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Old 25 June 2003, 11:00   #41
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To try to get this thread back on an even keel again (did I just type that?).

Never mind the extreme situation, but is it not true that a hard nose will tend to push waves away, to each side of the boat, "slicing" through the water rather than trying to "push" the wave away with a "fat" blunt ended tube?
Thus, in this mode, making for a more even progress?
And, is it not an extension of this principal (carried forward much further, of course) that leads into "wave piercing" designs?

BTW anyone heard from Jon Aldiss recently?
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Old 25 June 2003, 12:17   #42
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Too right Brian - this topic fascinates me. Our seemingly indestructible ribs have failed on a number of occassions, at the point where they meet the water head-on. I won't bore anyone with the details but I was told by many people in the industry that they would consider a hard-nose on most cabin ribs due to the extra weight which forces the bow into the wave when you have stuffed it badly. If you are in the middle of the ocean and this sort of thing happens it can lead to dire consequences.

I merely raised the thread due to our good friends suffering a similar fate and thought it would be interesting to hear forum member's thoughts on the subject. As it is pointed out elsewhere, most of us are not rib builders, BUT a good many have loads of sea-miles and experience under their belts and can offer their insight.

ps- Jon F, give me a call when next over here and we can have a cup of tea together, is that one lump or two? (Milk?)
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Old 25 June 2003, 12:35   #43
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Charles

You have presure release valves on your boat don't you. Would one on the bow section make a difference by relaesing the presure when it hits a wave hard and so taking the impact like a crumple zone on a car. would be better having a slightly flat tube than a rubber ring that is not attached!
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Old 25 June 2003, 12:52   #44
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Maybe some of us should get in touch with the KNRM lifeboat instituation and let them know there 1 million+ life boat ribs are flawed cos they dont have a hard nose.

Also we better let the RNLI know about the atlantic 75s limitations,and I better call Halmatic and Zodiac and Avon and Delta about there commercial boats before its to late.

Maybe we should try and stop Alan P from crossing the atlantic and Bear as they havet got a hard nose either.

Ooh what is to become of us all,?

see http://www.knrm.nl/vlootschouw/

And Mr No freeboard , but it dont show when she is on the plain Fuller,when is the Poker run as I am looking forward to a real hoot and a few pints and a brew.
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Old 25 June 2003, 14:14   #45
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Quote:
Originally posted by dgpw
Charles

You have presure release valves on your boat don't you. Would one on the bow section make a difference by relaesing the presure when it hits a wave hard and so taking the impact like a crumple zone on a car. would be better having a slightly flat tube than a rubber ring that is not attached!
I do indeed have pressure release valves. I have had a hard nose put on my rib as the manufacturer strongly suggested it - read into that what you will.
CH- maybe we ought to define a cabin rib? Alan Priddy's as well as other similar craft are more like ribs with wheel houses, not cabin ribs don't you think. You have been on my boat, the weight upfront due to the design is slightly different than other 'cabin ribs' or wheel-houses.
There is no need in being sarcastic.
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Old 25 June 2003, 14:59   #46
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OOps I am chilled Charles

Charles,my point is that providing it is designd well and built strong enough,Then it makes no odds weather IMHO you have a hard nose on the front of you rib or a soft one,unless your selling them.

If you want a wave piercer then it will be a little bumpy with a Tube around the front.I would think?.


But The rest of the world is still sat on the fence,including builders of all weather life boats and commercial opperaters here and abroad who sell hundreds of boats each yr.

So to be fair ,Lets not say you got to have a hard nosed rib or its not capable in an offshore capacity as some of the hard nosed ribs we are Talking about arnt even used in any commercial offshore enviroment and I dont know wether any even have any Solas or MCA tickets for over 60 miles offshore?

And even with light leisure use some seem to have had there problems in the past

But I loved your beasti Charles and had a great deal of fun,but for real offshore cruising then its Mr P type of boat for me,with a secured bow Tube,its slower ,goes further,has more room,and costs a lot less to run,and in my oppinion is more in keeping with offshore long distance cruising.

Thats my oppinion at present.


But I still want some tea a bikis when we come and say Yoo Hoo Charles were here.



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Old 30 June 2003, 03:22   #47
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For What It's Worth...

I have now had time to reflect on the causes of my "decollaring" and they are these...

1 The boat was designed for light use in the Solent by an elderly gent. It was not up to being trashed about by a stupid old fart. The high volume tube construction, particularly round the bow, was flimsy. As soon as one thin layer of hypalon was ripped the whole lot peeled back.

2 I had inflated the tubes too hard and there was no "give". I did this in my inexperience cos several people had told me (including you, Charles ) that I needed to get some air into them. With hindsight I now know that in rough water, the type of tubes I have need to flex and wobble. (Alan P told me this long ago but on this occasion I chose to do do something different. Mark W also told me in the aftermath that I should see how soft Mike Deacon runs them on Hot Lemon.)

3 I was experimenting with the use of trim tabs. In a following sea that was moving slower than the boat I found that landing on the flatter aft section of the hull was very painful for my old back. By tipping the ride forward and landing on the deep-V section of the bow it was a lot softer. It also made it easy for the boat to dive into the hole I found on the far side of a backless wave.

Those are the causes. The solution, for me, is...

1 To have the front end beefed up. Ed Carter (Ribraff) and former Henshaw man, Paul Tilley are working on that as I write.

2 To run the tubes softer.

3 To drive in a manner that suits the boat, my back and the sea state. I'm working on that and am - slowly - improving.

On the hard nose v soft nose argument, I believe the answer lies in what the boat is designed to do and how it is to be driven. That, and personal preference.
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Old 30 June 2003, 05:53   #48
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I have had several RIBís in the past all with Ďsoftí noses and have also had them fold back on me.

My first RIB, a 6m Delta, has a very pronounced nose and never even looked like folding back even when Iíve been through a wave whereas my BWM 28 stuffed and the tubes folded back, allowing a whole lot of water in the boat.

Alan P and various other people who know a whole lot more than me have expressed the opinion that they should fold back, but over time I would have thought that this would cause stress failures in or around the nose. Iím probably wrong here but this is my simple non-exper view.

Since having a hard nose on my Scorpion I cannot praise it enough. The only issue is that a hard nose will piece the wave, if pushed hard enough, and the force of water must go somewhere else. The next stop is the console and windscreen. I have heard of several RIBís that have had broken windscreens. My only comment is that the water deflects up the windscreen and goes straight down your top !

As for the recent incident there were several occasions where my boat pushed through a wave and I felt assured that with a hard nose, apart from a drenching, we would come out the other side, smiling. I was just lucky that the wave Mike found, unluckily, would have caused my boat to fill with water, no problem there, and then wait for the elephant trunks and holding tank which has a bilge pump in it to empty the boat. As the air intakes are above the water line I would still have power.

Regards

Mark
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Old 01 July 2003, 05:59   #49
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Hard Nose

I actually designed the Red Bay 9m+ range which all have a hard nose fitted! I've also designed and built a lot of ribs with a soft nose!
It very much depends on the size of the Rib and generally what type of use it is going to get. I do think below about 8m the cost of having a hard nose probably isn't worth it as the boats are within a weight range which the tubes can or should handle having the bow stuffed!
However once you start moving into the larger range of ribs (9m+) the boat weights tend to be in the region of 3.5tonnes and upwards. Take one of these boats doing 40knots and stuff the bow of a soft boat and you'll be lucky not to do damage to tube or the bonding flange. It might not happen the first time but stuff it regularly and eventually damage will be done! With a soft nose being stuffed the deceleration is very dramatic and the boat will come to an almost dead stop!
It is here that I have to disagree with some of the earlier replies about hard nose boats giving a harder ride as they do not deflect the same as a tube! The hard nose on the Red Bay and they larger Scorpion have an inverted under side. This in effect gives a smooth cutting motion into the oncoming wave as well as displacing the water away from the boat and therefore a very dry experience which would normally have soaked everyone in the boat! The big difference is the comfort onboard, you feel practically no declereration in a stuffing incident as the bow simply cuts into the oncoming wave!
I can't speak for the scorpion but I have covered many thousands of miles in the large Red Bay's off the West Coast of Scotland in extreme conditions and the hard nose makes it possible to have a trip in bad conditions in great comfort and with the minimum of stresses being exerted on the boat and the crew.
Finally my own rib is 8m and has a soft nose and I'm very happy with it. However if I was going for a bigger rib it would most definitely have a hard nose!
In my opinion there is nothing in wrong with a soft nose rib, it is just that on big ribs a hard nose is without a doubt much much better!
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Old 01 July 2003, 07:57   #50
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Thanks Joe, I guess that sums it up for me. There is no doubt that stuffing the big round nose of my 9m Ribtec - which weighs in excess of 5 tons - is not, on a regular basis, a good idea. Lesson learned!
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