Recommended boat hull/steel

[David Mack]

1) Generally a 'boat builder' will 'build' a shell (hull) from random bits of flat steel.

2) A boat 'fitter' will generally fit out a pre-sourced shell.

3) Some boat builders employ boat fitters (either on site or elsewhere) and do both jobs so you end up with a finished boat.

Not sure about that. I think there are firms out there who call themselves "boatbuilders" who buy in shells and fit them out themselves, as well as those who build the shells and subcontract the fitting out.

[gazza]

i agree with you on the grp i have seen some old boats in our yard on the slipway and for the most they have been in very good condition. i was very tempted with one but they upped the price when they realised i was serious about buying

Cheeky buggers!

 

The osmosis thing is a worry for the WAFIS, they get hung up on the potential of losing .01 of a knot, forgetting that a dirty bottom has the same effect!

 

I have worked on a terribly delaminated Buckingham 25, Something had gone wrong when it was laid up, sheets of gell coat were falling off it. Was totally watertight and not likely to sink anytime soon.

 

A few osmotic blisters are neither here nor there!

 

The RNLI considered GRP suitable for there purposes too

[blackrose]

Osmosis is not as big a problem as those that want to make money out of it would have you believe.

Boats don't sink from osmosis, they do from rotten wood and teabag steel.

 

As for the knock comment, that's bollocks too, if you whack something hard enough to split GRP you shouldn't be boating.

 

No, you're the one talking bollocks. I've personally seen a friend's GRP boat in France that was leaking from osmosis and had to be hauled out and repaired. Boats can and do sink from osmosis. Any boat made from any material can sink if it's not properly maintained and if a boat has teabag steel or rotten wood it certainly wasn't and that's just down to neglect.

 

The other thing I saw on the Thames was a GRP boat that was hit by a steel boat and badly damaged. Perhaps you're right and the owner of the steel boat shouldn't have been boating but unfortunately that was something the GRP boat owner had no control over. You have a bit of a blind spot in your thinking if you think the only way a boat gets a whack is down to its own skipper.

Edited February 12, 2016 by blackrose

[gazza]

No, you're the one talking bollocks. I've personally seen a friend's GRP boat in France that was leaking from osmosis and had to be hauled out and repaired.

 

The other thing I saw on the Thames was a GRP boat that was hit by a steel boat and badly damaged. Perhaps you're right and the owner of the steel boat shouldn't have been boating but unfortunately that was something the GRP owner had no control over.

We agree on the second point

 

Osmosis doesn't sink boats.

 

Poor quality lay up will.

 

I'd be fairly certain a poorly wetted out area would have been the culprit, not an osmosis bubble in the gel coat. The fact the bubble was in that area will have been incidental to the repair needed.

I never once suggested all GRP boats are built to the highest standards, merely that the scaremongering about osmosis is just that.

 

As I said earlier, the Buckingham 25 with the gel coat flaking off was 100% watertight.

 

I'll give you a wee bit of an inside line, our firm is in the business of squirting resin into fibreglass pipe liners, I have a good knowledge of resins and their application

Mike you edited your post as I submitted mine, that was the point I was subtlety making.

If anyone causes a boat significant damage, be it the skipper of the damaged boat or the idiot that hit it they shouldn't be in charge of the remote control leave alone a boat

Edited February 12, 2016 by gazza

[John V]

The Royal Navy have a good opinion of them as well...... they build the Hunt class from GRP

[Phil Ambrose]

Osmosis is a bit of a bogey man and as we all know bogey men are not to be feared. On the Broads for 10 years and never saw or heard of a boat out of all the 5000 or so boats registered that had terminal osmosis. In fact the saying was that any boat with osmosis would outlast it's owner.

Phil

[___]

Other than the odd experiment in stainless I suspect all steel narrow boats are constructed in low-carbon 'mild' steel and always have been. Anyone know any different?

 

This is the stuff that accounts for about 90% of world steel production and is used for it's balance of cost, ease of welding, elastic behaviour, fracture toughness and strength. It's a jack of all trades essentially and is readily available for a low technology application such as building a narrow boat which under normal circumstances won't even come close to testing the mechanical properties of the metal itself.

 

Corrosion resistance properties of steel are a product of the chemical mix so given the base material hasn't changed - it's origin or even absolute 'quality' isn't really a factor - then there is no basis in fact that modern steel rusts more easily than older steel.

 

Over time the manufacturing processes of steel have changed to eliminate impurities and the effects such as drawdown and chemical segregation associated with cooling large blocks of material from liquid to solid state. In terms of engineering performance modern steels are superior to those of 50 years ago. That's really of no great significance in boat building because narrow boats are built not engineered. There is no point talking about yield strength and thickness in terms of the strength of the hull if you haven't calculated loads and modelled the structural form and who has ever done that for their boat?

 

The brokerage where I bought Vulpes were adamant that modern boats corrode more easily than older ones. I will take that at face value because they have seen lots of them in their line of work and I have seen very few. However I assert that it's not about the steel.

 

There are a few folk on here who understand the metallurgy and supply chain of steel far better than I do, my own experience is in being accountable for performance of rail steels in a safety critical high performance environment. The advice these folk give in this and other threads should be heeded. Essentially worry about the preparation, welding and protection of the steel but the steel itself should not be a concern.

 

JP

[mark99]

Try the 'ex-Hudson' yard at Glascote. I understand that it has been taken over by Norton Canes staff, so between the two they should come up with an awesome build.

 

 

Hudson Canes?

 

<Dave is gonna kill me>

[sarahavfc]

 

 

Hudson Canes?

 

<Dave is gonna kill me>

I'll help him ?

 

That's one thing that will never happen...

[blackrose]

We agree on the second point

 

Osmosis doesn't sink boats.

 

Poor quality lay up will.

 

I'd be fairly certain a poorly wetted out area would have been the culprit, not an osmosis bubble in the gel coat. The fact the bubble was in that area will have been incidental to the repair needed.

I never once suggested all GRP boats are built to the highest standards, merely that the scaremongering about osmosis is just that.

 

As I said earlier, the Buckingham 25 with the gel coat flaking off was 100% watertight.

 

I'll give you a wee bit of an inside line, our firm is in the business of squirting resin into fibreglass pipe liners, I have a good knowledge of resins and their application

Mike you edited your post as I submitted mine, that was the point I was subtlety making.

If anyone causes a boat significant damage, be it the skipper of the damaged boat or the idiot that hit it they shouldn't be in charge of the remote control leave alone a boat

 

Well, whether it's osmosis that actually sinks the boat or not is not really the point. If the GRP suffers badly from osmosis it will have to be taken out of the water and repaired eventually. So if talk of osmosis is scaremongering then by the same token so is talk of rotten wood and "teabag" steel.

Osmosis is a bit of a bogey man and as we all know bogey men are not to be feared. On the Broads for 10 years and never saw or heard of a boat out of all the 5000 or so boats registered that had terminal osmosis. In fact the saying was that any boat with osmosis would outlast it's owner.

Phil

 

I accept that it shouldn't be feared, but I've certainly seen one with terminal osmosis.

The Royal Navy have a good opinion of them as well...... they build the Hunt class from GRP

 

As far as I'm aware the Royal Navy have a few steel boats too...

 

All hull materials have their advantages and disadvantages.

Edited February 13, 2016 by blackrose

[John V]

The Hunt class ships with the RN are all about 30 years old of the 9, (still in the RN) 8 are in commission in active service including the Persian Gulf.

1 is a training vessel, 2 sold to the Hellenic Navy and are in commission. 2 sold to the Lithuanian Navy and still in commission. Pretty good record for GRP

Edited February 13, 2016 by John V

[Midnight]

Get Norton Canes to build it.

 

Yes I often dream about that too!

 

However it's a very good point and I will ask Graham to build my next shell if I live long enough to save up the money.

 

Sorry to labour the point regarding different grades of steel but I am really trying to understand what causes different types of corrosion. The boat club where we moor has a dry dock so I regularly get to see boats out of the water. Last week for instance I saw an Evans & Son boat. Some of the delaminated rust scrapings off the bottom plate were over 5mm thick that surely wasn't mill scale was it? I saw the same on a 4 year old Liverpool shell once.

 

My own boat from a middle-weight builder is quite different. The sides were grit blasted and two-packed from new so no worries there. The baseplate however wasn't initially blacked 'cos I was told "no need...not much oxygen... etc" Now I realise I should have consulted the fish but none-less-less I naively carried on until after 8 years I inspected the baseplate because the dry dock has large stanchions allowing easy access underneath. To my horror I found small amounts of what I can only describe as ringlets of powdery rust which when brushed off revealed perfectly round concave holes up to 4mm deep -loads of them! Amazingly the surface around those holes came up like bright shiny steel after a good wire wheeling. Inside the holes when cleaned looked like the ends of steel laminations and a local boat builder of some repute suggested it was mill steel (whatever that is).

 

I have since welded up the deepest holes and blacked the bottom each year with Comastic - and no it doesn't get scraped off any more than the odd scrape along the hull sides. Next time I dry dock I am going to get the baseplate grit blasted and do that in two-pack as well.

 

As a bit of a thicky when it comes to steel I will follow a few self imposed rules if I ever get another shell built. This isn't for everyone but it may help those in my position.

 

1/ use the best shell builder you can afford and spec the best steel (pickled?) - high end builder if you can afford it

2/ 12-15mm baseplate

3/ regardless of above have the whole shell grit blasted and two-packed primer above gunwales two-pack coal tar epoxy below

4/ fit galvanic isolater and dry dock every two years max

 

The technical bod from McDuff once told me anodes only work after the hull coating breaks down - my experience suggests this to be correct as my own anodes are 12 years old and seem to be fit for a few more yet.

 

Edited February 13, 2016 by Midnight

[Alan de Enfield]

 

 

 

Sorry to labour the point regarding different grades of steel but I am really trying to understand what causes different types of corrosion.

 

 

I think you have answered your own question - the 'different grades' of steel play absolutely no part in determining the type / amount of corrosion.

As had been said numerous times in this thread - its what you subsequently do with it that's important.

 

Quit worrying and start enjoying your boat / boating.

Edited February 13, 2016 by Alan de Enfield

[X Alan W]

Thanks very much for a great set of responses, so yes reputable boat builder looks like the way forward, now the search is for a reputable builder, I'm in Surrey and know of a few, if there are any builders reading this thread then they might want to get in contact ?

I think you will find that a reputable Hull/ Boat builder will have work that will require you to book a build slot & in the case of a premier division company will possibly be a year or more from the time you place the order + the slot start time may possibly be up to a year before they can make a start , for the last few years the best builders have had long lead times & as far as I'm aware are busy enough to not actively have to seek orders the work comes to them not the other way around

[Midnight]

 

I think you have answered your own question - the 'different grades' of steel play absolutely no part in determining the type / amount of corrosion.

As had been said numerous times in this thread - its what you subsequently do with it that's important.

 

Quit worrying and start enjoying your boat / boating.

 

 

Not worrying just trying to understand the difference - why does my corroded baseplate have concave holes all about 25mm diameter with shiny as new steel around them and other boats have rust that when scraped off leaves a rusty corroded rough baseplate minus a few mm?

 

If that isn't the difference between steel grades what is it?

[RLWP]

 

 

Not worrying just trying to understand the difference - why does my corroded baseplate have concave holes all about 25mm diameter with shiny as new steel around them and other boats have rust that when scraped off leaves a rusty corroded rough baseplate minus a few mm?

 

If that isn't the difference between steel grades what is it?

 

It's a difference in corrosion methods. In my opinion, those shiny pits are actually microbial corrosion. Read around the subject and you find the shiny pits and rusty water are characteristic of this. Tawny had some of these pits first time we had her out of the water. I have never seen them again on subsequent dockings

 

It is Microbial corrosion that is eating away the Titanic

 

Richard

Richard

[Midnight]

 

It's a difference in corrosion methods. In my opinion, those shiny pits are actually microbial corrosion. Read around the subject and you find the shiny pits and rusty water are characteristic of this. Tawny had some of these pits first time we had her out of the water. I have never seen them again on subsequent dockings

 

It is Microbial corrosion that is eating away the Titanic

 

Richard

Richard

 

Now that's quite interesting Richard I think you have the answered the question I've been puzzling over .

 

In the first 7 years we moored at Ripon Marina where the water quality was said to be very good. Freshwater mussels used to cling to the baseplate of most boats (not many to ours) but there was lots of marsh gas. When we used to arrive on a Friday evening you could hear the trapped gas escape from under the baseplate as the boat rocked when we stepped aboard. I guess those bubbles would be similar profile to the pitting.

 

Since we moved to the Calder after a short spell on the L&L there's been no further deterioration but obviously that's because I now black the baseplate regularly. That still doesn't explain why the unaffected steel comes up smooth and shiny - or maybe it does?

 

That Norton Canes boat I mentioned also moored at Ripon for over half of it's lifetime but has a V-bottom which would prevent gas collecting underneath and so did the Springer - hmmmmm!

 

Alan d E is correct IMO, it probably doesn't matter what grade of steel is used as long you protect it well.

 

V-bottom?

Two-pack sides and baseplate

Max two years between dry docking

[___]

 

It is Microbial corrosion that is eating away the Titanic

 

Richard

Do you know the owners Richard? Better tell them to get it blacked before it sinks.

 

JP

[RLWP]

There's some complicated insurance thing going on, I think

 

Richard

[___]

There's some complicated insurance thing going on, I think

 

Richard

Interestingly the Titanic was constructed from one inch thick mild steel plate. The likely point of critical failure was sub-standard wrought iron rivets.

 

Rather puts the steel thickness and grade debate into perspective.

 

JP

[WotEver]

And if Titanic II ever gets built it will be welded.

[ditchcrawler]

i would go for 15mm bottom no ballast, and given our canals are getting shallower it should last a lifetime, without needing edging which can be a problem for high canal miles boats. as for builders its still tyler wilson for me as they keep on winning at crick with their shells

But who votes for the winners ?

[dave moore]

Those who know no better!

 

Dave

[___]

And if Titanic II ever gets built it will be welded.

...with fake rivets

[WotEver]

...with fake rivets

That's an idea... I'll drop the guy an email...