Brent Swain in his own words

[daneo]

I read this posting from Brent Swain on SSCA and being in the marine business for 20 years I am dumb founded by the ignorance of this guy. I would be curious to hear the thoughts of other marine professionals?



"Posted: 11 Apr 2006 17:15
Quote

ABS approves fibreglass boats for offshore work. Go buy yourself a stock ABS approved fibreglass boat and we'll have a demolition derby against my steel boat and we'll test the value of ABS rules. They also, I'm told ,call for plastic thru hulls on steel boats, you know, the kind that break off and leave a 2 inch hole in your hull whenever someting heavy shifts and sheers them off. They have a credibilty problem.
Lloyds calls for stainless keel bolts in wooden boats , which corrode thru in short order due to oxygen starvation, yet they won't approve any wooden boat that doesn't make the mandatory screwup.
My first boat was a Kinney designed "Pipe Dream" ,tank tested in the Davidson lab ,one of the top tank testing facilities in the world, doing all the tank testing on the Americas Cup defenders at the time . The boat was a total abortion, almost uncontrolable down wind. I managed to get her from BC to New Zealand where I made what I'm sure were unnaproved changes , which made light years improvement in control , and abilty to self steer. Thus I have little confidence in the opinions of so called "World famous experts " who have very little experience in what they promote.

[marshmat]

I was always under the impression that ABS, Lloyd's, etc. were just the minimum standards a boat needed to meet to be licensed and insured. Don't most builders working on boats that need to bear these certifications only use them as a minimum guide and do their own designing and component specifying, within the rules but generally a bit better?

[Tad]

daneo,

ignorance, yes...absolutely, about many things. Mr. Swain also has much experience that we can learn from.

There are some, "designers", whose work should be taken as philosophical statements, rather than technical works. Buehler, Bombigher, and a few others (piver) also fall (IMO) into this category. While the philosophy behind the work is rather admirable, technically it is questionable at best. I have a feeling that this is the only way this work can be presented. If we require all philosophers to become engineers the work will be diminished, and we (boat designers in general) desperately need those who are willing to stand up and say, "no".

Occasionally alternate philosophy is coupled with technical brilliance, Dick Newick comes to mind, but this is extremely rare.

Tad

[Corpus Skipper]

There are some, "designers", whose work should be taken as philosophical statements, rather than technical works. Buehler, Bombigher,
Might I ask what's wrong with Buehler's designs? He rather overbuilds boats in my opinion, and has some "radical" ideas pertaining to rigging and such. The Diesel Duck is a pretty straight foreward and seaworthy design, also in my opinion. Just for curiosity's sake.

[Tad]

Craig,

Since there is no right or wrong in boat design, there is nothing "wrong" with anybody’s designs. But there are very different areas of focus or emphasis. I believe that safety and performance should be the primary focus of any "right" or good design. The styling, construction method, arrangement and cost should all come secondary (and naturally flow from) those first factors.

In my opinion a designer who sells plans for an ocean going motor yacht and states that "you may need some ballast", is negligent. That the designer includes no tanks in the drawings and states, "you can have as much fuel as you want", is also stunning. That the designer indicates no location or amount for the above mentioned fuel and ballast is, to me, unbelievable. These technical factors are, to me, the basics of a design, and ensuring stability and floatation at various load conditions should be the basic job of the designer.

Mr. Buehler continues to publish incorrect figures for propulsion, stating "the computer says"...so & so HP is required. Well, as the NA in charge you cannot blame anything on a machine in your control, you must know, if you don't know find out! If you make a mistake, correct it ASAP!

All the best, Tad

[Gilbert]

Then there was the professional engineer who confessed to designing a vessel that when launched laid over on it's side. He found he had forgotten to multiply by 2 when he used his planimeter on the half sections in the body plan to calculate the displacement.

[MikeJohns]

I read this posting from Brent Swain...........

Lloyds calls for stainless keel bolts in wooden boats , which corrode thru in short order due to oxygen starvation, .

That I would agree with........ Lloyds gets this wrong in my opinion too. Stainless can be a very poor choice for keel bolts.

As for the rest of his philosophy.....that's just his opinions and we are all biased to some extent.:)

[Tad]

This is what I find in Lloyd's Rules concerning keel bolts. No mention of specific material.

All the best, Tad

-----------------------------------------------------------------------------------------------------------

Rules and Regulations for the Classification of Special Service Craft
Special Considerations for Sailing Yachts Part 4, Chapter 3
6.3 Keel bolts
6.3.1 The keel bolts are to be of a corrosion resistant
material. The nuts, washers etc., are to be of a material the
same as, or compatible with, that of the keel bolts. The specifications
of these materials are to be submitted for appraisal.
6.3.2 The diameter of keel bolts, dk, is to be that determined
from the following formula, or 14 mm, whichever is the
greater:
dk =
where w = the portion of the weight of ballast keel
supported by the bolt, in kg
dcg = vertical distance of the centre of gravity of
weight w below top of ballast keel, in mm
bk = breadth of top of ballast keel in way of bolt, in
mm
u = ultimate tensile strength of the bolt material, in
N/mm2
When determining w for the bolt at the ends of the keel, the
weight of any overhang is to be included.
6.3.3 Where double bolts are to be fitted, the total
cross-sectional area of the bolts is to be not less than 1,2
times the cross-sectional area of the bolt determined in accordance
with 6.3.2.
6.3.4 Keel bolts are to be fitted alternately on opposite
sides of the middle line, and as close as is practicable to the
bottom floor structure.
6.3.5 The ballast keel is to be secured by through bolting,
but where this is not practicable, short keel bolts or studs
may be fitted.
6.3.6 A substantial plate washer is to be fitted under the
head of the keel bolt. The diameter and thickness are to be not
less than 4,0 and 0,25 times the bolt diameter, respectively,
but the thickness need not exceed 8 mm. Washer plates,
where square or rectangular, are to have suitably radiused
corners. In composite and wood craft the washer plates are to
have all edges dressed smooth in addition to being suitably
radiused.
6.3.7 The bottoms of short keel bolts are to be secured
by nuts and washers fitted in pockets in the keel, or by square
plate nuts cast in with the keel. Where cast in, the square plate
nuts are to have a breadth and depth not less than 3,0 and 1,0
times the bolt diameter, respectively.
6.3.8 Where studs are fitted, the length of the threaded
portion into the cast iron or steel keel is to be not less than 1,5
or 2,5 times the stud diameter where through tapped or blind
tapped respectively.
6.3.9 It is recommended that the design of the keel bolt
is such that it can be withdrawn for survey and is not cast
permanently into the ballast keel.
6.3.10 Details of the proposed torque to be applied to
the keel bolts is to be indicated on the relevant plans and
submitted.

[MikeJohns]

Tad

They do not specifically require Stainless but they allow it and require corrosion resistant materials so Mr Swain is not far off the mark saying they "call for it" .

I agree with you that some of the rest of what he is reported as saying is a bit unprofessional.


Stainless keel bolts in wooden boats and Lloys attitude to this is one of the few cases of Lloyds getting it very wrong.

As they say they "require" corrosion resistant keel bolts which precludes mild steel. They approve 316 keel bolts in wet wood which appears to designers who know no better to presume that this means they are suitable. This has been the subject of some controversy in the past as even mild steel would be a much better choice in many regards.

Stainless can and often does crevice corrode very quickly in that application and is a very poor choice of material. Fatigue corrosion leads to very rapid deterioration of S.S. in a wet oxygen starved environment.

Other metals of course are considerably better than mild steel but stainless should be prohibited in this application.

The saving grace is that generally one or two of the bolts are unaffected and there is sufficient factor of safety for these remaining bolts to do the bulk of the job up to the point where the loose head is noticed, but as each successive bolt fails the stresses go up in the remaining so their life shortens too.

In the past designers have thought they were designing strong boats because they adhered to some rule base, keel attachment in composite boats under relatively recent ABS rules was for example poorly conceived and lead to some catastrophic failure.

It is always a great pity when it is a Coroners report that finally changes the rule.

cheers

[longliner45]

what kind of bolts should be used?please hurry with your reply I only have 8 points left.

[DanishBagger]

what kind of bolts should be used?please hurry with your reply I only have 8 points left.


Hahaha, that had me laughing out loud (literally, not the sms-way) :D

Anyway, I would assume they would go for some silicon bronze, or perhaps, yups, titanium!

[MikeJohns]

what kind of bolts should be used?please hurry with your reply I only have 8 points left.

Longliner
8 points ! Someone took umbrage did they? you really should learn to behave yourself :)

On a wooden boat it depends on the ballast material attached. If its cast iron then galvanised mild steel bolts are the best. If it's lead then Monel or Silicon-Bronze should be used but never stainless steel (neither 304 or 316).

On other hulls it's a different story and stainless is at times required. but the propensity of wooden hulls to soak makes them prone to causing the failure of stainless steels in short order.

Also as Danish bagger says ....titanium would be ok if you can find the $$$.

Incidently remember that the cut thread is a stress raiser so never use threaded rod always thread the ends of round bar.

Cheers

[FAST FRED]

The various groups LLoyds ABS ect ONLY look at hull scantlings and the parts and ,eg. hull thickness in GRP can be made of all mat ! and still earn a LLoyds A+.

They make NO claims the any design is at all suitability for any purpose at all.

No claim a sail boat can actually sail , or a motorboat can go foward.

Although I believe the Ice Class does require a certain amount of HP per ton.

There groups are pencil "engineers" that give permission for companys to gamble and give the vessel insurance. THATS IT!

If you need a "Good Boat" one of the usual folks with a nice eye ,
Bill Gardner , Phil Rhodes , Herrishoff, or my choice Maurice Griffiths will have on file anything conventional.

And you will be assured the boat will sail,or power as well as look grand.

FAST FRED

[Tad]

Mike,

Absolutely, I understand and agree totally with everything you say regarding SS bolts in a wet environment. It's just that out of context statements regarding materials and Lloyd's rules are totally misleading unless one is careful to, as you have, add context. Hopefully your post will add to the body of awareness regarding this problem. The plan approval guys at Lloyd's are one thing, but the individual inspector should know better and refuse to accept SS bolts in a traditional wood boat situation.

As new traditional construction to Lloyd's is becoming very rare, it's the refit people who need to be aware as well. I admit that my 1966 copy of Lloyd's rules for construction of wooden yachts does indeed call for, "bronze, galvanized steel, stainless steel, or galvanized iron".

In "modern" wooden yacht construction the bolts are sealed inside the keel/hull interface and corrosion of the bolts is a much smaller concern, with other problems, material strength, supply, etc, taking precedence. The last big keel I had a small part in was this one, http://www.marsmetal.com/newpages/schpages/marsphoto.html which does use stainless bolts in a wooden vessel which was classed by Lloyd's. The engineering of all that was done by Chris Franklin. If I recall correctly one of the major problems was just finding enough material to make the bolts within the lead-time we had.

Tad

[longliner45]

not my thread but thanks guys,,longliner