All steel boats are painted. Some(most) alu boats are painted. In general, all boats are painted, including fiberglass and wood. Over last 20 years, average re-coat intervals are about 10 years, at very low cost due to ease of prep for steel hull. Its an easy process, that does not need anything special- Primer, filler (opt) barrier coat, top coat. Brush, roller, spray, whatever. There were many many good comments; Passagemaker hull - suggestions: ---------------------- Lets start with hull- by far, the best boatbuilding material is wood. But it may not be the best *boat material*. I explain... It is the strongest material by weight, about 30-50% stronger than steel. (Cross-laminated plywood, epoxy glued, ie cold-molded). Its easy to patch, available worldwide, durable, flexible without losing strength, easy to work with. It is a natural insulator. Will not bleed, rust, get osmosis, or leak. Easy to patch later in small or large sizes, temporary patches are easy. *Emergency repairs are very easy*. Bang a spare piece of plywood onto the hull with nails and hammer in case of large hole due to container collision etc. There are many houses and boats over 100 years old. But ... Wood requires air-movement ie ventilation and a dry bilge. With these two requirements, wood hulls will last indefinitely, provided that it has an antifouling coat of some kind. The only error that will destroy a wood hull is water, like coating it with plastic, allowing condensation to develop inside, or leaving standing water within the boat/bilges. Most large ships (sail) were built with wood and were extremely successful. When they sank, it was not due to hull failures (I do not know of ANY) but collision with reefs etc. in storm where any hull, failing due to natural forces, quickly sinks. When old-time sailing ships sunk, they did not have modern engines, pumps, nav instruments, storm warning etc etc. However, I do not advocate a wood hull. A good wood hull, for lets say 50 ft (I prefer 70 ft - cost is *not* related to length but to systems and mass, but we will talk about this later) , should be approximately 50 mm thick. This would not tend to reassure purchasers (unfortunately). Due to "market perception" resale value will be poor. Work must be done in a low-cost country - but could then easily be done to an exceptional quality/standard. I suggest not using wood due to market perception, lack of skilled designers *for large passagemakers*. Anyone can draw one - but how many large passagemakers have been built in last 10 years of wood ? Wood is a good option, but only suitable for someone who does not care about others peoples opinions, and is not worried about ultimate strength. Aluminium has many of the same good qualities of wood, in that it is easy to work with, rel. strong, except that; - Certain kinds of corrosion are possible. This is not a real problem. - Aluminium has 3 times the thermal conductivity of steel. It will be cold, and must be well insulated. Insulation has benefits, and all passagemakers should be insulated anyway. -Cost Alu is very expensive in small runs. I therefore rule out alu on grounds of cost. Fiberglass Long term osmosis/structural issues (theoretical): - as the Nordhans show, hull strength/longevity/quality is not an issue. In catastrophic accidents, fiberglass hulls are the only ones not salvageable. Lots of examples. They tear and break apart. Need large production runs for low cost - not possible in the passagemaker market. Most fbr hulls are flimsy, unlike the Nordhavns, for example. Maybe Krogen or Selene are good (no personal experience yet), and certainly any hulls can be made well. -Fibreglass is a good option, except for major repairs and cost. Steel Steel is easy to work with, cheap, skilled labour is available worldwide, so is steel, its easy to repair, emergency repairs are easy. Steel hulls, are by far, the strongest of all hulls in passagemakers. Steel and alu are the only ones that will survive hitting large submerged containers and reefs at speed more/less intact and able to contine. NO fiberglasss hull in production will survive a container or reef. In hurricane conditions steel and alu are by far the safest. Of these, steel is cheapest, easiest, strongest. For small run passagemakers, an 70k steel hull would be 200k in fbr or 400k in aluminium *for equivalent strength* best/suitable for passagemaker. For this reason, production hulls are built *far flimsier* and far less strong than steel hulls. Steel also needs insulation, like alu and fbr. Cermis coatings, like paints, are available, as are a variety of insulation systems. No commercial craft suffer any problems or costs due to steel hull maintenance issues. There just is no problem. Steel is not heavy. In a large craft, steel hull mass is not appreciable heavier. And in general, the heavier the better. This is also supported to a great extent by the fact that all commercial craft (fishing, trawlers, navy, etc) are built in steel. In engineering terms, steel is not a structurally heavy material. Aluminium would need to be very thick to have equivalent strength to steel. Extremely expensive makes it a poor choice. Wood composites would work - needed large amounts of manpower and lack of current expertise and tooling make it a non-optimum choice. Using modern cnc machinery, wood hulls would be cheap and strong, when built in the right places, there is just a lack of customer demand. So, based on these parameters, I suggest steel as the best choice. Lets continue on this !