Stainless Hull?

[David M]

Tin based bottom paint was banned for use on commercial aluminum vessels about 4 years ago. For yachts it was a few years before that.

Aluminum is actually an excellent hull material if you do what is necessary to stop electrolysis. Many smaller commercial boats and a handful of very large passenger ferrys, oil spill boats, research vessels, pilot boats, etc are being made of aluminum now. It has a high strength to weight ratio and no mold is necessary to make an aluminum boat. Molds are expensive to make and therefore require a number of boats be made from that mold to justify the cost. Many commercial boats are custom designs where there will be very few hulls made from the same plans.

Its not necessarily true that putting a dissimilar metal near will cause an aluminum hull to corrode from electrolysis. There are ways of stopping this and professional naval architects and builders know of the ways of stopping electrolysis. Its the backyard amateur built aluminum boats that seem to have the corrosion problems. I would not buy any aluminum boat built by a company without a lot of experience building aluminum boats and certainly not by an amateur builder.

[Stillraining]

Originally Posted by bob kingsland

You mean drawbacks other than expense?

Well, titanium would be great but awfully difficult to weld... you need a very well controlled environment to do it well, and the ability to get argon to the back side of all welds... it's best welded in a full argon environment, impossible on something that size unless you're a large government agency.

Copper too soft.

Monel the perfect material other than expense. Quite a few boats have been built in it... usually by some one who has access to it (20 years ago a guy who was the purchasing agent for a large Saudi oil company built a 50ish sail boat hull in Saudi... wonder how he got the material?). Four
60 or 70' shrimpers were built in it for a company in Africa, also about 20 years ago... I'm sure there are others.

There's a guy right now in Montreal building a steel hull with a stainless 304 deck...://http://www.alesya.org/journalconstruction.htm ...
he says it's fairly common in france, to cut down on deck maintainance.

Many very successful aluminum boats have been done.

Best, Bob S/V Restless

Good to see your post Bob...Id really like to see more of them..

Maybe we could talk about SuperCubs every once in a while and reel you in closer..

Happy New year!

[bob kingsland]

Thanks Scott: my problem is time... I haven't got any. If I'm not working at work, I'm either in the truck commuting 2 1/2 hours/day, or I'm in the shop working on the boat and trying to stay away from the computer so I can get something done. I scan a couple of forums, (including one on Super Cubs ) but find it hard to get the time to post, unless it's a topic I know a little about.

Monel or cupro-nickel (they're very similar) are ideal materials for a hull, other than expense. But then so is aluminum, in my opinion, and the europeans are way ahead of us on that. The electrolysis issues have been adequately addressed for years with that material. With today's epoxies and a little care, steel's not a bad material either, but then I may be a tad bit biased.

Best, Bob S/V Restless

[Hydra]

Rustypirate,
Inox was built by Marcel Bardiaux from 1960 to 1968. She ran aground on Gaspésie shore in 1996. It took one year to Bardiaux to repair her. Inox is still afloat in Redon, the Breton town where Bardiaux passed away in 2000.

It is well known that Bardiaux had to take special precautions to avoid corrosion between dissimilar types of stainless steel. In the end, he made his own bolts and screws, to be sure that they were compatible with the hull.

For yards building aluminum yachts, see for example:
Alliage, chantier naval aluminium : construction de voilier en alu, et bateau Ã* moteur avec coque alu
Alubat - des bateaux en aluminium Ã* vos mesures
----ALLURES Yachting--------------

Alain

[Pblais]

Metallurgy is a science not meant for the amateur. It's all too easy to assume you can come up with a perfect solution. Given the science has been around a long time the issue of cost and efficacy comes to play. Bottom paint is still cheap. At some point you can afford to pay someone else to paint the bottom often and be money ahead.

Aluminum pleasure boats seem to get the most play as the best metal alternative considering cost and function. Aluminum science has been going on a very long time and the metal seems to develop new purposes all the time even now. The alloy process to works exceptionally well with it and you'll find a huge number of variations for many specific applications even within the marine industry.

[Morganministry]

Delmarrey,
Thanks for the link, that was very informative.

Thanks again to every one else for the replies.
I've learned alot in the last 24hrs.

Scott

[IslandHopper]

The corrosion problems between Aluminum and Steel are pretty much a thing of the past these days, if done correctly that is

The construction of ships with Steel hull and Aluminum superstructure is also fairly common, it involves "welding" the two together using a process called Bi-Metalic Explosion Welding, but the costs of doing this in the recreational arena would be astronomical i would think...

If your up to it have a read of this...

http://www.dynamicmaterials.com/data...per%202-04.pdf

[knottybuoyz]

Originally Posted by Blue Stocking

Could an alloy that is substantially tin-based be strong enough.
Or are you referring to galvanized iron or steel, as in corrugated "tin" sheets.
The latter is well known--curious as to what your thoughts are on the former

A couple of years ago I watched a documentary about a famous British ship salvager (can't remember the name). They were recovering strategic materials from sunken WWII convoy ships. One of the most strategic metals (at the time) was Tin. They'd lower explosive devices to the wrecks to open them up and then scoop out the cargo with buckets. Some of these recoveries were supervised by an operator in a diving bell. They showed some of the tin ingots that were recovered after many years being submerged and the fine printing on them was totally legible. They said that tin was virtually indestructible in salt water. At least that's what I remember.

I assume that tin is mostly used in alloying processes. My Grandpa was a tool & die maker for a company that produced packaging cans (tins). He build a steam powered tin boat that we played with in the creek behind the house. It sat outside most of the time in all kinds of incliment weather and always looked shiney as new. He also referred to his 16' aluminum boat as the "ole' Tin Boat!"

[Canibul]

Aluminum corrodes extremely well if it touches any other metal. Even other alloys of aluminum. I think sometimes it makes a better sacrificial anode than zinc does. Sure seems that way.

[dpons]

The thing about SS is that it needs an oxygen-rich environment to avoid rust. Underwater it is deprived of oxygen and it rusts quickly.

Years ago, for a similar thread elsewhere, I calculated that water has 20 times less oxygen than air (I don't remember exactly the details, I think by % of weight).

[goboatingnow]

in my opinion. steel is the best compromise, combined with modern coatings. last forever with regular maintenance.

[barnakiel]

I have seen one SS boat, she may still be on the yachtworld perhaps. I know there is a boatyard in Poland getting tooling to make SS hulls.

I would not like one for myself, many reasons, one the difficulty to paint it, then the way it breaks down with little warning.

b.

[GordMay]

Michael Kasten covers the pros & cons of various metals for boatbuilding:
Metal Boats For Blue Water - Kasten Marine Design, Inc.

[seandepagnier]

What do you guys think about making the hull as the same stuff thru holes are made of?

I am curious about silicon bronze as well as marelon.. any comments?

[delmarrey]

Originally Posted by geckosenator

What do you guys think about making the hull as the same stuff thru holes are made of?

I am curious about silicon bronze as well as marelon.. any comments?

Silicon Bronze? Very expensive! And any welded joint would be a weak area.

Marelon? well, boats these days are already made of plastic and glass. Marlon would be more expensive, as well. Plus, I don't know of any adhesive that would bond Marelon.

Materials for building boats has been thought out for thousands of years and still continues and now even planes are being built of carbon fiber. UWTV Program: Building the Future of Commercial Aviation: Boeing's 787 Dreamliner

I foresee the cost of some new boats are going to increase due to the demand for materials now.