I believe that "ranking" saeworthiness is a blunt way of standardization of several aspects, that may apply to certain boats in favour of others, based on the "point" scheme.

The fact that Mercedes have anti-skid brakes, traction control and gps guided maping does not compensate for unqualified drivers.

Many boats may have large safety and seaworthiness values, that can be reduced to zero in the hands of an idiot. Comparatively a less seaworthy vessel could perform better in the hands of a good sailor.

Seaworthiness should be evaluated having in mind an average "driver" seaworthines...and that does not exist yet.

Prevailing sailing conditions are part of his numbers?

 

Prevailing sailing conditions are part of his numbers?

You're right, because boats vary in strength and stability. Probably only the Southern Ocean racers are at the cutting edge of "seaworthy" and "fast", because they get rolled, dismasted and sometimes inverted, and yet only a couple of sailors (by definition among the world's best...most of us couldn't even do the qualifying races) have died or gone missing.

For the rest of us, prevailing conditions play a big role. Alex, up to 40 knots I would take your boat, but higher than that I would rather be in mine. Part of that is simply that a pilothouse is a better place to be when the spray is like nails hitting you in the face...another part is that your boat is engineered for speed and CAN be broken (remember your exploding boom?). If you have the right boat in the wrong conditions, all bets are off. If you have the right boat in harsh but survivable conditions, but only one guy knows how to sail the boat, after 36 hours, that guy will collapse from fatigue.

For anyone interested in the topic, I recommend strongly a book called "Rescue in the Pacific", about a 1994 "weather bomb" that hit a cruising rally between New Zealand and Fiji. Fatigue, and not seaworthiness, were the biggest problems: People who simply couldn't continue (or who were injured in capsizes) had to be rescued from boats that were seaworthy enough to eventually be found intact or run aground.

Here's some sample pages. I found the last chapters (what worked and what didn't) very informative.
http://books.google.ca/books?id=RGF...q=Rescue+in+the+Pacific&btnG=Google+Search&meta=&sa=X&oi=print&ct=title#PPP1,M1

 

Two things come to mind. First, the seaworthiness of boats usually outlasts the seaworthiness of sailors. And second, Sailors usually get their boats into trouble, not the other way around.

 

Along that line V, I just read a short National Geographic article about the '75(?) Fastnet race that ended in disaster. Did you see that one? I think there is a book or two on it also. I would also like to add to my post above that I am not condoning disregarding build quality.

 

Fastnet Force 10 by none other than John Rousmaniere is the book in question (it was 1979). Read that book, Rescue in the Pacific and Heavy Weather Sailing and you've got a lot of decent information for the first time you run into 40 knots or better at sea (Hal Roth is good, too).

I am less emamoured of the Pardeys' and the Dashews' advice, because I think they are at opposite ends of the spectrum in terms of the boats they sail, and most boats are between the two (although mine is more Pardeyesque, I suppose, being a full keeler).

 

Hey BF...welcome back...hope all is well!

 

BF, that Fastnet was in '79, and it's a fascinating story. Many abandonded boats were later found afloat, lending credence to your "sailors fail before boats" theory.

RG, I agree that such a scoring system is not going to provide a equalized rating that can be taken on its own. There are too many variables (and subjective views) for a universal code to determine a vessel's appropriateness for whatever purpose is intended.

And, as Giu points out, no matter how "idiot proof" someone may make a boat and its systems, somewhere, somehow a "better" class of idiot will turn up.

 

Hi Cam! Yes, all is well, kind of....a little stressful coming back to reality full force. The Yucatan is a wonderful place. I will post a thread on my findings a little later, with photos. The admiral had no idea that I could just "check out" forever. She thinks that just because I worry about all the details here in the states, I can't just walk away from it all. Hah! little does she know it has been a life long dream. So, today I made fresh salsa (a recipe I will post too) homemade tortilla chips, and am washing it down with a Negra Modelo. Mariachi music on the itunes.

 

today I made fresh salsa (a recipe I will post too) homemade tortilla chips, and am washing it down with a Negra Modelo. Mariachi music on the itunes.

Welcome back Bro! glad to hear all is well! waiting for the details of the trip, pics and the Salsa recipe. chillin the cerveza at this very moment, and oh yeah mariachi. my neighbors think i'm a nutcase for playing it(another thread)

 

So much of the seaworthiness of a vessel depends on the captain and crew IMHO. I'd rather go to sea with an experienced captain in a Hunter 37C than in a Swan 45 with a complete newbie, unless I got to keep the boat.

 

So much of the seaworthiness of a vessel depends on the captain and crew IMHO. I'd rather go to sea with an experienced captain in a Hunter 37C than in a Swan 45 with a complete newbie, unless I got to keep the boat.

Gasp! Can this be? SD is coveting a lead-mine monohull?!?

 

Robert,

John Vigor's seaworthiness test is sort of like one of those "rate yourself as a lover" pseudo-psychology quizzes in a woman's magazine.

Regards,

Tim

 

Sea KINDLINESS is by the design of a boat, etc.

SeaWORTHINESS is due to the inbuilt strength of the boat.
A 'seaworthy' boat is usually built with on-purpose *redundant strength* to handle all conditions possibly encountered. A 'seaworthy' boat, a boat built to take care of itself in ALL conditions possibly encountered on a LONG voyage or ocean passage, will typically be built 5 to 6 times STRONGER than the 'design' loading. This 5 to 6 times 'stronger' than functional design is called 'factor of safety' .... and usually defines a 'blue water' boat. Historical or insurance 'scantlings' show that a boat built at FS=5 FS=6 will be capable of long passages ... without often having them pay a 'loss' claim.

Blue water boats typically have a safety factor built-in at 5X or 6X; (although a 'balls to the wall' racing effort will use/chance less safety factor to save weight, etc.)
a 'coastal design' will have ~3X safety factor;
an 'inshore' design will sometimes only have a safety factor of 2.

Has nothing to do with the 'experience' or 'lack of experience' of the crew; although, an inexperienced crew can easily structurally destroy even a FS=6 boat in no time.

 

This is an interesting read:

http://www.smallcraftadvisor.com/content/seaworthiness/

It's about small boats (trailer sailors) but I think most, if not all, the same criteria applies to all boats. It's just that the trade offs inherent in making a boat trailerable force the builders to set priorities. It's interesting that the "experts" in that particular article don't agree about speed.

Count me as one more "me too" on the obvious point about the skipper and crew and I would add that what they do prior to departure also comes into play - are there sufficient stores in case the passage takes considerably longer than expected? If you lost the mast and the engine would not run, do you have some other means of propulsion? Could you patch a hole at sea? What if lightning takes out all electronics? etc, etc, etc...

 

The score might have some value as one of many pieces of information...certainly not absolute, but then neither is hull speed as generally calculated. As well, there is another formula frequently used to postulate how comfortable a boat might be at sea which would be subject to so many variables that it can only be taken as a very rough indicator.

I suppose if the person who developed the formula allocated the same weight to each predictor as the person who was interpreting it, the "score" would be of some value. Sailors being the obtuse lot that they are however, that is not likely to happen too regularly. The criteria that determine seaworthiness vary widely, and are usually based on individual experience.

 

More ideas

DESIGN

A seakindly design, intelligent engineering & solid construction. A hull that doesn't pound, & takes a punch. A soft ride reduces fatigue.

A hull shape that can track upwind. There is plenty of windward sailing offshore. Close windedness is less important than the ability to track well while making little leeway.

A well-balanced hull & rig that respond well to self steering, wind vane or auto pilot.

A keel that can survive a grounding and a skeg to protect the rudder. Sooner or later you will hit or snag something.

A sailplan that is easy to handle yet can be tweeked for better performance. The 2 biggest secrets of cruising is there is more light air than heavy, and cruisers motor more than they should. A light boat is not the answer a generous rig is.

A deck layout that keeps you secure when going forward in a blow. no matter how many lines are led aft, you will have to go forward. Bulwarks, tall stiff stanchions & lifelines, & well placed handrails.

A comfortable and seaworthy cockpit. This is where you spend most of your time @ sea & port. Good visibility from the helm, easy access to sailing controls, benches long enough to stretch out on, well-angled seat backs, and bridgedeck.

An interior arrangement that works for you. Privacy is important but ventilation, light sea berths, and functional galley are much more so.

As for performance & stability ratios there is no doubt that sail area-displacement, displacement-length, ballast-displacement, are useful when determining an offshore boat. However these ratios are so distorted on an older used boat that they are nearly useless.

CONSTRUCTION & ENGINEERING
Smart engineering and solid construction often (but not always) go hand in hand. a boat with massive bronze deck fittings, a husky teak boom crotch, & solid bulkheads may be well built but poorly engineered, who needs all that weight. Heavier does not mean safer or better.

PREFERENCES Fiberglass is a preference over steel, or aluminum, (less maintenance) Composites are also very good, not yet as common as glass.
Solid uncored hulls, below the water line. Above the waterline coring is good, huge weight savings.
A hull to deck joint that doesn't leak.
A laminated hull to deck joint over a mechanically fastened one, they are harder to find. Many production boats have joints that are through-bolted as well as chemically bonded.
A hull with transverse floors & longitudinal stringers instead of liners & molded pieces.
A boat with internal lead ballast.
A deck-cored with water-resistant material & solid laminate in load bearing areas. Most boats are balsa cored, this may or may not be an issue in an older boat. Some boats have plywood cores & these are almost always a problem.

 

RichH says,
“Sea KINDLINESS is by the design of a boat, etc.”

I agree with you but isn’t everything “by the design of the boat”. Is sea kindliness something separate and above other factors in the design? Or is just one more factor making up the overall package called seaworthy.

RichH goes on to say,
“SeaWORTHINESS is due to the inbuilt strength of the boat.”

I think seaworthiness is more then just the ultimate strength of the boat. A strong boat that can’t claw off a lee shore is not seaworthy and a boat with such a violent movement that the crew can’t sleep or work the boat is not very seaworthy.

RichH then says,
“A 'seaworthy' boat is usually built with on-purpose *redundant strength* to handle all conditions possibly encountered. A 'seaworthy' boat, a boat built to take care of itself in ALL conditions possibly encountered on a LONG voyage or ocean passage, will typically be built 5 to 6 times STRONGER than the 'design' loading. This 5 to 6 times 'stronger' than functional design is called 'factor of safety' .... and usually defines a 'blue water' boat. Historical or insurance 'scantlings' show that a boat built at FS=5 FS=6 will be capable of long passages ... without often having them pay a 'loss' claim.

Blue water boats typically have a safety factor built-in at 5X or 6X; (although a 'balls to the wall' racing effort will use/chance less safety factor to save weight, etc.)
a 'coastal design' will have ~3X safety factor;
an 'inshore' design will sometimes only have a safety factor of 2.

Once again RichH you are by yourself as far as the numbers go. I can understand your not wanting to take my word for it but why ("why" added 9-21-07) you do you dismiss the body of work in print that says you are wrong. Have you looked at any of the references I pointed out? Not that long ago you asked Bob Perry what his office uses for a safety factor. You have said in the past that you like Bob Perry’s work so why do you dismiss his direct answer to you. He said in a response to you on 8-16-05 on the CSBB forum and I quote,

“We use safety factors varying from 2.00 to 4.00. We never use more than four and we never use less than 2.00. It depends upon the boat and it's use. For our typical cruising boats of moderate displacement we go with four. For our "cruising sled" series of light cruising boats we drop the safety factor in order to help reduce weight. It's my attitude that there are components of your cruising boat you should be able to take for granted: rig, rudder and laminate schedule.”

In engineering there is a very large difference between something designed to withstand 4 times a strain and the same thing designed to withstand 6 times a strain and of course the difference between 2 and 6 is extreme. The only boat that I have seen with a safety factor larger then 4 was a 37 foot steel ketch with telephone poles for masts and ¾” galvanized wire for rigging. But this isn’t your typical boat by anybody’s definition. Also scantling rules come from places like the ABS, RCD, and ISO/CEN Standard 12215-5 to name just a few. Insurance companies have nothing to do with this.

RichH finishes by saying,
”Has nothing to do with the 'experience' or 'lack of experience' of the crew; although, an inexperienced crew can easily structurally destroy even a FS=6 boat in no time.”

This is very true and many boats survive after the crew abandons them. Since the beginning of offshore sailing or in fact since the beginning of boating it has been possible for an incompetent captain to drive a boat under. A skilled captain with a marginal boat will do just fine but an idiot with the best boat is in trouble.
All the best,
Robert Gainer

 

I have not read the SCA article yet-it's in the pile! I've read Mr. Vigor's seaworthiness check list elsewhere though.

One area I've not heard discussed, because we really should be talking about boats, not who and how they're sailed, is the debate over stiff versus tender. In my opinion, we reflexively opt for stiff and overlook the stresses such a boat endures as well as her crew. Tender may produce the more sea-kindly motion alluded to earlier. I do not have a boat in this race, but am interested in Mr.Ganier's and other's thoughts on the matter.

 

One area I've not heard discussed, because we really should be talking about boats, not who and how they're sailed, is the debate over stiff versus tender. In my opinion, we reflexively opt for stiff and overlook the stresses such a boat endures as well as her crew. Tender may produce the more sea-kindly motion alluded to earlier. I do not have a boat in this race, but am interested in Mr.Ganier's and other's thoughts on the matter.

A few years back I spent some months on the big white thing you'll see in the "Anchoring Problems" thread. This ship was built in 1916 and is the world's oldest active passenger vessel - meaning it was designed and built as rivetted construction.

One thing I never realised was that, unlike welded steel, rivetted hulls flex. After so many decades of welded patches for hull repairs she now has a really strange tender/stiff/tender jerkiness in any decent sort of sea.

Methinks tender is good - but unfortunately pretty rare these days because it's more expensive to build.

--Cameron

 

Cameron,

There are a few different uses of the term "tender" amongst sailorfolk. As well as the usage you have employed, it can refer to a smaller boat for ferrying back and forth between a slip and a larger boat, or it can be used to refer to a boat that tends to heel easily. Conversely, a boat that has substantial initial stability is referred to as "stiff", as it takes more force to make it lean over.

I think that the second connotation of tender is what Sailaway meant in his post. The stresses that he goes on to mention, are the forces placed on the windward side of the hull by the shrouds holding the mast in position. His point is that because a boat experiences less pressure on its sails as it heels, the shrouds would be placing less stress on the hull in a tender boat than they would in a stiff one, where the sails remained closer to the vertical.

Hope that I am not making myself sound like a know-it-all, just trying to help you become a bit more fluent in the (ever-confusing) lingo.

 

Sailormann, I'd assumed by his talking about "the stresses such a boat endures as well as her crew. Tender may produce the more sea-kindly motion alluded to earlier" he was talking about hull stresses in general.

Thanks for trying to clear things up for me..

--Cameron

 

Sailaway21,
Are you advocating a tender boat to reduce the ultimate stress in the rig? It would do that but isn’t a tender boat more likely to be rolled over and that puts a greater strain on everything then just the wind load no matter what the wind speed is. Very few boats roll and come up with their rigs intact. So, I think preventing a rollover is high on the list of things to do when in extreme conditions, at least in my play book

If you look at the amount of area under the curve of righting moments for a given design you will see that it takes more energy to roll over a stiff boat then a tender one. I suspect that this means a stiff boat needs a larger, steeper wave to be rolled over compared to a tender one. But a boat with less draft is more likely to slide instead of trip in this situation so a stiff shoal draft boat would be more seaworthy then a deep draft narrow boat such as was popular during the CCA days. I think this is contrary to popular belief and people imagine the perfect offshore boat to be full keel deep draft heavy and narrow. I am beginning to think the perfect boat is wide, (not as wide as today’s boats) stiff and has less draft then in the popular notion.

Now add to this the published report that a wide stiff boat will stay with the profile of the wave and keep her deck edge above water. A tender narrow boat will roll easily and put her deck under which drops the righting moment suddenly and I think a roll is now just a heartbeat away.

Is a stiff boat more uncomfortable? When you get into the type of weather where the boats survival is in question I wouldn’t worry too much about comfort. Besides, in that type of wind speed the boat is held down by the wind so stability and comfort aren’t tied together. Comfort is now related to wave shape and size. If you have more then 80 knots of wind and seas larger then 60 feet any boat is going to be uncomfortable and the key question is now survivability. This is not to say that when bashing to windward in 30 knots comfort shouldn’t be considered a factor. But now its longitudinal stiffness and not stability that determines comfort. Sailing on your ear isn’t uncomfortable but pitching is. Now the best boat is exactly the opposite thing. A deep narrow boat pitches less then a wide flattish bottom boat does. I don’t plan on spending much time going to weather so my Tartan 34C is the best compromise for what I do right now.

In the end it’s six of one and a half dozen of another. All combinations of beam, draft and displacement have been at the same time successful and unsuccessful. The two factors that have had the greatest influence on survivability, every time, time and time again have been luck and skill not boat shape or size.
All the best,
Robert Gainer

 

I haven't seen more than 40 knots or so, but now I've seen that speed in a narrow fin keeler and in a larger full keeler and the movement is considerably different. The full keeler's movement is definitely more ponderous, and considerably drier (although this could easily be a function of freeboard).

The fin keeler is far more responsive, but it is easier to get "whacked" by a wave mid-tack and it is sometimes hard to get back on course, whereas the full keeler just more or less plows onwards.

Basically, none of this is news to experienced sailors, but it confirms not only what I've read but what I think is going to be more "seakindly" in the long run for us: the full keeler. Yes, we will spend a few extra days on passage, but I can see actually sleeping in 12 foot waves on the new boat, whereas the old fin keeler, while fast, is far too "snappy" to consider sleeping in such oceanic conditions. I mean, I suppose I could, but only with a multi-person crew to "spot" me. The racer-cruiser simply demands a lot of active sailing that the full keeler doesn't.

 

I don't have enough information to know the answer to this, but aren't full keelers built with considerably more displacement than fin or even cutaways? If that is the routine, then it would also be a function of weight, and where it is put, not just the length of the keel. I am of the opinion that it is more than just one thing. Shape of the hull, ballast, displacement, and keel, all contribute together. I would believe that you can have a very seakindly boat with a cutaway or even fin keel if the rest is designed right. That is what I see with a lot of modern, well respected, "open ocean" boats.

 

Yes, it's more than just one thing. Full keelers present more lateral resistance in some respects, hence the reputation for good tracking under windvane, but can't get the CG super low (like a "shark" on a stick... ). Internal tankage becomes critical then, as does the total wetted surface. I definitely sacrificed total potential speed for comfort, tankage and a certain amount of "bombproofing" that a steel hull, a box keel (think like a narrow but extremely elongated wing keel, a keel-stepped rudder and a slight improvement in draft. This represented a good compromise, because I didn't have the money for a robust fin keeler with a skeg-hung rudder and a waterline 90% of the total length. There are few boats out there like that, because there are few people out there willing to pay a premium for a performance cruiser that falls on the cruiser side, rather than the racing side.

Shearwater 45, anyone? Put a skeg hung rudder on it and it's near perfect.

 

While all the talk about a suitable boat is fine don’t forget the luck factor in the equation.

Good luck bad boat bad skipper
Good luck bad boat good skipper
Good luck good boat bad skipper
Good luck good boat good skipper

Bad luck bad boat bad skipper
Bad luck bad boat good skipper
Bad luck good boat bad skipper
Bad luck good boat good skipper

I have known all of the permutations containing the bad luck factor to not make it some of the time. But I have also known some to survive the bad bad bad combination just because the amount of any one category bad was not sufficient to sink the trip. And bad luck with good boat and good skipper will usually survive because the right decisions with good equipment will save the day most of the time.

On the other hand I don't know of any trips that failed while containing the good luck factor even with both of the other components of the equation being bad. I think in the end good luck is more important then skill, experience and proper choice of boat.

But even if you can't control luck you can control the good boat part and good skipper part of the equation and then you have a better chance of succeeding instead of leaving everything to random chance and make no effort at selecting a boat and training yourself or doing any preparations at all. But it is unfortunate that we can’t control luck.
Good luck and all the best,
Robert Gainer

Early in the day waiting for the crew so we can start the engines and get to work. We are escorting a kayak race today.

 

Robert,

Doesn't the factor of safety calculation depend on what stress you assume to be the ultimate stress for which you are designing?

Bob Perry's calculation of FS=4 could result in the exact same specification as RichH's calculation of FS=6 if they are considering different ultimate stress criteria...?

 

I think this quote from Eric W. Sponberg sums it up better then I could. Just to put this person into perspective, Mr. Sponberg is a life member of the Society of Naval Architects and Marine Engineers as well as a licensed Professional Engineer in the state of Connecticut. Mr. Sponberg is also a corporate member and licensed Chartered Engineer of the Royal Institution of Naval Architects in the United Kingdom. He has a naval architectural degree from the University of Michigan. He is a contributor to both technical and popular magazines and a former technical editor for Cruising World. His web site is www.sponbergyachtdesign.com. The snippet by the way, is from a thread discussing mast design originally appearing 7-20-06 on www.boatdesign.net.

START
"There is not really any "rule of thumb" because generally the loads are pretty easy to identify, and they all come from the righting moment of the boat. Typically what I and many designers do is assume that the wind loading on the sails is equal and opposite to the righting moment of the boat. This moment is assumed to come from a distributed load along the mast multiplied by the center of its area above the waterline or above the CLR, depending on how you like to design. "Skene's Elements of Yacht Design" by Francis Kinney (therefore what used to be standard practice by Sparkman and Stephens) assumed that this distributed load along the mast was uniform, i.e. a constant value up the mast. Other designers such as myself assume that the load is larger at the top of the mast, smaller at the bottom. In my case, the top half of the mast is uniformly loaded, and the bottom half of the mast has an increasing distribution from zero at deck level to the same value at mid-height as the upper half of the mast. To summarize, then, the lower half of the mast is a triangular load distribution, and the upper half is a uniform distribution. The total moment of these two distributions (center of its distribution for each area to the waterline) is equal and opposite to the righting moment of the boat.

I hope that's clear. This is a live load. Therefore, you need some factor of safety on top of that somewhere in the analysis, either an allowable stress under live load, or multiply your live load by some FoS and calculate back to the yield stress, ultimate stress, or buckling stress, whichever is appropriate. Typical factors of safety may be anywhere from 1.1 to 4.0. My personal belief is that if you have to use a FoS over 5.0, you don't know enough about the problem to engineer it properly. FoS over 5 and you are overbuilding.

So to answer your question, there is a fairly well defined procedure for identifying the loads, therefore we don't need to rely on a "rule of thumb"."
END
All the best,
Robert Gainer