Steel or Aluminum

[hpeer]

I think your nuts.

Thankfully you are not alone. This guy also has a screwy dream. Check it out. He learned a lot about welding aluminum.

alu sailboat buliding - WeldingWeb™ - Welding forum for pros and enthusiasts

DO NOT, NOT, NOT get some tech school or laid off guys to help. Seen that done and it ain't pretty. Went to closing on a aluminum schooner only to walk away over the weld quality. Very erratic, not up to standard, too little, too rough, near burn throughs, etc. shame really. Otherwise would have been a real nice boat.

Footage measurements on boats are poor measures. Size increases as the cube, so a 65' boat is HUGE compared to a 44'er. Displacement is a much better measure, if comparing roughly similar vessels. Our 33' boat is 8 tons, the 44' boat is 22 tons and is well over twice the living size of the smaller boat. Frankly, you cant afford a 65' boat, just the dockage and hauling would be prohibitive given you building budget.

As for electric propulsion and your 15 HP motor size.....
Check out Nigel Calder, he knows way more than all us combined. EU is sponsoring him in electric propulsion research. He was at the Annapolis SSCA gam this fall.

http://www.cruisersforum.com/forums/...ble-27411.html

We looked at a 52' Ruddy Choy cat, real light glass over ply construction. Choy was very speed minded and kept weight low. That boat had two 40hp engines, and was a sailboat. In fact we didn't pursue this boat because the hull was a single layer of 1/4" ply, not two as advertised. I doubt that boat was over powered, but it was well designed. Hull thickness was obvious where the owner had run a hunk of coral through the AMA (NOT pontoon).

http://en.wikipedia.org/wiki/Ama_(sailing)

[scoobert]

the propulsion system i am using will work like this.
the props will be driver by a large pully, two electric engines each with their own belt.
the electrical system will be 24 volt.
the electric engines will be A/C, with a converter controller.
total electric power will be 80HP, about 300HP diesel equivalent.
there will be two diesel engines.
engine A will be 40HP diesel. driving a DC 24 volt generator
engine B will be a 300HP diesel, driving a DC 24 volt generator.
typical operation will be small engine plus solar for a trawler, or for the cat solar alone.
in case anyone does not know, solar can be had now for $0.95 a watt, TODAY.
in a year or three when i will need it it will be less. i anticipate $0.75-$0.50 per watt.
the most panels i can fit on a 58' trawler is about 20,000 watts. or 25-35HP depending on sun. so i CAN drive the boat slowly on solar. and lets face it... most people make a passage every few years, not constantly.
i have had this part planned firmly for a long time.
i have a electrical motor builder lined up for the DC generator. very very cheep.
the electric engines will be bought from a supplier.
i stole the drive system idea(pulleys and belts) from planet solar.

[scoobert]

do you think a mono-hull would be an easier ship to construct?

[SabreKai]

Absolutely. With a cat or a tri you are essentially building two or 3 hulls. they may be smaller but length wise it's still a heck of a lot of welding, Then add in the bridging structure, also fairly long and the cabin works. Monohull, one hull (admittedly wider but say the same length), no bridging structure and a smaller cabin structure.

[downunder]

Link attached is to Harwood Marine who build the 48ft Mumby in Australia and Cebu, Phillipines.

Harwood Marine Ship Building and Marine Services Australia


blog of Canadian couple building one in Phillipines


s/v Silver Tern: May 2011

[scoobert]

Originally Posted by downunder

blog of Canadian couple building one in Phillipines


s/v Silver Tern: May 2011

i wish they would have listed a build price....
very nice looking so far thou.

[downunder]

The builder is hard to track down.

I think they are flat out without other builds.

[homeless]

Originally Posted by downunder

The builder is hard to track down.

I think they are flat out without other builds.

That is an understatement. Harwoods ignored my emails, phone calls, and phone messages for over a year before finally giving me a very high quote on bare hull, and were not at all interested in answering my questions or negotiating on price.

However ... Tim Mumby (the designer of the boat) is now building boats in the Philippines, gave a more reasonable quote, and I get quick answers to my email questions, so I recommend you also contact him if you are interested in getting one of his boats built.

[scoobert]

i am interested in pricing.
i mean how much can labor or materials be there.
aluminum straight from china,
i would love to see the price per pound...

[scoobert]

aluminum per metric ton is $2000-$2500 in china by what i can find.
wow, thats cheap.

[scoobert]

even if i did the whole yacht from aluminum it would only cost 60,000 for materials, 80,000 if you count waste.

wish i had a good idea of labor costs

[Mr B]

There is a large solar powered Catamaran operating in Sydney harbour, and its not slow,

with steel, use a two pack paint, the trick is to shot blast a section and paint immediately, Preferably on a hot day only,
If you wait before painting, you will have an inbuilt rust problem. Moisture in the air creates oxidisation on the steel,
Put a nice shiny steel nail in a glass of water and watch it rust before your very eyes if you dont believe me,

If you already have a Mig welder, To change to aluminium, or stainless wire, you need to change the liners, wire and gas, thats it, you dont need to buy a new Mig welder,

Buy a second hand Mig welder from a bankruptcy auction, That way you get a good welder for near nothing,

Liners are approx $8-00 from Lincoln or other welding machine manufacturer, , to fit your Mig, Wire comes in a 15 KG roll,
The gas is the expensive part,

Do not use learners to weld on your boat. under any circumstances,
Get professionals, They cost more, But do know what they are doing and do it well,

If you buy all your steel sheet in one hit, You buy it by the ton, its a hell of a lot cheaper than buying it by the sheet,

The steel for my 40 foot sailing cat cost me $10,000-00 all up, sheet, RHS, pipe, angle, plate, Its all sitting there under cover and painted with a single coat, I painted all the sheets myself before I stacked it,

17 ton finished, Wet, 3000 litres of diesel, and 5 ton of drive train, And just because it is heavy does not mean it is a slug in the water, Mine does 37 knots on one motor, But economy is not a required factor if I am injured on it,

About $250,000-00 in the drink and sailaway, complete, with two marinised 300 HP diesels, The props I was going to build myself, 28 inch as they were $24000 each, Thats what I got quoted,

Make a jig and make all your stringers in the jig at the same time, That way they are all the same, for both Hulls,
I estimated working full time on it, 8 hour days, it would take me 3 months to fully build my cat, But I am a professional welder, 100 % Xray quality, On site boilermaker, with my own gear, Engineering Blacksmith by trade, so I do know what I am doing,

I sold my second house, Retired and bought a 32 foot F/B Cat because I wanted to go sailing now, which I did,

Wish you luck, But do your home work on it first,

[Pelagic]

If you decide to build with steel, consider using COR-TEN Steel
Beauty of this product is that if coatings are damaged or exposed, it protects itself and seals out serious oxidization.

Weathering steel - Wikipedia, the free encyclopedia
Use the Rust-Rich Metal for a Variety of Exterior Applications

My own boat was well built with this in Holland and after 30 years, I have no rust issues.

[scoobert]

Originally Posted by Mr B

There is a large solar powered Catamaran operating in Sydney harbour, and its not slow,

with steel, use a two pack paint, the trick is to shot blast a section and paint immediately, Preferably on a hot day only,
If you wait before painting, you will have an inbuilt rust problem. Moisture in the air creates oxidisation on the steel,
Put a nice shiny steel nail in a glass of water and watch it rust before your very eyes if you dont believe me,

If you already have a Mig welder, To change to aluminium, or stainless wire, you need to change the liners, wire and gas, thats it, you dont need to buy a new Mig welder,

Buy a second hand Mig welder from a bankruptcy auction, That way you get a good welder for near nothing,

Liners are approx $8-00 from Lincoln or other welding machine manufacturer, , to fit your Mig, Wire comes in a 15 KG roll,
The gas is the expensive part,

Do not use learners to weld on your boat. under any circumstances,
Get professionals, They cost more, But do know what they are doing and do it well,

If you buy all your steel sheet in one hit, You buy it by the ton, its a hell of a lot cheaper than buying it by the sheet,

The steel for my 40 foot sailing cat cost me $10,000-00 all up, sheet, RHS, pipe, angle, plate, Its all sitting there under cover and painted with a single coat, I painted all the sheets myself before I stacked it,

17 ton finished, Wet, 3000 litres of diesel, and 5 ton of drive train, And just because it is heavy does not mean it is a slug in the water, Mine does 37 knots on one motor, But economy is not a required factor if I am injured on it,

About $250,000-00 in the drink and sailaway, complete, with two marinised 300 HP diesels, The props I was going to build myself, 28 inch as they were $24000 each, Thats what I got quoted,

Make a jig and make all your stringers in the jig at the same time, That way they are all the same, for both Hulls,
I estimated working full time on it, 8 hour days, it would take me 3 months to fully build my cat, But I am a professional welder, 100 % Xray quality, On site boilermaker, with my own gear, Engineering Blacksmith by trade, so I do know what I am doing,

I sold my second house, Retired and bought a 32 foot F/B Cat because I wanted to go sailing now, which I did,

Wish you luck, But do your home work on it first,

great info, thank you.
seems steel is only $600 per 2200#
i wonder how much the primer adds to that price, plus shipping to the USA?
how much can you get pre primed steel for here?

[scoobert]

and you must be one skinny guy to own a gemini. i have tours them at the factory, they are tiny!