Boden Boat Plans custom Alloy Sea Boat

Boden Boat Plans Alloy Sea Boat


What do you do when you want to learn how to weld, love fishing and want to save some money? Build yourself a boat, obviously. But what do you do when you realise the boat you built is better than you expected and you want to go further? Add a hard top and massive fuel tank so you can go further, obviously.

That’s what Brett from Queensland did. Five years ago he started with an Alloy Sea Boat paper plan from Boden Boat Plans. He grabbed himself a 250amp, single-phase mig welder from Trade Tools (running pure Argon gas) and some 5356 marine alloy from his local supplier and got stuck in.

This is where it starts. Simple, right?

The plan asked for a 4mm hull with 3mm sides, but who follows the plan? Brett went all out, upgrading to 6mm for the hull and 5mm for the sides. With a little redesign, he expanded to a 400 litre fuel tank under the centre console of the 6.2m hull.

Brett had welded steel before but never alloy. He says it’s not too hard, just practice and you will figure it out.

"If you plan to cut and grind in your backyard, bribe your neighbours or move to the bush," says Brett.


On the other hand, adds Brett, welding alloy isn't that hard to learn.

His original build took him two years, including building a dual-axle, alloy trailer; fitting an Evinrude Ocean Pro and marine electronics. The total cost then, a paltry $12,000 – cheaper than some off-the-shelf alloy trailers.

Over time, Brett did what most of us do and found a few bargains he couldn’t refuse, like two Garmin 7021s combos with mid-range chirp transducer and Raymarine autopilot. The Ocean Pro turned out to be a bit of a dud and after too many reliability problems, on went a newer 225hp Yamaha four-stroke V6 outboard motor.

After a few years running the boat as a centre console and slowly upgrading bits and pieces, Brett wanted more. He knew the 400 litre fuel tank was holding him back. Constantly getting wet was also becoming tiresome.

A plan was hatched to nearly double the fuel capacity and he sat down to draw how he wanted the hard top to look.

Back in the shed he went, where the centre console and floor were pulled out to allow for a full redesign of the tank. The result was a whopping 700 litres of fuel capacity.

Brett wisely left the coamings on the sides and the anchorwell in place, building the hardtop off the already strong structure.

Wisely Brett left the coamings in place as the superstructure went on, helping keep it all square.


The hardtop close to completion.

The result took only seven months, including some hull dent repairs. This was much quicker than the original build and incorporated LED lights, rod holders, sliding windows and an access hatch.

Where to from here? Fishing obviously.

First dip in the drink after the new hard top was installed. 


Boden Boat Plans | Custom Alloy Sea Boat specs

Year 2011

Length 6.2m

Beam 2.45m


Boden Boat Plans project boat cost

First build $12,000

Materials $5000

Engine and marine electronics $29,000

TOTAL COST $55,000


5 project boat restoration tips

From Brett

1. If you want that ground-back weld look, do it as you go, otherwise you’ll hate the size of the job at the end.

2. Welding a boat isn’t hard. Read a bit and learn from trying.

3. If you plan to cut and grind in your backyard, bribe your neighbours or move to the bush.

4. When deciding on the alloy thickness, overdo it. It’s cheap insurance.

5. You can never have enough fuel capacity.


Published in Trade-A-Boat #476, on sale March 24, 2016.