snatches) If the towing vessel should need to make an emergency maneuver to avoid something then again, problems could arise for the vessel behind. As Willk says, a long tow rope is the key...especially the faster you go as the catenary (the fact that the tow rope will sag in the middle) of the tow rope will act as a shock absorber taking out a great deal of the shock loading. The rope will actually stretch also giving a slight spring effect which also helps.
In my line of work we tow much larger objects (oil rigs etc..) but the basic principles remain the same There are times when some of our vessels have stretched the tow out to 1200-1300 meters depending on the weather conditions and the object being towed.

A rib towing something relatively heavy will handle differently also (especially turning) so i suppose some care should be taken when first setting out.

AS for leaving the outboatd in the down position....well i dont think i would as the thrust on the propellor will be reversed ie; instead of the prop pushing against the leg it will be pulled away from it causing a reversal of thrust on the bearings inside. It would be a bit like running astern for extended periods of time at 25kts...not really what the outboard was designed for.

Simon
__________________
C'est pas l'homme qui prend la mer, c'est la mer qui prend l'homme....
Anchorhandler is offline   Reply With Quote
Old 24 July 2011, 12:20   #6
Member
 
Country: UK - England
Town: Southampton
Make: Ballistic
Length: 7m +
Engine: Yam 225
Join Date: Jun 2010
Posts: 977
I've towed a 6.5+ dive rib with divers on board at planing speeds from a 5.5 Humber across from West angle to Dale (Milford haven Mouth) after they flattened their batteries leaving all the gear on for a whole day.

Long slow acceleration , long tow line, was no problem.

I carry Jump leads now, much easier.
__________________
Starovich is offline   Reply With Quote
Old 25 July 2011, 06:41   #7
Member
 
longjohn's Avatar
 
Country: UK - England
Town: Bournemouth
Boat name: Seadrive
Make: Capelli Tempest 470
Length: 4m +
Engine: Suzuki DF70
MMSI: 235079113
Join Date: Jul 2008
Posts: 540
Quote:
Originally Posted by 250kts View Post
Whilst refuelling today, we came across a family on a 6m Zodiac that had broken down. They needed to get back to the slipway at Swanage for their car and trailer. They offered an acceptable fee and we agreed to tow them round.

We put the family aboard the Parker, with the owner/skipper on the Zodiac and made up a bridle for the tow. In the harbour we had to stick to the 10kts limit and to be honest, it was hard to tell we were towing another RIB at all. Once clear of the speed limit, I pushed on to 14kts, the Parker still not planning and the Zodiac nice and stable in our wake (but did look like it was planning).

So whilst we didn't, it would have been so easy to have raised the speed a little more and had both boats planning at about 16-18kts. The sea state was smooth/slight. Has anybody towed at planning speeds, is it sensible/safe??

I dont expect to do this again, but it just set the mind off wondering about the subject. We had a huge surplus of power and the other boat looked very stable.

Steve
Hi Steve
I saw you towing on the way out of Poole past the training bank - I turned round to get a better look. Was impressed - the Zody certainly looked like it was planning as did the Parker really.
Cool
John
__________________
longjohn is offline   Reply With Quote
Old 25 July 2011, 08:31   #8
RIBnet supporter
 
Country: UK - England
Town: South Coast
Length: 7m +
Join Date: Apr 2008
Posts: 1,445
Thanks for the comments and link.

As it was not another boat we owned or even a friends boat, I exercised caution and got the job done without incident.

The advice given is helpful and if such an unfortunate incident occurs in the future, would do the same, but if its Pete's or David's boat, might be tempted to push on ....
__________________
250kts is offline   Reply With Quote
Old 25 July 2011, 14:49   #9
Member
 
Country: UK - England
Town: Dorset & Hants
Boat name: Streaker/Orange
Make: Avon/Ribcraft
Length: 4m +
Engine: 50Yam/25 Mariner
Join Date: Apr 2007
Posts: 5,551
Quote:
Originally Posted by 250kts View Post
Thanks for the comments and link.

As it was not another boat we owned or even a friends boat, I exercised caution and got the job done without incident.

The advice given is helpful and if such an unfortunate incident occurs in the future, would do the same, but if its Pete's or David's boat, might be tempted to push on ....

Best not mention David & towing.....more than enough of that I feel...
__________________

__________________
PeterM 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





Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -5. The time now is 21:39.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.