Steel or Aluminum

[44'cruisingcat]

The boat would be lighter in Aluminium, there's no getting around that. So it could use smaller motors, carry less fuel and ultimately be cheaper to operate. Steel will be cheaper to build.

How it all balances out probably depends on your planned mileage.

[noelex 77]

Originally Posted by scoobert

i have never welded aluminum.

I would not contemplate building a boat in aluminium.

Whatever you decide make sure you have the funds to complete the boat. Many home built boats, especially steel, are never finished because of the gradual realisation that the hull cost is only a small fraction of the total cost.

On a tight budget a second hand boat will generally work out much cheaper.

Good luck

[scoobert]

Originally Posted by noelex 77

On a tight budget a second hand boat will generally work out much cheaper.

Good luck

i wish that they made 65' steel or alloy cats 30-40 years ago...
the best used boat i found was an aluminum 58' trawler that needs major repairs. i doubt they would ever accept the offer i would give them for it, seeing as how it needs over 1500 hours to get it back into shape.

when you say hull is 1/3 the cost of the ship, what are the other costs?

propulsion? i dont see anymore then $40,000 spent here for the diesel/solar-electric drive system i have planned.

navigation and electrical systems? $20,000

food storage systems $3500

exterior, all $8000

interior, finish $20,000

i figure the hull to be 58,000 in steel, 150,000 in aluminum.

am i missing something major?

[noelex 77]

Originally Posted by scoobert

i cant even find a 5383 alu supplier. so i would have to save up the $150,000 for the raw aluminum just to start the job..

5383 is a very new grade of marine aluminium so is very difficult to find. It, together the the also new sealium have only been used on a small number of vessels.

5083 or the slightly inferior 5086 are the most common boatbuilding alloys.5052 is also frequently used and although its considerably less strong its cheaper and perhaps worth considering if you are on a tight budget.

[scoobert]

Originally Posted by noelex 77

5383 is a very new grade of marine aluminium so is very difficult to find. It, together the the also new sealium have only been used on a small number of vessels.

5083 or the slightly inferior 5086 are the most common boatbuilding alloys.5052 is also frequently used and although its considerably less strong its cheaper and perhaps worth considering if you are on a tight budget.

i did my pricing on 6061. is the 5052 that much cheaper?
also of issue are the other problems. i cant weld it, i dont have the welder for it.
do you think its that many times better?

[noelex 77]

It depends on the level of finish, how much you can scrounge etc.

As a ball park figure I would suggest a steel or aluminium home built ocean going 65 foot cat will cost in the region of $700000 in todays terms to build excluding labour. Steel might be 10% cheaper.

A large vessel like this is not a project to undertake lightly. A lot are started and never finished when the reality of the time and money it takes to build such a vessel hit home.

Do a lot of research before you begin.

[noelex 77]

Originally Posted by scoobert

i did my pricing on 6061. is the 5052 that much cheaper?
also of issue are the other problems. i cant weld it, i dont have the welder for it.
do you think its that many times better?

6061 is used for extrusions (T and L sections) it is not generally used in sheet form for boatbuilding.

[scoobert]

Originally Posted by noelex 77

Do a lot of research before you begin.

been working on research for two full years now on building, 4 years on living aboard.
wow, 700000?
it would take me over 5 years to save that up!!!
my max budget was $200,000 and 3 years of work.
but i plan to do most of it myself, over 90%.
lucky for me i went to mechanical school, not that schooling will help, but
it can't hurt.
i worked out many ideas, but 65' is the smallest i want to raise a family on, and spend the rest of my life on. the two of us could live in less. in fact we are in 400 sq ft right now, but with 2-4 kids? no way. i loosely follow a blog where they have two kids on a 40' class sailboat, they sleep in the kitchen so the kids can have a room each. and they are both babies. if i had to make bets, they will be moving back to land before the kids are in their teens.
mono's are out too. the sheer energy to move those boats at any speed is crazy. the designer said 35-45HP just to move in calm water at 3-5KTs on a 52' mono.
the same for the cat was 15hp.
i can run 15 HP on solar alone for inner-coastal travel.
so i have no idea what i would do if it did indeed run to 700,000.

[44'cruisingcat]

Originally Posted by noelex 77

It depends on the level of finish, how much you can scrounge etc.

As a ball park figure I would suggest a steel or aluminium home built ocean going 65 foot cat will cost in the region of $700000 in todays terms to build excluding labour. Steel might be 10% cheaper.

A large vessel like this is not a project to undertake lightly. A lot are started and never finished when the reality of the time and money it takes to build such a vessel hit home.

Do a lot of research before you begin.

$700,000 for materials only? Seems very high to me.

$200,000 and 3 years is optimistic though. Took me $200k and 4 years for a 44 foot sailing cat.

[atoll]

sounds like what you are planning on building is a raft!

why not use 2 steel tubes and weld up the ends,telegraph poles as cross beams,and a porta cabin on top?

[scoobert]

Originally Posted by 44'cruisingcat

$700,000 for materials only? Seems very high to me.

$200,000 and 3 years is optimistic though. Took me $200k and 4 years for a 44 foot sailing cat.

fiber seemed harder to me.
building a female mold for each part... sounds like a ton of work compared to cutting and welding.
then i was always worried about osmosis. i mean what if in 5 years you have to go down to the hull and fix the gel coat?, stress cracking... why did you decide to do fiber?

[scoobert]

Originally Posted by atoll

sounds like what you are planning on building is a raft!

why not use 2 steel tubes and weld up the ends,telegraph poles as cross beams,and a porta cabin on top?

telegraph poles? holy crud, did they still not get telephones in England yet?
i will have to brush up on my Morris Code before i visit.

[44'cruisingcat]

Originally Posted by scoobert

fiber seemed harder to me.
building a female mold for each part... sounds like a ton of work compared to cutting and welding.
then i was always worried about osmosis. i mean what if in 5 years you have to go down to the hull and fix the gel coat?, stress cracking... why did you decide to do fiber?

It's epoxy, so no osmosis. Polyurethane paint, so gel coat either. No female moulds, it's built from prefabricated panels.

I used fibreglass because I wanted a good performing sailboat. Metal would have been too heavy.

If you're interested, there are some photo's here: Member Galleries - Cruisers & Sailing Photo Gallery

What's the projected displacement of your boat? Who designed it?

[scoobert]

Bruce Roberts, steel boat plans, boat building, boatbuilding, steel boat kits, boat kits

[Boracay]

A 65' cat may be about equivalent to a 90' mono.

So if man hours go up as the cube of the length and a 30 mono takes 3000 man hours then your 65' cat will take 81,000 man hours.

Or if a 45' mono takes 5000 hours the the 65' cat would take 20,000 hours.

Either way, my bet is you'll die of old age before launch, let alone completion. That is, if bankruptcy doesn't get you first.

I've built two (21' ply, 32' ferro) boats from scratch, rebuilt my present 44' steelie from a bare hull and owned a 26' fibreglass yacht.

From my bitter experience DIY is only worthwhile for boats under 28'.

In terms of cash and time I understand there are some very nice larger (40' or so) cats available for a good price.

Please excuse the photo. I was scanning my old negatives and this is the 21'6" Van De Stadt that I built in New Guinea. It was a great project.