ALLY BOAT TRAILERS. Calling all owners.

[hellfish]

G,day all. Thinking of doing some tinkering and was wondering how many alluminium boat trailers are getting around out there also how they are in coparison to steel. The pros and the cons.
Cheers, rhys

[finga]

what size?

[hellfish]

Any size. Tinny to titanic.

[finga]

Main problem is strength to weight ratio.
Need about the same weight in alloy to get the same strength as steel.
Cost is a down side as is ability to repair, modify and attach metal bits like springs etc.

[dfox]

Riptide boats often build alloy trailers for there customers. I believe they have built around 20 or more, and several are for pro's so they really cop a hiding.
I havent heard of any cracking and many do the regular trek to fraser ... foxy

[GBC]

Telwater (quintrex) do a hybrid one for their bigger models. I was looking at one today at the Crew marine auction, but I had to buy the bloody boat that was on it too- looks O.K. for what it is - not as flash as that riptide one though.

[finding_time]

It probably doesn't help you but my KC trailer is alloy and 20 years old , no cracking , but being for a cat it's pretty simple design with no great angled welds that could fail over time! Pros for me are Light , less maintainance , and longevity if it had been a gal trailer i would probably be up for the boats third trailer soon!


Ian

[hellfish]

That riptide trailer looks tho goods. Thanks for the pics foxy. 20 years is a bloody good run for one trailer and likely a symptom of good design. Ihave heard that they work harden and get to a point where you are welding cracks after every trip but the bloke who told me this i know is not much of a welder. Im thinking of replicating one that i made last year but doing the frame in ally only to solve to problem of rust.

[finga]

What would be the weight of that trailer Foxy?

[megafish71]

What would be the weight of that trailer Foxy?

The one I built came in just on 500kg.


More pics of the trailer and its build plus all info on this thread http://www.ausfish.com.au/vforum/showthread.php?t=123414

Cheers Ron

[Crocodile]

The back crossmember on my trailer is getting rusty.
It is a simple 50mm square with a couple of rollers and skids only.
4.3m Webster sitting on it.
Any ideas on how to replace it with a bolt-on aluminium piece.
I am thinking of using very solid alloy square angles and stainless bolts.

[Alchemy]

The one I built came in just on 500kg.


More pics of the trailer and its build plus all info on this thread http://www.ausfish.com.au/vforum/showthread.php?t=123414

Cheers Ron

Hi Ron,

Are you getting close to a launch date?

Dave.

[Fishbait]

Nice Avatar Ron :o

[megafish71]

Hi Ron,

Are you getting close to a launch date?

Dave.

4 to 6weeks hopefully Dave.

[hellfish]

Croc, the problem with bolting ally to steel (espesialy gal steel) is electrolisis. You will get very agresive corosion where the two metals touch.

[gofishin]

Main problem is strength to weight ratio.
Need about the same weight in alloy to get the same strength as steel…

Finga, although this may be true for general ally vs mild steel, this is not correct when we are talking about aluminium alloys used where high strength-to-weight is available, and where an appropriate design is employed. {young’s modulus (E) of ally is one third that of MS, but the density of MS is three times as great – hence weight is the same comparing flexural rigidity (EI) of ‘same section’ members of alloy & steel}. Otherwise, why do they make planes out of mostly aluminium?

There is indeed good potential to save a lot of weight with alloy trailers, let alone the benefits of longevity. I saved 300kg on my hi-tensile alloy trailer (500 vs 800kg), and don’t have any concerns with the strength of it. Sure it flexes, but this is what it is supposed to do. It is a US (skid) trailer (Rocket International), and the U.S. design philosophy is different to what we adopt here - they bolt, using very high tensile alloys, we weld, probably with mostly structural grade T6 alloy (although this is only a guess). Welded designs cannot be subjected to the same flexing as bolted designs, else they will fatigue/crack. Obviously there are many good welded alloy trailers being built here, else they wouldn’t be lasting so long, as Ian’s and many other trailers much older than 20yrs. If both types are designed and built correctly, and not abused, they will probably outlast the boat.


Croc, the problem with bolting ally to steel (espesialy gal steel) is electrolisis. You will get very agresive corosion where the two metals touch.Hellfish, the correct term is galvanic corrosion, not electrolysis, although it is a bit like cavitation and ventilation, mostly always used incorrectly – not taking the pi$$ either, just making a point. Actually, gal steel is the best dissimilar metal to use with alloy in a saltwater environment, and is better than s/steel, especially passive s/steels. Hard to fathom I know, but to prove this we need to consult with science, and the galvanic table of metals, sometimes referred to as the “Table of Nobility”. If you’re going to mix metals, generally try and choose them so that they are close together on the Galvanic Table. Problem is that the gal bolts/nuts eventually corrode together, hence some prefer to use active s/steel and suffer slightly accelerated galvanic corrosion rates, and still be able to undo their bolted joints.
Cheers

[Reefmaster]

There seems to be a theory going around that Alloy trailers crack which is false. The problem that can occur with alloy trailers is within the welding and if done poorly can then become the weakest part and cracks can form around these welds. Alloy trailers are huge in the US and fastly becoming very popular here in Aus. Most alloy trailers in the US and whats available here in Aus are bolt togethor alloy trailers which elimates fatigue cracking around the welds if not done properly. Unfortunately the cost of making alloy trailers is pretty high but will far out live a gal steel trailer and take very little time look after.

As foxy said Riptide has made loads of alloy trailers now and not one has had a problem and some were made a fair while ago. Riptide make the trailers out of 5083 marine grade alloy 250mm C channel which is 11mm thick. These trailers come in just over 700kg.

They are extremely solid and mine as well as many others have seen the harsh trek up to the Fraser comp and if they can handle that they will handle anything.
I'm wrapped I went for an alloy trailer as is everyone else that has one and I know if there is something I need modified or fixed it can be done with ease.

Cheers,
Greg


http://i248.photobucket.com/albums/gg161/Greg_L/newboat626.jpg

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http://i248.photobucket.com/albums/gg161/Greg_L/newboat707.jpg

http://i248.photobucket.com/albums/gg161/Greg_L/newboat700.jpg

[rodneyk]

ROD HERE alloy trailers are the future when built correctly probably not yet for small boats corrosion is only minor compared to things like brakes &bearings you still need some steel components cant get away from that but with newer coatings now available galvinizing is becomeing expensive steel has tripled in price and you never have to coat alloy in this application alloy sections available today are more than adequate to carry load required mono hull trailers are abit more difficult to design and manufacture than cat trailers we at ARKMARINE have built severalcat trailers in recent times and a small alloy trailer for quintrex 4.2 explorer trophy went off road several times no issues the big issues are for large is big gain in weight saving 300kg is normally the figure depending on running gear :)

[finga]

Have you got a closeup of the spring setup and how it attaches reefmaster?

[gofishin]

Greg, that trailer is an absolute beauty, hope you don't put in the saltwater...:P. Nice d/bar extension setup too. What does she weigh and what running gear - Alko torsion or leafs on a carriage etc? PS. Nice boat too!

Here's an alloy yanky skid trailer. Pics when i first got it, done a few mods since. Shot of how they bolt the X-members plus bracing to reduce twisting of the main I-beams.
cheers
Brendon