Survey’s Tale - How To Refasten a Hull

[garbler]

I’m willing to forget the ‘ naked trapeze artist ‘ if you will

I’m living and working under my own name now in New England and I get a call to do a kind of multifaceted valuation and general fleet condition report for Stonewall Insurance a large Atlanta broker and their bank. There were four shrimpers three steel and one Desco built 70 something wood hull down at No Name shipyard in Bayou La Bartre, Alabama. The steel hulls were afloat but coming up one at a time for a wash and shave, zincs maybe stern bearings and prop swap. The Desco was side tracked on blocks and I could see five or six guys refastening her. They had sand swept the underbody mostly to reveal fastener locations and had two guys ahead sanding off remaining paint at the frames. Respirators were apparently optional.

Everybody was using pneumatic tools and they looked pretty organized. Next was a guy drilling and counter boring for new #20 galvy screws followed by a guy placing new screws in the hole and lighting tapping them to get them started straight. Finally we’re two big guys with heavy hammers and they were driving the screws home. One guy drove them flush then the next had a small spike maul to sink them. I couldn’t believe my eyes and stood their laughing to myself and shaking my head when the yard foreman comes up and says hi offers me a cigarette and I decline then says we’ll have her back in the water in two days. I’m thinking to myself I guess so if your hammering the screws in. Then he ask me where I’m from as in you dumb Yankee ! As if he were reading my mind makes a statement I’ll never forget. ‘ We always fasten these boats like this - screw drivers are for taking screws out ‘ I almost choked trying to suppress laughing.

Rick

 

[Xlantic]

 

[Lepke]

With a crew, it's not that hard to refasten correctly. They might as well used nails. Steel fasteners, galvanized or not is why wood boats have rust streaks.

 

[garbler]

With a crew, it's not that hard to refasten correctly. They might as well used nails. Steel fasteners, galvanized or not is why wood boats have rust streaks.

Only ring shank nails like ‘ Anchorfast ‘ will work and they are monel or bronze and hard to get and pricey. The Desco hulls are galvanized fastened so mixing metals will be a problem beside expensive. Plus these hulls are typically planked with soft rot resistant cypress so nails need a washer under the heads or they will pull through the soft wood. Nails and washers need a flat bottom hole which is another step without special tooling which they apparently didn’t saavy. This is the yard’s way of doing it so. Ever see an old wood shrimper that wasn’t streaked with rust ? Anyway I agree with you 100% I just thought I’d pass on this weird operation.
Is your name Paul ?

Rick

 

[Simi 60]

Ever see an old wood shrimper that wasn’t streaked with rust ?

The only place our timber "prawn" trawler has rust streaks is from a few fasteners above deck level and, over time, these are getting replaced.

Everything below deck level is silicone bronze.

 

[Comodave]

The only place our timber "prawn" trawler has rust streaks is from a few fasteners above deck level and, over time, these are getting replaced.

Everything below deck level is silicone bronze.

But do you hammer the screws in???

 

[Simi 60]

But do you hammer the screws in???

I'm still trying to get my head around people being that dumb.
Bit to much of this going on perhaps?

 

[Comodave]

I guess it may be a lack of leadership at the yard. The workers learn that this kind of crap is acceptable.

 

[Circumnavigator]

Old boatyard interchange:


"Hand me that [nationality deleted] screwdriver."
"There's no screwdriver here."
"The hammer, newbie."




Jim

 

[garbler]

I’m glad some of you guys weren’t with me cause there would be no way to control the laugh valve and we’d have been shown the door with bubba the sheriff waiting for us. But I’ve seen strange stuff in many yards not just Southern

 

[PM]

My Father in law probably laid a million miles of carpet in Northern Wisconsin. He always used a hammer for the transition strips and everything else that was held in place with screws. Except for one time a lady told him "We use screwdrivers in my house"

pete

 

[garbler]

I guess it may be a lack of leadership at the yard. The workers learn that this kind of crap is acceptable.

I respect your comments that’s a given, but no way this crew was operating except under the foreman’s direct orders. He came up to me and face to face told me this is what they do. I passed on the cigarette but I listened and watched and it was real obvious that this crew jumped when he snaps his fingers. I also talked with the vessels owner who couldn’t say enough good things about the yard and the job they were doing. This tells me that this practice may be somewhat prevalent. So this I’m guessing maybe, or seems like, I’m a ‘ yankee assed surveyor who don’t know squat ‘ situation.I can’t teach em or fight em so I put my tail between my legs and move on and out. Had a great catfish dinner though

Rick

 

[Delta Riverat]

Not to mention a battery powered drill/driver will put them in even faster than a hammer.

Amazing.

 

[Comodave]

Not to mention a battery powered drill/driver will put them in even faster than a hammer.

Amazing.

Absolutely, and not strip out the wood in the process. I love my drivers. I never use a drill anymore to drive a screw.

 

[BruceK]

As a kid I spent time at Jervis Bay on the south coast of NSW state. There is a naval base there, and it was(?is) a training establishment for navy personnel. There was an associated Navy air arm base nearby.
We marveled at the "crash boats", fast timber boats designed for air sea rescue. Some were locally built, perhaps by Halvorsen, some were US or US personnel built. I was told the US built ones had the screws installed by big hammers, not screw drivers. Faster to build I guess.

 

[SteveK]

A guy could make a fortune selling nail guns that shoot screws.

 

[Comodave]

Good one, Steve.

 

[Delta Riverat]

Maybe these were "fast threads" like 1 inch / rev? You could drive something like that with a hammer w/o tearing up the wood.

 

[fgarriso]

 

[Nightsky]

Maybe these were "fast threads" like 1 inch / rev? You could drive something like that with a hammer w/o tearing up the wood.

That makes sense!

 

[Bmarler]

I don’t think I’d discount the method till I did some actual testing. Sure, on the surface it seems pretty dumb, but think about the way a screw would move through the fibers and point the severed ends towards the point of the screw. This would lock the screw in place really firmly. Like a ring shank on steroids.
If the screw was driven in with a driver, the torn ends of the fiber would be oriented parallel to the threads instead of perpendicular. Interesting to think about.

 

[psneeld]

I don’t think I’d discount the method till I did some actual testing. Sure, on the surface it seems pretty dumb, but think about the way a screw would move through the fibers and point the severed ends towards the point of the screw. This would lock the screw in place really firmly. Like a ring shank on steroids.
If the screw was driven in with a driver, the torn ends of the fiber would be oriented parallel to the threads instead of perpendicular. Interesting to think about.

I agree.... I am not discounting it at all...different cultures often prove our way of thinking lopsided.

I have worked enough with wooden boats to know that screws in older, wet wood often strip way too easily from overtightening. The fact that on a wooden boat, the wood absorbs water and planks/frames swell.

The method described might be superior to screwing screws. Can't say for sure it works well, but a well known and used yard may know/think differently.

 

[garbler]

I can tell you this whole question was thought about and tested with various fastener measurements etc. years ago after I witnessed this spectacle. I can assure you that in the instance of this shrimper the scheme was a bad idea. I wrote a paper on this over thirty years ago and gave it to the USCG New London where a number of wood hull experts were called in looking for some magic instrument they could use for fastener inspection. I brought ultrasonics to the game but wasn’t feasible for them. This was right after the El Toro accident. I didn’t think a paper like this belonged here but I could give you some of the hi lights later on when I get home.

Rick

 

[Bmarler]

I can tell you this whole question was thought about and tested with various fastener measurements etc. years ago after I witnessed this spectacle. I can assure you that in the instance of this shrimper the scheme was a bad idea. I wrote a paper on this over thirty years ago and gave it to the USCG New London where a number of wood hull experts were called in looking for some magic instrument they could use for fastener inspection. I brought ultrasonics to the game but wasn’t feasible for them. This was right after the El Toro accident. I didn’t think a paper like this belonged here but I could give you some of the hi lights later on when I get home.

Rick

i'd like to see this please. i've been involved with engineered wood products all my working life and find the subject interesting. like you say, could be a bit much for this forum, but still...
you are quite right about doing forensic diagnosics on the can be difficult as there's no easy way to examine the fiber structure of the sample. x-ray would be tough with the way the screw would obscure the wood fiber. newer high def x-ray might give a better picture but i don't have access to that technology. taking a slice and examining it under a microscope might give a reasonable picture, but preparing the sample relies heavily on the talent of the person doing the prep. freezing the sample before slicing perhaps? i don't know. very hard to get a good sample without disturbing the structure. interesting subject though.
you were there to see it first hand, so i'd defer to your knowledge of the subject, but really i'd love to see the research.

 

[garbler]

Bmarler you have it about right on all counts regarding NDT testing of hull plank fasteners so I will add this and please understand I’m not trying to blow my own horn here it’s just the way it was.

In 1995 I was contacted by USCG’s Research & Development Center’s Kurt Hansen to discuss demonstrating my ultrasonic equipment and techniques that I’d used for the USN MSO minesweepers and USS Constitution and various Lloyd’s of London surveys. They were looking for a practical NDT method to ascertain hull plank fasteners. The entire program was driven by the recent El Toro passenger vessel casualty on the Chesapeake. I and four or five other surveyors and several NDT equipment firms all met at a wooden test vessel in East Haven, CT. The procedure included demonstration of different equipment and methods at four different locations of a 40’ wood small passenger ferry now out of service.

My equipment consisted of a Krautkramer Branson USD-10 and Sonatest 160 and various common and custom focused probes. Before starting I informed the Coast Guard that since typical hull plank fastener screws come to a sharp point I could not receive a back wall signal and therefore no information. That my equipment was reliable and repetitive with bolts and shafts that terminate with a flat. They however were adamant that I attempt shooting screws only to confirm my advice. Bolts however provided sound readings on wastage, cracks, corrosion of stainless bolts and dezincafication of bronze bolts. In conclusion only real time X-Ray could provide decent visual information on screws but only those where the physical characteristics allowed access for their equipment. The X-Rays did not reliably show small degrees of wastage or reduction of fastener diameter. Plus the equipment and operation is prohibitively expensive and legally cumbersome a moving radioactive isotopes across state lines.

Rick

 

[Bmarler]

Interesting stuff. My thought with the hammer screws is the way the grain would respond to the screw. As soon as the screw starts wasting, that effect is diminished. Same as nail fastened planks. I remember as a kid growing up in Sitka, we would scour the beach and find double ended nails from old Russian boats. Copper if I remember correctly. After many decades they were still in fantastic condition.