building trailer, gal dipped steel or bolt together ally. price comparison

[lembo]

I have an 18 foot sharkcat that needs new trailer soon.
I will build myself but considering Gal dipped steel vs bolt together aluminium (couple of welds)
I live in mackay and closest galvanizer is Townsville (they have depot at mackay but they freight it up)
I can get a bit of a discount on steel and aluminium.
and can get most stainless bolts from work too ( for ally trailer).
so regarding cost. what would work out cheaper ? just buying ally, building trailer and using it vs building steel then going to get it gal dipped with freight.?
hows the cost ally vs steel ? obviously ally is more costly and you need thicker material but I don't actually know how much either material is and the difference..
plus ally I build it and use it straight away, steel I build put on running gear, transport remove running gear, gal dip then put gear back on which is a pain in the arse.
what do you guys recon the best avenue is ?
id prefer ally trailer but if its a lot more expensive id just do steel.
I don't have a clue what a trailer this size would cost to gal dip.

[shaungonemad]

If you go steel make it bolt together cheaper for freight and dipping plus you can replace part of it easier if it rusts out.

[Dan5]

If your not towing over rough roads i'd go Alloy especially on a larger boat like the Sharky.....No need for stainless bolts either imo Galv would be better and use oversized washers to help strengthen around the hole as that's where most alloy trailers I've seen crack.
Is there anyone in t your area that has a section bender?....that would help eliminate some of the welding also.

[lembo]

not a bad idea making it steel bolt together, yeah I can get gal bolts too no problem. if I built it all steel anyone know what gal dipping would cost ? im still leaning towards ally im sure someone can ben I beam for me, plenty of fabrication places in mackay.

[Dan5]

Ring up the galvanizer's and ask how much per kg and what coverage they would expect then work out you surface area.

[shaungonemad]

My mate went bolt together because he was told there was a big price difference between the baths they use the large bath must be a fair bit more and he could fit it all on the back of his ute to save transport and it is mainly made from C channel.

[Noelm]

Sharkcat trailers are simple to build, there is almost no bending, I would probably use steel I beams, or aluminium square/rectangle tube, and weld the thing together.

[gpz1991]

If you go down the alloy path use SS bolts gal with corrode the alloy in a marine enviroment

[Dan5]

If you go down the alloy path use SS bolts gal with corrode the alloy in a marine enviroment

Zinc and Aluminium are close on the Galvanic scale and Stainless (chromium) is way down the chart....Zinc is a better choice.......Stainless will corrode alloy if un insulated quicker than a galvanised bolt........been debated on Ausfish heaps of times.......

[McKnight]

As Dan5 said Gal bolts are the best choice. Why do you have zinc blocks for anodic protection on your outboard, if they aren't the best way to stop corrosion. If you go through the effort to completely isolate the stainless bolts from the aluminium, you will still have issues once the bolted joints get submerged.

http://www.corrosionist.com/Corros1.gif

[lembo]

yeah the sharky trailers are very easy to build compared to mono hulls. if I go ally I will bend just the 2 chassis rails to meet up in the middle at the front, if I go steel I wont bend anything. I guess I just need to call gal place to find out price as that's the main thing that affecting my decision.

[Lovey80]

Lembo don't bother bending the rails. Build it in two sections. A boxed section with top cross girders that your skids will get riveted to and then two simple beams that run across the corners of the box and meet at the front. From the time everything is cut to length a decent welder should have all the ally finished in a day with a helper to clean up after him.

P.S. Definitely go Ally. The trailer will last decades that way.