Swain BS_36 Stability curve

Discussion in 'Stability' started by junk2lee, Mar 9, 2011.

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  1. welder/fitter
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    welder/fitter Senior Member

    My point was, as you probably recognized, aimed at trying to get Brent to recognize that going offshore in any marine vessel may teach one many things about what works & what doesn't - in comparison to day-sailing in protected/unprotected waters, but it doesn't teach the fundamentals of design.

    While I thank Wynand for the compliment, I don't ever consider myself an "expert", just someone with some degree of knowledge about welding. Ad Hoc, Mike Johns, Wynand, & others, may be far more knowledgeable than I in many areas. I just contribute where I can, have put in a lot of years welding, inspecting, & have inherited a phenomenal resource library(my father's). The vast majority of my practical experience is with stick & flux-core(ss & gs), however, with my mig work being mostly aluminum.

    First, I agree with Tom, that the wire manufacturer will give you the best mix for a given wire. Having said that, While I can only assume that prices are on a similar scale to here, I'd suggest Argon & 1-2% Oxygen. With "mig", imo, you'll want very clean surfaces/edges, post-heat to cool slowly & uniformly to reduce surface granular corrosion & cracking(stainless is more brittle than mild steel), and you'll want to keep your whip as straight as possible because the wire is stiffer and will wreak havoc on your liner & cause bird-nests. A tri-mix, 90%He-7.5%Ar-2.5%CO2 for instance, is good for welding stainless, but why complicate the situation & increase costs further?

    The benefit of using solid wire over stick is that you'll find better penetration & less distortion(higher travel speed). But, you really have to watch for "holidays" with the wire, get into those corners/edges.

    There are several people on these forums who are very well-versed in using solid wire, but I often forget usernames, so you might search "mig welding". Murielle & Mark come to mind, Kmorin - who Dean Smith mentions - is?/was on here, as well.
     
  2. pdwiley
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    pdwiley Senior Member

    How true. I have far more sea time than Brent has, for sure, in far more 'robust' environments, and I wouldn't design a dinghy. The main thing I learnt from spending a number of years at sea in the Southern Ocean was to not go there in anything smaller than a 6500 tonne ship.

    Sitting at anchor in a bay doesn't count as sea time.

    I strongly suspect that the majority of his time at sea is on the milk run from Canada to the South Pacific anyway and that's not difficult sailing. There's a 2.7m (yes, I *mean* 2.7m) aluminium sailboat in the Brisbane Maritime Museum that managed the trip from Canada to Australia.

    One of the biggest hassles here is bottle rental. It adds up fast. I hate paying it but there's no alternative and I already have 2 - oxygen for cutting and the Migshield. The gas is expensive but that's the cost of welding. Flux cored wire is more expensive.

    Post-heat isn't really going to be possible - well, pretty unfeasible anyway. Nearly all the welds I have in mind will be horizontal/vertical fillets, pretty much the easiest weld to do regardless of weld option. Only exceptions are for the cabin trunk door openings where I plan on using some 50x5 s/s flat bar so probably vertical-down welds on both sides. I'll have to experiment a bit to get the feel for how the stainless wire behaves. I thought it would be somewhat more ductile than the carbon steel wire.

    I may end up using the stick electrodes for all the H/V welds and just use the MIG for vertical and overhead welds. It sounds worth trying the standard gas mix before getting another bottle. Time to weld up a few coupons and then break them I guess.

    PDW
     
  3. Dean Smith

    Dean Smith Previous Member

    there was some debate about a builder who had no sailing experience, being able to build sailing yachts
    Well there are sailing yachts and sailing yachts
    For anything that is designed with some performance in mind, a builder needs experience
    Often a design will not have dwgs for placement of blocks, running rigging , boom brakes and many other things
    Often if he is a good and experienced sailor he will see things on plan and make changes
    Once when choosing a design for myself, I got hold of a set from C.Paine, and the attention to detail on deck left nothing to guess at. Mind you for the price one would expect such
    I had a couple of excellent wood finishers with me and when I tried to explain how boats fell metres off of waves and the loads and shock that came on things like hinges on open doors etc they simply could not comprehend
    if I was a person contemplating a build and was checking out yards I would look at that side of thing carefully, if two yards had equal skill, but one had only built power I would certainly not choose that builder unless I was on site to manage the job
     
  4. Ad Hoc
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    Ad Hoc Naval Architect


    Whole heartily agree with these statemens.

    I cook every day, does that make me a professional/expert cook like Jamie Oliver??!!

    One must differentiate between “quality” and “quantity” in such throw away statements as we get from BS et al.

    I think you do yourself an injustice, you have far more knowledgeable than perhaps you realise…or just very modest.

    A builder, needs experience in building and the methods of fabrication and what is the right way and the wrong way…anything else is a bonus. The emphasise here is on the “builder”, not “designing/er”.

    But, anymore “experience” leads into a different aspect of a “builder”.

    If a builder is supplied every single dwg required, then the builder just..well, builds, as per the dwg. Thus their skill and experince in building is more important.

    But, if the builder has just a handful of dwgs, (because they are too much of a skin-flint to buy a proper full set or they don’t have a full set, or whatever reason) then the builder will be required to “gap fill”.

    The gap-filling also has no perquisite for sailing per se. It helps, but it is not a requirement to provide a quality build. Knowing which winches to use and how to fix them to the deck is a role that the builder may under take, for example, owing to lack of information.

    And just as in the statements above, doing this for years does not automatically assume quality or “design” on the part of the builder, because they have done this for years.

    Knowing the correct sequence of ********/welding etc is far more important than whether the builder knows which winches to buy! Job knowledge in their field, fabrication, in this case boats, is the essential element. Since a welder that erects structures for skyscrapers, for example would not be my first choice to weld a boat! Not because their “quality” is questionable, but simple they would not know the correct sequencing for ********/fabrication of a boat. Thus will create problems and mistakes and errors which can be avoided.

    That’s a shipwrights job (even more so if details not provided on any dwg). Not a welders/fabricators job. Nice if they know such stuff, but I would rather the builder knows how to fabricate properly and the shipwright knows how to read a dwg and when the dwg is wrong and state reasons why; such as door hinges are facing the wrong way.

    Anyway, this I far removed from the Stability, or rather lack of providing any stability data of any of BS’s boats.
     
  5. Jack Hickson
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    Jack Hickson New Member

    Winston's hull was 1/8th inch, no transverse frames of any kind. No problems going through the NW passage, not even a dent. Winston designed the pilot house.
    You guys continue to claim that a boat which has proven it's ability to survive 16 days in large surf, and was pulled off through 8 to 12 foot surf, being lifted and dropped on hard sand every wave for 1/4 mile ,without any serious damage ,is not strong enough , but a boat which would have broken up in minutes in the same conditions which is" approved" according to your calculations , is strong enough.
    Wynand, on another site, said he prefers plywood boats to steel . Would he feel safer in the conditions he described, in a plywood boat? Who would?.
    Is this the type of judgement one should base ones choices on?
     
  6. Dean Smith

    Dean Smith Previous Member

    John you are very opinionated, you make statements which you insist are facts, you never say -I think-- or IMO

    your opinions are always facts--- builders of small ships
    Well we do not have hinge size on dwgs
    Also builders of small sailing and yachts, we do all from hydraulics to electrical, from paint to weld, to form plate to design structure. We have to, if we did not we would sell nothing, the costs would simply balloon
    From your website you are not involved in small sailing yachts
     
  7. Nurb
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    Nurb Junior Member

    Numbers are facts. I think we assume what someone says is their opinion if it isn't backed up by calculations or factual examples that are documented.
     
  8. Dean Smith

    Dean Smith Previous Member

    I am not talking abt number crunching I am talking abt statements such as-- that is a shipwrights job-- and so on .I am not in a position to talk higher math.
    I am a practical boat builder-- and was an employer of many trades people
    and to welder/fitter
    i had to remind Wynand not to say ONLY A BOATBUILDER You are good at what you do, I know this and I am good at what I do
    There is no Hierarchy here, only in your mind, so hold your head up :)
     
  9. welder/fitter
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    welder/fitter Senior Member

    Well, it has been a long time but as I recall Dove III had transverse framing, a centreboard, & I still believe that the skin was thicker, but could be wrong, it's been a long time.

    As for the "16 days in large surf..." I've never claimed anything, although I have been told that the mantra is much exaggerated. As I consider "he said/she said" to be anecdotal, at best, I've never felt it of value to state that (Name) told me...
     
  10. welder/fitter
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    welder/fitter Senior Member

    I don't think that I suggested that there is a hierarchy here, but I have learned much from yourself & many others & can assess my own level of knowledge & skill set in comparison. Sure, every once in a while someone comes along & hoodwinks me, but sooner or later I see enough evidence to "clue-in". As an example of weaknesses I recognize that I have, the days I spent with Tad Roberts made me realize how very far I need to go in both my cad skills & design knowledge.
     
  11. welder/fitter
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    welder/fitter Senior Member

    OK, Brent, we've heard about the "16 days.." and the "T-boned a barge", many times, but why not talk one of the owners of a BS36 into dropping by Tad's? Sure, you will get some static from some folk if the numbers suggest less than decent stats. But, who cares, you just tweak it a bit here & there until things are more reasonable. From my perspective, egos are for politicians, not designers and/or builders of boats.
     
  12. Wynand N
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    Wynand N Retired Steelboatbuilder

    Brent Swain, read this carefully, step out of your little universe and ideology and understand what I try to tell you.

    For starters, do not use my preferences of building material to promote your steel bins, and therefor since I prefer another material than your universe of steel, make the statement of my preference being poor judgement....

    Yes, I did said I prefer epoxy strip molded plywood hulls over steel and for your benefit, just said it here as well. If I have to build myself another boat now, it would be just such a boat.
    These boats are light, very strong, fast and relative cheap to build. Wont have rust problems etc etc. Any decent shape is possible - something you would not understand looking at your narrow boxy creations. Im not interested in derby demolitions to proof strength of a boat which speaks of the mentality (lack of) issues to proof something by doing this. Furthermore, stranding and collisions are not an issue since that is the makings of poor seamanship and lack of discipline of the skipper.

    Because Im a qualified boilermaker, I built boats in steel because it is a material Im comfortable with but that does not mean it is my favorite or best material at hand. I had built boats you can only dream of like the Dix 65 and Dix 57 for example and many other types as well. I had seen it all in steel, being there done that - more than you can lay claim to.
    But, I had ALSO built boats in GRP during and after my last steel built and still doing it but on much smaller scale from home after my retirement.

    And still you have the audacity to ask people if my choice of building medium is a wise one to base a decision upon. This is the remark of a fool to be blunt and straight in your face.

    By the way, have you looked around you or anywhere in the world for that matter which is the material of choice for sail boats (or power) under the 70ft range :?: Yes. like it or not, its GRP, and does that make it a sub standard material because it is not steel?? Can all these people decisions to own such a boat be foolish? I would venture to say that at least 90% of all boats in this range are GRP with steel, alu and wood etc making up the other 10% . Get real man.
     
  13. Dean Smith

    Dean Smith Previous Member

    Wynand

    yes Steel Alu, we have betwixt 2 of us built many
    BUT if I had a choice for under , say 70 feet, I would get Greens of Eng. to build me a carbon yacht .
    I stand corrected, but i think down under steel leaves a lot to be desired, whereas in say Netherlands one can be assured that at least you are buying ship grade staal.
    USA does not have a tradition of fine steel builds, nor does Canada. I will not put BS down, perhaps we should all chip in buy him a ticket to HSWAW boat show on water in Holland. Maybe then he would realise.
     
  14. pdwiley
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    pdwiley Senior Member

    I think that has a lot more to do with economies of manufacture once you've got a mould rather than the inherent structural advantages of GRP.

    WRT epoxy/ply, I agree with you but I'd never build one. I thought about it but didn't want to deal with the epoxy. I'd happily own one however.

    I'm building in steel because I prefer it and it is a far better match for my navigation abilities/seamanship. The mishap that holed & trashed Hal Roth's GRP yacht in Patagonia probably wouldn't even have dented my Witch (or even a BS 36). Bernie Harberts hit a wreck coming into East London, skidded straight over the top. A GRP boat would likely have left its keel behind.

    If I was rich I'd build round bilge in cupronickel.

    PDW
     

  15. Jack Hickson
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    Jack Hickson New Member

    If I won the lottery tomorrow, I wouldn't change boats. What I have suits perfectly the type of cruising and lifestyle I enjoy, It's my third ,a product of 40 years of refinement, to fit my personal needs. If you gave me a 70 footer ,I would sell it immediately, before its costs and complexity screwed up my lifestyle.
    Fibreglass was cheap, but no longer so, if properly built, given todays costs of materials and labour.
    Origami building methods has brought the cost of a new steel boat within reach of the not so rich , both in terms of time and money.
    It never was anywhere near as strong and forgiving as steel . Promotion, salesmanship and mass production, and the time consuming , outdated building methods of steel have given FG an advantage for many years, for those who want to simply buy whats available. For a boat which spends 99% of its lifetime in a marina , which most do, FG is definitely better.
    With so many older, but better FG boats being practically given away, for a fraction the cost of materials in them, a new FG boat makes no sense at all.
     
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