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Old 09-12-2014, 01:32 PM   #1
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Building a S/D 34' trawler in steel?

Hi All,

Nothing compares to steel for cheapness and strength for home building at 500/ton for 6mm plate. build outside, weld outside, transport in sections, paint with two pack industrial bridge paint: change parts of the design during the build!

so I was thinking if you could build a semi-displacement trawler of about 34' in Steel it would be a very very economical and quick to fabricate trawler project.

Came across these Pedro Dutch trawler designers in steel, but displacement not S/D.

http://www.pedro-boat.co.uk/pages/mo...-donky-34.html

7 tons 34', right 'on the money' for a GRP 34' trawler!

Could this design be easily adapted to semi-displacement?

Technical specification
Length o.a.: 10,30 m
Beam: 3,40 m
Draught: 1,00 m
Air draught: +/- 2,55 m
Fuel tank: 400 liter
Fresh water tank: 250 liter
Holding tank: 250 liter
Berths: 2 - 4
Weight: 7.100 kg
Engine: Perkins M92B, 64 kW (86 hp)*
Other engines possible
CE-design category: B



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Old 09-12-2014, 04:14 PM   #2
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Just noticed these boats are Cat: B offshore. Wow!

RCD Cat:
B) OFFSHORE -
Designed for waves of up to 4m significant height and a wind of Beaufort Force 8 or less.
Such conditions may be encountered on offshore voyages of sufficient length or on coasts
where shelter may not always be immediately available. Such conditions may also be
experienced on inland seas of sufficient size for the wave height to be generated.

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Old 09-12-2014, 04:24 PM   #3
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Old 09-12-2014, 05:54 PM   #4
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I can't find photos of the frameless construction techniques; here's a different boat.

Building the hull the wrong way around! (hull supported on temporary frames underneath)

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Old 09-12-2014, 06:34 PM   #5
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Civil War. Clearly misunderstood. Deafening silence. Devout Athiest. Found missing. Icy hot. Congressional smarts. Jumbo shrimp. Militant Pacifist. Steel Semi-Displacement.

Is it possible? Perhaps. But it's just really an oxymoron. And to get the balance and performance. Steel doesn't lend itself well to what you're talking about.
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Old 09-12-2014, 07:18 PM   #6
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Civil War. Clearly misunderstood. Deafening silence. Devout Athiest. Found missing. Icy hot. Congressional smarts. Jumbo shrimp. Militant Pacifist. Steel Semi-Displacement.

Is it possible? Perhaps. But it's just really an oxymoron. And to get the balance and performance. Steel doesn't lend itself well to what you're talking about.
A true Forest Gump moment!

But......
Let's look a very recent S/D trawler design, the Swift trawler 34'.

Swift Trawler 34 / Swift Trawler / Motorboats - BENETEAU

Length Over All :
10,98 m - 36’0’’
Hull Length :
9,98 m - 32’9’’
Hull Beam :
4,00 m - 13’1’’
Light displacement :
7 450 kg (CE) -16,420 lbs
Fuel tank capacity :
800 L - 211 US Gal
Fresh water capacity :
320 L - 85 US Gal
Max Engine Power (Hp) :
425 CV - 425 HP

Propulsion :
Propeller Shaft
CE Certification :
B8/C10/D11

It weighs 1/2 ton MORE than the Pedro steel 34'!!!!

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Old 09-12-2014, 07:47 PM   #7
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Quote:
Originally Posted by Rustybarge View Post
A true Forest Gump moment!

But......
Let's look a very recent S/D trawler design, the Swift trawler 34'.

Swift Trawler 34 / Swift Trawler / Motorboats - BENETEAU

Length Over All :
10,98 m - 360
Hull Length :
9,98 m - 329
Hull Beam :
4,00 m - 131
Light displacement :
7 450 kg (CE) -16,420 lbs
Fuel tank capacity :
800 L - 211 US Gal
Fresh water capacity :
320 L - 85 US Gal
Max Engine Power (Hp) :
425 CV - 425 HP

Propulsion :
Propeller Shaft
CE Certification :
B8/C10/D11

It weighs 1/2 ton MORE than the Pedro steel 34'!!!!

Yes and two feet longer. Molding the steel into the design and shape necessary and maintaining the strength just seems very challenging to me. Some of the ST weight is also up top. I'm not saying it can't be done. Just seems a bit of a strange and difficult path.
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Old 09-13-2014, 04:50 AM   #8
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Yes and two feet longer. Molding the steel into the design and shape necessary and maintaining the strength just seems very challenging to me. Some of the ST weight is also up top. I'm not saying it can't be done. Just seems a bit of a strange and difficult path.
My logic goes like this:

I can't afford a new or recent boat, so I would have to buy a 30 year old GRP trawler. My concern is the condition of the hull and decks; water ingress. I have a little 13' dory (Boston whaler type) from the late 60's that's been outside all that time: there's delamination, there are soft spots, if you try to bolt through the GRP it crumbles and cracks.....in other words the GRP is coming to the end of its life, admittedly after over 40 years.

Buying an old boat means old engines; if they go bang re-powering could cost an eye watering amount.

So a 30 year boat is not for me, instead I'd like to build a new trawler.

Plywood/epoxy;it's probably cheaper to buy a ready made moulding, takes years to build, has to sanded and faired which takes months of work.

Buy a ready made moulding: still costs plenty, more than 1k/ ft, so a 34' hull will probably cost 34k plus tax= over 40k.....

Steel: 7 ton boat, materials about 3.5k, build time about. 6 months full time, but obviously rust is a big worry.

Finished hull primed 4k
Cummins 6 BT reconditioned 330hp $15k ex states
Prop shaft, prop, stuffing box. 1.5k
Glass. 1.5k
Everything else home made.......say 20k.

Plus of course the design cost for a NA.
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Old 09-13-2014, 08:50 AM   #9
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Originally Posted by Rustybarge View Post
My logic goes like this:

I can't afford a new or recent boat, so I would have to buy a 30 year old GRP trawler. My concern is the condition of the hull and decks; water ingress. I have a little 13' dory (Boston whaler type) from the late 60's that's been outside all that time: there's delamination, there are soft spots, if you try to bolt through the GRP it crumbles and cracks.....in other words the GRP is coming to the end of its life, admittedly after over 40 years.

Buying an old boat means old engines; if they go bang re-powering could cost an eye watering amount.

So a 30 year boat is not for me, instead I'd like to build a new trawler.

Plywood/epoxy;it's probably cheaper to buy a ready made moulding, takes years to build, has to sanded and faired which takes months of work.

Buy a ready made moulding: still costs plenty, more than 1k/ ft, so a 34' hull will probably cost 34k plus tax= over 40k.....

Steel: 7 ton boat, materials about 3.5k, build time about. 6 months full time, but obviously rust is a big worry.

Finished hull primed 4k
Cummins 6 BT reconditioned 330hp $15k ex states
Prop shaft, prop, stuffing box. 1.5k
Glass. 1.5k
Everything else home made.......say 20k.

Plus of course the design cost for a NA.
That may all well work. I don't know enough about personally building a boat to know. But I'd think perhaps getting comfortable with building it to be full displacement simplifies things and keeps you from trying to go down a new path.

Now as to basing the life of a GRP trawler on your 13' Dory of non Boston Whaler brand, I wouldn't do that. Yes, many older boats of all materials do have problems. However, I also know many boats from the 50's and 60's that have held up great and others that with a bit of restoration are jewels. Look at Hatteras in that period for a prime example. Obviously any would need a good survey. And I'd add one small note. Boat building has improved over the years so a boat now 30 years old and taken good care of may never have the issues a boat now 40 years old has, not even with 10 or 20 years more use.

But building your own steel boat would be interesting. I would question your estimated costs and time however. There are manufacturers who struggle to do it in six months. So for a DIY builder I'd see that as unlikely. And I just don't see it with your costs, especially the everything else.

And my last note to you is insurance. I'm assuming you might be fine without hull coverage but you'd need the rest and I don't know what you'd face getting it on a DIY boat. I assume, but don't know, that you can get it registered without problem?

Good luck with your project if that's the way you decide to go.
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Old 09-13-2014, 08:56 AM   #10
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I've sent off an email to this guy to get a price for designing a boat like the swift trawler 34' in Steel.
WOLSTENHOLME YACHT DESIGN

Andrew Wolstenholm is a famous designer here in the UK, he's THE expert in S/D design, having designed the Hardy range of boats, the broom range and lots of sea going barges including sailing barges.

So if it is possible to have a steel S/D trawler this guy will be able to design it, and it should make it easier to sell second hand with that provenance.

Just wondering how much he will quote.
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Old 09-13-2014, 09:04 AM   #11
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Build out of aluminum it faster and easier to work with. The huge plus factor is it does not rust when you drill a hole in it or scratch the paint.
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Old 09-13-2014, 09:12 AM   #12
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That may all well work. I don't know enough about personally building a boat to know. But I'd think perhaps getting comfortable with building it to be full displacement simplifies things and keeps you from trying to go down a new path.

Now as to basing the life of a GRP trawler on your 13' Dory of non Boston Whaler brand, I wouldn't do that. Yes, many older boats of all materials do have problems. However, I also know many boats from the 50's and 60's that have held up great and others that with a bit of restoration are jewels. Look at Hatteras in that period for a prime example. Obviously any would need a good survey. And I'd add one small note. Boat building has improved over the years so a boat now 30 years old and taken good care of may never have the issues a boat now 40 years old has, not even with 10 or 20 years more use.

But building your own steel boat would be interesting. I would question your estimated costs and time however. There are manufacturers who struggle to do it in six months. So for a DIY builder I'd see that as unlikely. And I just don't see it with your costs, especially the everything else.

And my last note to you is insurance. I'm assuming you might be fine without hull coverage but you'd need the rest and I don't know what you'd face getting it on a DIY boat. I assume, but don't know, that you can get it registered without problem?

Good luck with your project if that's the way you decide to go.

In the Eu boats have to an official those rating called the RCD before they can be bought or sold, even privately.

...but a self build boat is exempt from the requirement if is it is not sold for 5 years; no RCD certification needed.

My interest in steel boats is from an authenticity angle; I go to a Marina and look at all the boats bobbing up and down and think how horrid they are made out of plastic. At least steel and cast iron has been in used for boat building since the Victorian age, it has a history behind it.

I've built a steel boat before, and I'm getting very close to 60 years old. I feel I have one more boat in me before I hit the buffers!
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Old 09-13-2014, 09:16 AM   #13
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Build out of aluminum it faster and easier to work with. The huge plus factor is it does not rust when you drill a hole in it or scratch the paint.
I've been considering alloy, but after talking to the guys on the boat design forum they said this: 'you can learn to weld alloy, but but your first 4 boats will crack apart: the 5th will probably be good'

Also alloy is 6 times more expensive than steel: A professionally built alloy hull will cost a least double the cost of a steel one.

Why are boats so annoying!!!
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Old 09-13-2014, 09:27 AM   #14
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Just some photos for you guys that aren't familiar with this French design.

Does it look a bit like e Mainship 34' mk 1 or what?





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Old 09-13-2014, 09:30 AM   #15
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Old 09-13-2014, 09:32 AM   #16
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I love the interior layout too.


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Old 09-13-2014, 09:32 AM   #17
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Building a S/D 34' trawler in steel?

The trick is to hire out the welder on weekends and evening to come by and do the majority of your welds. You can cut and fit when he not around if you plan on keeping this boat for a long time aluminum cost less in time and headaches. I have owned both and will not own another steel boat.
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Old 09-13-2014, 09:42 AM   #18
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The trick is to hire out the welder on weekends and evening to come by and do the majority of your welds. You can cut and fit when he not around if you plan on keeping this boat for a long time aluminum cost less in time and headaches. I have owned both and will not own another steel boat.
I suggested this to the experts; I'd tack weld the boat together and get the expert in to weld it up.

The response was ' there's no way I would put my name to somebodies else's work, you'd never get the gaps right, and lots of places have to assembled and welded in one go'.

There's also the problem that alloy welding has to be done inside in a sheltered environment, and the conditions have to be surgically clean to get a decent quality of weld.

I was told in no uncertain words: 'alloy welding is only for trainer professionals carried out in perfect controlled conditions....'

I sort of got the message after that......
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Old 09-13-2014, 10:06 AM   #19
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Wow I would like see those boat yards it sound like the aerospace industry. I understand where they are coming from, I can see there point but it is still a "home" built boat and you are the owner. I would still look around for a good welder for the longer seams.
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Old 09-13-2014, 10:09 AM   #20
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Re. The naval architect, I'm hoping to get just the hull offsets and plate thickness' for the S/D design. I can build in my my own preferences for the detailing of the wheel house, decks, flybridge etc. Basically the structure details.

This should reduce the cost considerably, as I don't need any of the fiddly small details draw for me.


Anyone like to guess how much it will cost ?
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