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Old 22-02-2008, 13:52   #1
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Hull material

I can see the many pros and cons to all the hull materiales used out there. but i was wondering what your choice is and why. i rather hear it from people who have sailed on it rather than read it in a book and some day i hope to sail on each one to make up my mind
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Old 22-02-2008, 14:22   #2
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My alternative choices for sailboats would be...........

Up to 45" , fiberglass.

45' to 80' I'd settle for aluminum (cost).

over 60' I'd accept steel.

But I'd prefer fiberglass all the way up to 120' because of the corrosion/erosion
factor.

It seems steel boats under 45' the metal is not thick enough to make it worth the constant maintenance. The paint has to be sand blasted to clean enough for repaint. Chipping/grinding will dent/wear the hull/deck.

Alum. boats over 80' start getting expensive. And these choices are based on all the boats I've been around in the past 30 years. Others may disagree.
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Old 22-02-2008, 14:57   #3
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Assuming referring to a cruising sail boat able to cruise independantly -

We have a 40 foot big volumed steel sloop which is fully faired and looks like glass. Don't know if were to build again whether would be steel or aluminium - probably aluminium which has advanced in the 12 years since our boat was built (I have never owned an aluminium boat but have project managed their construction and had other to do with them) but would be a close call.

However, if budget was completely unlimited I would go for a very expensive construction using advanced composites.

For steel, 40 foot is about the minimum without starting to incur a weight penalty (which will be a big penalty if care is not taken in sizing scantlings). We had ours custom built with a lot of attention to keeping weight down and ended up about the same weight as a moderate displacement fibreglass cruising yacht of similar volume but far stronger.

When using steel, doing things like going to a composite spade rudder (so no heavy steel barn gate type rudder and no heavy steel skeg - skegs are also a common weak point due to fatigue at the root), sensible plate thicknesses, etc mean big weight savings compared to if doing the same in other constructions. Amateurs aften add a mm to bottom plate thickness for no sensible reason at all and incur a big weight penalty upon which others incorrectly judge all steel boats.

Our maximum plate thickness is 4mm and much of the deck/cockpit is 3mm. Maintenance is no problem at all and I suspect is less than a frp boat (for a start it is a doddle repairing damage to an epoxy/polyurethane paint system compared to repairing gelcoat) - a high quality paint system was used when built, inside and out, ss in wear areas, and there is the added protection of the fairing thickness. There are still quite a few years left in the existing coatings at which time it will just need a sand back and spray over (not a blast back to steel as many claim).

Steel gets a bad name due to the poor understanding of construction by amateur builders and the very poor advice they receive from their fellows. A good professionally built custom steel yacht will cost as much as a timber/glass laminate one will due to the extra work required for interior linings, insulation, etc. An aluminium one more again. That means that to build a good one an amateur will need to put in as many or more manhours than he would for any other construction material except timber - of, course they don't and therein lies the cause for the bad press.
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Old 22-02-2008, 15:22   #4
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...steel for most of the reasons above. Weight penalty's are over rated. The difference of 500 kg is less likely to dramaticaly slow the boat than crapy sails. As to poor advice, _-_-_ you CAN get good advice ..join the Metal Boat Society. Welcome to the Metal Boat Society There are now methods that make the hull building of steel and ally boats very quick and reasonably easy. Traditional steel boat building is just an extension of timber boat building. It was done this way because thats how they knew how to do it. Forget your frames and stringers and all that stuff.......
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Old 22-02-2008, 15:30   #5
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just for the record i'm not going to be building a boat ( unless its one of my strip kayaks in my back yard LOL ) im just reading on it right now.

i figuer i better know everything about a cruiser build before i start to sail and then learn how it reacts by my own feel and expriance. i'm just courious on what others think.
get a well rounded opinion from many sources. then make my own opinion with the information and experiance i have at hand
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Old 23-02-2008, 16:51   #6
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I agree with MidLandOne about everything. Our boat is 20 yrs old since we built it. As long as you prep the boat right and paint it right, you should not have any problems. Like all boats, you need to pay attention to all aspects of the boat. Leave something loose, say an anchor and it will chew upo the paint and you will have problems, FRP boat and you would have a new place to drop your anchor from. All materials have their ups and downs. I just prefer steel personally.
After 20 yrs, have repainted once, and have onle found 3 rust spots in that time. 2 spots under the overhang of the pilothouse and one spot where I dropped a 55lb anchor against the gunwale and forgot to fix it immediately. My bad.
There is probably, no lets change that, there is no perfect building material, maybe one day they will come out with a material that you can build a 76' yacht that ways 10,000 lbs, will never look dirty, pound on the rocks for days without getting scratched, sounds like a twilight zone episode.
Good Luck on whatever you decide, if I was ever goinjg to build another, then it would probably be aluminum...
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Old 23-02-2008, 17:09   #7
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Fiberglass for upkeep ease and resale value.

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Old 23-02-2008, 17:35   #8
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I can only echo all the other comments, that each has an advantage and a disadvantage. But taking the advantages and disadvanatges out of the equation, I truely honestly think Ferrocement makes the best hull, especially on builds of 40ft and up. And seeing as some mighty large vessels have been made in FC, size is not an issue. We don't see it today as much, because we don't have the labour to do the plastering anymore. A vessel can easily be built by one in a backyard in steel. Not so in FC.
As far as the medium is concerned however, FC has several major advantages. The biggest one is it's ability to "breath". No condensation, it's strength, it's ease of repair, it's self protection fromm electrolysis, the list goes on.
BUT and it's a really big but, it compleatly depends on what the boat you are building is intended for. And that is why there are so many materials and so many designs and why many designs are not seen in certain materials.
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Old 23-02-2008, 18:45   #9
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Hello All
I sail a steel hulled Radford 450 a contemporary design with a raised salon that actually raised in that you do not have to stand up to see out. The boat is 45 ft on deck and waterline is just over 42 ft giving it a hull speed of 8.75kts. The hull is round bottom with long fin keel and skeg hung rudder. It is good in light air and loves a strong wind and big sea. The boat is easy to maintain as it has all the proper coatings and no exterior wood on the toe rails etc. The boat is insulated with 2 inches of closed cell foam which make it very quite and dry dry dry no condensation in northern or southern climates. The best feature is knowing that you can never get a stronger hull. Allen mentioned Fero Cement hulls in and earlier post, the reason I started thinkng about steel boats was while in George Town Bahamas 25 years ago a steel boat came in the wrong entrance to the harbor in storm conditions and pounded on the reef for three straight days. A tug was brought down and worked the boat out of the surf, the boat sailed away under it's own power with out so much as a leak. Three years later while again in George Town a Fero Cement boat came in the same opening in much milder conditions and was totaly ground up in a ball of chicken wire and cement in under an hour. Steel is strong and the right design will give you one heck of a boat. You can see the design of my boat on the designers web site, just Google Graham Radford Yacht Design and look at the Radford 450 pilot house design, it's a good one
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Old 23-02-2008, 18:56   #10
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Lots of materials have specific advantages. The big advantage of glass is the mold. Lots of boats can be pulled from a single mold and therefore lots of folks can own them.
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Old 23-02-2008, 21:59   #11
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And the composites make for extrememly light weight boats designed for speed.
Hmmm, I wonder if anyone ever attempted an FC cat or Tri. Yikes that would be scary.
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Old 23-02-2008, 23:14   #12
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I skipper an aluminum boat for a living. I hate aluminum. Ultimatly, paint will not stick to it. I have sanded off or had sand blasted off, hundreds of square meters of blistering paint over the years. All it takes is one nick or an area that traps water and blisters will start. I will never own an aluminum boat for myself...except if I leave it unpainted. Unfortunately, a grey boat in the tropics would make an excellent absorber of heat and aluminum conducts heat very well.

Without foam insulation sprayed around the inside of the hull, the inside of the boat sounds like you are riding around inside a dumpster.

Aluminum boats also have to be faired out and it is not always that the fairing compound holds itself, after water creeps in under it.

The welding is expensive as well. Try finding a Coast Guard certified welder that works for cheap...they don't exist.

Corrosion is manageable if you do half a dozen different things. With aluminum, it is foolish to go more than a year without a haulout because the hull can be eaten away in a relatively short amount of time if not caught in time.

With bottom paint, Tributyltin is now illegal to use and you cannot use copper paint on an aluminum hull unless you want the first nick to turn your hull into a battery....and corrode a hole right through the hull.

The bottom paint you get now for aluminum is absolute crap (Trilux 33) which replaced Micron 33 that used to have TBT. There is a growth around your waterline within 2 weeks now.

Advantages to aluminum?
It has a high strength to weight ratio.
It is easy, although expensive, to make major modifications.
Its more likely to bend than splinter or shatter in a collision.
Aluminum oxide once established works as an excellent corrosion inhibitor.
Aluminum will never leave rust stains down your hull.

You don't want aluminum....not for a yacht.
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Old 24-02-2008, 10:51   #13
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Quote:
Ultimatly, paint will not stick to it.
Ummm, David, honestly I would have to say the Ally has not be prepared properly before hand. The paint should not blister if done correctly.
Quote:
Aluminum boats also have to be faired out and it is not always that the fairing compound holds itself, after water creeps in under it.
Once again, not done properly.
I agree 100% with all your other statments. Although I find Ally tears in an impact. And you can't just bend it back as any bending weakens it.
And you have to keep Copper at least a metre away fromt he ally. Even in a case where the hull is isolated by a great paint barrier job, the copper placed on the paint barrier will cause an action/reaction under the paint barrier and it will bubble. I am not sure why, it maybe due to the two conductive materials Aluminium/copper, held apart by and insulator(paint barrier) becoming a capcacitor.
Quote:
Aluminum oxide once established works as an excellent corrosion inhibitor.
I wonder if it's possible to dip and entire boat into an acid bath and anodise it. Hmmm.
The first boat I ever looked at buying was Ally. 50ft sailing vessel. After five minutes below, I felt seasick and we were still on the swing mooring. The thing bobed around like a cork under our movement. Not sure if the seasick feelign was due to movement, or the "rabbit warren" feel of the internal design, or a combination. But she is still for sail I believe and that was 5 yrs ago when I first looked at her.
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Old 24-02-2008, 12:20   #14
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Originally Posted by Alan Wheeler View Post
Ummm, David, honestly I would have to say the Ally has not be prepared properly before hand. The paint should not blister if done correctly.
Once again, not done properly.
Alan,
I have consulted with a number of boatyards and Awlgrip themselves on what to do about paint blistering over aluminum. I have had others do prep-work and apply different chemicals to aluminum such as Aluminiprep and other chemical etches and coatings before priming and painting. Each time the aluminum was either blasted or sanded down to bright unoxidized aluminum. Basically, I have tried everything known to mankind. J. Still, I get paint that blisters over aluminum. At least I think I have it nailed down as to why it does it. When water or that concentrated water/salt gunk sits over any aluminum/paint interface, the aluminum oxidizes at that interface. When aluminum oxidizes it also expands, pushing the paint upwards causing the blistering. One trick I found is to never paint aluminum right up to an edge, such as where teak might be contacting the deck, because this interface will hold water, accelerating the oxidation process. So I have painters put down 1/8 inch tape which radically slows down the blistering instead of running the paint right up against something like teak.


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And you have to keep copper at least a metre away fromt he ally. Even in a case where the hull is isolated by a great paint barrier job, the copper placed on the paint barrier will cause an action/reaction under the paint barrier and it will bubble. I am not sure why, it maybe due to the two conductive materials Aluminium/copper, held apart by and insulator(paint barrier) becoming a capcacitor.
As far as using copper on an aluminum hull, doing so could turn your boat into a battery. The reason is that copper is higher on the Nobel scale than aluminum and placing dissimilar metals in an electrolyte such as salt water creates a potential difference between the metals, therefore you have a battery. It is possible to place an epoxy barrier coat between the dissimilar metals which would act as an insulator, but if you get even one nick in the paint which goes down to the bare aluminum then suddenly you have a battery with the aluminum being the anode and the copper being the cathode. I'm not so sure about it becoming a capacitor since a capacitor is a temporary storage of a charge and/or a filter for screening in or out different AC frequencies depending on the farad number.

Quote:
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I agree 100% with all your other statments. Although I find Ally tears in an impact. And you can't just bend it back as any bending weakens it.
As far as aluminum goes as a hull material: Yes you are correct, aluminums strength degrades as it is bent, especially when it is cycled (metal fatigue)…therefore the stress crack problems with the first high speed aluminum ferries. Much of that has been remedied with new types of aluminum alloys. Aluminum will also tear if hit hard enough. Aluminums real advantage in a collision is its ability to absorb energy. The bending of metal absorbs energy. I’m sure you have noticed the heat produced when you bend a piece of metal back and forth. Energy in a collision is converted to heat energy much better than energy that is absorbed by resin and glass in a collision. Yes a tear could occur destroying the watertight integrity…but it takes more energy for aluminum than with resin and glass, which tends to fracture rather severely because of that fact that it is more brittle than aluminum. Of course the metal that has been bent will have to be replaced but it served its purpose in (hopefully) maintaining watertight integrity. I have no idea about Kevlar’s energy absorption which I imagine is much better than glass. From what I have read, carbon fiber, although strong is very brittle and not so good with respect to collisions and energy absorption….all of this of course has to be compared to weight per amount of surface area because obviously a one inch hull is going to be weaker than a 2 inch hull, just to pick some numbers out of the air.


Quote:
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The first boat I ever looked at buying was Ally. 50ft sailing vessel. After five minutes below, I felt seasick and we were still on the swing mooring. The thing bobed around like a cork under our movement. Not sure if the seasick feelign was due to movement, or the "rabbit warren" feel of the internal design, or a combination. But she is still for sail I believe and that was 5 yrs ago when I first looked at her.
My only guess is that aluminum has less mass per amount of surface area and therefore is more prone to movement with even the smallest wave impacts. Being down inside an aluminum vessel is much like being inside a dumpster. Its kind of a freaky feeling realizing that there is 7/16" or less of hull plating between you and the ocean...for many aluminum boats. Plus hearing the smallest waves lapping against the hull.

I wonder what a carbon boat would feel like underway?..similar to the dumpster feeling of an aluminum hull? I have only had the opportunity to go aboard a carbon maxi-racer at the dock. One of the crew told me it creaked and groaned as the rig became loaded and unloaded.
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Old 24-02-2008, 15:31   #15
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[quote=nylarlathotep;137143]I can see the many pros and cons to all the hull materiales used out there. but i was wondering what your choice is and why. i rather hear it from people who have sailed on it rather than read it in a book and some day i hope to sail on each one to make up my mind[/quote\\

Nylarlathotep
  • You asked for answers from people who sail boats made of a particular hull material and it seems you have answers on steel and aluminum with fiberglass. I answered due to the fact that I sail steel and I it suits me just fine, but if you want a strong boat that will not suffer from osmosis blistering as fiberglass does (this is a huge problem that is covered up by all concerned) rot and leaks on wood boats, electrolisis with Aluminum or corrosion with steel go a with cold molded wood hull, Cold molded hulls are super strong being built with many layers of wood impregnated with epoxy resin it is impervious to rot, blisters,corrosion and electrolissi. No one material is perfect but cold molding finishes high on the list.
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