Materials and Design Required. Advice would be great :)

Hey guys, new to this forum and will be on here for answers plenty of the next few months->years whilst I start building a 6.8m centre cab.

At present I will be working with an ex ship drafter/Cad designer, so at this stage I know the boat I want, but just need the design.

I am an engineer by profession so working out weight distributions for settings to my liking will be the fun part, but the Hull design and so forth wont be too easy.

I will be building the boat with 5mm hull thickness of 5083 aluminium, and the sides will be 4mm. That’s about all I know other than the style of boat I am after.

So my first question is, where is the best place in Brisbane or Australia to source material? I have been pricing up materials based on a rough take off and its looking quite expensive, almost to the point where buying a kit boat would be cheaper.

Second question is, can anyone suggest a good design firm, or somebody with blue prints/cad files of 6.8m centre cabs or similar sizes who are willing to part with them for a fee of course? If you can do the design, by all means contact me with what you need and what price you will require for your services. I especially want the walk around cab and also the raised bow sides. Self draining deck, 250L fuel tank, Kill Tank and so forth is also a must.

Attached are some images of similar boats I am interested in.

Thanks for reading.

Cheers

 

As you are in QLD then G James will be your best bet for ali as they specialise in marine and have all the standard extrusions that you will need. You are right that a kit might be cheaper as designers/builders get better prices than the public in most cases - doesnt hurt to get quotes though.

As for plans/kits there are plenty to choose from. Just be aware that Australian Standard 1799 has just been updated so make sure that any kit/design that you buy has been checked for compliance with the new criteria. The power and capacity criteria have changed and the stability criteria has changed also. You can download the standard for free at
http://www.nmsc.gov.au/recreational_boating/index.php?MID=26&COMID=1&CID=26 There is also everything on the builders plate there too.

Also check out the different construction methods on offer. Some are easier to build than others and some are more structurally sound than others. Some need jigs, some dont.

Get plenty of welding practise before you start. It's very easy to turn a nice design into a buckled mess. Also consider using an air powered miller instead of electrical. With air you can set the pressure so they stall rather than kick - very dangerous hand tool.

You will probably come across the hand cut vs machine cut debate. Machine cutting costs money but will save you time and you will purchase less plate due to nesting optimisation. Depends on how you value your time. A builder here that cuts by hand just built a boat for us and came in 35 hours under his quote, which saved us more than the cost of cutting. If you go for machine then get router cut instead of plasma, better cut and no clean up needed.

A boat of the size you want will take the pro's around 200 hours to build so you should consider how much time you can dedicate to it each week to get an idea of how long before you are on the water. You will also need enough height to turn the hull over at some stage.

If you want to try and draw your own hull then google delftship. It's free. Dont buy the one being sold for around $50, it's the same program re-badged. Check out the software section of the forum.

Enjoy it - its great fun!

 

Thanks heaps for that. Really appreciate it.

I have heard the amount of time can take many many hours, but I am blessed with 1 week off after 2 weeks of working, which really does free up my time. I think the hardest part will be surpressing the urge to take my current boat out fishing, but I will get through it I suppose. So yes, I am definately aiming at the many months mark to get this completed, and am not going to take short cuts because at the end of the day, there is no real rush.

I have welded almost everything but aluminium, so yes I am a novice for sure. However, my uncle has worked as a welder for about 30 years and will definately lend a hand and show me the technique, and maybe go through and do the more important welds.

Room is no drama as I have a large shed where I plan to do the lot.

Thanks for the heads up on the program. You dont know of any hull templates that I can go off for the similar design do you?? I know im probably wishing but worth a try

I was looking at your website and I really like the look of the 6.1m walkaround. Do you have designs and cut files for something slightly larger but of similar profile? Feel free to PM me the details if you like

Thanks again for the reply.

 

Thanks for the feedback on our website. We dont have anything as big as you need - not much demand compared to smaller boats, but seeing as though you have a drafter and are doing your own weight estimate, I could do you up a hull shape similar to the one we have and give you the file and flattened panels. Your drafter could detail the rest. Cost would be $550.

As for welding the simple rule is hot and fast. Since ali is such a good conductor of heat you need to turn the heat up, which means you then have to travel fast to stop it burning through. Use 0.9mm wire for the lighter stuff and dont over weld it. Also get your machine set up with push pull hand piece and teflon liner.

 

I am very keen to take you up on that offer. What details would you require and so forth?? I really want a walkaround cabin, but one which can sleep 2 comfortably. I love your design and if it were possible for a larger version(7m or so) to accomodate bunks in the cabin, and fishing room out the back that would be excellent.

What other details would you require with regards to the hull? I want this to be an offshore boat so will have to tackle the bars, and also deal with the chop present 99% of the time in the moreton bay. I need a slightly larger deadrise as handling the rough is more important to me than saving a few $$.

Anyhow, if you could let me know a list of what information you would need from me that would be great. Also, is there any cheap way to get aluminium suitable for marine?? Pricing I have received is just extremely expensive. Any good suppliers out there?

 

Sent you an email alidesigner. Look forward to your reply