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Old 28-11-2012, 15:04   #616
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Re: Bluewater Cruising Capability

Well, I always did challenge my professors and old habits die hard .

Unlike the times when I was just an inexperienced freshman though, I have now had a good few offshore miles under my belt, so feel I have earned my place at the table rather than just being consigned to listening to and reading and rereading the advice of experts. So here goes with presenting my views, but can I repeat that I am simply giving my opinion so please give me a hearing without crucifying me .

In response to a few issues raised by goboatingnow:

Quote:
Originally Posted by goboatingnow View Post
Things that arnt important
1. The hull strength. , you rarely hit anything most production boats have sufficient
Strikes with containers or other floating debris and whales are becoming more common. These can result in very rapid sinking, which even the most experienced crew with the best equipment is lucky to survive. It is impossible to produce a boat that guarantees integrity in these circumstances (look at the Titanic ), but while features such as a metal boat and watertight bulkheads and a long keel are by no means essential, I believe these factors contribute to safety.

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Originally Posted by goboatingnow View Post
Things that arnt important
......
2. The keel length., its provide set of disadvantages and advantages
I agree they all have their advantages and drawbacks. You pick your poison.

Quote:
Originally Posted by goboatingnow View Post
Things that arnt important
......
3. The AVS , have you been in a rollover or a 90+ knockdown. The results are nasty stuff detaches, people are inevitably injured and almost always the epirb gets triggered. It's not the survivabilty of the vessel ( it most always re-rights ) its the condition and mental state of the crew. I laugh when people talk about getting a boat that survives rollovers or pitch pole . Wrong focus.
During 27 years of sailing I have been in a number of knockdowns. Thankfully the only rollovers have been in small racing cats and dinghies and I have no desire to repeat that experience in a larger vessel. So the AVS does matter to me. And cats don't re-right.
I think you make a good point about crew injuries in these situations, but here I would place more emphasis on the boat's features such as strong latches on cupboards, secured floorboards, secured batteries and many handholds etc than the experience of the crew when it comes to minimising trauma. I do have to add though that I think we would both agree that an experienced crew would be less likely to get themselves in this situation.

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Originally Posted by goboatingnow View Post
firstly you or I can't determine "good features " is a particular aluminium boat better then grp , how do you know, there's no independent destructible testing.
The large plastic deformation range of metal structures means they are far less likely to loose watertight integrity in the event of a collision. This is just simple engineering.
This doesn't mean the only suitable offshore boats are metal, but it is a factor contributing to the safety of the vessel.

Quote:
Originally Posted by goboatingnow View Post
What are " good features" mostly they are theorectical beliefs from owners based on what they purchased
I am not just saying this to justify my purchase, an aluminium boat was specifically searched for, not the other way around.

I fully agree that the experience of the crew and familiarity with the boat they are sailing is a huge factor when it comes to safety. I am not even vaguely discounting this, but some boats are just better than others when it comes to safety offshore.
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Old 28-11-2012, 15:27   #617
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Re: Bluewater Cruising Capability

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Originally Posted by carstenb View Post
My contention is that most modern boats are perfectly capable. All will have some sort of bug that will need correction (companionway doors - f.eks.). Otherwise - it is up to the crew to get her there.
You are correct.. just that some boats are more perfectly capable than others for some of us and vice versa. It all depends where and how long you sail, what crew you have, likings etc
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Old 28-11-2012, 16:23   #618
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Re: Bluewater Cruising Capability

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Originally Posted by Seaworthy Lass View Post
....During 27 years of sailing I have been in a number of knockdowns. Thankfully the only rollovers have been in small racing cats and dinghies and I have no desire to repeat that experience in a larger vessel. So the AVS does matter to me. ....
AVS would matter to me too, if I worried about the sort of capsizes racing cats and dinghies (and harbour and inshore racing vessels generally) are prone to.

Namely, being knocked down - essentially due to being overcanvassed for their stability - in relatively flat water. To me this is a different kettle of fish, with little relevance for 'bluewater cruising'.

I happen to agree with those who consider AVS to be relatively unhelpful as a guide to determining whether a knockdown will happen to a vessel which finds itself beam-on to a high sea when it breaks.

It certainly misses all the dynamic factors. To me AVS is little more relevant to deepwater capsize than, say, ability to lift weights would be to a sprinter.

In some situations there is a relation between AVS and inverted stability, which is something to think about, but it's better in my view to focus directly on whether there's a problem here and if so, what to do about it.
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Old 28-11-2012, 18:06   #619
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Re: Bluewater Cruising Capability

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Originally Posted by Dockhead View Post
In real life, in say a university, we would never see freshman arguing stubbornly with a full professor with a Nobel nomination, but on the Internet, we get just that. I'm not saying that any particular conversation in this particular thread is exactly like that, and probably isn't like that, but we have had some threads which were really close to that analogy.

I disagree with you here. The good professors not only welcome the debate but encourage it. The exceptional ones then take the time to prove their points(aka teach), by using facts or opinions gained through their experience and greater knowledge, can use specific examples instead of generalizations and hearsay, and would never answer a question with "that's just the way it's always been done" or everybody's favorite "because I said so".

I've seen both approaches in this and other threads.
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Old 28-11-2012, 18:35   #620
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Quote:
Originally Posted by Seaworthy Lass
Well, I always did challenge my professors and old habits die hard .

Unlike the times when I was just an inexperienced freshman though, I have now had a good few offshore miles under my belt, so feel I have earned my place at the table rather than just being consigned to listening to and reading and rereading the advice of experts. So here goes with presenting my views, but can I repeat that I am simply giving my opinion so please give me a hearing without crucifying me .
I don't beleive anyone's crucifying you. It's a debate.

Quote:
In response to a few issues raised by goboatingnow:

Strikes with containers or other floating debris and whales are becoming more common. These can result in very rapid sinking, which even the most experienced crew with the best equipment is lucky to survive. It is impossible to produce a boat that guarantees integrity in these circumstances (look at the Titanic ), but while features such as a metal boat and watertight bulkheads and a long keel are by no means essential, I believe these factors contribute to safety.
Facts and evidence lass, where is it. Most GRP hulls are impregnated with high impact resistant fibres many are better then the thin metals used in leisure boats. See you tube. Equally where is the evidence suggesting statistically increased chances or a actual incidents you mention. I don't see , in fact in zillions of miles I only seen a container once.

We have no data to suggest that metal leisure boats are better , the compromises in panel thickness in under 50 foot are significant in metal boats , we just have no data ( other then belief) is a SUV better in a crash then a car, many " beleive " so NCAP testing suggests otherwise. Metal leisure boats in under 50 feet are a tiny tiny proportion of the market, few if any comparative testing has been done. We simply don't know.

Titanic sank because of exactly the issues I have argued against here, the search for the ultimate boat.

I don't personally beleive metal boats in typical cruising configurations under 50 feet offer any advantages , they are often heavy , slow , need frequent upkeep, etc. they are useful for low volume semi custom one offs

There is no evidence that long keels are " safer" they are different that's all. Modern naval architectures would differ with you

Equally in e vast majority of designs especially under 50 feet its very difficult to build a boat that makes uses of water tight compartments. Equally the number of incidents where boats might have been saved seemed small ( that we know off)


Quote:

During 27 years of sailing I have been in a number of knockdowns. Thankfully the only rollovers have been in small racing cats and dinghies and I have no desire to repeat that experience in a larger vessel. So the AVS does matter to me. And cats don't re-right.
I think you make a good point about crew injuries in these situations, but here I would place more emphasis on the boat's features such as strong latches on cupboards, secured floorboards, secured batteries and many handholds etc than the experience of the crew when it comes to minimising trauma. I do have to add though that I think we would both agree that an experienced crew would be less likely to get themselves in this situation.
AVS is an appalling metric , it's not of much use . Sure cats don't rewrite , but they stay afloat. Monos too tend to re right but you generally ain't sailing off anywhere after it. It's an Epirb job. ( in a storm roll or pitch pole)

The things you mention are all more useful then a long keel.


Quote:
The large plastic deformation range of metal structures means they are far less likely to loose watertight integrity in the event of a collision. This is just simple engineering.
This doesn't mean the only suitable offshore boats are metal, but it is a factor contributing to the safety of the vessel.

I am not just saying this to justify my purchase, an aluminium boat was specifically searched for, not the other way around.

I fully agree that the experience of the crew and familiarity with the boat they are sailing is a huge factor when it comes to safety. I am not even vaguely discounting this, but some boats are just better than others when it comes to safety offshore.
Firstly you have no data to compare your actual boat against a GRP one. Secondly the puncture resistance of modern GRP laminates combined with exotic aramids is higher then aluminium. Again yours is a belief. ( your buying a SUV again )

I in no way denigrate your choice of vessel, merely that it is bought like many others , on faith, perception and preference rather then any particular hard facts.


Dave.
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Old 28-11-2012, 18:46   #621
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Re: Bluewater Cruising Capability

One thing we do know, unless designers have now found a way around physics, is that the faster you go the more inertia you generate and therefore the forces in a collision will be greater on a faster boat. So, won't these modern boats that are sailing a lot faster also endure higher forces when they do hit something? Plus, an advantage of the traditional hull shape with a long slope to the keel is that it tends to ride up over something in comparison to the vertical leading edge of some of these fin/bulb jobs. The rudder is rather protected at the end of the keel on a traditional boat, whereas we see spade rudders being damaged all the time. Another factor, depending on where you want to sail, is draft and mast height. Here on the East Coast I wouldn't even consider a boat with over 6-foot draft and a mast height of around 62 feet because you just couldn't go anywhere. Reduce that to under 55 feet and less than 4 or 5 feet of draft and you probably double the number of wonderful places you can go. Even though you do have to cross oceans in a bluewater boat, you are very much more likely to get into trouble in shallow coastal waters, so a true bluewater boat has to be able to handle them too. What's the use of crossing oceans if you can't enjoy the places you get to?
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Old 28-11-2012, 19:09   #622
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Quote:
Originally Posted by Kettlewell
One thing we do know, unless designers have now found a way around physics, is that the faster you go the more inertia you generate and therefore the forces in a collision will be greater on a faster boat. So, won't these modern boats that are sailing a lot faster also endure higher forces when they do hit something? Plus, an advantage of the traditional hull shape with a long slope to the keel is that it tends to ride up over something in comparison to the vertical leading edge of some of these fin/bulb jobs. The rudder is rather protected at the end of the keel on a traditional boat, whereas we see spade rudders being damaged all the time. Another factor, depending on where you want to sail, is draft and mast height. Here on the East Coast I wouldn't even consider a boat with over 6-foot draft and a mast height of around 62 feet because you just couldn't go anywhere. Reduce that to under 55 feet and less than 4 or 5 feet of draft and you probably double the number of wonderful places you can go. Even though you do have to cross oceans in a bluewater boat, you are very much more likely to get into trouble in shallow coastal waters, so a true bluewater boat has to be able to handle them too. What's the use of crossing oceans if you can't enjoy the places you get to?
Well it's a combination of mass and speed.

The high tech boats with exotic fibres can be built to be better then steel. RNLI lifeboats travel at 25 knots a d have been using composite hulls for some time.

As to long keels. There's no evidence they are better in collisions , see the DuFour ( I beleive) you tube video of a fin keel hitting. Rocks at full speed repeatedly , I seen fin keel racers hit at full speed too,

At least if I damage the fin keel I don't let water pour into the interior , which can happen in integral keels , removing that water can be a bummer, and I hope the steel stampings don't expand !!

Long keels existed partly as a result of wooden construction, partly as a race tactic , etc. certainly not as a " safety feature "

We don't see spade rudders " damaged all the time ". Most rudders are damaged by groundings or backing into things , these generally are not protected by Skeg or semi Skeg. The fact is as materials and understanding improves all boats are converting to spade or semi Skeg. The issues you mention simply don't occur statistically enough to warrant not going to the far better hydrodynamic spade. You are trading something you will use every day sailing for a feature you may never need in your whole sailing career.

Ive seen semi Skeg hung rudders virtually tear off the Skeg and leave a big hole. Sometimes I think the rudder is there to hold the Skeg and the marketing dept figured its a bluewater feature

Draft and mast height tend to be very location specific. In general deeper draft is better.
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Old 28-11-2012, 19:18   #623
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Re: Bluewater Cruising Capability

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Originally Posted by goboatingnow View Post

Titanic sank because of exactly the issues I have argued against here, the search for the ultimate boat.

Dave.
The design of the Titanic or attempting to make her the ultimate ship of her time had little if anything to do with her sinking. Some over confidence in her capabilities my have been contributing factors. But I think most would agree, human error is the real reason for this tragic event.

Rob
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Old 28-11-2012, 19:29   #624
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Re: Bluewater Cruising Capability

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someone used the term "ill advised" about taking some boats offshore earlier, but ill advised by whom? Themselves of course. Because i would not do it does not mean that others should not. It is total arrogance to say that "This is my opinion and therefore all others are wrong" which does seem to be the norm for some folks.
There are some boats that I would be quite comfortable stating that a particular offshore passage would be ill-advised, regardless of the skipper. This would be based on my subjective evaluation of some very objective criteria. I wouldn't say this about many boats, but there have been a few.

Niagara Falls in a barrel? Ill-advised.
Cape Horn in a 1980 Catalina 27? Ill-advised.
[...]
Long Beach to Catalina in a (just about any modern boat)? Advised.

At some point in this continuum we may reasonably disagree, but to say there are no inappropriate boats/voyages is just silly.
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Old 28-11-2012, 20:05   #625
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Originally Posted by rsneek928

The design of the Titanic or attempting to make her the ultimate ship of her time had little if anything to do with her sinking. Some over confidence in her capabilities my have been contributing factors. But I think most would agree, human error is the real reason for this tragic event.

Rob
It has everything to do with her sinking , it was a classic 4x4 stuck in a drift problem. A search to build an unsinkable boat, a reliance on the product to get them out of trouble and the over confidence in that design that caused foolish decisions to be made.

Dave
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Old 28-11-2012, 20:08   #626
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Re: Bluewater Cruising Capability

Take a look at the Latitude 38 Circumnavigators list, and see what boats people DID sail around the world. There are some surprisingly small production boats (like a Columbia 24), and I think the Valiant 40's were the most numerous.

Latitude 38 - West Coast Circumnavigators' List
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Old 28-11-2012, 20:18   #627
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Take a look at the Latitude 38 Circumnavigators list, and see what boats people DID sail around the world. There are some surprisingly small production boats (like a Columbia 24), and I think the Valiant 40's were the most numerous.

Latitude 38 - West Coast Circumnavigators' List
Yes 10 valiants of all sizes 7 40s , in a list of Several several hundred , there was 6 home builds too. !!

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Old 28-11-2012, 20:20   #628
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Re: Bluewater Cruising Capability

Niagara Falls in a barrel?? lollllll

My favorite blue water whatever can be ,,,, a super strong material if im planing to sail in hig latitudes, lets say steel or alu with a smooth curve hull, easy sea motion and not the bang bang of flat bottom hulls, robust rigging with all the hardware related , lets say chainplates to, able to beat to windward for hundred of miles in rough weather, cutter sailplan, a galley made for cooking , confy bunks for crew, tanks big enough for at least 1000 miles under engine , a safe cockpit, well the list is endless....

Now the dude saying that a exotic plastic hull can be stronger than a metal one dont know what is talking about,,,, in terms of weight , maintenance , yes, in terms of a hipotetic collision or grounding ,No.

Cape Horn in a Hunter 33 ,,, wait for weather.... mega window???
Southern Ocean in a coronado, yeahh im going to die...

So saying this everything is a compromise, dont expect to see a bad build it production boat dealing with conditions made for the big dogs....

Luck is everywhere, size is important to...
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Old 28-11-2012, 20:24   #629
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Re: Bluewater Cruising Capability

Re the Titanic sinking:

another problem was the poor metallurgy of the steel:

the composition was not under proper control, meaning that (even by the standards of the day) the transition temperature at which failure became brittle rather than ductile was unnecessarily high.
This is why the hull skin ruptured across so many compartments, rather than deforming.
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Old 28-11-2012, 20:52   #630
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Re: Bluewater Cruising Capability

The Titanic and her sister ship the Eastern star were both unsinkable,

Till they cheated and removed 10,000 pounds worth of iron from the Titanic, Thats money not weight,
They removed 18 inches of iron from the full length of her, from the top of the bulkheads and the floor above, allowing any water ingress to flow the full length of the Titanic, any hole in her bottom would have sunk her,
the Eastern star sailed into New York Harbour under full power with a hole 3 times the size of the Titanics,
But they didnt cheat with the Eastern Stars Hull, so it stayed afloat, it was unsinkable, As the Titanic should have been,

as the water could not go past any bulkhead that had a hole in it, it was contained in the holds with holes only.

I am an Engineering Blacksmith, When I was doing my trade the theory teacher hated me,

Not only did I say the book he was teaching me from was wrong, I could back it up with hard Facts and Proof,
Engineering Blacksmith was the master craft of all the Black trades, FWIW, I was also the last year that they taught that Curiculum.

They took the Practising Engineer out of it, and shortened the apprenticeship to four years,
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