Grab ropes & introduction

Dan1 · 28 January 2010, 22:50

Hello all. My name is Dan, I'm a newcomer to the forum and RIBs. I got my first RIB, which is also my first boat, 3 weeks ago. I got the boat for the purpose of freedive spearfishing in south Florida. The boat is an 18' Zodiac but I'm not sure what model, it's 16 years old but in great condition. Over the last three weeks I've been working on it, rearranging everything to make maximum use of the small space available. I finally have it ready to go for this weekend although there are many other small details I'd like to work on.

One of these is the grab ropes, at least that's what I think they're called. The boat has them but I don't like the way they lay and want to rerig them. The way they are now the rope is spliced through itself at every D ring which creates a big knot. Since we'll be getting in and out of the water a lot over the sides I think it's better if everything was more streamlined. I was thinking of splicing an eye only at each end and just running it through the rest of the D rings. My question is if there is a disadvantage doing it this way? Is the stress of a pull on the ropes, such as when a person is in the water and hanging on, more evenly distributed when the rope is attached to each ring? Thank in advance.

Pic of the boat.

Poly · 28 January 2010, 23:08

Welcome to the forum.

I would generally call them 'life lines' rather than 'grab ropes' which might help if you are searching.

I'm not sure what you are suggesting - but I think you are proposing having one length of rope which is 'free running' through all the eyes and only fixed at each end. If each loop hangs down say 6" and you have say 4 loops will you not end up with 2' of drop as soon as you put any weight on it which is probably pointless?

Ian M · 28 January 2010, 23:20

Not quite the same configuration, but my Osprey Vipermax (a British designed and built rib) is rigged similarly to what you are proposing. Contrary to what Polwart describes, the lifelines on Ospreys are rigged relatively tight such that there is very little 'sag'. The only difference between Ospreys and what you are suggesting is that the Ossy has webbing loops that the lifelines pass through rather the D rings. Seems to work OK.
Nice boat by the way, and I wish we had your weather over here

Dan1 · 28 January 2010, 23:31

Thanks for the replies guys.

Quote:

Originally Posted by Polwart

I think you are proposing having one length of rope which is 'free running' through all the eyes and only fixed at each end.

Yes, this is what I had in mind.

Wouldn't the sagging problem be fixed by tying the rope with less slack?

My main concern is that since the rope is only attached at the ends, that those D rings will always bear all the weight and will deteriorate fast.

BTW the boat has a flat strap that runs along the top of the tubes through another set of flat "holders". This strap is very tight.

Poly · 28 January 2010, 23:43

Quote:

Originally Posted by Dan1

Thanks for the replies guys.Yes, this is what I had in mind.

Wouldn't the sagging problem be fixed by tying the rope with less slack?

yes you/Ian are probably right (thinking about it mine are like that!). I would suggest if multiple people will be in the water using them at the same time then the current setup would be better.

Quote:

My main concern is that since the rope is only attached at the ends, that those D rings will always bear all the weight and will deteriorate fast.

they won't bear all the weight, some of it will be shared on the others. But I don't think it will be a short term problem anyway. Long term they are relatively easy to replace if required. Realistically with your current setup you will find a preferred spot for boarding and be loading the same points all the time anyway.

Dan1 · 29 January 2010, 03:23

Thanks for the suggestions. I think I will proceed with having the lifeline running free through the eyes. I look forward to rigging it because I only have to splice the rope at the attachment points as opposed to each and every eye.

With regards to a preferred spot for boarding, I think I already found one. Should that area of the tube get some extra protection? Another layer of something?

9D280 · 29 January 2010, 08:57

Hi Dan, and welcome,

Mine is an ex Safety boat form an offashore supply vessel (or so I am told), but the two interesting things are that the outer "grab lines" are incredibly slack at the bow, but get progressivley tighter towards the stern, rigged as yours are now. Best look see how it sits in the water - a tihght grab line is useless if nobody can reach it form the water.

As for protecting the toobs, mine has an extra layer of fabric bonded across the first 2' of the bow & the last 3' form the stern. (The bow one I thinkk probably more for protection against ropes, but I also had 3 lengths of flat rubbing strake bonded over the top - I believe this would have been the "official entry point" for the helmsman before it was winched down.

Other optin - is a boarding ladder that you deploy when at site - someone sells one that is designed to flop over the top of the toobs & has a weight at the bottom to make sure you can get your feet on the bottom step.

Nice boat

jyasaki · 29 January 2010, 16:21

The other factor in the slack equation is how high you want the line relative to the water. Generally, if you're coming up over the tubes, you want them within reach, but high enough so that once you straight-arm yourself up onto the line, you're high enough that you can roll into a sitting position on the tube (or kick a foot over, anyway.) That flopping face-first onto the deck thing doesn't look very coordinated.

jky

Ian M · 29 January 2010, 18:11

1

Stoo · 30 January 2010, 00:51

Dan, welcome to Rib.net.

I have a Zodiac Hurricane with lifelines as yours. I use my boat for diving and so I am in an out all the time as well... Although not as much you "pneumo" types.

I'd suggest you try diving from your boat for a few days before you change anything. I've been diving from inflatables for 35 years, and until I read your post, the "knots" never even occurred to me as being problematic.

Incidentally, that tight nylon strap you refer to serves a structural purpose, so don't be messing with it!

Stoo · 30 January 2010, 00:52

Quote:

Originally Posted by jyasaki

That flopping face-first onto the deck thing doesn't look very coordinated.

I knew I was doing something wrong. I've spent a fortune on masks and dental work over the years...

jyasaki · 01 February 2010, 17:32

A dive buddy of mine was reboarding her boat (fairly rough water, and a hellacious current running), and got most of the way in when the line attaching her boarding ladder parted. She ended up falling into her RIB in full scuba kit, and ended up on her tank, with her legs over the tube. Having just transitioned to a backplate and wing (no quick-release on the harness, as most tech wannabes do), she found herself unable to right herself, unable to get out of the rig, and generally just lay there struggling for about 10 minutes. I finally convinced her husband ( still at the side, looking up at her feet flailing around) to swim over and board my boat, then put another buddy onto hers to help her. Funniest thing I've ever seen...

jky

Dan1 · 28 February 2010, 15:50

I finished rigging the life lines a while back, used the boat for diving, and thought I'd share the results. The biggest challenge after learning how to splice rope was to rig the ropes in such a way that when tension is put on them the D ring points straight down as opposed to being pulled at an awkward angle thus making it more probable that it will eventually tear out. I had to redo the splicing a couple of times to achieve this. I can't say I have a formula to get this right, I just had to go by feel.

You can see in the pic how far down the rope sags when pulled. This had no bearing for my purposes as to get in the boat we'd grab the rope by the thick spliced part near the D ring. The sagging is lessened because the rope doesn't run free through all the D rings, there are two sections per side therefore 4 attachment points per side. You can also see the rope free section which is the boat exit/entry point, visible is the chaffing that occurred when using that entry point sliding over the rope that was there originally.

I'm pleased with the results and would recommend rigging this way for a similar application. Thanks again everyone for your suggestions.