DIY Plate Alloy 6.8m Island Cab

[mustang5]

Ok guys, the time has come for me to upgrade my old 5.5m half cabin to something which I feel comfortable in going long distances without the worry of being swamped or capsized etc.etc. I have persevered with the old girl for about 5 years now (I am only 24 so I shouldn’t be complaining ), but being blessed with a 2 week on 1 week off roster has freed up a lot of play time which I have to start utilizing. I have been pricing up brand new boats for quite some time now but although I am on a pretty good wicket, and I do have the backing of the missus (I have successfully given her the boating bug J), I just cant part with the large amounts of money people are asking for the larger boats (6m+).

Another reason for the upgrade is not only for reliability sakes, but I also have a 3yo son who as any father would want to do, is get him into fishing and boating, and especially camping. I have camped Moreton about 3 times a year for 5 years now and it’s a tradition that all of the family should enjoy. Again though, its just another piece of mind.

Anyhow, I see through searching for a while now on this forum that a few of you have succeeded in building your own plate alloy boat, and the results I have seen are inspiring to say the least.

I am looking to build a 6.8m centre cab similar to that of the kit that plate alloy sell, but of course optioned to what I want. I am looking at kill tanks where I want them, live bait tanks, much larger fuel tank and specific areas for fridges and so forth. Just the little things that would make me happy to suit what I’m after.

I am working with a cad designer who used to do the drawings and cut profiles for ships and ferries, I have shown him what I want and he says he is happy to look over it and provide what I need. So I am thankful I have sourced a great deal.

Basically where I am at now is pricing the materials. I have quotes from onesteel and after doing the math, seems extremely expensive for 5083 aluminium at 5mm thickness. So that brings my first question, Does anybody know a great supplier (Brisbane) for 5083 aluminium steel, one who preferably cuts do given sections as per cad drawings?

The second question is, What welder should I be looking at to do this work with? I have welded plenty of stainless steel over the years, but nothing as large scale as this of course, and I have researched that aluminium is a completely different ball game to stainless. Borrowing a welder for months doesn’t work too well so I will have to purchase one, which is no great drama at all. I am not going to be cheap on this aspect as we all know the welds are what holds it together. I have an uncle and a few mates who are welders so with there help at the important stages will be utilised for sure. So are we talking gas or gasless tigs? How many Amps and so forth. If somebody with welding plate alloy could help me out with what to use and what to look out for that would be great J

I am looking at doing this in stages, one reason is for the budget and the other is well, who knows how long this will take me. Which doesn’t bother me as I have nothing to rush for as I will be keeping the old half cabin until nearing completion (Funding from sale will go to brand new outboard etc.etc). I am looking to do this at home where I have a section perfect for the size of boat and room I require. So again I am lucky with that respect.

So I suppose that’s enough for now, its very early stages but everyone starts somewhere. I love DIY projects and have many different achievements under the belt(back deck, car refurbishments, panel work etc.etc). yes there are always hassles but that’s what makes it all the more sweeter at the end of the day.

Thanks for reading gents. Hopefully I can provide a more interesting read over the next few months with your help.

Cheers

[PinHead]

my first suggestion would be to get a naval architect to look over everything such a placement of fuel tanks, kill tanks etc..anything that will affect the weight distribution on the boat....do you have to get certification from someone qualified so that you can insure the boat on completion?
If you have mates who are welders, surely they could tell you what type of welder to buy.
I think there is a lot more to building a boat than just welding some plates together...good luck with it.

[Matt76]

Mate I have a $2500 CIGweld 200 amp single phase mig and I wouldn't even consider using it for a project like that, it is just not good enough. A mate of mine is a boat builder and his mig cost $15,000. You will not be able to TIG it, it will need to be mig'd.

[mustang5]

Of course its more than just welding things together, thats a no brainer. And yes I do have mates who are welders, but the reason I ask for the suggestion on what to use is in the hope that somebody who has welded 5083 aluminium sheets for a similar project would share their results. The more input the better..

I am an engineer myself and have been calculating the weight distributions with different setups.

[Noelm]

I guess you could use almost any welder, but a good/big one will have a duty cycle more conducive to big jobs, and a TIG will also probably be needed as well.

[dunks84]

About 18 months ago I seriously considered a similiar project, albeit a little smaller in size (6m cuddy cab). I invested a lot of time gathering info from mates, welders, boat builders and pricing new boats. Welders - everyone I spoke to said pretty much the same thing, to do a quality job you will need a mig, 3 phase, min 250 amp and must have a push/pull feed set-up. My mate recommended fronius welders, not cheap @ $10000 -$15000. He said that you can acheive great results with cheaper welders but generally speaking you get what you pay for and with a cheaper welder it will be more difficult to reproduce good, neat welds. In the end the time and effort did not justify the monetary savings. Generally speaking I think the bigger you go the larger the savings. Maybe you would consider getting the hot work done by a boat builder (to your specifications) and doing all the fitout yourself.

I am not a welder so take everything said with a grain of salt, this is just my two bob. A few of the blokes on here have built their own so somenone should have better/more info than me.

[Spaniard_King]

some good info here http://www.platealloy.com/welders.htm

Not sure that you need the top of the range welder to get good work.. the ability of the welder is going to make the biggest difference in quality of workmanship

[Mudlicker]

get yourself a good 3 phase pulse mig , any of the reputable brands will do the job , lincoln, cigweld , kempi , eutectic and so on the list is quite large . The push - pull gun while a great tool is not absolutely necessary if you have the right liners and feed rollers for your wire feed unit , also you will find the grade of welding wire makes a huge difference if you are having any feed problems.Hope this helps somewhat !

ps. good on you for having a go ;D

[bigjimg]

I had Shane of SMC Welding do some work for me on my Tinnie some time ago.Mobile and bloody good looking welds.He had some fancy looking gear in the ute,pretty sure he is in the phone book.Jim

[blueline]

for weilding i use a transmig 330, 3 phase i run 1.2mm wire and works atreat.
up here (cairns) 5083, 6.1m by5mm $990 a sheet

[Hunt-N-Gather]

Hey ya Mustang

Quickly looking at the design it looks allot like "sea life" if so, a mate got a kit threw these guys and we tacked it together pretty easy , (still unfinished many years later though) If you're going to load the old girl up with stoves /fridge and no doubt a heap of fresh water etc you really need to think about weight distribution and lay out before you start.
If you've never welded Ali or built a small tinnie out of the same I definitely wouldn't start with a big boat, keeping the heat out of the material to avoid buckling and distortion doesn't come second nature overnight, if you blow it, its scrap bin time and start again:'( . So get some HELP mate.
You also need the facilities to house this thing out of the wind & weather and consider you may need to roll it over several times before you go to the next step.:-?

I'm a boiler maker by trade and have used a 270 Castolin Eutectic for Ali work (MIG) they were the clear leaders for many years, many other brands now not only have caught up but over taken the space race with technological improvements, These new machines can turn a beginner into a pro overnight, went to a show recently and swung of the latest Kemppi and stood back in amazement. Baring in mind that you can also Tig with these machines, but not Ali, as they are only DC machines and you need AC/DC currant for that.
The only thing you may have to Tig is your fuel tank the rest (pulse) MIG is fine. A machine around 250 ta 270 amps will be able to weld up to approx 10mm comfortably.
IMHO wouldn't spend the extra dollars on a push pull gun the Kemppi has a 6mtr snake gun that still works even when you literally tie it in a knot. With that said don't over look the ESAB welders but reckon the Kemppi has the edge at present.
Good on ya for having a go mate, keep us posted, will offer advice as we go hopefully good! ;)
Keith.

[suzygs1000]

Hey, Mustang.

You can do the job successfully with a good single phase mig around the 240/250 amps. It makes it a lot easier with a traveller, and if you can hang the traveller to run along a piece of pipe a couple of metres off the ground, it will make the job of welding inside the hull a lot easier.

Sure , the job is a lot easier with a three phase pulse mig welder, but all this will do is give you much neater welds, for an extra 10 or 15 grand. You can't see the welds under the floor, and these are the ones which need to be strong. Most of the welds that are readily visible are easier enough to dress up after.,

I don't think you need any more than 5mm sheet for the bottom plates on a boat of 6 metres. I even reckon 4mm is sufficient, as long as it has plenty of ribs and longitudinals.


Dave.

[yowie3]

Mustang5,

Good for you for having a go!! i would love to undertake a project like this but.......am a tad concerned with my ability to do the hot work!

As you stated the design you are contemplating is similar to the plate alloy kit boats. I noticed on there site that they provide some info about welders and liners etc look here: http://www.platealloy.com/welders.htm
might be worth a look or perhaps attending one of the courses they run?

I would not go any smaller then 5mm bottom on a boat of this size. I am not in the trade as a boat builder, however i have seen, first hand, the end result of a vessel with too thinner a bottom and several years of fatigue resulting in the vessel sinking with dire results. The bottom buckled and cracked where it sat on the rollers of the trailer.

I will watch out for your progress with anticipation.

Good Luck.

[mustang5]

Thanks for all the input fellas!! Really appreciate the fact that you guys happily share your experiences and expertise!!

I got a quote from plate alloy and the welder they suggested is a Unimig 250 Inverter MIG welder, with grade 5356 welding wire. Quote came back at $1699+GST.

I have worked out the sheet sections I need for CNC cut based on design.\

1x 6100x1830x5mm
1x 6100x1525x5mm
9x 6100x1830x4mm

So the request for quotes have been sent off, but getting replies seems as hard as pissing into the wind... The big guys only want to talk to the big customers I suppose.

[Matt76]

Thanks for all the input fellas!! Really appreciate the fact that you guys happily share your experiences and expertise!!

I got a quote from plate alloy and the welder they suggested is a Unimig 250 Inverter MIG welder, with grade 5356 welding wire. Quote came back at $1699+GST.

I have worked out the sheet sections I need for CNC cut based on design.\

1x 6100x1830x5mm
1x 6100x1525x5mm
9x 6100x1830x4mm

So the request for quotes have been sent off, but getting replies seems as hard as pissing into the wind... The big guys only want to talk to the big customers I suppose.

Thats a fair bit of money's worth of sheets there mate! They should be jumping at the chance to quote it. Try some of the smaller sellers aswell, they may be more keen and actually be cheaper.

I just bought a 200 amp unimig ACDC Tig welder, its actually really nice to use, I'm not sure if that equates the the mig being the same but here's hoping!

[mustang5]

Yeah well, getting quoted $14000 for the sheet metal is hilarious if you ask me.

Can get the full flat pack for that, cut to size and with all the required accessories.

I will keep on my search. Again if anyone knows any places which sell aluminium plate, let me know :)

[stew60]

I built a 5mt kit boat from plate alloy australia about a year ago and the kit was a piece of cake to assemble and had no problems welding it up with a 250amp cig transmig welder but i dont think i would go any smaller, just make sure you use a good quality welding wire i used SAFRA brand which worked great

Cheers kev

[boatie_72]

Try the following

1. apple aluminium

2. Sheet Metal Supplies

3. Onesteel Aluminium

4. Caparal Aluminium

5. Ullrick Aluminium

Those type of sheets you are chasing are never going to be cheap, and not always avaiable from every supplier, as those sizes are used alot in the truck industry. Even if you get them at a good Kg rate, are you sure you need that many shounds like a lot for one boat.

I am taking it you have been quote approx $9.49 +GST a kg and a approx weight of 1341.12kg.

See how you go with those guys.