Hard versus Soft Nose!? - Page 2

jwalker · 23 June 2003, 23:36

CH, that's the most rational thing I've ever heard you say!

JW.

Nick · 24 June 2003, 02:31

As Charles has asked, here is my 2p's worth;
For most Ribs a soft nose is better, I agree with Tony Lee Elliot, although I think he goes over the top with the webbing straps (but the big Flatacrafts have a long nose overhanging the hull, which gives a bigger lever to rip the tubes off in the event of a stuff.)
One of the main reasons to put tubes round a boat is to give a softer ride, and if you remove this property around the bow, then if you stuff you lose all the shock absorbing qualities (Instruments popping out of consoles, just think of all the other places in the boat which are suffering similar stresses, including you)
As others have pointed out in this thread, a well fixed soft nose should not come adrift in the normal course of events, In three of the failures I have seen, the tubes have come off because the tubes have been fixed too rigidly and therefore not been able to flex or deform enough and the stress is beyond the strentgh of the hypalon bonding strip. Once it starts tearing under the nose the rip can continue along the length of the boat. In these 3 cases 2 have been Ribs with a cabin, and one had a large bow locker which meant the tubes were trapped top and bottom. Other failures I have seen have been caused by bad workmanship or design (sharp edged flanges, poor gluing, bonding strips stretched too tight etc)

So for a cabin rib where the tubes are bonded tight to the cabin top a hard nose is probably appropriate. Alan Priddys rib had a flexible joint between the tubes and the cabin top if I remember rightly.

I was in a rib off Cape Wrath when we had an almighty stuff. Normaly you have time to duck behind the console to avoid the worst of the wave about to hit you , but this time it happened so suddenly I was still loking at the front of the boat as the bows buried themselves in the back of the wave. I could hardly believe what I saw, the soft nose turned virtualy inside out and then popped back into shape as the bows rose again, There was no damage at all to the tubes or bonding strips, and the shock imparted to the boat (and the crew) must have been dramaticaly reduced.

As for Hot Lemon 2's first hard nose which got smashed off during the 98 round Scotland race , well it was probably made too light, The next, stronger version has never suffered nor have similar noses fitted to subsequent boats. If you see how strong and heavy a hard nose has to be to survive it makes you realise just how tough a well fitted soft nose is.

Manos · 24 June 2003, 06:58

Absolutely CH absolutely.
Is a pity that not many people know it

Well said!!

Cookee · 24 June 2003, 07:22

I think it's fairly obvious what I prefer!

Charles · 24 June 2003, 08:38

Thanks Nick, for your expert opinion.
To summarise then, a well designed rib with correctly attached tubes and attention to build quality should pose no problems with a soft bow nose, even in the event of a heavy 'stuffing' (No Keith, we are not talking about stuffing a turkey!!

) If one were to have a cabin rib or heavier locker up front it would be advisable to insist on a hard nose, CH is maybe the exception as well as one or two others. Maybe it would be a worthwhile exercise discussing this with your manufacturer when ordering and 'speccing' your new rib.
Manos, you can stop looking for an answer now......

BTW Cookee, that is a fantastic photo.

Julian · 24 June 2003, 08:49

Morning All

I have to say that we wont buy a boat with a soft nose again, When you stuff a boat with a soft nose the boat normall goes from 30 knots to Zero very quickly which can cause you to go flying out of the boat or through the console etc, when you stuff a boat with a hard nose although obviously you lose speed the boat keeps going and you normall end up staying in it. Never had any problems stuffing a boat with a hard nose and when we had a humber we tore the tubes of twice. No comparison.

Julian

Manos · 24 June 2003, 10:07

Hi Charles,
Good thread. I am looking to find a cabin RIB (not right now as will keep the Falcon for the next 3 years or so) as the family gets older and they all want more comforts on a boat.
I have looked at some but nothing really yet (except of 1 or two) has interested me. Need something with 4 berths, proper shower and toilet, galley, saloon and plenty of outside space and with air con configuration.
My mates in SAfrica say that they will produce one 9-10 mtr cabin RIB in the next 2 years or so (is on design stage right now) and will have a look at that too.
The boat that I looked from close and it looks REALLY NICE with all comforts but EXPENSSIVE and also do not know anything about how it performs in the water is the Italian made SOLEMAR 10 mtr.
Is VERY NICE inside (4 berths in 2 cabin, and all other staff) and you can have 2in inboards or outboards, has lots of space outside and lots of space inside with an Italian flare in design. But have not been onboard yet in the sea and everything else construction wise is a 'mystery' still. Guess I have plenty of time!!
Any way good luck with your boat!!

Charles · 24 June 2003, 10:38

Willem De Vries Lentsch based in the Netherlands build life-boats for the Dutch Lifeboat Institution and also build serious leisure cabin-ribs. Unfortunately their web-site is not very good, actually completely useless. Try a google search and see what you come up with.

Manos · 24 June 2003, 10:53

Nice boats but this is like what I have in mind

Manos · 24 June 2003, 11:01

Upss sorry the above is not the 27 but the 40+ft they do.
The 27 is like this and these are the specs fresh from Italy:

Solemar Oceanic 27 : 2 cabine, 4 posti letto, 2 prendisoli, divano

Caratteristiche tecniche :

Lunghezza f.t : mt 8.50
Lunghezza omologazione : mt 7.48
Larghezza f.t. : mt 3.25
Diametro tubolari : mt 0.62
Compartimenti stagni : 6
Peso : Kg 1.300
Portata Persone : n.10
Potenza max : Kw 210 hp 285
Gambo : XL/XXL
Omologazione CE cat.B

crazyhorse · 24 June 2003, 17:32

My point is you need look a little further into why the tubes came off the rib,It dosnt hold water with me that it is only a Cabin rib problem with a bow locker?

I am not sure what the logics behind those assumptions are,maybe Nick could explain ?

Nick could you give us any details of any work you have had to do as far as Cabin ribs go to stop the problem of bow tube loss on cabin ribs?

Before I suggest any changes to a design that is used commercialy and tested with in exess of 5yrs safe operation commercialy offshore, I would like more info.

I dont buy into the idea that its only a Cabin rib problem with a fixed bow locker and that it has to have a hard nose? but I do buy into the idea that people want to sell there concept of rib and they will try and find a unique selling point to justifie this.

Nick have you done any tube work on any Cabin hard nosed ribs that have coused you to come to the conclusion that a Cabin rib needs hard nose to be seaworthy?,as the stats prove this to be the opposite for commercial ribs used all day and every day ?

I appologise if I sound a little sceptical on this point, but I can understand the joy and satisfaction for those selling hard nose ribs, if they are able to establish that it is there ribs only, that are the way forward for a seaworthy boat, this tries and prohibits otheres ever owning one with a soft nose.

And its Salesmans Dream and total crap in my oppinion.

If its design right then its hard or soft in my oppinion both have advantages and disadvantages,but its not terminal unless eithere is designed and built badly and they come off,when you dont want it to.

jwalker · 24 June 2003, 22:23

Reading NIck's comments, it occurs to me that whilst a tube attachment failure is bad it is made much worse if the intial tear is able to travel down the attachment strips to release a whole length of tube. Since fabrics tear most easily longitudinally or transversely, there is a case for cutting these strips diagonally so that both the weave and the weft are across the joint strip. It is likely that a tear would run off to the edge rather than travel along the strip.

jwalker · 24 June 2003, 22:29

I've just checked a couple of bits of hypalon. I should have done it before the last post 'cause some of what I've suggested is bollocks. Nothing new in that I suppose. One type is woven with the fibres diagonally placed but the other make is not. So maybe tube builders need to be selective depenent upon which fabric they use. Perhaps some are.
Just a though, no criticism intended.

JW.

CH, just another though about bolt on tubes...Tear along the dotted line. Perhaps.

John Kennett · 24 June 2003, 22:39

Quote:

Originally posted by jwalker
One type is woven with the fibres diagonally placed but the other make is not.

Were those pieces as they came off the roll? Or is it possible that one of them had actually been cut on the diagonal?

John

crazyhorse · 24 June 2003, 22:50

JW We all might as well go get a hard boat Eh ?

jwalker · 24 June 2003, 23:14

JK, the diagonal fabric is a couple of metre length off the roll. The other bits are cut off a length also. They are wear patches which I cut a couple of years ago but never fitted.

JW.

CH, calm down. You've been over on the other channel too much!

Jonny Fuller · 25 June 2003, 10:00

JW, thats excellent lateral thinking! very similar thinking is used with the woven matt in many of the structural bits of my boat, although it's a little wasteful cutting matt diagonally (+ &- 45 deg matt is available on the roll but it's not woven)

I think a more important aspect to this hard nose business is how fast the boat is! at 70mph, the stagnation pressure of water is around 70psi, with only a few psi in your tubes they will just get pushed out of the way in a serious stuff, once they're deformed and "flapping" around on the front of your boat(during the stuff), starting the tear line would seem almost inevitable. so I reckon if you're gonna go quick, and hull design is of a type that means the fwd tube is likely to do a lot of head-plants, you need a hard beak!

Were the cabin ribs with failures refered to, "high performance"?

soon you'll extend the hard nose right round the topsides and hey-presto, a real boat!

Dirk Diggler · 25 June 2003, 10:25

Quote:

Originally posted by Jon Fuller
you need a hard beak!

Isn't that what Manos had fitted to his racing Rib.

dgpw · 25 June 2003, 10:57

Just a thought If you had a pressure release valve on the bow section then if you stuffed it harder then usual would the pressure be released rather than the bow ripping off?

Not sure if it would release fast enough any comments?

Jonny Fuller · 25 June 2003, 11:03

Quote:

Originally posted by dgpw
Just a thought If you had a pressure release valve on the bow section then if you stuffed it harder then usual would the pressure be released rather than the bow ripping off?

Not sure if it would release fast enough any comments?

After a few 'stuffs', you'd be all deflated LOL