New trailer frame needed - buy or make

[charleville]

I tapped the rest away and sprayed immediately with cold galv...it has never even looked like rusting in the weld...gets immersed each time.

That is very interesting. I have never used cold galv in a immersed marine environment but I have always been impressed at its longevity on welded projects around the home. That is why I wonder if, to get a few extra years out of a faithful old trailer, simply welding on new members made out of blue steel and cold galvanising them might do the trick well enough. For box sections, that necessitates welding a nut on top over a hole and pouring oil into that and sealing with a bolt.

[charleville]

Just had my trailer frame re-galvanised and it was an easy exercise........

I would have no hesitation sending a frame off for hot dip galvanising now that I have done it myself.

What preparation on the trailer is necessary for galvanising, please? eg sandblasting or anything like that?

[johncar]

I think that there are plenty of ways to build and protect your trailer. A "C" channel for the home builder makes good sense particularly if you want to save on hot dip galv costs.
I think anyone building one just needs to consider the reduced strength of C compared to box and build in additional strength and bracing. The great thing about building in C section is the ability to easily paint it inside and out and a good industrial coating can be as good if not better than hot dip.
Thinking back to a Quintrex fishabout I owned was 20 or so years old still on it's original trailer I was told, a tilting C channel trailer painted in grey killrust not a sign of rust in the frame anywhere.
So if I had to build a new trailer frame on a budget I would build the frame and cross members out of suitable size for the boat and intended use Duragal C section with a compatible size duragal Box section drawbar. Definitely a bit trickier to build than using Box but should last a lot longer.
Cold Gal primer thoroughly all the cuts, joints and welds, then paint the whole thing with a quality paint, more coats the better.

Doing what ozscott is saying about using box, sealing and filling with oil has been done too heaps and should be fine but you just have to consider a few things like wiring and any future work, drilling, welding, little stress cracks and the oil may be inconvenient in those situations. I would probably prefer an open style construction where its easy to wash and maintain but plenty of ways to consider doing the job.

[blairv70]

I think that there are plenty of ways to build and protect your trailer. A "C" channel for the home builder makes good sense particularly if you want to save on hot dip galv costs.
I think anyone building one just needs to consider the reduced strength of C compared to box and build in additional strength and bracing. The great thing about building in C section is the ability to easily paint it inside and out and a good industrial coating can be as good if not better than hot dip.
Thinking back to a Quintrex fishabout I owned was 20 or so years old still on it's original trailer I was told, a tilting C channel trailer painted in grey killrust not a sign of rust in the frame anywhere.
So if I had to build a new trailer frame on a budget I would build the frame and cross members out of suitable size for the boat and intended use Duragal C section with a compatible size duragal Box section drawbar. Definitely a bit trickier to build than using Box but should last a lot longer.
Cold Gal primer thoroughly all the cuts, joints and welds, then paint the whole thing with a quality paint, more coats the better.

Doing what ozscott is saying about using box, sealing and filling with oil has been done too heaps and should be fine but you just have to consider a few things like wiring and any future work, drilling, welding, little stress cracks and the oil may be inconvenient in those situations. I would probably prefer an open style construction where its easy to wash and maintain but plenty of ways to consider doing the job.

Johncar thanks for the sound advise - thanks everyone actually I have learned a thing or two.

Now who is a welder out there who wants to help me? Payment in whatever currency you like

[johncar]

blairv70,
If you have the skills and gear to do your design, procure and accurately cut and prepare all your materials ready for tacking up and welding. It shouldn't cost much to get it welded up even if you have to go to a shop. Most of the cost is in the prep making sure all your joints are good with no or minimal gaps and finishing. Who ever is welding it may prefer that the edges to be welded have the gal sanded off too.

Someone on here may be happy to weld it up for you or as I said should only be a couple of hours or more for a shop to weld it up depending how complex you design it. I think the Welding Shed at Caboolture charges about $90 per hour.

[blairv70]

blairv70,
If you have the skills and gear to do your design, procure and accurately cut and prepare all your materials ready for tacking up and welding. It shouldn't cost much to get it welded up even if you have to go to a shop. Most of the cost is in the prep making sure all your joints are good with no or minimal gaps and finishing. Who ever is welding it may prefer that the edges to be welded have the gal sanded off too.

Someone on here may be happy to weld it up for you or as I said should only be a couple of hours or more for a shop to weld it up depending how complex you design it. I think the Welding Shed at Caboolture charges about $90 per hour.

Johncar, unfortunately though I have most of the skills it is the time I lack :-(

But will give the welding shed a call and make some enquires

Thanks

Blair