The pro's and cons of steel boat building

[rotrax]

thanks for that Roger, very interesting article.
As for those welding pics in the other posts, well not very good, but it does not have to be very pretty to be pretty strong. There are plenty of agricultural bodge welds that hold. However I would be very concerned about porosity as well as strength.
At the end of the day if he wants to sail a boat welded like that then that's fine for him.
But I do hope he has not welded anything up for anyone else. For someone who extols the virtues of a monocoque there also appears to be little understanding of what may or may not be structural. Anything that is welded to a monocoque imparts a load across the stressed skin , and the flex of the skin imparts a load across those welded members.

You are wasting your time-BS will not understand.

His empirical testing consists of lashing one bit to a mature tree, the other bit to a car and then driving the car away.

It it dont break, its OK.............................................

 

[solent clown]

You are wasting your time-BS will not understand.

His empirical testing consists of lashing one bit to a mature tree, the other bit to a car and then driving the car away.

It it dont break, its OK.............................................

if it does your rear windscreen is gone, lol

 

[Daydream believer]

Re picture post 471...............................Thing is that tradesmen with skills tend to make everything properly. By that i mean that the joiners that I employed in my workshop would cut a joint properly even if it was for a simple item. A skilled welder would make the welds in the picture above properly because it would come naturally & he would find it difficult to bodge in that way. One would not need to "grind" to tidy it up it would be perfectly fine first time round. I would suggest that whoever welded the parts shown were not skilled in the art of welding & not capable of welding something like a yacht properly ; regardless of their protestations to the contrary

 

[Brent Swain]

Gunnery targets are built to be relatively cheap but they are built by professional welders; a shit weld doesn’t save any money over a decent one.

This is the quality of fabrication and welding that Brent is happy to display on his promotional DVD:

Go bounce that lot off a reef?

Pete

The keel along that side is 8 feet long, attached to 3/16th plate, tensile strength of 11,250 lbs per linear inch. Times 96 inches gives me 1,080,000 lbs total tensile strength, on a boat under 20,000 lbs. The outside of the keel another 1,080,000 lbs, times 4, for the entire tensile strength of the keels attachement. Another 1,080So how relevant is that little bit ,structurally . It ties the keel web into the side of the tank top, triangulated off the centreline, 8 ft of tank top, a fully welded, horizontal 3/16th steel bulkhead, a curved side meeting a curved hull plate, and a curved keel side, a super strong point. Can someone post a picture of a stock twin keeler ,with a stronger attachment of keel to hull. On BD.net, they claimed that was not strong enough, then, after banning me ,praised the stock boats , with only a foot of keel attachment to the hull , on plastic boats!
You CAN'T determine the strength of a 6011 weld, by looking at the slag on top of it! It was ground after this photo was taken , and another pass made over it. Even with a smooth weld ,best grind it , before making another pass over it. Otherwise, slight bumps get magnified with each pass.
At any rate , that piece is buried in foam, and never seen again.
On BD,net I suggested one can fair a hull considerably from inside, with a hydraulic jack on a telescoping pole and with some flat bar welded in.
I was attacked and ridiculed, for suggesting that what the steel looks like inside ,behind the foam, is less important than avoiding the need for excessive fairing compound on the outside.
Perhaps steel boat builders question my building times, based on the naive assumption that I waste as much time on things which don't matter, as they do.
Before wasting huge amounts of time on things which don't matter, ask your self how important it really is, and save your energy for that which is important. That is what prevents a one year project from turning into a ten year project. The armchair critics are not doing the work for you!
My welds have survived pounding for weeks in big surf , on lee shores in open ocean swell , a far better test than speculation ,based on looking at the top of 6011 slag. None has ever broken , in over 40 years of steel boat building, and hundreds of thousands of miles of cruising.

 

[john_morris_uk]

Brent, can I just check something with you? Is the first part of the above how you calculate keel loads and strength requirements for the keel attachment?

May I ask how you calculate mast compression loads and rigging loads to know what size mast section and rigging sections to specify?

 

[solent clown]

utterly irrelevant when nothing is properly welded anyway. In my previous post I was trying to be a tad diplomatic. BUT FRANKLY YOUR WELDING IS Appalling, DANGEROUS, AND AN EMBARRASSMENT. Just because you assert nothing has broken yet it does not mean nothing will. My little boy could make a batter job with a set of jump leads , a battery and a coat hanger. That is no joke. He could.

"You CAN'T determine the strength of a 6011 weld, by looking at the slag on top of it! It was ground after this photo was taken" what you mean is YOU cant tell. You have no idea whatsoever what on earth you are doing, You scare me. I am very glad you "sail" the other side of the pond.

 

[rotrax]

As I have suggested many times before, I believe BS comes within the scope of a little Irishism I heard at the Skerries 100 in 1978.

A local hero, loudmouthing it in the pits about the speed of his bike and his skill as a rider was told, very clearly, by a senior competitor who held the IOM lap record at the time :-

" Shut the ( four letter expletive, left out for fear of the mods) up! Sure, you are a figment of your OWN imagination! "

It worked that time.

Not so sure with BS though............................

 

[DownWest]

Brent, can I just check something with you? Is the first part of the above how you calculate keel loads and strength requirements for the keel attachment?

May I ask how you calculate mast compression loads and rigging loads to know what size mast section and rigging sections to specify?

Good luck John
His calcs are based on the strength of steel, not how it works in a structure, or related to welding. Elswhere, there were comments about some of his earlier efforts had 'waggy' keels due to lack of transverse framing . Probably all lies, doubtless from 'plastic' salespeople
I think I noted earlier that there were offers of help from known NAs on the calculations, when he showed some ignorance on the subject. Brushed off as not needed.

 

[JumbleDuck]

Good luck John
His calcs are based on the strength of steel, not how it works in a structure, or related to welding. Elswhere, there were comments about some of his earlier efforts had 'waggy' keels due to lack of transverse framing . Probably all lies, doubtless from 'plastic' salespeople
I think I noted earlier that there were offers of help from known NAs on the calculations, when he showed some ignorance on the subject. Brushed off as not needed.

It would be interesting to run a finite element analysis on one of his designs. The chined hull itself ought to be pretty strong, but the devil will be in the detail of attachments of (as you say) keel, (as john_morris_uk) says rig and so on. It get the impression that these are not ocean racers and do not spend much of their lives thrashing to windward, so the sailing forces may not be terribly high.

 

[john_morris_uk]

Good luck John
His calcs are based on the strength of steel, not how it works in a structure, or related to welding. Elswhere, there were comments about some of his earlier efforts had 'waggy' keels due to lack of transverse framing . Probably all lies, doubtless from 'plastic' salespeople
I think I noted earlier that there were offers of help from known NAs on the calculations, when he showed some ignorance on the subject. Brushed off as not needed.

Give him a chance. I haven’t asked about how he calculates the prismatic coefficient or what he considers a desirable half angle of entrance to be yet.

I don’t mind people tacking together rough and ready steel boats in a field but when you start selling the designs and encouraging people to build and sail them and make extravagant claims about them then there are responsibilities involved.

 

[dom]

Give him a chance. I haven’t asked about how he calculates the prismatic coefficient or what he considers a desirable half angle of entrance to be yet.

I don’t mind people tacking together rough and ready steel boats in a field but when you start selling the designs and encouraging people to build and sail them and make extravagant claims about them then there are responsibilities involved.

The most occasional glance at this thread confirms what must be apparent to all: a self-esteem problem, age related, a dose of the blues, who knows. But something isn’t right as those tragic welding pictures make painfully clear.

And let’s not make any pretence that some unsuspecting punter might stumble on BS’s ‘designs’ and set to work. That isn’t going to happen, is it?

Surely we’ve poked this poor bear enough? Our own mothers would have told us so.

 

[john_morris_uk]

The most occasional glance at this thread confirms what must be apparent to all: a self-esteem problem, age related, a dose of the blues, who knows. But something isn’t right as those tragic welding pictures make painfully clear.

And let’s not make any pretence that some unsuspecting punter might stumble on BS’s ‘designs’ and set to work. That isn’t going to happen, is it?

Surely we’ve poked this poor bear enough? Our own mothers would have told us so.

You’re probably right. However it appears that he’s very persuasive to some people but hopefully these same people are savvy enough to do a bit of research and find threads like this.

Otherwise they’ll just find the Origami boat website that deletes all criticism or difficult questions. (And I believe is moderated by Brent etc)

 

[dom]

You’re probably right. However it appears that he’s very persuasive to some people but hopefully these same people are savvy enough to do a bit of research and find threads like this.

Otherwise they’ll just find the Origami boat website that deletes all criticism or difficult questions. (And I believe is moderated by Brent etc)

For sure, woe betide anyone who unquestioningly ventures down this path; the lack of scantlings, structural calcs, and official accreditation brings caveat d’emptor to the table in its most literal sense.

That said, I would say that more insidious risks exist on a public forums, not from the odd eccentric, but from those who give equally bad advice, just in an altogether more convincing way. Even there, most forumites I have met have turned out pretty much as imagined.

Speaking of which, since you’re in the Solent now, why not pop over to Cherbourg if you happen to be free w/e 22/23 Sep?

 

[john_morris_uk]

Speaking of which, since you’re in the Solent now, why not pop over to Cherbourg if you happen to be free w/e 22/23 Sep?

Regrettably I’m involved in a couple of things that weekend that it’s impossible for me to get out of. One of which is a diamond anniversary of the building of a public building I nominally own. I can’t not be there for the party that’s planned.

 

[Brent Swain]

Brent, can I just check something with you? Is the first part of the above how you calculate keel loads and strength requirements for the keel attachment?

May I ask how you calculate mast compression loads and rigging loads to know what size mast section and rigging sections to specify?

Boats of the same size and specs, which have done tens of thousands of miles of ocean cruising , all have the same rigging and spar sizes, regardless of how many time they are calculated, or how many $175 hours to you pay a con artist to calculate it.
I just sold a set of plans to an Alaskan who sailed one of my 36 footers to Australia and back with a steel mast. Then he put an aluminium mast in, and did a couple of more years around the S Pacific. Couldn't notice any difference.
Bob Perry mentioned designing a super light carbon fibre mast for a boat ,at great expense. After circumnavigating Vancouver Island, Perry asked him if it made much difference, and the guy said he couldn't notice the difference . Several of my 36 footers have gone from steel to aluminium masts, and all said the difference was minimal. I use 5/16th rigging wire on my 36 , 11,500 tensile strength, which Moitessier had on his 40 footer, and none ever broke.
That is pretty standard on cruising boats 40 ft and under. I advocate 3/8th for a 40 footer. There are many boats the size of my 36 which use considerably lighter wire, for decades with no problems. The difference between 1/4 and 5/16th is about 17 lbs total, centred below the half way point.
Ditto mast sections. Whatever has worked for the same size boats, for decades and hundreds of thousands of sea miles, with no problems, will continue to work. No serious penalty in going for a bit bigger section, if one comes up . Most use what we can find free or cheap. That is why we go full time cruising, while others go to work for another ten years, to pay the con artists.
For keels, Skene's Elements of Yacht Design specifies around one sq inch of keel bolt cross section for every 1500 lbs. For my single keel 36 , there is over 40 ft of 3/16th plate holding the keel on at 11250 lbs tensile per inch, 5,400,000 lbs tensile strength for a 5700 lb keel . I think that is a good safety margin. 90 sq inches cross section, where under 4 sq inches is considered adequate. Similar overkill for twin keelers. Can you post pictures of drawings for plastic boats with that kind of overkill?That is typical of the difference between steel and other, non metal materials . Steel is almost invariably, a huge overkill.

I suspect the reason keels fall of modern boats is because they don't do "public school" engineering, around 6th grade ,I believe.
"Force time force arm equals weight times weight arm."
As keels get deeper the weight arm gets longer. As their attachment to the hull gets narrower, the force arm gets shorter, and the leverage load on keel bolts gets much greater. I have seen keels with the bolts on the centreline, of a very narrow attachment to the hull, creating huge loads on that connection, even bending loads on the bolts themselves.
The best high aspect keel attachments I have seen are on Thunderbirds and Haida 26's, a wider flange on top, to widen the spread of the keel bolts. This also makes it easy to remove ,check and, if necessary, replace any keel bolt any time ,easily .

 

[Brent Swain]

You’re probably right. However it appears that he’s very persuasive to some people but hopefully these same people are savvy enough to do a bit of research and find threads like this.

Otherwise they’ll just find the Origami boat website that deletes all criticism or difficult questions. (And I believe is moderated by Brent etc)

We have had raging debates on the origami boats site. The only thing deleted was when Perry tired to use it as his personal facebook page, and swamp it with posts which had nothing to do with boats. All he posted, relevant to boats, is still there. He has sabotaged a lot of threads into uselessness ,by that method, studiously avoiding the title ,subject matter of the thread.

Unlike most origami boats discussions, people there have actual hands on experience on the subject matter, unlike most, where the loudest have no hands on knowledge of the subject, and have never seen ,sailed on, built, nor cruised in an origami steel boat. They continue to claim that a design which has over 350,000 accumulated miles of ocean cruising, with zero serious structural problems at sea, is not strong enough ,not as strong as stock boats which have had a miriad of serious structural problems, in far fewer miles, and much milder conditions . It is saying "that which has not broken in over 350,000 miles of ocean cruising ,just might break!"
It is saying that , it is dangerous to go to sea in a design with that kind of safety track record, so you best play it safe, and stick to that which has had far more problems; and deaths.

 

[rotrax]

So you dont use calculations to be sure that the mast and rigging you have chosen empiricaly will be adequatly supported by your hull and coachroof.

That was one of the questions Brent.

Instead of repeating endless heresay you sould have answered " I dont calculate anything, I just weld 'em up. "

Lets get to GRP having far more problems and deaths.

Lots of steel boats which are rotten in Portsmouth Harbour Brent, none are long for this world. The " end of usefull life steel dogs " are far higher in proportion to GRP boats in a similar condition. I would estimate that 65% of the steel boats I regularly see on my trips in and out of the Harbour are no hopers.

Perhaps I% of the GRP boats fall into the same category.

You are correct, some keels have become detatched from GRP sailboats. But it is nowhere near as widespead as you would have us believe.

How you can suggest that stock boats have " a miriad of structural problems in far fewer miles and in much milder conditions " I dont know.

Unless you were present on these vessels when they encountered these problems you are not in a position to know. Same with the milage-how do you know.

Heresay again, or you usual embellishment and stretching of the facts to suit your own viewpoint?

My chosen GRP boats keel wont become detatched, it wont suffer structural problems unless something hits it, or the boat hits something.

As my boat ALWAYS has a watchkeeper, has AIS, radar and first class nav gear. I am prepared to risk sailing 1500 NM'S a year on average in challenging busy waters and not lose sleep.

I have full confidence that my boat will get me there and remain afloat.

I would, however, be very worried having welds like those shown holding ANY boat together..................................

 

[Deleted member 36384]

So you dont use calculations to be sure that the mast and rigging you have chosen empiricaly will be adequatly supported by your hull and coachroof. ....... .

To be fair, I have read in some design books the various tables of standard sizes for all sorts of things on yachts. It is also a recognised method for designing standard things, using ratios, dimensions, weights that are known to be successful and commonly exploited. Ian Nicolson, a well published yacht designer, has published books that state this method as the basis of the initial design. He does of course develop his initial designs with detailed design calculations, where that is required.

https://www.waterstones.com/author/ian-nicolson/539840, the boat data book being a notable example. Brent Swain's design method is not that weird, copying proven methods and sizes.

 

[lpdsn]

We have had raging debates on the origami boats site. The only thing deleted was when Perry tired to use it as his personal facebook page, and swamp it with posts which had nothing to do with boats. All he posted, relevant to boats, is still there. He has sabotaged a lot of threads into uselessness ,by that method, studiously avoiding the title ,subject matter of the thread.

Now that really surprises me. From what I've seen Bob Perry is one of the most respected posters on Sailing Anarchy. He's a very experienced professional yacht designer and I've seen him give detailed free advice to other posters on quite a number of occasions. I'm very surprised at the allegation that he trolled your website, to the extent I find it highly implausible.

 

[DownWest]

Now that really surprises me. From what I've seen Bob Perry is one of the most respected posters on Sailing Anarchy. He's a very experienced professional yacht designer and I've seen him give detailed free advice to other posters on quite a number of occasions. I'm very surprised at the allegation that he trolled your website, to the extent I find it highly implausible.

I read quite a few of Bob Perry's comments on the SA site. Helpfull and considerate. Might be that he tried to help BS, but not welcome.