More on Trailers - Construction / Protection etc.

[Scott79]

A similar thread on Protective Coatings for Trailers recently got me thinking about a few other questions, decided not to hijack the existing thread...

# Has anybody tried coating their trailer in Cold Gal (spray or brush) when it was new for added protection?

# Do any trailer manufacturer's actually recommend additional protective coatings be applied periodically?

# Why aren't trailers made out of stuff like "Duragal" which already has a gal content, and then hot dipped galvanised? Is it purely a cost saving or is it an issue with the material not being able to be 're-galvanised'?

# Why aren't Galvanised trailers made more modular? So when the Rear Cross Beam rusts out, you can ring the manufacturer and they send you a new hot dipped one, bolt it in place and away you go? Too simple?

Scott.

[finga]

A similar thread on Protective Coatings for Trailers recently got me thinking about a few other questions, decided not to hijack the existing thread...

# Has anybody tried coating their trailer in Cold Gal (spray or brush) when it was new for added protection?
I haven't but someone might have. Cleaning the trailer appropriately before applying coating the trailer would be a priority
# Do any trailer manufacturer's actually recommend additional protective coatings be applied periodically?
Don't know. No idea

# Why aren't trailers made out of stuff like "Duragal" which already has a gal content, and then hot dipped galvanised? Is it purely a cost saving or is it an issue with the material not being able to be 're-galvanised'?
Not a wise move to make out of Duragal (the duragal bit is only a coating. It's not in the metal itself) and the like as any coating on the steel has to be removed to be able to be galvanised. And you pay for it's removal.
You can however get things dipped twice or 3 times. Just more cost.

# Why aren't Galvanised trailers made more modular? So when the Rear Cross Beam rusts out, you can ring the manufacturer and they send you a new hot dipped one, bolt it in place and away you go? Too simple?
Strength, ease of manufacture, time taken to build and assemble (a welded trailer will take about 1/4, or even less, of the time it would take to build a trailer that 'pulls apart' to replace bits.). It all boils down to cost.
I would imagine having replaceable cross members would add at least 5-8 hours onto the time taken to simply weld cross members in. And that would be for a simple tiny tinny trailer with only a couple of cross members.
For a welded trailer it's lay the pieces in a jig and start welding.
For a pull apart trailer it's put each piece in it's own jig and weld.

There is also a chance that each individual piece will twist or warp when it's galvanised so a 'reject' factor may need to be built into the price of a pull apart trailer
Storage problems would then exist for the spare cross members they would need.

Scott.

Trailers are made to suit the market so they can sell a lot of them.
Most people want the cheapest option so trailers are made to suit this market.
Those who don't want the cheapest option will find someone to build a trailer that will suit.
A prime example of this is any of the fold up trailers. they're made of heaps of bits and look at the price of them. Hooly dooly.

Cheers Alfred

[Noelm]

Lots of people actually paint their new trailers before using them, similarly, lots coat them on all sorts of sprays and laquers, the problem with using gal material in the first place is welding the trailer together, this either burns off the gal anyway, makes it harder to weld, and causes toxic fumes for the welder. bolt together trailers have been made, but there is the added drama of bolts coming loose and the time it takes to drill holes and assemble the trailer adds to the cost, as mentioned, people want the cheapst trailer they can find, it is the most over looked part of a package deal, and some shabby dealers will fit a tiny shit trailer under a good boat to make it look cheaper to get the deal.

[Noelm]

I guess to add, I reckon the material the trailer is made out of governs it's life span (to an extent) square section is almost always used, simply because it looks good and is easy to work with, but, it rusts from the inside out, there is ways to slow it down, in almost every size square section, you can buy plastic end caps, and I have seen (and done myself) the caps siliconed on and a hole drilled in the top to fill the tube with old sump oil, then a bolt screwed into the hole, works a treat, but is a lot of work. far better (in my opinion) to make the trailer out of another section, say "I" beam or decent angle, so water cant get in and sit in nooks and crannies.

[Scott79]

Thanks for the good replies gents.

Noelm,
Not doubting that box section trailers do rust from the inside, but alot of the trailers you see at the ramp on any busy day look pretty shabby on the outside. Is "I" beam construction actually going to solve this? I would suspect that the outside will deteriorate at a similar rate to that of box section, the main difference being that you won't get any nasty surprises from the inside. What do you think?

Scott.

[TheRealAndy]

Best trailer I ever had was one made out of "c" section. It was nearly 40 years old when I got it, and it was covered in many layers of paint. I just kept painting it. Only part that failed was the torsion bar suspension and bearings, both bolt on parts. I sold the boat about 7 years ago, and it has found its way back to the club, on the same trailer!

[Lovey80]

Scott79, I think what Noelm is referring to is the fact that with Universal Beam or C section there is no places that salt water can sit and eat through the beam from the inside out. Also all the surfaces are exposed so you can easily wash all surfaces that will get exposed to salt water.

If I was to build another trailer out of steel, I would do exactly what Noelm has suggested. Start with raw blue C section or Universal Beam steel and weld it together then get it gal dipped. Basically build the whole trailer, drill all the right holes for axles and lights to bolt on etc then pull it apart and have steel sections hot dipped. You should get a solid 12-15 years at least out of a properly galvanised trailer.

[TheRealAndy]

If I was to build another trailer out of steel, I would do exactly what Noelm has suggested. Start with raw blue C section or Universal Beam steel and weld it together then get it gal dipped. Basically build the whole trailer, drill all the right holes for axles and lights to bolt on etc then pull it apart and have steel sections hot dipped. You should get a solid 12-15 years at least out of a properly galvanised trailer.

You will get much more life out of a 'c' section trailer, because you can see al the points that start to rust, and fix it before it becomes a problem.

[Noelm]

either I beam or C section will be a miilion times better than square (in my opinion) almost all commercially built trailers in the "good old days" were C section, makes like Boeing , Brooker and Jawar all used it, my current trailer is around 1982 vinatge C section and is almost rust free! however, my mate has built a few trailers over the years and one he used heavy angle (kind of looks like square when finished) and later ones I beam, the I beam is the pick of them (I reckon) looks good, easy to hose off and reasonably easy to construct, I guess there would need some sort of expert to select the correct size material at the start for you, but from then on, it is easy as pie to use

[Noelm]

Thanks for the good replies gents.

Noelm,
Not doubting that box section trailers do rust from the inside, but alot of the trailers you see at the ramp on any busy day look pretty shabby on the outside. Is "I" beam construction actually going to solve this? I would suspect that the outside will deteriorate at a similar rate to that of box section, the main difference being that you won't get any nasty surprises from the inside. What do you think?
Scott.

Most of the "shabby" trailers at the ramp are due to neglect, or piss poor galvanising from new, If I was to buy a brand new trailer (or build one) I would get it hot dipped, then paint it before it went anywhere near the water, or spray it with any number of propriety products out there.

[Fed]

I'm sure the water is saltier in Qld I've never had a rust problem on a trailer frame and half the time I don't even wash them.

My beef is with the nuts & bolts, cad plated crap.

[Noelm]

I suspect the problem with QLD is the warmer water, and the humidity, makes corrosion/rust really get going.

[bigfella23]

Just some thoughts from a trailer company viewpoint:
1/Cold gal can be used to touch up rusty areas. Coating thickness in the brush on is about 90 microns , where normal gal coverage on a 5mm thick item would be about 70 microns.
2/ Most manufacturers like to see the trailers washed and dried prior to storage. I know Dunbier recomends that if a customer wants to use aditional products , we only recommend Inox , we have had a dreadful time with Lanolin based products.
3/ Using Duragal prior to galvanising is pointless. The gal process is similar to a chroming process. As the gal becomes part of the steel structure , not a coating over the top , Duragal would be lost in the process. The thickness of the gal is determined by the thickness of the material getting dipped ie 1.6mm material would get approx 30 micron coverage , where 5mm would get approx 70 microns.
4/ We have looked at C section , but we have found it difficult to roll , and our engineers have an issue with strength compared to box section.
Hope this helps.

[ozscott]

Thanks for that post mate - good to hear from the manufacturer's viewpoint. What is the problem with lanolin - is it because its sticky and salt sticks to it (end may eventually wear through as a sticky salty mixture?)

Cheers

[Noelm]

without doubt, C section is harder to build with, but it is far superior to square, can you explain why the gal thickness is thicker on different gauge metal?

[johncar]

Just build it so you can keep it clean, as much C or I section as practical, no closed off box sections, keep any ends open as much as practical, thoroughly seal all the steel with Galv or industrial grade coatings. A new Gal or Ally finish will keep looking well with a regular hit with Inox, good on all those Cad bolts, nuts too.
Any surface will look shabby in time if no maintenance is done.
I may just have to build a little boat trailer shortly so I will be looking a C section for the bulk of the rear section and probably some box at the drawbar end only.

[bigfella23]

Apparently is it the electronic process , that more zinc is drwn to thicker metal , thickness coating is proportional to metal thickness.

[bigfella23]

Hi, We found that the Lanolin allowed salt to pass right through it, and eat out the gal from behind. I mean stuff a whole frame in 6 mths !
We also found that areas that were missed in the spraying process ate away incredibly quickly.

[murf]

http://www.galvanizeit.org/images/uploads/publicationPDFs/Zinc_Coatings.pdf

its up to the HDG people how much zinc they put on (dependent on steel thickness), I believe thats why some cheaper trailers have cheaper HDG jobs done on them and don't last much over 12 months, I have seen some shockers :'(

http://i362.photobucket.com/albums/oo64/murfgq/HDG.jpg

cheers Murf

[tunaticer]

Technically, using PFC (C section) is slightly different in design to using RHS (box section) because the strength of its design does not fall in the middle of the flanges. It is quite easy to adapt the design to accommodate this but I think most people building a new trailer would just measure the centre of the flanges as the load bearing centre. Unibeams (I beams) are much easier to get the load centres right because it is centred for load on the flanges.
Both Unibeams and PFC's should incorporate gussets at strategic locations to maintain the members integrity, neither likes tortion being placed upon it. Something to keep in mind when you rest your 2.5 tonnes of pride and joy on it and drag it down the road at 100kph.
In both cases it is easy enough to design around effectively to maintain a safe trailer.

[tunaticer]

without doubt, C section is harder to build with, but it is far superior to square, can you explain why the gal thickness is thicker on different gauge metal?

When things are hot dip galvanized they are placed into the bath for a period of time to A. heat the parent metal enough to bond with the galvanizing and B. to effectively drain off any excess galvanizing as it is lifted from being submerged in the molten bath of zinc. Heavier sections take longer to heat and thinner sections take less time, hence when removing from the bath the thinner hotter sections drain off more zinc than the colder heavier sections. There is also a minute gravitational force as well that Prof Julius Sumner Miller would explain, but I digress from that avenue of physics.

[murf]

When things are hot dip galvanized they are placed into the bath for a period of time to A. heat the parent metal enough to bond with the galvanizing and B. to effectively drain off any excess galvanizing as it is lifted from being submerged in the molten bath of zinc. Heavier sections take longer to heat and thinner sections take less time, hence when removing from the bath the thinner hotter sections drain off more zinc than the colder heavier sections. There is also a minute gravitational force as well that Prof Julius Sumner Miller would explain, but I digress from that avenue of physics.

a glass and a half of full cream dairy milk in every trailer ;)

cheers Murf

[trymyluck]

A couple of people have commented on the use of duragal, having never worked in the hot dip galvanising industry I can not say for certain but I would think that the process of galvanising would welcome the use of duragal over painted steel sections simply because it is much easier to strip the zinc off then paint.
We do electrolysis zinc at work and we will not touch anything that is fabricated out painted steel, its a pain to get clean enough to get the zinc to through on to.

Mark

[murf]

Duragal is a waste of time for something dipped into salt water. good for inside a shed though :)

cheers Murf

[Tangles]

Hi, We found that the Lanolin allowed salt to pass right through it, and eat out the gal from behind. I mean stuff a whole frame in 6 mths !
We also found that areas that were missed in the spraying process ate away incredibly quickly.

My experience:

Last boat in 2007 new trailer sprayed it with Lanolin but after it was dunked from memory a couple of times, trailer was a Redco, no issues

New boat last year again sprayed it with Lanolin from new and before dunked, trailer was again a Redco/Tinker ( Cruisecraft).
I treated both trailers the same, ie washed down and stored in the same garage, no difference other than i didnt spray the Lanolin straight up from new.

With this trailer i noticed that i was getting some white rust on the trailer where it wasnt dunked and interestingly where i had quite a thick layer of Lanolin. I have removed the Lanolin over a period of 2 weekends and found that Citraforce was the only product to really rip it off, caught it in time...

Rather bizarre frankly and i wont do that again, think i wont bother with any new trailer too much i may get other than Inox on the brakes/hubs etc, thats my experience.

cheers
mike