Rib stability & capsize

matiboy · 03 April 2003, 21:51

Other than from sheer overdoing it ( I have heard of two people recently been seperated from their boats ) anyone know of any cases of ribs being capsized in reasonable conditions ?

Crossed the Solent two weeks ago blowing only an easterly 3/4 wind against tide in a 36 ' yaght and beam on we were being really thrown around - waves wouldnt have appealed to me being in a 5 metre rib at all- they looked horrible, short , steep & beginning to break.

Funny enough I didnt see any ribs out to see how they handled it.

Maybe I underestimate their capability ? Particularly when I read manufacturers websites which state that a 5.5 metre plus rib can handle most seas !

Seems to me that yes the boats might be able to handle it, but all the occupants would probably have been bounced out of the boat.

I also read with interest the Sib expedition being planned & the possibilty of crossing notorious waters, this I would think is even harder for the occupants as sitting on the side of tubes must be very precarious in the slightest of seas ?

thewavehumper · 03 April 2003, 22:04

I guess if the ribs didn't capsize then there wouldn't be a need for Self righting equipment and you do see alot of it on military and rescue spec RIBs which have to go out in all weathers.

It is my understanding that a Camel trophy RIB was rolled near a reef by a large beam on wave at quite slow speed

Jelly · 04 April 2003, 08:22

It is possible to flip a rib, I know of two instances, one foolhardiness - driving rib at a large breaking wave stright on and getting pitch poled.
The other was when an instructor teaching a coming along side manover with a larger hard boat missed the fact that the student once gaining 'lock-on' had applied full throttle. Thus when a personel transfer was underway and the transferee jumped onto the sponson this broke the 'lock-on' and the rib powered under and flipped. No one was hurt and I was told by one of the people involved that there is an air pocket because thats were he was when she flipped.
Jelly

Keith Hart · 04 April 2003, 13:01

Quote:

I also read with interest the Sib expedition being planned & the possibilty of crossing notorious waters, this I would think is even harder for the occupants as sitting on the side of tubes must be very precarious in the slightest of seas ?

Yes, but what the heck, it's fun!

Actually I always hang on with a rope tied to the front of the boat.

Keith Hart

matiboy · 04 April 2003, 15:26

Quote:

Originally posted by Keith Hart

Actually I always hang on with a rope tied to the front of the boat.

Keith Hart

Hows that gonna keep you in the boat !

Keith as you have had a few years experience now in your sib what sort of conditions do you go out in ?, I have never seen any Sibs out in the Solent ever when its choppy, but I gather they are quite capable and very stable cos the bottoms really can stick to the water.

You must get bounced around like a cork though ?

Phill · 04 April 2003, 21:35

Have used a Zodiac 12 footer and an Avon 18 footer regularly, 12 months of the year, timed sampling. (Timed by the date, not the weather). Zodiac, single 30, 3 cylinder, two stroke, Yamaha - tiller steered. Avon, twin inflatable keels, twin outboard, same yams, tiller steered, remote throttle and gears. No real problems - read the water, sit on the tubes in a "floppy" manner.

Nick · 04 April 2003, 21:59

For an interesting account of flipping a rib look at Hot ribs.com and go to article 14 in the features section entitled "over and out"

Mike Garside · 05 April 2003, 07:36

Quote:

Originally posted by matiboy
....I have never seen any Sibs out in the Solent ever when its choppy, but I gather they are quite capable and very stable cos the bottoms really can stick to the water.

Hmmm...not in my experience Matiboy. I was very successfully flipped in my SIB.

I was sitting on the starboard sponson to avoid the spray from a bit of a blow coming beam-on from the port side when the breeze got under the boat and unceremoniously dumped me in the briney.

Stick they don't.

If alone, always sit on the windward side of a SIB!

crazyhorse · 05 April 2003, 08:36

A sib/rib boat can be flipped by the force of any breaking wave that is higher than the size of its beam.

Phill That Zodiac configuration is used extensively for inshore rescues in NZ and Aus off the beach in quite big rollers.

There is a Rope attached to the bow ,where the third crew member hangs on,close up front to keep the nose down,whilst going through {Head On] the white water off the beach.

I would actualy say the best place to sit IMHO in a swell in a sib is all crew inboard on the centrline.Stay as low down as poss. For Head on stuff ,Man up front low down.

Jonny Fuller · 05 April 2003, 08:44

Quote:

Originally posted by Mike Garside

Hmmm...not in my experience Matiboy. I was very successfully flipped in my SIB.

I was sitting on the starboard sponson to avoid the spray from a bit of a blow coming beam-on from the port side when the breeze got under the boat and unceremoniously dumped me in the briney.

Stick they don't.

If alone, always sit on the windward side of a SIB!

I geuss this is the trade off! CH talks about the extra stability you get with the displacement of the tubes, with very little extra weight, after all, the PVC/Hypalon can't weigh much.

but that weightless extra area must be like a huge sail on a lightweight sib once the old wind gets under it!

crazyhorse · 05 April 2003, 08:51

Evening all

Keith Hart · 05 April 2003, 15:31

Okay then, before anyone else says it (Bill) my SIB carries quite a bit of weight when I'm onboard!

Yes, I go out when it's quite choppy. I hang on to the rope attached to the front and have a crew member sat in the nose. This helps to keep the boat stable and as a welcome by product deflects a lot of the spray off me

(see article in RI). Now I am not as cruel as it may seem (oh yes?) as I have now brought my crew drysuits (thanks to the chaps who sold them to me - Noel is now known a Bananaman JK).

I am hanging onto the engine with one hand and the rope attached to the front with the other. In fact I saw the Australian lifeguards doing this in their SIBs, which are only about as big as mine. I sit on the right (sorry Starboard) tube. If it gets really jumpy I kneel inside. Quite comfortable with an 'airdeck'.

I look upon sibbing as a 'watersport', like waterskiing, ie. getting wet (on the outside) is a part of the fun. Quicksilver is a wet boat.

I pay attention to the wind and tide and plan my trips to start off against the wind (the more diffiult to make headway) and come back with the wind. This way I always know that if it took me a hour to get 'out' I will most likely be quicker getting back. I also keep myself aware of any intermediate possible landfalls.

I always try to keep the waves head on as it can be a tad 'hairy' with them on the beam.

In a choppy sea I do not try to make quick progress. I go for steady and careful progress as I know that my little SIB can not 'fly' over the larger waves.

The boat is VERY buoyant (!) and even when there is loads of H2O sloshing about it does not seem to make much difference. Until you come to lift it out of the water that is!

A couple of times I thought that I had mysteriously lost all my strength and was hardly able to lift the boat out, only to find that there was about 20 gallons of water in the bottom. There is a one way drain hole but is is very small and it takes quite a while to drain the water out.

I suppose you could flip any boat given the right (wrong) circumstances. Certainly the c of g of Quicksilver is very low.

Keith (Pentland Firth here we come) Hart