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Building a S/D 34' trawler in steel?
- Thread starter Rustybarge
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Rustybarge
Guru
I love the pilothouse with rear cabin layout; works really well even in a small boat.
Ski in NC
Technical Guru
Recognize that building in steel means no compound curves unless the plate is shaped somehow. You can bend plate one way, you can bend it the other way, but not both. So unless you have some elaborate construction techniques, the hull is not easy to build with pretty lines or good hydrodynamics.
I've built stuff in steel, not a boat though, and I've built a cold molded boat. Both are miserable projects involving dust, noise, heat, and injuries. But I would much rather go cold molded over steel. The amount of cutting and grinding necessary is staggering. And unless an expert, hull will be bumpy.
Alloy, no way. Steel corrodes at a slow predictable rate. When alloy gets into a corrosive situation, it can attack rapidly and locally. And hard to weld properly. I can't weld alloy worth a crap. Steel, no problem.
I've built stuff in steel, not a boat though, and I've built a cold molded boat. Both are miserable projects involving dust, noise, heat, and injuries. But I would much rather go cold molded over steel. The amount of cutting and grinding necessary is staggering. And unless an expert, hull will be bumpy.
Alloy, no way. Steel corrodes at a slow predictable rate. When alloy gets into a corrosive situation, it can attack rapidly and locally. And hard to weld properly. I can't weld alloy worth a crap. Steel, no problem.
OP
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Rustybarge
Guru
Whatever about steel rusting, if your anti fouls gets scratched on a alloy boat and you're tied up to a steel piling in a harbour in seawater, your alloy hull will dissolve in front of your eyes !
Are those stories about owners of alloy boats asking the crew to empty their pockets of copper coins true? (A couple of months to eat through the hull?)
LarryM
Guru
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- USA
- Vessel Name
- Pelago
- Vessel Make
- Wellcraft 3300 Coastal
Here are some links to the actual construction of several Union Jacks. I think you can get a pretty good idea of the process from them.
UNION JACK by Scott A. Ochocki (1-02)
UNION JACK by Pat Walsh, Ireland (8-04)
UNION JACK by David Ainge, Townsville, Australia (10-08)
UNION JACK by Seahorse Marine, Zhuhai, China
Happy browsing/dreaming
UNION JACK by Scott A. Ochocki (1-02)
UNION JACK by Pat Walsh, Ireland (8-04)
UNION JACK by David Ainge, Townsville, Australia (10-08)
UNION JACK by Seahorse Marine, Zhuhai, China
Happy browsing/dreaming
OP
OP
Rustybarge
Guru
Here are some links to the actual construction of several Union Jacks. I think you can get a pretty good idea of the process from them.
UNION JACK by Scott A. Ochocki (1-02)
UNION JACK by Pat Walsh, Ireland (8-04)
UNION JACK by David Ainge, Townsville, Australia (10-08)
UNION JACK by Seahorse Marine, Zhuhai, China
Happy browsing/dreaming
Thanks for your links.
She's a pretty hull, I'm going to ask how fast she could go into the low teens with a bigger engine.
eyschulman
Guru
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If you are not already aware of the fact that the hull no matter the material is the cheapest part of the boat ,know it now. Most of the time and money that go into a new build is based on the guts and finish. The only way the home build becomes a bargain is if owner builder has the skill/know-how and puts the time(lots of time) into the construction. If the home build is not very well done the real cost can come when you have to sell. For the vast majority a used production boat or somebody's used custom or home made is the best way to go. If you have the skills and time and really enjoy building go ahead but be aware that you probably will not save money in the long run. Steel is good building stuff so are all the other options with one big admonition, it has to be done right. For a home builder ply composite is probably easiest to get a good fair job and starting with a professionally molded bare hull such as a DE lobster hull even better. A lot to think about good luck. Ed.
OP
OP
Rustybarge
Guru
My ideas for the interior is free standing furniture, none of that fitted trailer type stuff: I think it's looks horrid when it get old and tatty! This should save thousands of $$$.
With led lights only one tiny live wire is needed to wire the whole boat with lights; even more money saved. Wi-Fi can be used for computer/TV/ hifi with no wiring.
Fitting a Honda 2kw suitcase genny on the swim platform would charge the batteries/ heat water; only a couple of wires needed.
Really with modern tech it's just an empty shell without any expensive fitting out.
So I'll try to create a long flat surface from the transom through to the saloon up to the inside helm with cheap oak floor boards to give a work boat look; the walls with a simple vertical tongue and groove pine boarding like in a classic trawler boat.
....this way the fitout should be really cheap, and look authentic as well!
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OP
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Rustybarge
Guru
Update: I've got a response from Andrew Wolstenholme the naval architect for the cost of designing a 34' steel trawler; just the general arrangement, scantlings and plate thickness' with a table of offsets, no detailing work included.
Anyone like to guess?
But I have also learnt some very useful information. I asked for a design that would max out at 15kts, and have a fast cruise of 12 kts. His response was that in a steel hull 15 kts is considered planing speed not S/D; he advised me to reduce my requirement to 12 kts max.
Just presuming that steel is going to be hard to shape into a good profile for a S/D hull with all its curved surfaces, which will severely limit the efficiency of the steel hull form over 12 kts.
Know we know why the glen l Union Jack is called a S /d design; it goes a few knots faster than hull speed!
The plot thickens as they say! Is 12 kts fast enough in a boat to run for cover?
PS: I think the NA is saying a steel s/d design is really a fast displacement design, rather than a proper s/d hull form that you could mould into a GRP boat.
Anyone like to guess?
But I have also learnt some very useful information. I asked for a design that would max out at 15kts, and have a fast cruise of 12 kts. His response was that in a steel hull 15 kts is considered planing speed not S/D; he advised me to reduce my requirement to 12 kts max.
Just presuming that steel is going to be hard to shape into a good profile for a S/D hull with all its curved surfaces, which will severely limit the efficiency of the steel hull form over 12 kts.
Know we know why the glen l Union Jack is called a S /d design; it goes a few knots faster than hull speed!
The plot thickens as they say! Is 12 kts fast enough in a boat to run for cover?
PS: I think the NA is saying a steel s/d design is really a fast displacement design, rather than a proper s/d hull form that you could mould into a GRP boat.
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funangler
Senior Member
A well built steel boat with a low center of gravity is like a turtle. Slow but well armored against the weather it just plods along. With the current forecasts good for at least 3 days of warning before you get winds over 40 knots I don't think running for cover is a big deal. I bet the change of plans is no less the 6000 us.
OP
OP
Rustybarge
Guru
Higher, higher......
OP
OP
Rustybarge
Guru
Where did I leave that lottery ticket...?
Where did I leave that lottery ticket...?
Well, I was on the low end of his range but did think it would be at least that. Naval architects don't come cheap. And obviously the speed you were expecting is gone. I couldn't see that boat being able to do that. I wouldn't be surprised to see 10-12 knots turn into 8-10.
OP
OP
Rustybarge
Guru
Exactly.
I think I'm able to answer the question : Can you build a S/D trawler in steel?
Ans: No.
Can you build a fast displacement trawler in steel?
Ans: Yes, expect a couple of kts over hull speed; ie: 10kts if you're lucky.
What advantage would a fast steel displacement hull have over a standard displacement type?
Ans: None , still not fast enough to run for shelter.
Why build in steel?
Ans: cost ........
Well at least we found some definite answers.
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@Peter, have you looked at Bruce Roberts website. An example is this workboat. Sold as CNC Cutting files. ( £1,595 )
Link: Bruce Roberts COASTWORKER
Link of the assembling: Kit assembling photos
Link: Bruce Roberts COASTWORKER
Link of the assembling: Kit assembling photos
Attachments
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OP
OP
Rustybarge
Guru
That's more in by budget!:lol:
It's a pretty hull, and the plans even include NC cutting files if you want to get the plates plasma cut. I suppose it's either stack em' high sell them cheap, or custom design for wealthy customers at £20k a pop.
Fantastic value from Bruce Roberts!
If you are only interrested in the hull then it can be even cheaper (£695,00) this is the same hull.
Link: EURO 12mtr.
OP
OP
Rustybarge
Guru
Now that's what you call real value.
...but unfortunately I was hoping to build a S/D trawler with a 15kts max cruise.
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Now that's what you call real value.
...but unfortunately I was hoping to build a S/D trawler with a 15kts max cruise.
ALUMINUM planing hull version would be capable of 20 - 25 knots when fitted with twin engines of suitable hp.
Ask Bruce what will be the maximum performance build in steel with twin engines installed.
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OP
OP
Rustybarge
Guru
Could you recommend a builder of Down East lobster boat hulls for home completion ?
OP
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Rustybarge
Guru
Thanks for that link, very interesting site.
OP
OP
Rustybarge
Guru
The westmac hull looks like a perfect choice to build a Devlin type boat with that beautiful bow section in GRP rather than plywood/epoxy.
The Devlin Topknot: http://store.devlinboat.com/topknot-10_meter.aspx
The Devlin Topknot: http://store.devlinboat.com/topknot-10_meter.aspx
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GeorgS
Veteran Member
Hi Peter, just in case steel isn't ruled out yet: I've spent some time on a Pedro Donky 30. These boats were built for higher than classical full-displacement speeds (look at the flat aft section). The weight is on the low side for a steel-boat of this size and the overall profile is rather low (a Swift-Trawler 34 or a Grand Banks 32 will "tower" the Donky's by a good bit).
Fuel Economy and simple tech in mind we opted for the old Volvo MD31 engine (62HP), but this one wasn't available anymore and we got a Volvo TAMD 31M (110HP) instead. Don't recall exact top-speed in calm water, but it was close to 8.5 knots (and way too loud for our taste).
Other Donky's had much more powerful engines installed, a speed of 12+ knots should be possible. I recall a Donky built for UK-based gents with trim-tabs and (if memory serves) two TAMD41B's (200HP each) installed.
So steel-construction and S/D-speeds can be brought or better forced in line, if really desired.
Please excuse my limited "English", Georg.
Fuel Economy and simple tech in mind we opted for the old Volvo MD31 engine (62HP), but this one wasn't available anymore and we got a Volvo TAMD 31M (110HP) instead. Don't recall exact top-speed in calm water, but it was close to 8.5 knots (and way too loud for our taste).
Other Donky's had much more powerful engines installed, a speed of 12+ knots should be possible. I recall a Donky built for UK-based gents with trim-tabs and (if memory serves) two TAMD41B's (200HP each) installed.
So steel-construction and S/D-speeds can be brought or better forced in line, if really desired.
Please excuse my limited "English", Georg.
Sailor of Fortune
Guru
I would look at the Muscle Ridge 42 instead of the Wesmac, unless you had very deep pockets. The Wesmacs are the gold standard of Downeast hulls but if your doing the build yourself, nobody will pay top retail for it down the road. The Muscle Ridge boats are very well built, hard chine (like Wesmac) and a nice platform to begin.
OP
OP
Rustybarge
Guru
You speak perfect English; better than the majority of Irish people with their own peculiar vernacular vocabulary!
I like the pedro designs; simple with lovely lines.
The Donkey is classified as cat:B offshore too, that's very impressive for what's basically an inland/estuary Dutch cruiser.
If I remember correctly the first pedro designs were frameless construction; but I think so little weight is saved it doesn't make sense as you have to use thicker steel plating to compensate.
OP
OP
Rustybarge
Guru
Thanks for that link.
Pretty boats, and there seems to be considerable saving against the Westmac versions.
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