towing a rib safely - Page 2

Searider · 22 February 2007, 16:24

Have towed a 7.3m Gemini with a 46' Sealine within the Solent for short periods.

Single line from one cleat on the Sealine to the bow eye on the Gemini. Outboards trimmed right up. Seemed mostly OK and we towed up to about 20 knots - the Gemini was stern heavy with two 200 optis on the back!

However, the tow rope did break when going ove the red jet wake and we did have one moment when the rib surfed outside the tow boats wake and nearly overtook us!

Would probably have been better with a bridle on the tow boat and someone in the rib to steer. We were only towing to give the RIB coxn a warm up and a cup of tea!

Poly · 22 February 2007, 16:59

IBWET - New climbing rope does have stretch/elasticity in it to reduce the load on the climber and the hardware during a fall. It does go stiff and horrible though with prologned exposure to salt water and UV. It may be that the poster who said it has "no give" was referring to old out of condition rope.

However, I don't think you will find 16mm climbing rope - 8-11mm is standard.

IBWET · 22 February 2007, 17:13

Quote:

Originally Posted by Polwart

IBWET - New climbing rope does have stretch/elasticity in it to reduce the load on the climber and the hardware during a fall. It does go stiff and horrible though with prologned exposure to salt water and UV. It may be that the poster who said it has "no give" was referring to old out of condition rope.

However, I don't think you will find 16mm climbing rope - 8-11mm is standard.

My original plan was for the tow rope to be climbing rope, with the two bridles be 16 mm (mainly because I've got lots of it lying around) the age changing implication is now making me think more along the lines of normal rope as the tow, I can splice a large S/S hard eye into both ends with one or two mooring rubber/shock absorbers along it's length, also one two other idea's already posted.

Nick Hearne · 22 February 2007, 17:14

I have been using old climbing rope for many years & yes it dose go hard over time, but then it was free!

alystra · 22 February 2007, 18:12

If you go for 'ordinary' rope, make sure it's nylon, which is often used for anchor line I think, and mooring lines. Nylon line stretches - up to 20 per cent I think, Try to avoid polyester, it has little stretch. I wouldn't even think about polypropylene etc.

IBWET · 22 February 2007, 19:40

Quote:

Originally Posted by alystra

If you go for 'ordinary' rope, make sure it's nylon, which is often used for anchor line I think, and mooring lines. Nylon line stretches - up to 20 per cent I think, Try to avoid polyester, it has little stretch. I wouldn't even think about polypropylene etc.

Thanks,

Very usefull

Iain.

Incidentally, are you going on the Coryveken trip?

alystra · 22 February 2007, 23:25

Quote:

Originally Posted by IBWET

Thanks,

Very usefull

Iain.

Incidentally, are you going on the Coryveken trip?

My pleasure, thanks.

Re. the Corry. I'm hoping to go but much depends on the weather. I've spent too long floating around this part of the sea in cold, wet and gales to do it for fun these days. If it's half decent and not too windy I'm hoping to be there. Made it the deadline for getting the boat back in the water anyway. (usually kept afloat on a relatively exposed mooring. Slip at Ardfern Yacht Centre is excellent, but getting the boat back into the drive it's kept in is a major undertaking for lots of reasons, so I try not to do it too often) I'm just about to order the wherewithall to make a tent for the rib so I can sleep aboard in Argyll weather. Probably won't get that finished in time though. If it's too wild and woolly I'll drive over to Craobh and perhaps meet up in the evening.

Tony

Jelly · 23 February 2007, 09:14

Talking of climbing rope watch out for black or occasionally white rope about 16mm, there is a type of climbing rope called "static" and its exactly that, it has no give in it.
Its designed for abseiling or SRT (single rope technique) - ascending as well as descending). Basically jobs where you don't want bounce!
Also climbing rope is designed to take one major fall normally, just something to bare in mind.
hope it helps
James

Mark Halliday · 23 February 2007, 14:20

Quote:

Originally Posted by IBWET

the lewmar snatch block I did find for 16mm, was £300!.

That just goes to show the people I used to race with had more money than sense. Sorry for the bum steer.

On the rope front. 8 or multiplat is pretty damn stretchy. Its used for Kinetic recovery rope by off roaders. A scary recovery method involving a slack rope and as much speed as you can get before the rope goes tight. This usually happens when you get 1/4 to 1/3 further apart than the length of the rope.

whiteminiman · 23 February 2007, 16:41

Quote:

Originally Posted by IBWET

Well that surprises me,the whole reason I was going down the climbing rope route was because the rope had give in it (so a falling climber dosen't get a broken back..) however it was an assumption I made.

Falling climbers aim to minimise the distance they can fall at anyone time to avoid breaking themselves, rather than relying on the stretchiness in the rope!

The thing is with "climbing rope" there are various different sorts for various different tasks. Principally, you can break them into two main types... static rope, and dynamic rope. Basically, one stretches A BIT (dynamic), and one doesn't (static). Personally, I can't see that either of them would be useful for towing boats.

Dynamic rope... which I'm assuming is what you've got is designed to be shock loaded once... and then binned. Although, admittedly that is where a second fall on the same rope would have potentially fatal consequences. Perhaps you feel that's an acceptable risk when towing on water?

Although I must say (as someone else has) I've never seen 16mm "climbing rope".

Cheers, WMM

IBWET · 20 April 2007, 23:37

to update this;

The rib needed to be towed before I got my act together,so three bits of 16mm mooring line 6 bowlines about 20m between the boats and it worked a treat. The only problem with this set up was the rib's center bowline working it's way over to the left,this made the rib tow to one side but still not a problem.

As usual after the plonk chat etc I forgot it was there,decided to press on turned round and there it was, up on the plane at 25knts....

I eased of the power and it took at bit of a fit as it climbed over the wake coming back into line.

this was a calm day, things I've no doubt will be different in the rough stuff .

codprawn · 21 April 2007, 01:40

One pretty obvious question - if you use rope that sinks and use a bridal arrangement if it goes slack wont it foul your prop?

IBWET · 21 April 2007, 13:24

Good point, It would, when I get round to making the correct set up I will use nylon rope, several floats and splicing.

As mentioned got caught short (good weather etc) ,so on this ocasion it was a wife standing on the swim platform at the back of the tow boat, pulling the rope in as it slowed and came to a stop, works also as your powering up.

As a precaution I had my diving kit on board just in case I did make an arse of it.

Quote:

Originally Posted by codprawn

One pretty obvious question - if you use rope that sinks and use a bridal arrangement if it goes slack wont it foul your prop?

wavecrosschris · 21 April 2007, 20:32

This might not be effective, but if using a bridle, I wonder if installing one of these each side would take the danger out of any snatching? - adding some stretch to the line - probably means the line wouldn't break... or maybe just one on the center rope??

The rope wraps through and around the rubber several times, so if the rubber does break the line is still attached...

http://www.marine-super-store.com/po...edpartno=COMPE