I had thought that 36' Springers were originally built with a "5mm" steel hull. As of Friday 13th Jan 2012, I am obliged to Ray Smith at farcebooks "JustCanals" forum for the following:
"Most of the early 1972/5 Springers ... were plated in 3/16" [plate]. Some were done in 1/8th plate for the cruiser style V hull without fore-deck. I had one of these new in 1975."
Pentargon has a cruiser stern and [almost] no fore-deck. She is, however, plated in 3/16"! I had the sole plates (landlubbers say floorboards!) lifted during 2012 to remove almost a metric tonne of concrete paving slabs as part of a re-ballasting exercise.
The (then current) owners had decided to do a '20' year survey about 2002, based on [erroneous] information that the boat was a late '70s build. Being 'advised' during that 'survey' that the wetted hull was 'iffy', they decided to have Pentargon 'bottomed' rather than patching bits on here and there'.
This tidbit, gleaned during initial enquiries, became the major factor in my decision to proceed. The yard where the work was done was deemed to have a 'reliable' reputation and if I was ready for libel it would now be named. What they did was 'shoddy' 'slipshod' 'opportunistic' crap and it would be reasonable to describe the principals as 'downright rogues'. My lips are sealed as to who buggered up a simple job in the most stupid way possible.
WHAT INSURERS REQUIRE
For comprehensive insurance, a narrowboat needs to show a minimum skin thickness of 4mm. all over the 'wetted surface' and this is to be demonstrated on an ultrasound device which has been calibrated and certified and used by a tester certified to use the said device. A single pitmark down 1mm, if found, must be brought up to show 4mm+ on ultrasound. This is why you find nominal sheet thicknesses on boats eg 8/6/5, with the 8mm being the bottom, 6mm being the sides and 5mm above gunnel height. It is simply insurance against subsequent pitting, caused by galvanic corrosion and owner stupidity. (The two go hand-in-hand.
In the case of Springers numbers like 5/4/3 are more likely. Part of Sam Springer's secret of mass production was to minimise steel and then add ballast usually concrete slabs to bring down the C of G. Sam Springer's original gasworks sheets (that story, by the way, is total bollox but never let the truth get in the way of a good story) were less than 5mm because Sam used imperial measures back in 1973. Pentargon's original bottom would have been less than 5mm from new because Sam's 3/16" is 4.75 in metric. The good news was that 3/16" was a real figure not a nominal one.
Come 2002 and the numbers coming from the surveyor for Pentargon's wetted hull were showing possible and slight weaknesses in the 4mm defence. There was no evidence that the 4mm minimum had been breached, just that they said they found readings close to 4mm. The then owner, a careful and trusting soul, decided that patching was asking for trouble and, having had some experience of sheet steel fabrication myself, I'd have agreed. But he really should have done nothing.
Sam Springer's 3/16" steel sheet is well over the odds on Pentargon to this day and 11 years later. In the surveying methodology, ultrasound picks up only the outside layer of steel. It 'ignores' what may be underneath. The previous owner fell for the most basic bit of roguery on t'cut: doing work that was patently not needed and I'll bet he got charged an arm and at least one leg for it.
WHAT OWNERS EXPECT
Like any decent gentleman, he left the work in the hands of a 'reputable' yard to do the "necessary"!! You don't need a degree in rocket science to figure that sheeting in 4mm sheet would not make much sense, because you would be starting off at the minimum acceptable. However, if you were then told that 4mm is 'nominal' and understood that to mean 'in name only' " you'd be right. Industry standards allow an almost unbelievable 10% margin on Reality. Imagine going out to buy a litre of milk and 'legally' receiving 900mls for your money?
With deadly accurate rollers, 4mm sheets can and do exude down to 3.71mm. That Indian multi-billionaire steel-man wot put up that funny metal tower in Stratford for the Olympics got rich not on 3.71mm he actually sold but on the non-existent 0.29mm that he did NOT sell but got paid for. 3.7 reality is priced at 4mm nominal. You won't find that kind of shite going on at the Waitrose cheese counter. They weigh the cheese and only then put it in the bag. If only marinas, canal-side fabricators and canal dry-docks worked the same way.
WHAT HAPPENS IN REALITY?
But what about a yard that patches the bottom of Pentargon with 4mm nominal, albeit with large patches that stretch as far as the protruding stringers? That's what was found at my survey. Nothing else had mattered to me other than that the hull under water be sound. Nothing else would be questioned. Ultrasound had to return the numbers, impossible in the circumstances, and by definition, as it transpired. It's the way the test works.
Even though the surveyor and the purchaser both knew there was good steel under the 'patches' we both knew that the surveyor (who is one of the best in the country) had to work to the standards imposed by his licence.
I invoked the get-out clause and got-out.
Down at least £1000 and no purchase to show;
not even a round turn and two half hitches.
In my favour now was the fact that Pentargon was unsaleable. The broker was stuck with it and the seller would have been mad to get salted for a second time by making her saleable. However she was sailable. Once 3rd party insurance was in place the boat could be sailed away. BSS has no interest whatever in the hull and such things and (in my case at least) Saga Insurance was not worried either.
Since 1973, most of Pentargon's wetted hull had held onto all of it's 3/16" steel and the original skin passed my surveyor's ultrasound in 2012, where-ever he found it. It was the 4mm nominal put on at .. OOOOPS .. in 2002 which failed it, by definition. The boat could continue sailing for maybe another 25 years just by re-doing the prow which showed signs of softening under the surveyor's hammer. I'd have fixed the prow anyway.
But I could never sell Pentargon with or without a clear conscience to some dope. It might even be 3rd party un-insurable at some future date. It was a gamble and I needed at least 24hrs to gauge the odds. I'd spent £1000 thus far and dedicated at least ten days and hundreds of diesel miles on Pentargon.
Now I needed to focus my thinking overnight. But I've lived on the balls of my feet all my life.
After letting the brokers stew for 24hrs, I came back and told them I was willing to buy Pentargon 'as was' at half my previous offer. Remember I'm out £1K for the survey and pull-out. They huffed and puffed and tried to raise the ante. But I stuck fast and, some days later, caved in. Pentargon was 'mine' subject only to the clearing of a cheque, which eventually happened some 13days later on Thursday 26th January 2012 and then only because of my applying irresistible pressure.
Canaltime works unerringly on all facets of in-activity on t'cut.
I went to Welton Hythe Marina on Friday 27th January at 3pm, collected the keys and eventually drove out the front gate onto the Leicester arm. I had not even known how to start it, let alone drive it, and there was no-one there to help me. The staff had all been let home early, apart from the receptionist. I had to self-educate myself as the sun went down on a Winter afternoon just to get the bloody boat out of the marina. I couldn't wait to see the back of them.
Nor did I much care. I found an isolator switch that enabled a start. The boat had no electricity, no water, but it had some diesel. As soon as I got round the first corner, I practiced mooring and breasted up to a BW butty and then a proper mooring for the night in fading light. The marina never knew that just for trying to fool me, they had been comprehensively stroked. For under 6K all-up Pentargon was mine. They'd misjudged me because I look like a cretin, sound like a cretin, and act like a cretin.
It's a major part of the magic of being Irish.