Log Arch trailer build with questions

[Biocmp]

I've begun a log arch trailer build and I have a few questions below but first some pics of where we are:



I finished placing an order for a mill a month or so ago and told my friend I need a way to get logs to the mill.  He told me they had a number of old trailers and he might have something for me so I drive over and he walks me back to this old boat trailer.  It had a little damage that bent a leaf spring (and I guess lost a tire?) but otherwise it was in decent shape. 21 foot total length, could carry a 17' log. 



We removed the old boat winch and cut off the original receiver and the surge brakes. That was a difficult decision but I want to operate this in the cold months and from what I've heard, they are illegal in the winter because they can freeze up?  Either way, we went and purchased a 12k receiver and welded it on and removed the boat supports. 

You can see my friend below working his magic with the angle grinder



There it is after all of the removals.  I ordered a 12k leaf spring kit and we're going to weld some new heavy duty fenders.   We're trying to decide how to deck it, my friend thinks he has some "scrap" 1/8" plate with some small holes in it that we could put on it. 

Also trying to decide how tall to make the arch, I'm guessing it should be half as tall as the longest log I plan on recovering? ie - if i want to grab a 17 footer, I'll need to 8.5 feet minimum to reach the middle of the trailer?  I know logs aren't perfect cylinders and there will be all sorts of load distributions but can anyone help me ballpark it?

And anyone have suggestions on the best place to purchase trailer brakes? And suggestions on type of tires for heavier loads (12kish)?  Much of this is foreign to me so I'm learning as I go. 

I purchased a 12k winch that I'll be running to the arch and back through a snatch block (or two) to help reduce the load on it.

Any other suggestions are very welcome

[doc henderson]

what is the original weight rating of the trailer.  you can push it off road, but over the road, better not.  the rating on tires need to add up to the total weight you are hauling.  so 3k each tire.  the trailer and hubs should also be rated for this, not just the tires and springs.  the frame may also be a weak link.  do not want to see you spend a lot of time and money to just bend it in half with a big log.  I assume you are making an arch to lift and move forward onto the trailer a log.  not sure you need decking as it will add to the total weight (subtract from tree weight that you can move)  others will chime in soon.
look behind the wheel and see if the axle is set up for brakes.  sounds like you took some off.

[Walnut Beast]

The trailer isn’t anywhere close to a 12k trailer rating. If your going to do some small stuff then the trailer would work. But for some bigger stuff no way. 
Instead of some decking use some heavy round pipe or rollers for less resistance

[TroyC]

If those are 14" trailer tires they are only rated for about 1700 lbs each. That would limit your load to approx 6K total figuring weight of trailer. If you go with 16" tires, you will need 3500 lb hubs and a 7K axle.  I agree with Doc, that boat trailer frame is not strong enough for a 12,000 lb load.

[Tom the Sawyer]

I called a friend who has a large bass boat with a similar trailer.  His trailer is rated at 6500 GVWR, I don't believe that trailer is adequate for the size logs you are projecting.  Unlike a log carrying arch, a trailer loading arch should not have anything to do with the length of the log.  If you built an 8.5' tall log loading arch, expecting it to put a full length log on the trailer in one pass, you would be lifting that log several feet above the deck before the break over point of the arch, at which point gravity takes over and dropping a log that big on the deck, with forward momentum, will result in a disaster.  Log loading arches should only be used to get the log past the balance point on the end of the trailer, then your winch should pull it on the rest of the way (and end rollers will help).  Once the arch passed the top part of the arc, you'll have no control.

[Biocmp]

Thanks for all of the replies.  Assuming I replace the axles/hubs/wheels/springs and we weld some additional cross members, do you believe that gets us closer being rated in the 9k+ range? 

Is there anything else I'm missing? The steel is moderately thick in the trailer tubing. I'll measure it next time I'm there.

[TroyC]

I think the trailer tubing itself is the limiting factor. Most boat trailers are thinwall tubing and  originally designed for the weight of a boat. The metal is only so thick and so strong. Many times the tubing corrodes from the inside (can't see it) and further weakens the frame. The tubing will break or bend and the welds themselves are not designed for that kind of weight. My 23' boat trailer is rated for 6K or so, galvanized tubing. Boat trailer manufacturers do not want to add unnecessary weight to a boat package.

My 14K trailer is made of heavy 6" channel. Big difference! Even changing out the axles, tires, springs, etc., you still have a 6K or so frame. Be careful! A broken down load of stuff on the side of the road is a bigger problem that something broken down at the shop!

[doc henderson]

most boat trailers are made to be light and strong, i.e. not too thick metal.  what does the tag on the trailer rate it at for weight.  If it is free and used on "the farm"  it is no big deal.  the integrity of the tubing is key, one bend in that trailer and it will never be the same.  i would look at other designs.  if you are beefing up and replacing all that, may just start from scratch.  again, if you try it and it fails, only you know what you have to loose.  It is hard to pass up a free trailer.  you may be ok to move only a tree/log at a time.  If all the parts are going to be free and you have time to kill, no biggie.  My car trailer is rated at 7k gross.  it weighs 1600#.  there is a calculator that will tell you how much a green log weighs.  if you know the species, and size you have available.  several have used a car trailer with an arch loader.  my goose neck is rated at 24 k and weight is 6k do i can haul 18k.  my old sailboat (O'Day 18 foot daysailer 2) trailer I could pick up by hand and scoot over.  If it were me, i would leave it as is, and use it to the rating on the tag.  you will need to support the trailer under the arch when loading, or you will crush/bend the back of the trailer.  there are some good threads on this.

[Crusarius]

all good points. 

Since the cross members are already bent to clear the bottom of the boat the strength is already compromised at that point. It will not take much to bend them even further. That is an area you should be welding a bridging cross member to prevent that before it happens.

Any idea what the tube dimensions are? I agree with the trailer is not up to the task you want to repurpose it for. 

Plus a breakdown on the side of the road will guarantee law enforcement and monetary transfers will be involved. Especially if there is damage or injury.

[Iwawoodwork]

I would use it as is. as stated prior you will need to either block the trailer frame below the arch area or install jacks on each side so you don't bend the frame when loading. I would weld a heavy thick wall 4" or larger pipe across the back (could slip a larger pipe sleeve over it for a roller), as far as the weight if you have 5  lug bolt axles probably 3500lb axles so 7500lb and definitely need some form of brakes if hiway hauling,  
I have converted 3 old boat trailers  to flat utility trailers and on those I welded a 4" to 6" pipe  down the center from tongue jack to the back end . Just laid the pipe ion top of the V braces and added flanges on each side of the pipe down to the cross beams, and have hauled some heavy loads without issues.

[mike_belben]

Run what ya brung but use your head and dont get anyone killed in the process.  When you outgrow it sell it and build a  better one.  

Fyi... Bigger gets serious fast in logs. Nothing wrong with staying small. 

[firefighter ontheside]

No need to make the arch that tall.  You can get the log on the trailer and then re-attach the chain a little further back to pull the log further.  I use tongs instead of trying to choke the log.

[kantuckid]

I used a salvage yard, rear axle assembly from a Chrysler brand minivan to build my log arch. They are a solid axle and you get the tires and all with most front hit vans on the cheap.
 I bought new sq steel tubing to fabricate the arch and A-frame. Mine had a rd steel solid bar on the incline from behind the hitch to the top of the arch, so it raised the log as you began the pull via a choker chain set up.
 I sold it as was too difficult to move around on these hill sides and my tractor pulls most any log to begin with, even very large logs once they're bucked w/o an arch to mess with.   

[Sixacresand]

My arch is home made from junk yard material.  I judge its limits on how much the tires flatten when I load it. Also the throat limits the size.  I have found that is is better to move the mill to a big log rather than risk tearing up the arch.  I am completely out of commission if the arch breaks down

[kantuckid]

I recently saw a newish, store bought, double axle trailer on FB Groups- the Woodmizer Group that has a log arch fastened to the rear corner of the trailer side rails as a pivoting arch. The pic shows a large short oak log on the trailer. In use you'd approach the log, and back towards it, and as the weight pushes against the arch it would swing toward the trailer and raise and load the log. I can see the log maybe hitting the trailers lower rear edge and spoiling your plans, depending on distances and such?
Not logical to maneuver in the woods around my region but if fetching flatland logs it would be a useful design.

It is similar to searches below the related threads called **trailer log arch**
In a similar thought-  I did a one time fetch of two yard tree, walnut logs in nearby city. I bolted a piece of angle to the front, upper cross angle of my utility trailer then bolted a HF cheapo winch (no continuously long duty cycles) on those stiffened angles  and pulled on the logs with my trailer tilted toward them. As we speak, I have a walnut I may go get in my wife's dead aunts yard as it's dead or dying says my BIL. FWIW, I'd tear the yard up right now as too soft to much around on, but it's 75 miles one way, so maybe the only logical way to load it.

[charles mann]

I use my 35’ 24k (17,300 load) rated gn as my log trailer. My arch is 8’ wide a d 10’ (i think 10’) tall when in the vertical position. Iv went through 1 HF 12k lb winch and on my sec 12k now bc i was lazy and didnt want to uncouple and drag the rats nest out of the cable a d ran the winch in power out and burned the brake out. Iv loaded 6000+ lb logs with it and have come close to the 17,300 capacity several times. 

The boat trailer might work but as others have said, stay within the data tag of the trailer esp if out on the public roads. 

A guy named matt cremona built him a special purpose log arch trailer. Might wanna youtube him and get some ideas. Iv also thought about building a fetching trailer to pull behind either my 1tn dually or my 5tn M936A2. 

[mike_belben]

Im pretty sure a guy on here built the first one but others on social media are getting the credit.  Where has DanG been?

[Al_Smith]

I don't have an actual log trailer but I do have a double axle machinery trailer I have side hauled big oak logs on .It's got two 9,000 pounds axles and 10 ply 14.5 tires that carry 100 PSI of air .I've hauled a 14,600 pound D4 Cat but I didn't pull it very fast .About 35 miles per hour .It's got brakes on both axles . Probably the largest log might have been 8.500 --9,000 pounds and is was on my own property .

[JRWoodchuck]

I rebuilt a tandem axle boat trailer into my log trailer. It has a pair of 3500lbs axels. I have loaded 3+cords of dead western larch logs on it which is 7500lbs on the light end. I decked mine in 2x6 larch with 2x5 channel down the center to level it then wrapped all the edges with 1.5 angle iron. It’s been a great trailer for me.