I Need Some Advice on How to Build a Pontoon

Hey all,

This is my third try writing this so I’m just going to sum up my situation for you all. I’m planning on building a pontoon boat and I need help with it. How should I make the floats? I was thinking rolling 3mm 5083 aluminium (I can get 1200mm x 2400mm) into a 25” tube. This will leave me with 400mm sheets which I can use for the fencing and the consoles (I was thinking of a side console design). My main problems are with the nose cones and the cross beams. Nobody sells nose cones in m y city, and I don’t know how to make them. I also don’t know how much cross bracing/beams I should put on it. I can buy the motor mount and the trailer, and am thinking about a 9.9hp Yamaha, connected up to a side console set up.

Anyways, cheers in advance.

(Just want to note that I am not the best metal worker).

 

This is easy.

First, welcome to the Forum.

If you're "not the best metal worker", then have them made by a competent shop.

But before you do that, look for a proven design of what you're wanting to build and just build to the design.
If you stick to the design then it will perform as expected and meet your needs.
The more you deviate from the design, the less chance it will perform the way you want or expect.

Cheers

 

Thanks mate, that’s a really good idea and I will probably use that.

 

I’m thinking that there should be some structural members inside those tubes!

 

How should they be? Should I do like a cross section in between the lengths of the logs before I weld them all together? Or should I get long bits of metal and put them lengthways through them?

 

Welcome to the forum.

The issue is, it needs to be designed first. And by that - I mean, how much 'weight' is being supported, as that leads to the size of the tubes, in terms of buoyancy.
You can't just build "some tubes" and hope it works. Well you can, but not advisable!

So, you really need to know what your pontoon is going to be doing, i.e. to work out how much it will weigh first.
The SOR in simple terms.

 

Thanks mate, that sounds quite wise ( I mean you are a naval engineer and I’m not ) and that does bring up a good point. Now that I think about it, I would probably bring about 650kgs of weight onto it at any one time. That does excludes the weight of the pontoon on top of the floats though. Pretty much all I’m going to be doing on it is taking it out with some family and spending a day out on the water with it.

 

Why are you choosing a pontoon? In general they are used because the low price of manufacturing at a factory. Write the SOR first and maybe other options will show to be better.

 

Well I’m choosing a pontoon because it’ll be stable, not be too deep in the water (so I can go and land it at a beach or whatever in a lake) and because it’s probably the easiest to build.

 

A flat bottomed monohull will draft less, require less horsepower, and still offer great stability. One hull is quicker to build, and will not involve cross beams and all the engineering that will require.
If you’re dead set on pontoons, consider this:Plastic Pontoon https://plasticpontoon.com/

 

Well yeah I found a place near me called MDS Marine Dock Systems and they sell them, and I can also get it with the decking, motor mount etc.