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Old 19-09-2005, 07:31   #1
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Aluminum boats

After the question about steel boats and the problems that they can have I started wondering about Aluminum and how it holds up as a boat building materal?
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Old 19-09-2005, 09:51   #2
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There are a wide range of aluminum alloys out there and they behave very differently. The best alloys constructed with care are remarkably rugged, low maintenance and long lived. While aluminum lacks the abrasion resistance of steel and the strength when measured on cross sectional area basis, aluminum has a significantly lower density which in turn allows for a much thicker plating for a given weight. Designers chose to use the weight advantage in a variety of ways including matching the weight of steel plating and framing, which produces a significantly stronger (aluminum) hull, or reducing the hull weight, and so depending on the particulars of the boats in question, can produce and equal strength hull that weighs substantially less. That weight savings can be applied to some combination of greater carrying capacity, greater ballasting, or simply reduced weight which can have its own advantages in terms of smaller rigs, engines, hardware tankage, etc.

Depending on the yard, the availability of the alloy in question, and the specifics of the design, an aluminum hull of similar design and finish level can be the same price or just a little bit more expensive than Steel. Aluminum is generally seen as being less expensive to maintain and depending on the alloy used, generally does have the problems of internal corrosion which is considered to be a critical problem with steel hulled boats.

Finding qualified welders who can work with aluminum tends to be harder than for steel. Cutting and shaping aluminum precisely is easier than with steel.

Industry studies on construction costs for one off boats suggest that cold molded/ composite construction still offers an initial cost advantage over aluminum and will result in lower long term maintenance costs. This is of course subject to change given some of the new aluminum alloys which do not require painting, and the spike in the price of petroleum.

Aluminum is less ductile than steel and so will not stretch as far as steel in an impact situation, but since the plating and framing is likely to be thicker in section, depending on the design may still offer similar puncture resistance. Depending on the alloys involved in a general sense. aluminum tends to be more prone to electrolysis problems than steel.

There seems to be a greater acceptance of aluminum boats in the marketplace perhaps because most aluminum boats built to date have been built by premium builders giving them a certain cache'.

Jeff
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Old 19-09-2005, 13:29   #3
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Alloy boat building has been a common technique down here in NZ for many years. I know of some that are at the minimum of 25yrs old and I can only presume there are many older.
I think one plus for the material in relation to the construction is the difficulty to weld it. Any backyarder can weld steel, which means some steel boats out there stay afloat by the grace of God. Aluminium is something that requires a bit of skill, some expensive and decent welding equipment and thus, results in the person doing the sticking together part, being a little more proficient at the art of welding. You can't really get Ali welding wrong. I mean by this, it either works or it doesn't. You can't hide bad welding of Alloy, where as you can with steel.
Here in NZ, we see both painted and unpainted and a combination of both and either or seem to stand up well to the elements. The painted versions, if done correctly, look stunning and you would not tell the difference between the alloy and plastic fantastic till you tapped it with your knuckles.
I also know of a manufacturer that had a very cool way of building Alloy hulls. He made a basic hull shape out of flat sheets. No shape at all. A mold was made in the ground of the shape of what the hull would be finished as. The flat sheets were droped into the hole in the ground and filled with water. An explosive charge was detonated inside the basic hull shape and the result of water not being able to be compressed, blew the sheets out into a perfect shape with little fairing required. It was a buitifuly formed hull.
If you want to check out just what can actually be done with Alloy boat building, check out this. www.alloyyachts.co.nz
Now from a personal perspective. When we looked at the big boat market two years ago. the first large boat I ever stepped foot on, was a 50ft Aluminium cutter. I hated it. It bobed around under me like a cork and I felt uncomfortable very quickly. Now, it maybe that the boat was not built correctly with the correct ballast or what ever, I dunno, but I hated the thing.
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Old 19-09-2005, 15:59   #4
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Properly designed and built to the drawings, the motion of an aluminum boat should feel no different than a boat built of any other material. I wonder whether this was a hard-chined boat. Hard chined boats will often have a corky motion as they rapidly build displacement near the chines creating some snappier motions.

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Old 19-09-2005, 17:18   #5
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nice web site wheels. i finally found a boat with a real bed. now for financing......
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Old 19-09-2005, 19:44   #6
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Thank you Jeff and Alan. I want to buy a large production motoryacht for a live aboard and to fix and resell. After reading the posts I'm thinking that fiberglass my well be the best material. But as far as I know Feadship, Broward, burger etc are mostly aluminum and they look sweet! I may need to look at Hatteris.
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Old 19-09-2005, 20:22   #7
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Most aluminum boats are made from 5086 material and welded with 5356 wire. For upright structures 5456 material is used (stronger material).

The biggest problem I've seen with aluminum is cracks in high stess areas, like in bulwark and stansions. But easily repaired as long as corrosion hasn't set in. Then it has to be ground or cut out like a cancer.

The other problem is the use of fasteners, aluminum rivets are better then (SS) screws and bolts. It takes two people to install a rivet thru a deck or bulkhead, excluding pop-rivets.

Aluminum boat building is becoming fairly popular here. One doesn't have to worry about the temperature. Fiberglass/resigns requires 60 - 80º to cure properly. That's only 2 months out of the year, here.
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Old 19-09-2005, 20:37   #8
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Material

Although I dream a lot and my mind wanders, when it comes time to actually plunk down MY $$, it will be on a solid fibreglass boat, or a cold moulded Kauri boat from NZ.
There is a reasonably priced Farr 37 in ME that got my attention.
Listed on Yacht World.
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Old 20-09-2005, 05:04   #9
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Hi Michael,

I have actually been aboard 'Relentless', the Farr 37 in Portland, Maine. While she is cosmetically rough, she seems to be reasonablty well equipped and in sound condition. While she has a reasonably large sail inventory, none of the sails that I saw were racing condition sails.

When I talked to the owner earlier this summer the owner was very anxious to get her sold.

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Old 20-09-2005, 08:30   #10
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Farr 37

I probably should have added to my post about what I would actually purchase.
I mentioned elsewhere that I also found a couple of Chris Craft Apache 37 boats and they look like a good sea worthy boat.
But when it comes right down to it I just can't bring myself to buy one of the older style hulls. I know they would be fine as a cruiser but I like the sportier performance.
So that leaves me looking at the Birdsall designs in NZ, or the Farr designs which are everywhere.
The final checks I would make other than the obvious, would be the strength of the keel connection and the soundeness ( strength ) of the hull.
Do you know if there are any specifications available for this boat.
I can send a note to the agent as well.
I need to add about 20% for the $$ exchange and 14% for BC and Federal taxes plus shipping to the West coast.
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Old 20-09-2005, 13:03   #11
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When I was in Portland, I met directly with the owner of the Farr 37 at the boat, who said he would email me a detailed listing but never did, so I do not have a complete listing. The boat did have radar and a reasonable variety of electronics. It had a brand new wheel steering system, which replaced the tiller steering that had been on the boat until the year before. The boat looked pretty good structurally. There were no obvious spider cracks or other signs of flexing. I basically liked the boat and thought was a pretty good deal. I had been trying to get an acqaintance of mine interested in the boat but that is another story.

Anyway, the down side of the Farr 37 is that they were designed as IOR boats and have some of the negatives associated with boats of that era. They are slightly faster than my Farr 38 and are much better light air boats, but they are harder boats to handle short-handed with their powerful masthead rigs. The Farr 37's had a nice interior finish but it is in a cometically grungy shape on the boat in question. I also do not think that this boat had the optional vee berth, although it simply may not have on the boat when I saw her. Feel free to email me directly if you wish.

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Jeff
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Old 06-10-2005, 19:49   #12
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Message re boats

Jeff, I sent you a message a few weeks ago. Did you get it? I sent it to the address listed here. Send me a note direct if you like. I would like to talk about a CC Apache 37.
Michael
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Old 06-10-2005, 21:42   #13
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Is anyone building aluminum trimarans? I have seen some cats, but no tris. When I first started looking at multihulls, this was a consideration, but I was only able to locate one, and it was way more boat than I wanted.
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