Cost to repaint Steel Hull?

[theloneoux]

I am looking at used steel hulled sailboats and I am trying to figure the cost of painting the exterior. Is it necessary to address the interior as well? I assume steel rusts on both the interior and exterior. Does anyone have a per foot cost or any measure of cost to refinish a steel hull? Also, is it necessary to remove all fixtures from the exterior? How does the interior of a steel boat get refinished and repainted?
I know this is quite a few questions but, they are critical to how much the boat will ultimately cost. Thank you all in advance for your time and effort.

[Alain d'HYLAS]

The ONLY way to paint a steel boat is to first SANDBLASTING the whole hull (interior and exterior) but before doing that, you should remove ALL..
And, after you have to re-place all what you have removed.. quite a lot of work..

I had a Friend who bought a beautiful steel boat and who wanted to make minor modifications.. he is still working Five years later to make the hull in a good shape

But after living and sailing full time on my own steel boat, the hull was still in very good condition..

[Alan Wheeler]

Depends on many factors. Firstly, is the exterior paint OK. If it is just dull and faded, then your first choice maybe a good cut a polish. If it is beyond that, then it may just need a good sand before undercoating and top coats. If it is loose, flaking paint and rust is coming through, then it is a major job as Alain has suggested. If the boat was painted correctly the first time, then the interior would just need a freshen up. But if it is rusting and flaking, then it's a major once again. The odd rust spot here an there can be hit with a rust neutralizer and then over painted.
When it comes to fitting, well you can approach that in two ways. Remove everything and it's much easier to prepare and paint and you know that fresh primers and top coats are under all fittings. It looks smarter when complete to have a fitting inplace over the paint than a paint line up to and around the fitting.
Most paint suppliers will give you a "how to" booklet for the paint system you are considering. These are full of uselful tips and a lot of info. But all products will have a basic three part system. Any bare steel will require a primer, followed by an undercoat and then the topcoat. Below waterline it is usually a primer, sometimes a barriercoat and then an undercoat for below waterline use. Every manufacturer will have different variations of that basic three part principle.
I suggest you use two pot paints. Especially below water line, Epoxy paints work best for the undercoat and barrier coat. A good epoxy all over, will result in a very hard waring moisture proof membrane that will stop any chance of rust occuring.
You will need a proffesional to apply these paints, as they are not good for the health if a full air supplied resperator is not used.

[theloneoux]

Allen,
Thanks for the insight. I am looking at a Bruce Roberts design boat that was built in a yard in Ontario, i.e. not by an individual in their backyard. My anxiety is that if I simply repaint the bottom and top exterior then the interior would have the potential to rust through. To repaint the interior would be a major undertaking as I would essentially have to remove the entire interior infrastructure in order to sandblast and paint. The boat is about 20 years old and I am curious if it is typical for the average steel boat to require such maintenance on the interior? Thanks again for all the input.

Rob

[Alan Wheeler]

You have to rmember one important thing. For steel to rust, it must come in contact with moisture and oxygen. So if your paint is sound, the steel will not rust. It's only when the paint starts flaking away, that you will have a problem. And for that to happen, it wasn't painted correctly in the first place. Many made the mistake if thinking they could just prime and nothing else. A few went the extra distance and undercoated and nothing else. But both primers and undercoats are porouse and eventually the moisture will penatrate to the stell and the surface rusts resulting in the paint breaking down and flaking away.
If you just have scratches that have gone through the layers of paint, then a simple touch up will suffice. If the scratch has gone to bare steel, the a primer is and undercoat should be used first before finishing with a topcoat, but once again, just a touch up of the area is all that is required.

[Boracay]

When I was looking to buy a boat the steel ones that I looked at all had some rust. I got the impression that rust and steel boats go together. The owner of a steel boat always has work to do.
What was surprising was that rust needs to be vey bad before it compromises the watertightness or structural integrity of the hull.
I think that the problem is that we would all like the perfect boat and steel boats are not perfect.
Having said that there are some parts of the boat that rust more than others. Midships along the stringers comes to mind. I really did not like any boat that had sprayed on insulation covering that area or the bilge so that it was not possible to do proper checks. It seems to be quite common for buyers (or owners) of steel boats to replace complete plates and this seems to be quite successfull, although really it is just buying time.
The metal Boat society at :-
http://www.metalboatsociety.com/phpBB2/index.php
has extensive discussions on this topic, with some very experieced members. They are a friendly bunch.

[Alan Wheeler]

There is no "perfect" hull material. Well maybe apart from Ferro cement
If you come across rust along weld joints, especially in 90 degree corners, it is often due to failure of the sandblasting getting right in to the corner. If the paint is sprayed on, the same thing can happen. It is good practice to go along all corner joints with a brush first, and then spray the rest. Rust on flat bulkheads is a sure sign some process has been shortcut.
Paint technology today, is such that a properly prepared steel surface can be made totaly water impregnable and corrosion proof. However, steel is a material that it can go wrong on much easier than any other surface material.

[ozskip]

All the steel boats here are painted electrostaticly so that you paint into the hard to get at places.If you have not seen one of these working ,it is an airless spraygun with an earth lead that neg. and the gun is pos the paint is attracted to the earth.This method is efficent that when you spray steel pipe it will paint it all the way round when painting from one side with very little overspray. Greg.

[boredinthecity]

Yes but when you have pre-existing rust behind stringers then the paint work is no better than the preparation

Paul

[Steve Kidson]

I have never had a steel boat, but have friends who have.

One, a boilermaker by trade, built a number of steel vessels and paid extra special attention to the inside of the hull, in his words "steel boats rust from the inside out", meaning there are many nooks and crannies where moisture can be trapped and sit un-noticed, and will only be identified when it becomes a serious problem.

Modern paint systems are very good, but adequate coverage to all surfaces is needed to ensure long term trouble free life.

Fair Winds

Steve

[Jeff H]

That has been my experience as well. I worked on the design for a number of steel boats in the early 1980's. I recently was aboard one that had been very well built and very well maintained and yet there was serious rust (more than half way through the plating at the longitudinals to the point that I would have recommended replating much of the boat, if that boat was to go offshore. This boat had been sand blasted coated with a zinc rich coal tar epoxy when she was built (considered the best there was at the time) The scary part was that boat had gotten a near clean survey not that long before I saw her and the interior of the hull looked great until I began to poke around in more detail. It was especially bad behind the sprayed on insulation.

Jeff

[theloneoux]

I appreciate the post Jeff H. I am looking at a 1981 Bruce Roberts. In my research about steel hulled boats I have run into most of what has been said here in this forum. Your last comment really addresses my biggest concern: the unseeable rust. The interior of this boat is quite nice but, how does one go about looking between the interior trim and the hull. There seems to be no way to make a complete inspection that would be at all comprehensive. Without assuming that the entire boat would require gutting and either repainting or replating it would seem to be foolish to purchase such a boat. The question I have is that if this is the case and in twenty years a steel hull requires almost a complete rebuild where is the value?

[Alan Wheeler]

Yes Steel rusts. But Wood rots and gets eaten. Glass can delaminate, crack and get pox. So no boat is perfect. Well, I know Jeff has a different "personal" view on Ferrocememt, but FC would be close to perfect as you are going to get, as far as longevity goes. (The oldest commercialy operating vessel in the world is built in FC and is over 200yrs old now, and still in use.)

But also like all the above materials, there are good and bad in all of them. I know of GRP hulls that are 40years old, and are perfect hulls. In know of old steel hulls that are in good shape and I have also seen steel hulls being built, not even finished, that I would never consider going to sea in. So where am I going with this? well it depends on the build/builder, NOT the material. There are no short cuts in boat building. And that's the problem. Too many backyarders (and sadly a few pro's ) that thought they new what they were doing but didn't, or the project became too big and they got tired and cut corners, or they thought they could do it cheap only to find it wasn't and run out of money and so the story goes on and on. All in all, boat building is a craft, a skill and a fine art. There can be no shortcuts taken in any matter. If a steel vessel is built and all preperation is carried out to the proper degree, problems should not exist (in most cases). Sometimes there are the odd few that something just doesn't work. It maybe a new product, or a new techneque, or someone just held their tongue wrong when it mattered most. I bet that was what was wrong with Jeffs Zinc rich paint episode.

So how do you tell?? Well first question you need to ask, was the boat professionally built or backyard? If pro, what quality boats have they built in the past? If amatuer, how has he gone about doing other jobs. You will soon see if it is slaped together or if the guy is a craftsman and has great patience. OK, that is a start.
Now take a look at areas you can get at. Chances are, if short cuts in preperation have been taken, you will see them anywhere and everywhere down in the bilge. Look for signs of rust streeks running down hull/bilge walls. Look around stringers, right in at the weld. Is it solid paint or is it loose flaky rust?
Insulation can be a problem. But it depends on what it is where the insulation has been placed. Some insulation, especially the older stuff was very porouse. New stuff today tends to be very adhesive and has a better surface to stop moisture and air from getting through. If air can't get in, then moisture can't either. If the insulation is up high on the walls, it doesn't seem to be as much of a problem either. If the water in the bilge can slosh up onto the insulation, it has a good chance of having water underneath the foam and therefore rust along with it.

Hope some of this helps and good luck.

[Jeff H]

Alan Wheeler,

I am very curious about your comment "The oldest commercialy operating vessel in the world is built in FC and is over 200yrs old now, and still in use."

I had always been taught (the Norther Hemisphere version of history) that iron reinforced hydraulic portland cement was rediscovered in the mid-19th century (the Romans had used portland cement but the technique had been forgotten) and ferro cement was first employed to build a small canal boat not much bigger than a skiff in the late 1800's (roughly 1885). That boat still exists in a French museum but is not in anything resembling a useable condition. That boat would be 120 years old. As I understand it, it was nearly 20 years later before ferro cement was applied to larger comercial vessels (barges).

I would like to know more about the vessel that you are referring to.

Back on topic.....In 1981 most boat builders were using standard A-36 high carbon steel and the best builders were sandblasting the hull 'white' and using a coal tar epoxy or a zinc rich epoxy as on the interior of the hulls. High carbon steel is very prone to rusting and it ws not posible to seal the steel that was behind the stringers so that water could not get to the steel at the contact point between the stringer and hull. In the 1980's someone chosing a Roberts design, and building in steel was trying to build a boat cheaply and so it is likely that some corners were cut. In other words, I agree with Alan that the durability of a boat is dependent on how it was built, and boats from this era are likely to have been built in a way that they are approaching the end of thier useful lives.

I do disagree with Alan that the quality of the interior tells you anything about how the boat was built. I have been on a steel boat built by a great welder whose carpentry really was extremely crude and a boat finished by a cabinet maker with a gorgeous interior but was extremely poorly built in all other ways.

Jeff

[theloneoux]

This is all very informative and in danger of beating a dead horse I will provide more info regarding the boat in question. I am prone to lean towards caution and stop looking at steel hulled boats of this vintage. I believe that given the issues that Jeff H. mentions the probability of this boat being in good condition would be against the odds. For your further examination here are the details of construction:

This steel hulled metallized with custom interior. Welded at Kanter Yachts, Ontario, July 1981. Launched in North Carolina November 1982.
Thickness of Steel: Keel Shoe 1/2" steel plate
Keel Sides 1/4"
Hull skin from skin to sheer 10 gauge
Deck 10 gauge
House Sides 1/4"
House top 10 gauge
Coating Scheme: 20 mils. cold-tar epozy below water line; 30 mils above water line.

I know this information is not enough to make a definitive determination but might add to the discussion. I appreciate all of your valuable input. Thank you,
Rob