Steel or Aluminum

[Mr B]

Originally Posted by scoobert

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?

Etch primer was about $150 for 20 litres, I used about 60 litres, Good quality,

Primed steel from the manufacturers, No idea, I dont think they do it,

For what its worth in shipping, duty customs etc, Shop around the various steel makers in the USA, You probably wont save much, Plus they will deliver it to your door,

I made a carry lift for my steel sheets, a very long handle welded to a set of car wheels on an axle, with a post vertically in the air, and a chain block on the top with a good G clamp to hold the sheets, use a flat plate under the screw on the G clamp to avoid dents in the sheets, and one sheet only at a time, Good Steel G clamps are about $60-00 each, They dont slip,

That way I could move the sheets for stacking, painting and holding in position when welding, I did it all on my own, No helpers,
It needs to be balanced, so when you put the handle on the ground, it holds the sheet up in the air with out dropping the sheet forwards,,

You cant compare Australian prices to the USA, Our prices are exorbitant to say the least,
Other then steel, I buy almost every thing online from China,

My F/b Cat was made in the USA, I bought it in Fiji, Half the price of here, My new electrics for it came from China,
My RV 36 foot Grand Villa came from USA, converted to OZ ADR's in California, and shipped to OZ, Still a lot cheaper than buying any thing here,
My new 25 HP tractor came from China, Very cheap compared to any thing else I can buy here,
This is just to give you an idea on prices here,

5-9 and 12 stone, The Gemini was all I could afford, But its a very nice boat and I can sail it by myself with out difficulty,

I still may finish my steel cat later, after I have finished my travels, Just to prove a point,
when I sell the Gemini, I will have the dollars to finish it,

[scoobert]

i liked the gemini. did you get the PDI gemini or the one built by the creator?
only things i didnt like
i had to go thru the doors sideways.
the sail drive leg.
the table was too small
not enough fuel for my liking.
the price on them is awesome, and they can sail long passages across open water.

as far as the steel cat. i would strongly prefer it be built for me.
where would you say the best place to find cheep labor in the US is?
any moron can mig weld. many can do it well.
with the recession i am betting i should be able to find someone unemployed,
who would jump at 3-4 months of solid off the books work.
what is a decent offer to make someone per hour that they would accept?
i am sure i can find a $40 per hour welding shop, but i want cheaper.
can i find someone willing to do this do you think for $12 per hour?
how much does a welding shop pay its guys per hour?

seems the material cost should be under $30,000.
if i could land 1800 hours of labor at $12 i could have the hull completed for under $70,000

i will need a new welder.
mine would be fine for tacking the parts together, able to weld up to 1/2" thick;
but i dont believe the duty cycle would be enough to make all the welds.
i dont see a used welder costing much thou.
the gas up here was not bad.

i think my small tank, 3' high to be filled was $35.

my real next step would be to visit a 65' cat. i really need an idea how big they are inside. i can look at photos until i go blind, and still not know.

and like i said, and everyone keeps missing that says it will take five years...
the interior can take as long as it takes.
plywood makes a great temp floor, and all i need to move on is a bed, bathroom, and a stove and fridge.
i would like to finish it in South America anyway.
$4 an hour would be good money to a cabinet maker there.
and they have some lovely woods.

[nimblemotors]

As many have said, building from scratch isn't going to save you any time or money.
From what I gather the boat hull itself isn't your big interest/goal, but the solar/hybrid drive. Once you get a large enough monohull, they are quite spacious inside,
and if not sailing, no need for the heavy ballast.

A quick look, here is a "fiber steel" (ferro cement i'm sure), 60ft vessel, 3br 2b,
selling for $15k. Now just think of what you can do to refinish/rebuild the topside
with another $50k, and you can start on the finish work already.



Another steel fishing boat, only 45ft, but you have a hull ready to go for $25k.

[hpeer]

Originally Posted by scoobert

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

There is some interesting stuff around about origami boats.

Home - Origamiboats: The Art of Frameless Steel Boatbuilding

Brent Swain used to hang out here. Interesting guy, lots of opinions.

His book is with the cost if you are going to building in steel.

[scoobert]

here is what worries me about mono's.
i want to stay at anchor 99% of the time. the water is going to be rough.
no doubt.
with a mono i am sure i would roll and pitch all over the place.
with a 60,000-100,000# cat i should be able to anchor anywhere, and not have any rolling????

i could not imagine the frustration of sitting down to dinner, and having a motor yacht go by, rocking your boat 20-40 degrees.

[goboatingnow]

Originally Posted by scoobert

here is what worries me about mono's.
i want to stay at anchor 99% of the time. the water is going to be rough.
no doubt.
with a mono i am sure i would roll and pitch all over the place.
with a 60,000-100,000# cat i should be able to anchor anywhere, and not have any rolling????

i could not imagine the frustration of sitting down to dinner, and having a motor yacht go by, rocking your boat 20-40 degrees.

But but , that allows us to run on deck and shout " stinkpot" etc, its half the fun.

Dave

[scoobert]

lol i get horns all the time here on the NY canals.
my boat is 25' and weighs about 4000$ and 25MPH i create a wake that does not last beyond 75'. i go by docks 200' away and they all blast their horns.
dock lovers are funny people. and most NYS canal boats at docks never move, just look at this:

2011 irene flooding - YouTube

[scoobert]

the other turn off to mono's is power requirements.
for my solar plan to work best i need the least amount of power to push the boat slowly.
if i can get that to the 15HP number bruce says the 65' cat should be i can run on pure solar without a massive battery bank. i would then only need enough battery's to run my gadgets inside all night.
a/c fridge, freezer, electric stove.
i was planning on 60KWH battery bank.

and if the batteries get too low i always have the DC gen.
i was just talking to my generator guy today.
(he repaired my winch) and took another look at the generator he has for me.
24V 300-400 amps. he can build it for almost any power output.

[44'cruisingcat]

Originally Posted by scoobert

total electric power will be 80HP, about 300HP diesel equivalent.

Sorry, but I can't see how this is right.

80hp is about 60 kW. You could run a 60 kW generator with a 74 kW diesel. 74kW = 100hp.

So a 100 horsepower diesel, if you connect it to a generator then electric motors (which both have losses) suddenly triples it's power to 300hp?

Later you're talking about 15hp. WHat's the design displacement of the Roberts cat in steel? At 65 feet it would have to be somewhere around 20 - 30 tonnes, at least. A 15 horsepower motor isn't going to make much impression on a 30 tonne boat.

[nimblemotors]

If you save $150k in building cost, you can spend a LOT of money on fuel. And if you are at the dock 99% of the time, what does it matter what fuel costs are?
A cat still rocks a wave lifts one hull then the other one, just not as much as a monohull, and they can still pitch. a big heavy mono doesn't move much anyway, it is the small ones that do.

I wanted to build my own cat too, or buy the one that is almost like I wanted, John Hitch's XIT,

but I didn't have $300k, nor 5 years to build it, so I'm making do modifying a 34ft cat I bought.

Originally Posted by scoobert

the other turn off to mono's is power requirements.
for my solar plan to work best i need the least amount of power to push the boat slowly.
if i can get that to the 15HP number bruce says the 65' cat should be i can run on pure solar without a massive battery bank. i would then only need enough battery's to run my gadgets inside all night.
a/c fridge, freezer, electric stove.
i was planning on 60KWH battery bank.

and if the batteries get too low i always have the DC gen.
i was just talking to my generator guy today.
(he repaired my winch) and took another look at the generator he has for me.
24V 300-400 amps. he can build it for almost any power output.

[scoobert]

Originally Posted by 44'cruisingcat

Sorry, but I can't see how this is right.

80hp is about 60 kW. You could run a 60 kW generator with a 74 kW diesel. 74kW = 100hp.

So a 100 horsepower diesel, if you connect it to a generator then electric motors (which both have losses) suddenly triples it's power to 300hp?

Later you're talking about 15hp. WHat's the design displacement of the Roberts cat in steel? At 65 feet it would have to be somewhere around 20 - 30 tonnes, at least. A 15 horsepower motor isn't going to make much impression on a 30 tonne boat.

its a common knowledge that an electric engine is 2-3 times the power of a diesel or gasoline.

how many times do you run your engines at full throttle? as in wide open?
well, that is your maximum power. for an electric engine maximum power is at 0 rpm. so i can run huge slow props at full power.

the 15HP figure comes from bruce roberts.
he is the one that said 35-45hp for a mono.
those are at 3-4kts and calm water.

the finished weight is about 60,000# plus all my gear, fuel, ect.
i am thinking 100,000# finished weight.

[scoobert]

Originally Posted by nimblemotors

If you save $150k in building cost, you can spend a LOT of money on fuel. And if you are at the dock 99% of the time, what does it matter what fuel costs are?
A cat still rocks a wave lifts one hull then the other one, just not as much as a monohull, and they can still pitch. a big heavy mono doesn't move much anyway, it is the small ones that do.

I wanted to build my own cat too, or buy the one that is almost like I wanted, John Hitch's XIT,

but I didn't have $300k, nor 5 years to build it, so I'm making do modifying a 34ft cat I bought.

i will be at anchor. no docking unless pumping out, or a massive resupply.
i bet it will move. i was on a floating restaurant a few years ago, and a 35' powerboat went by, the whole place moved. and that was a 120' barge.

after careful consideration i dont see it taking 5 years.
after buying the steel if it started taking a long time i would hire help.
no problem.
i have a good friend that is a welder, a pro.
he will bring his truck with mounted welder and an extra guy out for $75 an hour.
thats worst case, but that guy could get the boat done in no time flat. even if i just had him do 100 hours, every month i would be massively closer to done.

in fact once i build the two hulls at my home, and move them to the dock, i would call him to build the bridge and start the cabin.

[44'cruisingcat]

Originally Posted by scoobert

its a common knowledge that an electric engine is 2-3 times the power of a diesel or gasoline.

LOL! Common knowledge?

OK so here's a plan. Get a 1 KVA Honda genset. Run a 1kW electric motor off it. Because that 1 KVA electric motor is 3 times as powerful, run a 3 KVA generator off that. Then run a 3kW motor, 9 KVA genny, and so on.

Pretty soon you're getting a couple thousand horsepower out of a 1KVA genset. All through the magic of "common knowledge" and electric power multiplication.

Even better, start with a 25 Watt solar panel, and the motor out of an electric toothbrush...

[scoobert]

Originally Posted by 44'cruisingcat

LOL! Common knowledge?

OK so here's a plan. Get a 1 KVA Honda genset. Run a 1kW electric motor off it. Because that 1 KVA electric motor is 3 times as powerful, run a 3 KVA generator off that. Then run a 3kW motor, 9 KVA genny, and so on.

Pretty soon you're getting a couple thousand horsepower out of a 1KVA genset. All through the magic of "common knowledge" and electric power multiplication.

Even better, start with a 25 Watt solar panel, and the motor out of an electric toothbrush...

http://www.elcomotoryachts.com/pdf/E...zing-Chart.pdf

[nimblemotors]

So really, you have it figured out and don't need any input from CF.
To answer your OP question, use steel, you can hire cheap welders for it,
rather than Al, which requires highly skilled welding.
Be sure to put up a Blog and tell everyone how you got it done, how much it costs, and how long it takes, etc. We want to know.

Originally Posted by scoobert

i will be at anchor. no docking unless pumping out, or a massive resupply.
i bet it will move. i was on a floating restaurant a few years ago, and a 35' powerboat went by, the whole place moved. and that was a 120' barge.

after careful consideration i dont see it taking 5 years.
after buying the steel if it started taking a long time i would hire help.
no problem.
i have a good friend that is a welder, a pro.
he will bring his truck with mounted welder and an extra guy out for $75 an hour.
thats worst case, but that guy could get the boat done in no time flat. even if i just had him do 100 hours, every month i would be massively closer to done.

in fact once i build the two hulls at my home, and move them to the dock, i would call him to build the bridge and start the cabin.