4500BA Build – Part 2 – Plates and Frames

Build Instructions for the 4500BA – Assembly Part 1- Plates and Frames

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Finally, the time has come. Make sure you have those welding skills ready, don’t make this your first aluminium welding experience. Practice on some of the scrap that you get in the kit.

Lay those hull plates down edge to edge lining up the etched markings. Use some blocks of timber/ tyres or anything really to prop them up. As long as it’s the same on either side and will hold the plates steady. The blocks we used are about 130mm high. Meaning we get the desired angle at the aft, you could also try place a frame in to get the angle correct.


Note:- At CNC Marine most of our vessels use a variable deadrise. It starts at about 15 degrees at the transom but aggressively increases towards the bow. We’ve spent a lot of time and leading edge naval architecture software to come up with a hull that meets our requirements. This is to achieve a fine waterline entry but retain stability at rest and efficiency while on the move.

 Start at the aft end, and work your way forward putting a tack inside the fwd edge of one of the weld marks along the keel seam.

TIP:– When tacking up, put welds at the end of were you plan on finishing your final weld. That way you neatly cover the tack on your final run.

Go ahead and place that back frame in, in this case it’s called ‘F1’. Line it up with the etched markings shown on the hull plates.

NOTE:- The front edge of the frame lines up with the center of the etch or pen line marketed on the hull plates.

It’s generally good to put a tack on either side of where the stringer will go through. And then one close to the edge.

The cutouts vary depending on the kit, but most look like this. Stringers sit hard against the smaller face. There are extra cutouts blowing out the top and bottom. These cutouts make you able to get good access to weld the stringers to the frames.

Once you have completed the first three frames it’s time to insert the stringers. Making sure they are inserted curve up and slide easily through the cutouts in the frames. You can then go ahead and tack these every 200mm or so up until frame 3.


Note:- You can see in the previous picture that more than the first three frames had been put in by our boat builder. He had missed the part in the instructions to only put the first three frames in before inserting the stringers. This was not a problem but outlines the fact that it’s a good idea to pay close attention to the instructions.

The stringers align to markings on the bottom plate, these also show where you need to weld along the stringer. 

At the start you can put a tack at the end of these markings, and then when you go back and fully weld this tack should get covered.

It’s now time to start fitting the remaining frames. Start with frame 4 and pull together the hull as you go. You may have to use a pair of come-along’s at this stage to make it easier for you to pull the hull plates together.

Attach the transom. It sits slightly on top of the bottom plates. Here we have used a couple of offcuts tacked to hold it in place and give it a bit more support for the next couple of steps, at least until we have the sides tacked on.

Starting from the bow fit the chines, tacking every 100mm or where necessary to help pull the hull plates further into shape.


Tip:- In cases like this where the front of the chine is not quite lining up. We can employ a simple method to align the two. We grab an F-clamp and place it over the chine as in the below image. Close the clamp up lightly and then pull up on the end of it. This will cause a lever action and pulls the plate back in line. Use offcuts of timber to protect the ally.

We suggest using a bow lug cut from 100x10mm flat which we supply in each kit. In the kit you will find a template used to cut this out. Supplying this as a cut part wouldn’t work as we find it gets customised a lot and it is such a simple part for you to be able to make yourself.

CNC Marine gives you a measurement for positioning your bow lug, this is based on the ideal position for pulling your boat up onto a trailer. Though this can also be modified depending on the trailer setup that you go for. That is why we don’t provide a cut out in the bottom plates for positioning your bow lug.


Once you have figured out where you want your bow lug to go you will need to cut out a small slice between the bottom plates. Allowing you to fit your bow lug through. Once inserted through you are able to fully weld inside and out for support.

So, the bow lug is attached. Therfore it is time to fully weld the keel seam from the bow through to the third frame in, in regard to the 4500BA this is frame 5.


Tip:- Take your time to avoid putting too much heat into the bottom plates. Weld a section of about 15cm, then move and weld a spot at least a meter away. After the original section is cool, you can go back and continue this seam.

Welding this section of the seam takes you to cutting the stem bar. The stem bar should easily bend enough to be slotted through the cutouts at the keel seem. Tack this at intervals on each side and finish flush with the chine.


Note:- We provide an itemised cut list for all the parts that come as full length extrusions. Some people decide to go through and cut all these parts at the start, which means you have them all on hand when you need them. This is up to you.

4500BA Build Getting Started

Build Instructions for the 4500BA – Getting Started

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You’ve Ordered Your Kit

You’ve ordered your plate boat kit and its going to be a couple of weeks before it gets delivered. So its time to prepare! Start by preparing your work space, clean up that shed. Measure it up so that you know you can easily lay out your parts, depending on the size of your build you may need up to 9 meters in length. Think about access and movement while you build, and space to roll over your boat when it comes time. If you’re working with a small shed you may have to drag the boat out so that you can roll it over.

Tools Required; (More detail in Tools you need post)

  • Welder, Pulse Mig
  • Grinder, plus cutting disks
  • Array of clamps including come alongs
  • Drop saw
  • Drill
  • Orbital Sander
  • PPE Safety equipment



If you’ve decided to go the route of getting your kit delivered by crane truck than all you really need is to be a guide. 

What we will need: – Solid, ideally sealed area that we can pull a truck into and then at least 3 meters of space to the side of the truck for the sheets to be unloaded.

All kits 5m and below come in packs roughly 6.5m x 1.85m x .35m. While all vessels over 5m come in packs roughly 9m x 2.2m x .35m. Bare this in mind when ordering your kit. 

Now I know you just want to get welding and start seeing some progress, but you have a few things to do before you can. Starting with reading through the instructions.


Lets just start with a bit of organisation. The documents we sent you will have a material summary, parts list and extrusion list. Start by just going through and making sure you have everything, familiariseing yourself with the kit.

Soak it all in, have a cup of coffee and look over your plans once more.

Your parts are all held together in the sheet by small tabs that are not cut out when the sheet is on the cnc bed, grab your grinder and start cutting your parts out, they don’t take much as these tabs are fairly small.

Tip: – Your sheets are going to be pretty cumbersome to move around. Have some blocks of wood handy, pry up a corner of the first sheet and throw some blocks underneath to separate it from the sheet underneath. Now start cutting some of the tabs to release some of your parts.

Assembly Instructions

Assembly Instructions

Assembly Instructions

Assembly Instructions

Assembly Instructions

kit arrives

Laying out parts

The tabs leave a bump on the edge of all the parts, your going to need to grab your grinder and run along the edge to grind away all these tabs leaving a nice clean edge.

– You may want to go through this process for each part one at a time or complete each step on all your parts and then move on to the next step.

Tip: – Handle your parts as little as possible, try and stack them in the reverse order that you’ll need them so you don’t have to remove 50 parts to get to that frame you need right at the start.

Tip:  When you receive your material from us, it often has a fairly greasy coating left over from the cnc cutting operations. Take a rag soaked in methylated spirits and give each part a good wipe before putting it aside, this will remove any oil and debris and will mean next time you pull your part out its ready to go.

Craig’s 5000CC Build Log

Building a 5000CC

CNC Marine we are here to help

This is a great place to start if you’ve nver built a boat before. Craig will take you right through the process he took to build his own CNC Marine fishing boat. Starting from what to expect when your kit is arriving and what to have prepared. Then what tools are required, right through to installing electronics. Finally he has some really great shots of the finished product in all its glory.

Don’t be worried about building your own plate alloy fishing boat in your shed. Craig shows you how its done.

Remember that when purchasing a kit through CNC Marine you become part of our family, we will endeavor to guide you through whenever you are stuck.

Variable Deadrise

Our Planing Boats – Deadrise Explained

CNC Marine we are here to help

Deadrise Explained

A boats deadrise is defined by the angle formed between between the horizontal plane and the vessels hull. This is usually given by most manufacturers as an angle at the transom. To give you an example of this is shown in the transom section in the images below.

The angle is seen as essentially how much of a vee shape the hull makes. It is a shape that is most carefully engineered to achieve a certain result. Therefore this should be important to you, if you are after a vessel that can handle rough water, or shallow water. Whether you’re looking for overall smooth ride or high performance.

At CNC Marine

At CNC Marine most of our vessels use a variable deadrise which starts at about 15 degrees at the transom but aggressively increases towards the bow. We’ve spent a large amount of time and used leading edge naval architecture software to come up with a hull that meets our stringent requirements. We aimed to achieve a fine waterline entry while retaining stability and efficiency. We did this while also creating a structure that is easy to put together and does not require any jigs.

Our Answer to ‘What Deadrise do Your Vessels Have?’

It’s often hard to give an accurate answer when somebody asks us what deadrise each vessel has. Our answers are much like what is illustrated in the images below. These images show the varying deadrise of our 7500CC. As you can see at the transom it is 16 degrees and slowly changes through to the midships, this allows for a stable boat at rest. Continuing towards the bow the deadrise increases drastically. When we get to the entry point of this vessel you can see this increases to 52 degrees, allowing for a sharp crisp entry into swell.

Registering Your Boat

Registering Your CNC Marine

CNC Marine we are here to help

Australian Builders Plate (ABP)

In Australia you are required to fit an Australian Builders Plate. A blank builder’s plate complete with the associated calculations required is supplied with each CNC Marine kit. For registration in some States as an owner builder you are not required to affix the builders plate to the vessel, however if you ever want to sell the boat it will be required to have an Australia builders plate affixed. We therefore recommend you fit the ABP to each of our boats you build.

Currently there are no regulations around weld qualification nor is it necessary to get your boat professionally surveyed as a recreational vessel.

There are a number of requirements as part of the Australian Builders Plate (ABP); person capacity, engine capacity, build quality. As the builder you are self-assessing and filling in the Builders Plate to show that it meets these requirements. We provide you with the calculations to the standards, but you need to be satisfied as the builder and self-assessor that all welding is to a sufficient quality to maintain safety. If you are unsure, we recommend engaging a qualified surveyor to review your build.

Hull Identification Number (HIN)

A HIN or Boatcode is a unique number that is like a fingerprint for your boat, much like a VIN on a motor vehicle. Some states require this for registration, and others just suggest it. The main use is to provide a unique identifier to your boat in the unfortunate circumstances of your vessel being stolen.

CNC Marine supplies you with two blank HIN plates for you to fill out, one should be placed in a secret place, and the other in an obvious place.

Check your local state if you need it.


As an owner-built boat, some insurers may want the vessel to be surveyed, this depends on the insurer and the boat being insured. Often smaller CNC Marine vessels won’t require this. Check in regard to your boat and your desired insurer early, as you may want to engage a surveyor before you start so they can see the boat in its early build stages.


State By State

This information is a guide only and may be subject to change or misinterpretation. You should complete your own research into your requirements. Most states have detailed information on their respective government transport websites.

In Queensland you are required to go to your local department of transport and fill out a registration application. Also available online here.

In QLD you are required to have ABP, but a HIN is optional. Queensland transport will provide you with a SIN (Serial identification Number) if you don’t have a HIN.

In NSW you will need to book an appointment with Roads and Maritime service and will need to fill out an application for vessel registration, available here.

Finding a Boatcode/HIN agent in NSW is easy look here.

In NSW you are required to have ABP and HIN plates attached.

In Victoria you will need to register your vessel through VicRoads. A HIN is not required for vessels to be registered in Victoria, though it is always advised.

Check out registration details here.

In South Australia a HIN is required, you can go to your local Service SA customer service center and they will supply you with a temporary code to register the boat in your name. Once the vessel is registered in your name you are able to take it to a boat code agent to get a proper HIN number affixed.

A list of boat code agents  here.

In Western Australia you are required to fit HIN plates, a list of providers can be found here. You will need to register your vessel through the department of transport.

In Northern territory you do not need to register your boat. Although you are required to follow all safety regulations as per other states.



Plumbing In Your Kill Tank

Plumbing In Your Kill Tank

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There are a number of options for how you could plumb in your kill tank.

Opt. A  – The Simplest

On all boats with kill tanks we supply a tube that runs from the bottom most point at the aft side of the tank all the way back to the transom. Generally this will have holes pre-cut out of each frame so that this pipe can easily be threaded through.

Because the Kill tank, and the pipe are below water level, when you stop the boat, the kill tank will be flooded. When you are on way the kill tank will drain, this means that the kill tank is constantly being flushed out. If you wish to hold the water in, you need to install a plug on the inside end of the kill tank main drain pipe.


Opt. B  – With a Deck Wash System

If you’re considering installing a simple deck wash system than this may be the way to go for you. To save you the hassle of completely plumbing in a pump to your kill tank you can make sure your deck wash hose reaches your kill tank.

This coupled with a plug in your main drain allows you to fill this using the deck wash system pump.

You could also optionally install an overflow tube, but this is not really required, as you are unlikely to overfill.


Opt. C  – Completely Plumbed In

On most CNC Marine boats with kill tanks we supply pipes and details to completely plumb in your kill tank. You would plumb in your deck wash system, and then provide an extra t-intersection to also connect your kill tank in a top corner somewhere (in most models we have decided this for you and holes are pre-cut).

This option allows you to fill the kill tank to the top, and doesn’t require you to be still to fill the tank.

An overflow tube is required for this option as the pump will keep pumping water into the kill tank.