Pro's & Con's on steel hulls

Hi all,
Looking at purchasing a Trawler and was looking for the pro's & con's on steel hulls. I ran a search here at TF, however did not fine anything.

Thanks for the insight!

Hopefully markpierce will chime in on this one since he bought one. He's probably got a comprehensive list of pros and cons used in his decision making.

http://www.trawlerforum.com/forums/s3/steel-vs-fiberglass-trawlers-4197.html

http://www.trawlerforum.com/forums/s3/steel-hulled-aluminum-hulled-9932.html

http://www.trawlerforum.com/forums/s3/steel-vs-fiberglass-composite-16625.html

http://www.trawlerforum.com/forums/s3/hull-material-19650.html

Pros:
Less costly construction for low-volume production, resulting in lower original-build purchase price.
Most likely to be stronger.
No worry about failure of non-fiberglass "fillers" in decks and wherever.
(Let's not talk about wooden boats.)


Cons:
Annual paint touch-up needed to stay on top of any rust.
Likely to be heavier (comes with being stronger), but that's not a problem with a not-to-exceed-hull-speed boat.


Steel versus fiberglass was not part of my boat selection criteria. Nevertheless, most all commercial boats are made in steel for some reason.

One of the topics that always comes to the surface when discussing steel hulls is rust. Yes, rust can be and is a problem with steel hulled boats that were not properly painted and or not properly maintained.

You'll also find that most of the negative comments regarding steel hulled boats and rust come from those not truly in the know. To give you some credible information on the topic of rust and steel hulled boats here's a quote from a designer of serious ocean going boats, Tad Roberts (Note: He's also a well respected member here on TF):

"Once upon a time it was a terminal problem. Today with modern coatings, if properly cleaned, primed, and applied, there is no problem. Rust only appears where the coating has failed. All wear points like rub rails, cleats & bitts, hawse pipes, cabin edges, etc. should be stainless steel and radiused."

A lot depends on the size of the boat. For smaller boats (<35-40'' or so) there is a big weight penalty for a steel hull. That extra weight means that more power is needed for a given speed. In other words, a more costly engine than for an equivalent size glass boat. For larger boats the cost penalty goes away.

The next area of concern is corrosion. Ideally a steel hull needs to be properly coated inside as well as outside. Improper or no interior coating can lead to the boat rusting from the inside out. I have seen more than one steel boat with this problem.

Steel is also a better heat conductor than glass, so steel hulls need to be insulated or they will have significant condensation problems in colder water.

Construction methods and quality are also major considerations, but that is true with glass boats too. For a steel hull, the grade of steel used is significant. Mild steel will have a pretty short life if the coating system fails. You also need to be concerned with topsides weight. A steel house is heavy where you don't want weight. Many boats deal with this by using an aluminum house, but that introduces new corrosion problems if the paint fails at the steel-aluminum junction.

Finally cost - a steel hull can be cheaper than glass for a one off if the hull is hard chine and has only minor plate curvature that can be bent in during construction. If the hull has a round chine and requires shaped plates, the cost of construction will be MUCH greater. It is very expensive to shape steel plate.

Personally, for the size boats most of us have I see no real benefit to steel, unless you want an ice capable boat.

Can problem rust areas be treated with Ospho. It pickles the metal; as my dad use to tell me. He and I have used it on rusting items many time and a little goes a long way. I've had to 2 litter jug now going on 25 years .After treating a rusted surface and the pickling effect set in, the treated surface would never rusted again. Treated areas didn't even need painted after treatment. It does turn the treated area black though and will eat concrete if spilled on it...lol.

Thankfully, my steel boat is well insulated.


Eighty horsepower is quite sufficient, thank you.


My steel boat has a low profile, and the boat's steel thickness is reduced the father from the keel. Not worried there either.

On a used boat the steel hull will be MUCH cheaper in the USA , as steel is not well accepted here.

In Euroland steel has a great following .

Either way steel is easier to repair as even 3rd world areas are familiar with the material.

With proper design and materials , rust today is LESS of a problem , tho eventually the interior will need to be removed and the hull sand blasted and re painted, inside and out.

May now take 30 years for the 6-7-8 part paint scheme to die instead of only a decade orb so with red lead and paint , BUT the time does come.

AS this is well known R&R of the interior , as well as engines and electrical systems should have been part of the initial design.

As its almost all a labor expense a 3rd world shipyard would do fine.

Years ago the Polish yards would do a 45- 50 ft boat for $5,000 plus all materials.

bankerboy1 said:

Can problem rust areas be treated with Ospho. It pickles the metal; as my dad use to tell me. He and I have used it on rusting items many time and a little goes a long way. I've had to 2 litter jug now going on 25 years .After treating a rusted surface and the pickling effect set in, the treated surface would never rusted again. Treated areas didn't even need painted after treatment. It does turn the treated area black though and will eat concrete if spilled on it...lol.

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No treatment is perfect or lasts forever....otherwise everyone would know about it and use it.

Many rust converter products work pretty well if meticulous with prep and application and last if the over coating is good.

am I wrong in assuming galvanic corrosion can be a larger factor with a steel hull? is the solution just more zincs than what you'd have on a glass boat?

The interior out of sight places would concern me. We hear that steel diesel tanks are a worry after 15 years either from inside or outside rust. What protects steel frames and welds in damp locations.


Food for thought: Fiberglass tanks don't seem to fail but steel does.

As for hull material, I would like aluminum or steel! You have to paint the hull, but you have to buff fiberglass, so it's an equal trade. But the metal is tougher than fiberglass and more forgiving if you happen to meet a bottom lol.

52 years on my steel hull and still going strong. I have replated a few areas but those were primarily due to previous doublers installed. I have had no issues with the 2400 gallons of fuel tankage, but did with the water tank top.. Yes, you do use more zincs, about every eight feet along the hull. Steel/Alum. connection has been and will always be a problem.

dan

bankerboy1 said:

Can problem rust areas be treated with Ospho. It pickles the metal; as my dad use to tell me. He and I have used it on rusting items many time and a little goes a long way. I've had to 2 litter jug now going on 25 years .After treating a rusted surface and the pickling effect set in, the treated surface would never rusted again. Treated areas didn't even need painted after treatment. It does turn the treated area black though and will eat concrete if spilled on it...lol.

Click to expand...

Yes, Ospho can and should be used. It chemically changes rust into magnatite. I still would top coat any area that has been Ospho treated. I agree that many of the people who don't like steel, have little to no experience with it. Like any other material, it has its own pros and cons.

bankerboy1 said:

Hi all,
Looking at purchasing a Trawler and was looking for the pro's & con's on steel hulls.

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Well, what kind of steel trawler?

• Cape Horn
• Dutch Built
• Defever, Garden, etc.
• Converted fish boat

bankerboy1 said:

Can problem rust areas be treated with Ospho.

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And from a previous post:

bankerboy1 said:

I know this is a loaded question, so here goes....How difficult to is to restore a boat that sunk... I will be doing 90% of the work myself, plus the price is right for the boat. I'm purchasing it from a Salvage company.

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I'm going to go out on a limb here and guess it's not a steel trawler yacht, but a 30 to 50 year old (ex) fishing boat in very rough shape. So the discussion about properly prepared and maintained modern steel yachts doesn't really apply. There ARE some great advantages of steel, including the ability to build-in deck fittings like fairleads, integral tanks, structural support for deck cranes and paravanes, et cetera.

And then there's fitment for use: if it's a fish boat then probably every single piece of gear would be inappropriate for a cruising trawler.

And then there's the fact that rust never sleeps. I suggest you read:
Rust: The Longest War

Construction methods are crucial to determining the longevity of a coating systems. If attention is made to the ability of the structure to shed water that goes a long way toward the ease of maintaining a coating. As does the ability of the builder to eliminate sharp corners and edges, these are easily chipped and allow corrosion to start. Tanks should be lined and internal spaces provided with insulation and ventilation to eliminate sweating and excess moisture. You can build a good or bad boat from almost any material. I like steel due to it's strength and ease of repair. I've seen steel boats go through things that other boats may not want to have done.

bayview said:

The interior out of sight places would concern me. We hear that steel diesel tanks are a worry after 15 years either from inside or outside rust. What protects steel frames and welds in damp locations.


Food for thought: Fiberglass tanks don't seem to fail but steel does.

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Nobody seems to like your question but I'd want that answered before considering a steel boat. Those that like steel boats would tend to not like that question I think. On my FG boat there are many many places that I can't see and/or touch. Mirrors could help but not much I suspect.

I have a theory though. If you can't see it or touch it most sources of abrasion would most likely not be present. How are you going to gouge or scrape off a protective coating if you can't reach it? Perhaps there are robots that could do maintance in these places. I've had quite a few inside my body. That reminds me ... there's something that rattles behiend my port water tank.

In the early 50s there was a boat called a Steelcraft. 26' and a good looking boat. They sold quite a few but petered out.

Most steel tanks of any size (say fifty gallons or more) have or should have an access hatch that unbolts allowing you to inspect, clean or repair the interior. In the past we used coal tar, but modern coatings such as MDPE can be used as an effective lining that lasts quite a long time, I'm not sure how long because I'm not aware of a failure. Even in the old days steel tanks lasted a long time if provided with a water trap at the outlet to prevent water from sitting on the bottom, a feature that should still be employed today.

Fish53 said:

Even in the old days steel tanks lasted a long time if provided with a water trap at the outlet to prevent water from sitting on the bottom, a feature that should still be employed today.

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At the risk of offending some members I'm willing to guess over 50% of owners "with steel tanks" on their boats have no clue what you just said.

The almighty acquisition buck is more important than utility on a recreational boat, most lack any inspection ports on tanks let alone water traps.

No Mast said:

am I wrong in assuming galvanic corrosion can be a larger factor with a steel hull? is the solution just more zincs than what you'd have on a glass boat?

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In addition to zincs on rudder and propeller shaft, our boat has eight zincs along the hull bottom.

I apologize, my experience is almost 100% commercial on vessels of 50 to over 300 gross tons and I lose sight of reality when I think about boats (which is most of the time). Yes I am aware that manufacturers as opposed to builders of boats have different priorities. I have overseen a couple of new builds and several refits of large trawlers and even then you have to poke around continually to make sure there's no corner cutting. I can only imagine a production shop where the overseer isn't the end user or their representative but an accountant weighing resin and copper wire to control costs.

bankerboy1 said:

Hi all,
Looking at purchasing a Trawler and was looking for the pro's & con's on steel hulls. I ran a search here at TF, however did not fine anything.

Thanks for the insight!

Click to expand...

About half way down the page in the link is a bunch of articles about metal boats, Articles by Michael Kasten - Kasten Marine Design, Inc.. Kasten is a boat designer and for many years was the editor for the Metal Boat Society, Welcome to the Metal Boat Society.

Kasten will give you a very good education on metal boats.

Later,
Dan

If there was a working product for preventing long term rust,

I believe the bridge repainting crew would have found it by now.

markpierce said:

In addition to zincs on rudder and propeller shaft, our boat has eight zincs along the hull bottom.

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How do you attach the zincs along the hull?

Donsan said:

How do you attach the zincs along the hull?

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I don't do it. I leave that to the boatyard workers/experts to replace. Ask the builder for how the original set-up was done: Seahorse Marine.

looks like bolted to studs...typical install...


On many commercial vessels they are just welded to the hull...

The zinc plates bolted to the hull is often called a diver's plate or zinc. They can be replaced by a diver without lifting the boat on the hard. Welding is pretty typical.

As far as the bridge painting goes...We had to repaint the steel webbing of a bridge a few years ago after laying a 20" pipe under the bridge. All holes and attachment hardware were painted with some stuff that I do not even think is legal on boats. Ga. DOT supplied coating. Wish I had a few more gallons of it.

Florence A is my boat- 1/4 inch plate steel launched in 1964.
The next picture is a wooden boat about the same age.
Then we come to fiberglass boats both about 30 years old.
So while I can repair all of the boats shown - I like steel. Rust - well yup it does. No boat lasts forever.
What I like about steel the most is it bends when things go horribly wrong.
Fiberglass shatters. Wood - well it bends to until it breaks.
I can cut out a section of the steel hull and weld in a new plate and with x-ray I can be positive that I have 100% of original strength. Wood and fiberglass- less so.
Cons to steel hulls- heavy Florence tips the scale at 104,000 pounds and that is not full of fuel.

But all in all steel is not a bad thing to build boats out of. When looking at boats how well the boat has been maintained counts for a whole bunch more than what the hull is made from. Poor maintenance makes for a poor boat.

A better view of Florence A