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Author Topic:   Aluminum Trailers for Repeated Use in Saltwater
flyfisher1771 posted 03-19-2004 11:01 PM ET (US)   Profile for flyfisher1771   Send Email to flyfisher1771  
Are there any problems with using an aluminum trailer in salt water? Does the salt corrode the metal if you dunk an unpainted trailer? Thanks.
Plotman posted 03-20-2004 01:19 PM ET (US)     Profile for Plotman  Send Email to Plotman     
It depends on the specific alloy used, but the oil and fishing industries use unpainted aluminum workboats all the time. The aluminum oxidizes and forms a protective barrier.


flyfisher1771 posted 03-20-2004 08:18 PM ET (US)     Profile for flyfisher1771  Send Email to flyfisher1771     
Thanks for the info. I have a buddy who is looking at trailers and I figured that from an aesthetic standpoint he would be better off with a painted steel trailer. I know, I know, but it's for a old Chris Craft Riveria so it does matter what it looks like.
jimh posted 03-21-2004 01:08 PM ET (US)     Profile for jimh  Send Email to jimh     
There are many problems with using aluminum trailers in salt water, but not necessarily because of the aluminum content. In general, any trailer intended for repeated use in saltwater needs to be specially configured to protect against corrosion of its components.

Most aluminum trailers I have seen are not painted as a means of providing protection against corrosion. They may be painted for aesthetic reasons. Steel trailers are universally painted or galvanized as a protection against corrosion (rust).

It would be interesting to hear opinions regarding what potential advantage an aluminum trailer could have over a galvanized steel trailer when repeated use in saltwater is anticipated.

One thing I have noticed is that most aluminum trailers seem to be constructed by bolting the structure together, while some (not all) steel trailers are welded together.

Aluminum trailers also tend to be popular in the style where the trailer frame stops at the axles, and the boat is supported on two large wooden timbers that are cantilever mounted many feet beyond the termination of the actual trailer frame. In contrast, most steel trailers tend to have full length frames.

greyg8r posted 03-22-2004 01:53 AM ET (US)     Profile for greyg8r    

Yes, there will be galvanic corrosion that requires regular maintainance. I do not think it is physically or chemically possible to avoid galvanic corrosion between stainless steel and the aluminum.

I have never seen a factory painted aluminum trailer and, thus, I doubt there are any advantages to it. I certainly don't think it would prevent galvanic corrosion.

If the guy with the Chris Craft really is your buddy, I would STRONGLY discourage him from a painted steel trailer. I think aluminum is best for salt water, followed by galvanized steel, followed way back by ungalvanized (unpainted) steel. Non-galvanized steel will rust badly in salt water.

Jim, I think aluminum is far better than galvanized for salt water use and that is reflected in the price. My aluminum trailer for my Katama has no rust, but the galvanized trailers I have had and seen all have rust to varying degrees. And, aluminum is much lighter which affects the the total weight to be towed.

I am not in agreement with your assessment that aluminum trailers are generally shorter than galvanized trailers. It has been my observation that both trailers have frames of similar length.


jimh posted 03-22-2004 01:51 PM ET (US)     Profile for jimh  Send Email to jimh     
Regarding resistance to corrosion from exposure to water and weather of steel and aluminum:

Steel--the only people who seem to think that steel does not require a protective coating is automobile chassis manufacturers. Anywere else steel is exposed to water it is generally carefully treated with a top coat of some type.

Aluminum--generally aluminum can be left untreated and will withstand normal exposures. For continual exposure to water, however, and especially for saltwater, aluminum is generally painted or treated with a protective finish. A good example is an outboard motor lower unit.

Outboard motor makers also employ special alloys of aluminum which are designed to be corrosion resistant, more so than the typical alloy of aluminum (6061T-6) often used in constructing a trailer. Even so, practically every outboard motor ever made has been given a protective coating of paint or other finish to protect it against corrosion.

The density of steel is about three times greater than aluminum, however the strength of the materials is not equal. Actually the strength of aluminum and steel can vary quite a bit depending on what alloy is used. In general steel has greater tensile strength, and because of this I see that aluminum trailers tend to use larger sections of aluminum components than those found on steel trailers. Thus some of the weight saved is given back by greater volume in aluminum trailers.

Aluminum tends to cost more, particularly in special alloys with high strength and good corrosion resistance.

I found an article (hyperlink below) which discusses some of the relative virtues of aluminum and steel for structural components.

First Thought posted 03-22-2004 03:24 PM ET (US)     Profile for First Thought  Send Email to First Thought     
My boating is 95% saltwater. I have had galvanized and aluminum trailers,several of each. I only use aluminum trailers now, none of them have ever been painted or had any type of coating. I order them with SS fastners. I rinse them down throughly after each trip and once or twice a year spray down the springs etc, the only parts that are steel. I think the aluminum trailers have two advantages over the steel ones, the biggest is virtually no corrosion and also an alumimnum is lighter than the same size in steel, that saves gas and at todays prices it is adding up. I am starting my 7th year with the present trailer and the only rust I have is on the galvanized wheels. I don't remember ever having a galvanized that did not need fairly significant rework after 5 years. I personally would not go back to a galvanized trailer.
Mumbo Jumbo posted 03-22-2004 08:19 PM ET (US)     Profile for Mumbo Jumbo  Send Email to Mumbo Jumbo     
Ungalvanized steel trailers are a poor choice for salt water use. And, painted ungalvanized trailers for use in salt water are a horrible waste of money. How a trailer "looks" is of no moment. What should be foremost is the utility of the trailer in performing its basic function of transporting a boat from point
A to point B.

Galvanized steel trailers, if fitted with stainless fastemers, give trouble free performance. Routine replacement of the springs and lights, and lubrication of the wheel bearngs, are the only maintance issues if the trailer is outfitted with galvanized hubs, wheels and axles.

Aluminum trailers have no disadvantages other than high initial cost. Stainless fasteners are mandatory but do they do not present a problem regarding galvanic reaction unless they are greatly undersized.

DaveH posted 03-23-2004 11:40 AM ET (US)     Profile for DaveH  Send Email to DaveH     
I understand your rationale for placing generalities on materials such as aluminum and steel, however it should not be done. There are too many alloys of each type which upend your basic statements above that I caution you in using them.

In general, common aluminum trailers by well known manufacturers are best for use in salt water. I would stress to use all upgraded stainless steel bolts and accessories when possible. The added cost of these materials are well worth the cost over the long run, corrosion-wise.

Aluminum corrosion is not a concern with the alloys used on trailers due to the generation of passivation layers (white oxidation which naturally slows the corrosion down). With regard to the outboard engine paint for corrosion control, it depends on which casting alloy is used whether it is needed or not. I am not familiar with which alloy the outbaord manufacturers are using.

Bigshot posted 03-24-2004 01:15 PM ET (US)     Profile for Bigshot  Send Email to Bigshot     
I will never buy anything but aluminum trailer no matter what the water it is being dunked in. Saving 40% or so off of a galv trailers weight is reason enough. I also recommend the SS bolt kit($120+/-) even if you buy a galv trailer. The alum may be anodized and hence why we think it is untreated, yet it stays nice. I know when my friend buys alum to weld, it is all anodized with a clear coat.
Bigshot posted 03-24-2004 01:16 PM ET (US)     Profile for Bigshot  Send Email to Bigshot     
PS the ONLY trailer mfg that I know of that paints alum trailers is Myco.
flyfisher1771 posted 03-24-2004 07:31 PM ET (US)     Profile for flyfisher1771  Send Email to flyfisher1771     
I guess that makes sense. I just thought the process to anodize Al was so expensive that they wouldn't do it to a trailer. Anodized fly reels are familiar territory for me, trailers, not so much. Thanks for all the info.


alkar posted 03-25-2004 03:00 AM ET (US)     Profile for alkar  Send Email to alkar     
Painted steel trailers were quite popular out here during the 1980s, as many people were putting together color-matched truck, boat, and trailer packages. (We saw this mostly with "multi-purpose", "family", or "ski" boats, not ocean boats.).

As a result, we've had a chance to see how well the painted steel trailers held up repeated exposure to salt water. The answer is they held up very poorly, but the news is even worse. The frame members on the painted steel trailers are prone to corrode from the inside out. We saw a number of steel trailers that looked fine on the outside, but were severely corroded in several critical areas on the inside. In one case the corrosion was not discovered until the trailer tongue had actually broken (almost completely in half). Fortunately, the break occurred during a slow speed parking lot maneuver, and only three of the four sides of the tongue-tube broke, so the trailer was never completely separated from the truck that was pulling it. We looked at the area around the break and it STILL looked good - no blistering paint at all.

I have never heard of anything similar happening to a galvanized steel trailer. That's what I chose to buy when I needed to replace the trailer under my Outrage. I knew it would last, and the cost of the aluminum alternative was prohibitively high.

Lots of folks make custom aluminum boat trailers, and many of them have full frames and are welded. The boat manufacturer I worked for fabricated aluminum trailers for many of their larger boats, and most of the customers were willing to pay for the upgrade to aluminum. The aluminum trailers were bigger, stronger, less flexible, and lighter. They were also beautiful. We didn't paint them or anodize them, although we did polish some of them. (They polished to a beautiful mirror-like finish that made for a spectacularly brilliant presentation at boat shows. Of course, the finish would quickly dull after repeated exposure to sale water, so we discouraged polishing if the boat was likely to spend a lot of time in salt water.)

As others have already noted, there are many different alloys. The aluminum trailers had to be built with the proper alloys, the components had to be substantially larger than their steel counterparts, and there was substantially more fabrication time. All those factors translate into substantially higher cost. If memory serves, a polished aluminum trailer for a 21' inboard boat cost the customer an additional $4,000 (above the cost of the standard galvanized EZ Loader trailer). Amazingly, lots of folks chose to upgrade to the aluminum trailers. They were much prettier, and a little lighter - but today I'd rather spend the extra money on the boat!

greyg8r posted 03-25-2004 10:42 AM ET (US)     Profile for greyg8r    

I knew gasoline was way higher in Oregon, but trailers are even worse!

I was looking for an aluminum trailer for my 25' Grady (which is way bigger than the trailer you are referencing) for $4,500 total with stainless disk brakes on both axles (it looks shiny to me, but I don't know if it's polished). Your price was $4K above the price of the galvanized, which would put the price of the trailer at over 6K! By comparison, the galvanized trailers for a 25' boat were about $2200 without brakes. With brakes they would be about $3800. I think the extra $700 spent on the aluminum trailer is well worth it and would probably be recouped when I sell it.

My dos centavos.


Tom W Clark posted 03-25-2004 11:22 AM ET (US)     Profile for Tom W Clark  Send Email to Tom W Clark     
Boat trailers are a very regional thing. Here in the Pacific Northwest aluminum trailers are very rare. If you see one it is usually under a rather sun bleached boat with Florida registration numbers.

I have often wondered why aluminum trailers are not made and used in the PNW. At a boat show a couple years, I talked at length with a representative for a local trailer manufacturer about steel vs. aluminum trailers. It seems logical to think the PNW would be a great place for aluminum trailer manufacturers because so much aluminum comes from here.

He told me that for a while they did manufacture aluminum trailers but nobody bought them. It was as simple as that. Aluminum trailers cost a bit more to manufacture and galvanized steel trailers hold up very well. So they no longer bother making aluminum trailers.

He also speculated that perhaps the warm salt water environment of the Southeast is simply more corrosive than the cold salt environment of the Oregon, Washington, British Columbia and Alaska and that that was why few manufacturers in the South use steel.

And I agree, a painted steel boat trailer is just about worthless no matter where you live.

DaveH posted 03-25-2004 11:24 AM ET (US)     Profile for DaveH  Send Email to DaveH     
Gentlemen in the NW:

It seems that you may wish to gather some friends together and try a group purchase from a Florida Continental Trailer dealer. The shipping cost can be spread out by stacking several trailers and hauling them up there.

Other wise, hunt down a Continental dealer up there and arrange the same group buy and pay them for shipping from Florida. I would expect that a 10 trailer purchase (22'-25'aluminum tandem with 1 axle surge brakes) would cost about $2K to $2.5K each, plus shipping.

Your dealers up there are very proud of their aluminum trailers, aren't they?

LHG posted 03-25-2004 12:17 PM ET (US)     Profile for LHG    
I agree with Alkar and others that in ANY water condition, salt or fresh, a painted steel trailer is short term worthless junk. Don't let anybody sell you one, like I foolishly did when I purchased my 18 Outrage. Unfortunately, in the Midwest, they are popular because they are cheap, and many of us know that "cheap" trailers are the name of the game in the boating business. Even in fresh water and non-salt air environoments, they rust out internally from atmospheric moisture.

Mine was a tubular frame EZLoader, and it looked absoultely perfect on the outside. At only two years of age, the tongue failed (separated from the rest of the trailer) at 60 MPH, and both myself, passengers and the 18 Outrage itself are lucky to be here, believe me. The boat held the trailer together while we slowed down and pulled over (were in center lane of 3 lane Interstate). The light gauge tongue rusted through from the INSIDE.

The reason I am a great fan of all-welded channel frame trailers is that there are no unseen "insides" of the tubes, and there are no drilled/bolted connections, a source of rust, flex and squeaks. The welded frame channel section trailers are welded up before being hot-dipped.

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