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Trailer rust proofing

Posted: 31 Aug 2016 07:39
by David M
Don't want to hijack PC's trailer build thread so have started this new one.

Am building a new boat trailer that gets dunked in salt water so I have built it completely out of tapered U channel so that I can get a HP washer in everywhere to get the salt out.

PC is galvanising which I agree with on the offroad trailer but I find that the salt even gets to the galvanising over time and it is a mission to disassemble and regalvanise.

Am leaning towards just painting with NS4 which is easily touched up once every year or 2.

Comments would be appreciated.

Re: Trailer rust proofing

Posted: 31 Aug 2016 08:12
by Tinus lotz
Galvinised ....then paint over or powder coat make it all bolt together :salute:

Re: Trailer rust proofing

Posted: 31 Aug 2016 08:40
by ricster
Will NS4 last as a top coat? I assumed it was more a metal primer than top coat.

I think the biggest problem wit a coating is if a "bubble" forms between the paint and metal. This bubble may only be a tiny hard to see bubble but if any contaminant manages to get there it will be basically be sealed in there to start the corrosion process. I think this would happen mostly at the welds and joints where a flat surface is not always achieved. I would think that the NS4 or any paint for that matter would probably, once dry, become hard and for all intensive purposes be brittle. With the expansion co-efficiency of metal and paint being different, I assume small cracks would appear and thus allowing contaminants in.

I know paint doesn't like to stick to galvanized metal too well either, even with the best preparation..... just look at old houses with painted galvanized gutters. This is why Chromadec has become the favourite material for garage door and gutter manufacturers.

I would think that a full galvanized dip would be the best option. This will get into the corners and welds better than paint. What about anodizing? Is this better than galvanizing? Will look nicer than galvanizing.

I would also look at painting on a rubberizing ( stone chip ) paint on all areas that will be exposed to wear from stones and general bumping or even sand blasting from driving on a sand road.

Re: Trailer rust proofing

Posted: 31 Aug 2016 09:08
by Peter Connan
David, you can specify a thickness for hot-dipped galvanizing.

It corrodes a certain amount per year, depending on conditions.

Apart from just building the thing out of stainless steel (you may want to investigate 3CR12, it may not be that much more expensive), a thick layer of galvanizing with paint on top remains the best possible protection.

I like the idea of rubberizing instead of paint though. It will be heavy, but will last much longer. However there will obviously be areas where it would cause problems (the roller mounts and so forth).

Re: Trailer rust proofing

Posted: 31 Aug 2016 12:23
by Michael
I was born and raised in Richards bay, back then we were still allowed to drive on the beach and it was still safe to camp as well.

We went fishing with an old 1984 Isuzu 2.2d which was my dad's pride and joy. He rebuilt it not long after he bought it second hand and had the whole chassis galvanized. I think we must have fished every weekend for about 13 years straight. The chassis was in perfect condition throughout this whole time.

The load bin was changed about 3 times and finally got a fiberglass one as they just rust away within 2 years of constant beach driving. The cab was also changed a couple of times.

Basically my dad washed the chassis with fresh water every time we came from the beach. Also he drilled holes in it everywhere where the water or sea sand could accumulate.

Galvanizing is the best alternative to stainless steel in my opinion :thumbup:

Re: Trailer rust proofing

Posted: 31 Aug 2016 15:20
by David M
Thank you for the comments.

Seems like galvanising is still the best option and possibly coating thereafter.

Just won't go the rubberising route as you can not see the corrosion happening underneath and when you do it is too late.

Re: Trailer rust proofing

Posted: 31 Aug 2016 15:40
by ricster
" Just won't go the rubberising route as you can not see the corrosion happening underneath and when you do it is too late "... when I mentioned rubberizing in my earlier post, I was talking more along the lines of this....

http://www.duram.co.za/products/duram-88-stone-chip/

I used this on my Patrol from the back of the front mud guard to the front of the back mud guard at the bottom sills between the rock sliders. It is not a thick rubber type bakkie liner, but a tough thin paint..... apparently good in sea conditions too... and seems to stick like shhhhhh to a blanket. I did no prep work, just wiped it down with a wet cloth and put a masking tape line down to get a straight line and slapped the paint on. Its been stuck on the for 4 years now !!!

Re: Trailer rust proofing

Posted: 31 Aug 2016 20:39
by minwater
If rust is a big worry what about sacraficial anodes