Karavan Aluminum Trailers? [Archive]

BrionLutz

06-06-2003, 09:02 AM

Keta,

Eyow!

Can't imagine more vibration and twisting than in an aluminum boat, lots of torque loads, lots of vibes, lots of stress.

I saw a 21' Alumaweld stripped to the frame, used hard as a guide boat for 5 years and no sign of any stress cracks. The frame etc. were in great shape.

What do you think the time frame would be inspecting a heavily used aluminum runabout?

Brion

Keta

06-06-2003, 09:08 AM

Depends on the design. No vibration=no cracking.
Lightweight flimsy construction will harden and eventualy crack. See Ed Wing for the way an aluminum boat should be designed and built.

BrionLutz

06-06-2003, 09:16 AM

Keta,

QUOTE] Depends on the design. No vibration=no cracking.[/quote]

I think the aluminum boat equation is as follows:
Boat+water+HP=vibration.

I don't know of any Aluminum boat that doesn't fit that formula and I've been on all kinds of Aluminum boats from Palmer-Johnson 100+ footers to my 19' North River.

You are worrying me about the small aluminum runabouts. Glad I got the .250" one piece bottom.

Brion

Keta

06-06-2003, 10:12 AM

Thicker=better
Work hardening will happen to any aluminin that vibrates or flexes. It's just a matter of hrs use. Thick plate with lots of structure will last much longer. I have seen aluminun sein skifs with cracks due to improper design and/or manufacturing.

You're much better off with a heavily galvanized steel trailer.

Thumper

06-06-2003, 10:33 AM

JetPace made aluminum trailers for many years to tow its line of heavy 20+ ft. 460 inboard sleds. They are still out there towing away. Once in a while we would hear of a crack, but no more often than with steel. Excellent products. I can't see any reason for avoiding aluminum.

Remember that galvanized only keeps you free of rust until the first rock chip. Aluminum keeps you free of rust forever.

Thumper

06-06-2003, 03:51 PM

Yeah, that's why all those aluminum boats fall apart after a couple of years .... :tongue:

BrionLutz

06-06-2003, 05:22 PM

Thumper,

Yeah, that's why all those aluminum boats fall apart after a couple of years.That's what has me scratching my head...aluminum is used in all kinds of transporation stuff from rocket ships, boats, cars, planes, trains, navy ships etc. which all involve lots of vibration, stress, freezing, heating etc.

I thought aluminum was used due to its light weight, strength and durability.

Maybe I better get a glass boat vs. a new aluminum trailer for my aluminum boat.

Brion

Thumper

06-06-2003, 05:47 PM

Brion --- I don't know anything about the Karavan product, but there are no negatives to employing aluminum for trailers.

Get Bent

06-06-2003, 05:48 PM

dont compare apples to rocks there are differant grades of allum.

Keta

06-06-2003, 07:40 PM

And all grades of aluminum have some problems. Aluminum isn't the best of materials. Can't beat it for a boat that has the possability of coming into contact with the bottom, but that is about it.

There's a major aluminum boat manufacture (name will be witheld) that's curently using the wrong grade of aluminum and there boats will vaporise when exposed to water (slowly in fresh water but much faster in saltwater, even if zinked).

Thumper

06-06-2003, 08:43 PM

Vaporize?!? :shocked:

Reelentless

06-06-2003, 08:54 PM

I upgraded to the aluminum trailer when I bought my North River. The trailer was built by them. So far, so good. Ive only had it 3 years though.

Advantages: wont rust, looks great polished.

Disadvantage: needs polishing to stay looking great.

Im no expert, but it seems aluminum would be better at "absorbing" stress than steel. Steel, being more brittle, seems like it would develop cracks easier, especially if its rusted.

[ 06-06-2003, 08:55 PM: Message edited by: Northriverman ]

BrionLutz

06-06-2003, 10:19 PM

Northriverman,

Yeah...those NR aluminum trailers are super. I had one (dual axle...the works) for my NR 19' Sportster.

Nobody seems to mfg. anything like the NR trailer.

I looked at the Karavan today. It's utilitarian and I'll probably get it as it saves me 400# and I need to upgrade as my Zieman was underspeced from the dealer, not Zieman's fault.

Brion

Keta

06-06-2003, 10:37 PM

Northriverman,
Most steel is not brittle. Steel has a much higher tensile strength than the best aluminum. Some high carbon steels have over 100,000 PSI tensile strength.

drhall99

06-06-2003, 11:13 PM

Keta is right. Check out all of the old threads on cracking aluminum boats. This isn't a new problem. For most people an aluminum boat will last a lifetime but I would be very careful about buying a retired guide boat.
D.

Keta

06-07-2003, 12:20 AM

Aluminum oxidizes much faster than steel but it sticks and makes a corrosion barrier. There are other problems with aluminum like INTERGRANULAR COROSION (http://www.google.com/search?hl=en&ie=UTF-8&oe=UTF-8&q=inter+granular+corrosion.&btnG=Google+Search)

[ 06-06-2003, 12:22 PM: Message edited by: Keta ]

BrionLutz

06-07-2003, 09:36 AM

drhall99,

Hmmm...seems a bit contradictory with "cracking aluminum boats" and "lasting a lifetime".

I use my boat pretty hard, not crazy but the Columbia is a pretty choppy river, even going a few miles against the wind/current/tide chop can be pretty bouncy even slowed down to 20 miles an hour. And I've got a heavy (.250 bottom), deep V boat (16 degree all the way to jet intake), for the basic aluminum boat (12 deg with flat delta bottoms) it's a pounding...no way around it.

Aluminum either works in this environment or it doesn't.

Comments here seem to say that aluminum is not suitable for the very common boat construction we see here in NW.

Brion

Pete

06-07-2003, 09:41 AM

I really think the kind of stressing, jarring and flexing a boat sees on the water is different than what a trailer sees on the highway. Aluminum is just a much softer metal. Must be why we use steel screws, instead of aluminum ones for most applications.

Get Bent

06-07-2003, 03:30 PM

keta...
your wrong we used allm parts on our off road race trucks you cant tell me if it gets any more stresed than that so a trailor like a northriver that is boxed ang gusseted wont last and just in case you dident know they also build boats they probley know what kind of allm. to use graemlins/stupid.gif

FishinMission

06-07-2003, 04:16 PM

I think you guys are all missing the point. It seems to me that a boat isn't really supporting any weight, other than it's own.

Those welds on them aluminum trailers are supporting what...minimum 2,000 pounds of boat weight..and for you big inboard guys...probably double that??

Although aluminum might be pretty when it's polished, and may be corrosion free....I think I'd stick with the heavily galvanized steel stuff, thank you.

Do those boat manufacturers that produce aluminum trailers have any warranty to back them up?? Curious.

Mark

1pump

06-07-2003, 05:09 PM

My galvanized trailer weighs more than my little aluminum boat, and that's how I like it. Rock-solid going down the road, no swaying, no bounce. But I'm only talking about 1,100 lbs total for boat, motor, trailer and gear, so weight isn't much of an issue for me.

Ever look at a 48' flatbed going down the road, with a 45,000 lb load of plywood or steel? It's aluminum, and it flexes intensely. And there's a lot of 20 year-old flatbeds out there. They require a little more vigilance in regards to stress cracks and salt corrosion, but the tradeoff in weight is worth it. Same with tank trucks. Last week I pulled a set of insulated tank trailers to Madras. Ugliest things on the road. They looked like they'd been thru several wars, with patches, welds, and battered aluminum all over the place. I checked the build date- 1966. Almost 40 years on the road, and still going. Tank trailers don't have frames, so all the stress is on the aluminum tanks. The stuff will last, but you really have to keep an eye on it.

BrionLutz

06-07-2003, 08:50 PM

Keta,

I have said, “aluminum has problems." I'm sure every construction material "has problems". Steel rusts, weighs a lot, can be of poor quality or wrong composition, hard to work with etc. etc.

I'm pretty sure my aluminum hull has a lifetime warranty against material and workmanship failures.

I really liked my North River Aluminum trailer, it was a piece of art and a rock solid trailer. I've never heard of any problems with the NR trailers.

If NorthRiver, Extreme, Shorelander, Karavan and others make them and guarantee them, I'm sure they are taking into account all the good and bad properties of Aluminum.

I wasn't that concerned about the trailer being Aluminum. I was curious if anyone had heard anything good or bad about the Karvan brand of aluminum tailers or if anyone had any other brand of aluminum trailer to recommend or warn about.

Aluminum makes a good riverboat, but that’s all.And let's not forget a good jet airplane, US Navy ship, super yacht, rocket ship, engine, ocean sail boat, train, on road trailer and the foil is handy also <grin>.

Brion

Keta

06-07-2003, 09:50 PM

Aviation and aerospace gets little use and much inspection. Are you going to do a 100 hr on your trailer?

Steel is not hard to work, just look at the average welder (no cut on welders, I weld and my brother owns an aviation weld repair station)
and unprotected steel will out last unprotected aluminum when imersed in saltwater.

:laugh: Corporations wouldn't sell a bad product or lie in their advertising :laugh: :shrug:

:laugh: Aluminum engines :laugh:

Foil would make you a good hat liner :shocked:

There is no better material than aluminum for jet boats. Aluminum use in drift boats has some problems but it works there too.

When the bolts on your trailer start to come loose due to the aluminum compressing under the washers and the holes start to get wallered out I know a place that can do the repair and do a retrofit that will cure the problems.

Mr. Carp

06-07-2003, 10:32 PM

Keta, Everything you have said is exactly right about the properties of aluminum. :cheers:

BrionLutz

06-07-2003, 10:39 PM

Keta,

Aviation and aerospace gets little use and much inspection.I think you'll find jetliners are in the extremely high use range, flown almost continuously and last for many years past their engineered date.

While they are inspected often you don't see the aluminum air frames, wings and other high use, high stress parts being replaced. If that was the case, aluminum would be prohibitive to use. The reason for the frequent inspections has to do with consequence of failure at 30,000 feet, not due to problems with aluminum as the best material for the job.

As it is, it is successfully used in extreme use environment.

From my perspective, I'm fine with an aluminum trailer. Had one and loved it. I'm more concerned about getting viewpoints on specific mfgs. of aluminum trailers.

Brion

Keta

06-08-2003, 12:14 AM

Brion,
I'll type a bit slower this time for you.

I have said, “aluminum has problems”

Aluminum will work harden
Aluminum it is extremely susceptible to galvanic and other types of corrosion
The wrong grades of aluminum will oxidize in freshwater (the white powder on the surface)
Aluminum is soft but can become brittle with surprising little working
Aluminum is harder to repair
Contaminated aluminum is almost impossible to weld right
Stainless Steel (like in bolts) will electronically react (electrolyses and galvanic corosion) with aluminum and cause lots of problems

For a trailer I would recommend a HEAVLY Galvanized steel one.

I own an aluminum boat myself so it isn’t a slam on your pride and joy or to your manhood, but simply facts about aluminum. Aluminum makes a good riverboat, but that’s all.

Pete,
They do make some aircraft bolts out of aluminum.

boater

06-08-2003, 10:20 AM

Originally posted by Keta:

I have said, “aluminum has problems”
i agree 100 percent, and if people think aluminum is so great for boat trailers and can handle alot of stress then why isnt the axle on an aluminum boat trailer made out of aluminum, why are they galvanized steel ?

Reelentless

06-08-2003, 03:15 PM

Sheesh, if you dont like aluminum trailers, dont buy one.

Personally, I have faith in the engineers at North River. If its designed and constructed correctly, it should handle the load.

You can keep your ugly ole steel trailers with the plastic fenders. Ill take the polished aluminum with diamond plate and alloy wheels any day.

If it cracks and my boat falls off, oh well. Thats why I have insurance. :smile:

Keta

06-08-2003, 04:11 PM

What about the person your loose boat kills?
Looks can kill.

http://www.corrosion-doctors.org/Aircraft/Aloha.htm

http://www.engr.sjsu.edu/WofMatE/AAI.html

http://www2.acc.af.mil/accnews/jul02/02285.html

Reelentless

06-08-2003, 04:42 PM

Safety chains and straps.

My friend had to rebuild his steel trailer last summer because it rusted from the inside out causing it to crack.

Maybe you should email those links to the engineers at Boeing and tell them they are full of <feathers> and they should be building airplanes out of galvanized steel.

[ 06-08-2003, 04:45 PM: Message edited by: Pete ]

Keta

06-08-2003, 04:55 PM

Some of the engineers at Boeing are friends of mine. They know the problems of aluminum and try to design around them.

So if the trailer brakes 6" behind where your safety chains are attached (not likely) how much good are they?

The problems you will encounter with your trailer eventualy will be:
1- Stress cracks in the heat efected zone of the welds
2- Elongated bolt holes
3- Loose or missing bolts

Your best choice is still a "Heavily Galvanized" steel trailer. Built out of channel not tube.

I didn't mention aircraft and steel anywhere in this thread.

[ 06-08-2003, 07:46 PM: Message edited by: Keta ]

FishinMission

06-09-2003, 02:06 PM

I'm still watching this thread to see if any manufacturers offer a GUARANTEE on their aluminum trailers...You guys that are so proud of your pretty, polished, aluminum trailers have one??

For those of you that see aluminum semi trailers out there....If I'm not mistaken..they have STEEL frames.

Mark

[ 06-09-2003, 02:07 PM: Message edited by: FishinMission ]

fish_on

06-09-2003, 02:25 PM

Here is some information I found on the topic of work hardening of aluminum, the whole artical can be found here.

When I was in college I worked for a aluminum horse trailer manufacture (Charmac) their trailers had a steel frame we then bolted or hucked aluminum cross members to them built up from there. A aluminum frame would not have taken the stress of the road.

web page (http://www.liquidcooledairpower.com/lc-topendheat.shtml)

Aluminum has some great properties that make it ideal for use in aircraft both in terms of airframes and engines. However, aluminum also has a couple of significant drawbacks when compared to say, steel alloys. These are, (a) a relatively low melting point and (b) work hardening. The first drawback - a relatively low melting point is self explanatory, however the 'work hardening' problem needs to be better explained.

Work hardening is an effect that causes metallurgical structure of aluminum to break down and fracture. As an example, take a piece of aluminum sheet metal and bend it at a moderate angle of 45 to 60 degrees back and forth and after a few times it will harden up and then simply snap in half. A simpler more everyday test is to use a soda can. Bend the tab on top back and forth 20 to 30 degrees and in a matter of a few times - clink - it will break right off. This fracturing is known as work hardening. Aluminum doesn't like to be bent back and forth. Steel alloys however can handle such stresses quite easily but their weight penalty limits their use to structural areas that are absolutely necessary. 

[ 06-09-2003, 02:30 PM: Message edited by: fish_on ]

Mr. Carp

06-09-2003, 05:25 PM

Whoever posted the link about work hardening is exactly correctly. Just take a paper clip and ben it back and forth until it breaks. That is work hardening. Aluminum is soft and everything that Keta said will happen, will.

Most of you seem like intelligent people, so use some common sence. Do you honestly think everybody and their brother that makes trailers knows all about how the material performs at the microscopic level from an engineering standpoint. I am not trying to slam boat/trailer builders, but a lot of the people don't have the understanding. It doesn't take a rocket scientist to take some metal, weld it together, and take it to the DMV to have it OK'd for highway use. Besides, welding isn't always the best answer either. I have heard of a couple of boat manufacturers that have had some boats come back because the welds are breaking apart and the boat is falling apart. Get Bent: Not everyone has the knowledge you claim.

Those aluminum trailers do look nice especially when they are only take to lakes and rivers. When one of you guys takes your trailer to the salt water, let me know. I want to see that baby oxidize!!! :grin: Then you can spend the whole weekend polishing the trailer trying to make it pretty again, unless you like the hazy look instead.

[ 06-09-2003, 05:33 PM: Message edited by: Mr. Carp ]

Reelentless

06-09-2003, 05:43 PM

Oh my god, I cant believe I am bumping this again!

The trailer is DESIGNED not to flex past the point where hardening is an issue. Do you guys really think the boys at North River are a bunch of junk yard mechanics? Hey boyz, lets get some of that there scrap aluminum and see if we can make us a trailer!

No, its designed by ENGINEERS who are well aware of the physical properties of aluminum. The key word is DESIGNED! As in ENGINEERED. They know what the loads are on the trailer and they design a structure that supports it. It could be made of freakin wood!

Salt water SUCKS! :smile:

I have to polish it after each salt water trip. I like to keep my boat looking like chrome as well. This is why I have only put it in salt water once in 3 years.

Ironhead

06-09-2003, 07:29 PM

I will try to see if I can help .What I think Keta and the others is talking about is the problem with welded alumium. When alumium is welded the fillet is the hardest part of the joint then as the weld progress out it gets soft like it is annealed . Then it is the goes to the same hardness out in to the parent material. This creates a stress riser when the joint flexes it will crack right along the weld . If you notice that almost all alumium trailers, airplanes and such are assembled with a machanical type fasteners . Like rivits,screws and bolts to allow the joint to move or flex. Like when a trailer hitch is welded to the frame of a truck it is also bolted or should be .I just lately sold my Alumaweld boat that I had for 13 years because I was tired of repairing the welds. Once they start to crack it is almost impossible to prevent.

boater

06-09-2003, 09:33 PM

Originally posted by Northriverman:

No, its designed by ENGINEERS who are well aware of the physical properties of aluminum. if that is true then answer this, the transom of most northrivers is .190 aluminum, why are they beaking up the outside edges of it with a radious that is smaller than the thickness of the aluminum ? do you know what happens to aluminum when you break it with a die that has a radious that is smaller than the thickness ?

Mr. Carp

06-09-2003, 10:05 PM

Ironhead :cheers:

1pump

06-10-2003, 12:03 AM

For those of you that see aluminum semi trailers out there....If I'm not mistaken..they have STEEL frames. Some do, but most don't. More weight = less revenue. A lightweight trailer might not last as long, but will generate more income.
Every year, you see more aluminum and composite materials. It's getting scary.

Kaptn Ken

06-10-2003, 07:33 AM

graemlins/applause.gif You see...What they say about "Steel" must be right! Just think...If they had made the "Titanic" out of Aluminum..........Whoa! graemlins/applause.gif

PL Ken
:cheers:

P.S. $60,000 2000 Duckworth for sale: FOR SCRAP ONLY!!! (~ ; :wink:

Mr. Carp

06-10-2003, 09:29 AM

The titanic failed because the engineers that designed it didn't know about Ductile-Brittle transition temperatures. That is why it failed. If you believe that the same would happen to our ships today, you're mistaken. If aluminum was used for ships, everytime a tug pushed on it, there would be a huge dent in the side of one. :grin:

Get Bent

06-10-2003, 11:22 AM

FM because you have to know NORTHRIVER gives a two year warenty on the allum. trailor

BITE KILLER

06-11-2003, 12:59 AM

Ok,so you guys are looking for some trailer warranty info. I did a little research and found that EZ Loader offers a 2 year warranty on their trailer frames. Tricker also offers 2 year warranty on their trailer frames Baker offers a 1 year warranty on their welded galvanized trailer frames and North River has a 2 year warranty on their welded aluminum trailers frames

All of the above manufactures said that winches, lights,axels,tires,and bearings warranties where left to the discretion of the manufactures of those parts.