stability steel yachts

[Guest]

First post, new member, new thread => Beginner
Now that's out of the way.
I've managed to do my RYA Cmpetent Cew and Day Skipper stuff and presently working my way through my Yachtmaster's Theory, most enjoyable I must admit.
I haven't got a lot of experience you might say but I plan to do something about that.
I've read through many of the posts here and very interesting some of them are as well. Problem for me though is I need a boat. The added problem is an argument that I'm sure has gone on many times and that's what material do you choose. I don't know much about wood and less about grp so I've narrowed the field down to steel. I feel more comfortable with steel from a personal point of view and from some of the stuff I've read.
One of the factors that I have yet to explore, and it's a prime subject for me, is the relative stability of steel vessels over grp or wood. I agree that design criteria can produce any outcome that you want but I wouldjust like to be able to look at some curves for like for like vessels of different materials.
I read somewhere about steel bottoms and aluminium tops, presumably from a centre of gravity benefit so there must be some issue out there. I've searched around online for information but not found anything yet that has overcome my concerns or thoughts.
Anyone point me in the right direction please?
Oh and another thing does anyone know anything about a vessel type, steel, called a carrena 36'. I was also looking at the van de stadt 34.

 

[AndrewB]

There is a definite issue with stability in steel boats. Steel yachts cannot just be copies of GRP designs, and the fashionable deck house designs in particular can produce unstable yachts. Problems are frequently caused by amateur builders trying to add extra headroom to a perfectly good steel design. You must expect a deep draft, low headroom boat for a stable steel design, probably using lighter gauges of steel on deck than in the hull.

There is also a long-term maintenance issue with steel, even with modern epoxy coatings.

Set against that, steel is cheaper, a good deal tougher than other materials specially in situations like grounding on coral, and if you can weld, much easier to work.

My feeling is that unless you plan blue water cruising and are looking for a boat 36ft or more, it is better to go with GRP if possible.

There was a good, if very negative posting about the problems of steel recently on the Cruising World forum: see http://old.cruisingworld.com/forums/arch_066/index.pl?read=233678

 

[Mirelle]

Snap. There is a real problem with stability in steel boats. This is the Dark Secret of the steel boat fraternity.

Mixing metals was popular a few years ago but on the whole it is a Bad Plan; the combination of aluminium deck structures and steel hulls was very popular once, and the late SS Canberra was a good example. It did not stop her having a stability problem; she had 800 tons of cement in her bow for the whole of her long life! One America's Cup defender of around 1900 had aluminium topsides, steel frames and bronze underwater plating; she fizzed to pieces in a matter of weeks.

It is worth mentioning that the secondhand value of old steel boats is particularly low; this may be unfair to owners of good ones but it is what the market says.

Steel is good in large sizes; in smaller sizes there are other materials.

(By the way, Andrew B has a steel boat and I have a wooden one!)

 

[Guest]

Posible solution though I havent seen it done might be to loog at steel hull with wood, probably cold moulded or ply, topsides. Could reduce wt without galvanic problems. Wood composites are more stable than 'natural' timber and can have better strength wt ratios than steel for small ships. Topsides shapes are relativly simple and mostly flat or simple curved panels so the construction is simple ie bolt to steel frames. A word of caution though, if you look at fully encapsulating timber it looks great on paper but any fault can lead to the structur 'filling up' and the core rotting - wood needs to breath to last!

Roly, Voya Con Dios, Glasson, Lancaster http://www.voya.pwp.blueyonder.co.uk//MW1/Intropage.htm

 

[Ohdrat]

Aren't the BT Global Challenge boats steel.. but for a first boat I am going for grp.. the early ones 60's and early 70's were over built.. but many have the relatively deep and narrow hulls with little head room.. ho hum its all swings and roundabouts

 

[ean_p]

I think that this issue is really a function of size...that craft that are too small for the material...but beyond 36 ft I get the impression that the tables are slowly turned and that size for size a steel craft slowly becomes relatively lighter as the specified scantlings do not need to be increased as they do with other materials as there is adequate strength in them already...indeed that is the problem with smaller craft...the material is far more then is really necessary to do the job...but has that sizing in order to be worked well......as to maintenance, in general more then grp and less then timber. As to safety second to non and as to resale value...well a good boat has a good price re the Jongerts and Koopmans of the Dutch and a rust bucket is a rust bucket in much the same way that a rotten tub is a rotten tub. I think that each of the materials have their proponents that like the advantages of a particular material....for me its steel...I like its intrinsic safety and the fact that I can cure most problems with a cheap welder and an angle grinder at a pinch though it won't look pretty, and there is almost nothing a couple of days in a plating shop wont put to rights.....I'd dread a collision at nite with a baulk of timber or worse in a grp boat...or rot in a keelson in a timber boat......but there you go...what I do know is that she looks great (mmm fully round bilge and looks like plastic from 50 paces) and goes like a furry when she picks her skirts up and has full head room through out almost....what more can I ask for....

 

[johnsomerhausen]

Won't go in details about stablity, but I can tell you I saw a Dutch van de Stadt 34 at Puerto Williams (in the Beagle Channel, not far from Cape Horn) in 1992. Should tell you something about the design's seawothiness....
john

 

[summerwind]

I agree with all of the above (Well, most of it).

I started in cruising boats with GRP but as size increased (Both boat and beer belly) I migrated to steel. My current boat I bought as an almost abandoned project which had been professionally built to "Sailaway" stage but with an home built fit out - as far as it had gone. I was able to buy a much bigger boat than I could have otherwise have afforded. The great advantage as far as I am concerned is that I am able to sail when the weather is right and continue fitting out when it isn't.

I enjoy the safety that steel provides. I have ample head room and can walk upright almost throughout the boat. Yes, rust could be a problem with steel but if the hull is built from steel which has been blasted with zinc(?) at the production stage, it is much less so. Modern epoxy coatings are excellent. The only time I have problems is when I don't clear up the swarf properly after drilling etc.

One other small niggle with steel - because the boat is that much heavier, she is no racer. In light airs it is a real pain. The opposite is of course true, when the GRP hulls are bouncing around with three reefs, I am at maximum hull speed, driving through the seas as if they are not there and grinning from ear to ear.

I suppose you pays your money and takes your chance.

Good luck!

 

[jeanette]

Gaia is steel and I was grateful for it when we struck (what looked like) a telegraph pole when doing 5 knots off Beachy head this week-end! The long keel probably saved the prop too.

J

Jeanette