The new black

If you thought it was all coal tar, think again

Canal Boat - - Front Page - WORDS AND PIC­TURES BY MARTIN LUDGATE

In the old days, when it came to hull paint­ing it was, in­deed, largely a case of ‘black is black’. You put your boat in dry dock ev­ery cou­ple of years, pres­sure washed it and re-blacked it – and the only de­ci­sion was whether to use coal tar so­lu­tion or bi­tu­mi­nous paint. And to a cer­tain ex­tent, that de­ci­sion was made for you by what type of paint had been used pre­vi­ously.

Not any more. There are a whole range of dif­fer­ent coat­ings avail­able, with dif­fer­ent qual­i­ties and dif­fer­ent prices to match. There’s still ba­sic ‘stan­dard black’ – the suc­ces­sor to coal tar so­lu­tion – for a ‘cheap and cheer­ful’ re-black­ing last­ing two or three years. But there are sev­eral higher- qual­ity, longer-last­ing prod­ucts avail­able now.

Higher per­for­mance bitumen prod­ucts are avail­able that last bet­ter than tra­di­tional black bi­tu­mi­nous paint. They in­clude paints which have more re­sis­tance to oil and diesel (a prob­lem with tra­di­tional bi­tu­mi­nous), build up a thicker layer (‘bod­ied’ bi­tu­mi­nous paints) or pro­vide a harder gloss fin­ish.

Vinyl tar coat­ings are also on of­fer to­day, which have the oil and diesel re­sis­tance of stan­dard black, but are harder wear­ing, more flex­i­ble, durable and weather re­sis­tant.

Both of th­ese types of prod­uct may dry to a less shiny black fin­ish than the tra­di­tional ones, but you can al­ways over­coat them if the fin­ish is im­por­tant to you.

Th­ese more ad­vanced prod­ucts can ex­tend the in­ter­vals be­tween the ex­pense (and for DIY-ers like my­self, the not ter­ri­bly pleas­ant ex­pe­ri­ence of spend­ing a week in the bot­tom of a dry

dock) from two or three years to per­haps four or five years. But can we do bet­ter than that?

Canal Boat re­cently vis­ited a cou­ple of com­pa­nies who’ve been de­vel­op­ing more spe­cial­ist treat­ments, mainly based on two-pack epoxy sys­tems, and who be­lieve that the an­swer is ‘yes’.

The first of th­ese was Nap­ton-based boat­builders Blue­wa­ter Boats. They’ve been ad­vo­cates of ad­vanced two-pack epoxy paints for many years. But they’re the first to ad­mit that it’s a more ex­pen­sive al­ter­na­tive, par­tic­u­larly as it re­quires grit-blast­ing the hull first.

And we’re not just talk­ing about tak­ing old paint off here: Blue­wa­ter are mainly con­cerned with brand new boats, but even new steel is cov­ered in tiny frag­ments of ‘millscale’ from the man­u­fac­tur­ing process. It all has to be blasted off be­fore the paint­ing starts: Blue­wa­ter told us that even grade A steel may well be hid­ing 0.5mm deep pits un­der the millscale.

As for the paint it­self: Blue­wa­ter use a high-build epoxy, build­ing it up to a to­tal thick­ness of 400 mi­crons. All paint is per­me­able to a cer­tain ex­tent, but at that thick­ness, say Blue­wa­ter, the wa­ter re­ally won’t get through. That’s a lot of paint, and it’s ex­pen­sive stuff – it could add up to a cou­ple of thou­sand in paint costs alone. How­ever, they be­lieve it’s worth it when you’re spend­ing £100,000 or more on a new boat.

And is it? Up to now it’s been dif­fi­cult to tell, as two-pack epoxy paints haven’t been used on nar­row­boats for long enough to re­ally judge how long they last. Re­cently, though, came ‘the proof of the pud­ding’. The own­ers of nar­row­boat

Ari­adne (the sub­ject of our boat test in the May 2011 CanalBoat) brought their boat back to Blue­wa­ter for a check-up – and the good news is that the hull is still ba­si­cally pris­tine af­ter five years. Even where there’s dam­age (and un­for­tu­nately

Ari­adne suf­fered a bad scratch a year ear­lier) there’s been no ‘creep’ at all: where a hull painted with a nor­mal coat­ing would have seen rust spread­ing to the area around the dam­age, here it’s still lim­ited to the ac­tual scratch it­self.

That’s not the only ex­am­ple. Blue­wa­ter say they’ve re­cently looked at an 11-year- old boat and it’s still in ex­cel­lent con­di­tion. They guar­an­tee their coat­ings for seven years, but they say that the same paint is used on oil rigs, where it lasts for 15 plus years.

An­other com­pany we’ve vis­ited is Deb­dale Wharf near Fox­ton. While Blue­wa­ter are mainly about treat­ing new hulls, Deb­dale have de­vel­oped a spe­cial­ist treat­ment aimed more at

‘Th­ese ad­vanced prod­ucts can ex­tend the in­ter­vals from two or three years to per­haps four or five. But can we do bet­ter than that?’

‘Zinc coat­ing doesn’t come cheap. But, hav­ing started of­fer­ing the treat­ment two years ago, al­ready over 80 boaters have felt it worth­while’

re-black­ing older boats in­clud­ing his­toric craft. They, too, use two-pack epoxy paints, but it’s what they do first that’s their spe­cial­ity.

Deb­dale be­lieve they’re the only boat­yard in the coun­try to of­fer a zinc-coat­ing process for nar­row­boats. A ded­i­cated bay has been cre­ated for blast­ing and coat­ing: lined in rubber and steel, with spe­cial­ist ex­trac­tion plant, plus shroud­ing and suc­tion kit to stop any grit from get­ting in­side the cabin.

Here, the boats are grit-blasted and then coated us­ing a spray-gun which uses a pow­er­ful elec­tric cur­rent to melt the zinc be­fore ap­ply­ing it to the hull. Once the zinc­coat­ing is com­plete, the hull is painted with two-pack epoxy.

Again, it doesn’t come cheap. A typ­i­cal cost is around £4,500 inc vat – but hav­ing started of­fer­ing the treat­ment two years ago, al­ready over 80 boat own­ers have felt it worth­while. How long does it last? It’s dif­fi­cult to tell for sure as yet, but Deb­dale say that with just the Hem­pel 2-pack it would be ten years plus; so with the zinc, it’s much more – quite pos­si­bly, they reckon, in­def­i­nitely. Even in the harsher en­vi­ron­ment of salt wa­ter, sim­i­lar treat­ments last ten years. Their first boat came out of the wa­ter re­cently with “not a mark” – and they say boat own­ers can call them af­ter 4-5 years for a free lift- out and checkup, or any time if they’ve been in an ac­ci­dent.

So, to sum up: there are some in­ter­est­ing ad­vanced treat­ments avail­able th­ese days that of­fer hull pro­tec­tion go­ing a long way be­yond the tra­di­tional three coats of coal tar so­lu­tion. They’re not cheap – but given the much less fre­quent in­ter­vals needed for re­paint­ing, you might like to think about whether they’re worth it.

I’ll cer­tainly be think­ing about it, next time I’m in the bot­tom of a chilly dry dock with a brush in my hand, paint­ing the seem­ingly vast area of the boat’s bot­tom and re­al­is­ing I’ll be do­ing it all again in just a few years…

Any­thing that ex­tends the in­ter­vals be­tween do­ing this has to be good news!

Blue­wa­ter boat still looks good af­ter five years

Blue­wa­ter use the same treat­ment for tanks

The ex­trac­tion plant in­stalled at Deb­dale

Deb­dale’s treat­ment on a his­toric boat hull

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