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Go Back   SailNet Community > Skills and Seamanship > Seamanship & Navigation
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Seamanship & Navigation Forum devoted to seamanship and navigation topics, including paper and electronic charting tools.


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  #11  
Old 09-15-2007
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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)
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  #12  
Old 09-15-2007
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Gasp! Can this be? SD is coveting a lead-mine monohull?!?
Nah... I want it to sell... and finance buying a big Chris White trimaran.. Besides, I wanted to put it in terms you lead mine sailors would understand...
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  #13  
Old 09-15-2007
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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

Last edited by catamount; 09-15-2007 at 09:10 PM.
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  #14  
Old 09-16-2007
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Originally Posted by bestfriend View Post
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).
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  #15  
Old 09-17-2007
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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.

Last edited by RichH; 09-17-2007 at 10:56 AM.
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Old 09-17-2007
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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...
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  #17  
Old 09-17-2007
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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.
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  #18  
Old 09-17-2007
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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.
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  #19  
Old 09-18-2007
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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 ľ” 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

Last edited by Tartan34C; 09-21-2007 at 07:23 PM. Reason: Added the word “why”
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  #20  
Old 09-19-2007
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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.
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