Replacing Boat Trailer Bunks with Roller Bunks, Using Common Tools




I have a friend, John Wicklund, who likes to fish, but has had to downsize in his fishing machines because he now lives in a retirement center with covenants covering what he can park and where.  He did purchase a 14' aluminum Jon Boat, a 55-pound thrust Minn Kota, and an EZloader trailer for fishing lowland lakes for trout, Kokanee, perch, and bass.
The small trailer he purchased was apparently designed for boats with gas motors attached, which would have been heavier behind the axle than his electric trolling motor.  The axle could not be moved forward, so the tongue weight was more than he liked.  The trailer came with two 5-foot carpeted bunks plus a small support toward the bow.   Loading the boat by himself onto those two bunks proved very challenging for a older man with a replacement hip.  He needed a much simpler and easier arrangement.  
He initially made up a plywood platform with plastic “bunk slicks” and rear rollers attached, which included extending the plywood 15" to the rear to try to even out the tongue weight.  As he explains below, this worked much better than the carpeted bunks, but the “bunk slicks” had shortcomings.  It was apparent to him that rollers were needed. 
From the photos below, you can see that he is a pretty accomplished engineer and carpenter, utilizing wood that he can work with in his storage shed without access to a welder to accomplish his goals.
Below are photos he supplied and his account of what and why he did it.


Here was his early trailer configuration using the plastic/Nylon style bunk glides


"Just for the heck of it . . . . . .  A recent project.

When I bought a Jon boat and trailer a couple of years ago, I quickly discovered that  it was tough to load the boat onto the trailer by myself.  This cheap version of an E-Z Loader trailer came with two 5-foot carpeted bunks.  Also, unfortunately the design of the trailer is such that I cannot move the axle forward to reduce tongue weight with a boat that does not have an outboard motor on the transom.  
I saw no need to submerge the trailer for launching and retrieving a fairly light flat-bottom boat, so I replaced the carpeted bunks with 8-foot 2X4s with “bunk slicks” on them, plus a couple of rollers at the back to help get the boat started up onto the “bunk slicks” for reloading.  To reduce tongue weight, I extended the “slicks” and rollers about 15 inches beyond the end of the trailer.  And by moving the winch back, the transom of the boat rested a good 12 inches beyond those rollers.  Tongue weight was still 125 pounds.
Well, those “slicks” were not very slick, and I had to rub paraffin wax on them every time I launched.  Plus, the slicks in the rear were wearing down!  With more wear, the attaching screws would start scraping on the hull.
So I bought 2 double sets of 4-foot roller bunks from etrailer.com and installed them.  They also stick out 15 inches beyond the end of the trailer, and the manufacturer would not guarantee them because of that.  Thus, I added 2 parallel 2X4s with a cross member bolted under them at the back end.
When I would release the winch strap, I knew the boat would quickly roll right off the rollers, so I added a cleat on the winch stand for the bow rope to temporarily hold the boat when the strap is released.
Each of the 4-foot roller assemblies weighs over 20 pounds, and I hoped they would not bend when I winched the boat onto the trailer.  Even if they did, there is still a lot of support under the hull, much more than with those original 5-foot carpeted bunks. 
More detailed explanations:

1.  The rollers are to support a 14-foot flat-bottom Jon boat, with no weight of a gas motor on the transom.
2.  I saw no need to submerge the trailer to unload or load the boat.  Backing the wheels no more than hub-deep in the water is all that is needed for both unloading and loading. 


3.  I removed the two original 5-foot carpeted wooden bunks and their brackets.
4.  The curving shape of the trailer side rails prevents moving the axle forward to better balance with the motor-less, fairly light weight boat.  To reduce tongue weight, the boat needed to be positioned with the transom a little over 2 feet behind the rear trailer cross member.  
5.  I used four “U-bolts” (and lock nuts) to attach 3/4 inch plywood to the two trailer cross members.  The plywood extends 15 inches beyond the rear cross member.
6.  The bottom of the boat hull has 5 ribs, sticking down about 3/4”, with about 6 inches of flat space between each rib.
7.  Each of the four roller sets I purchased from etrailer.com is 4 feet long.  Each PAIR of rollers sets is advertised as being able to support 2500 pounds.  The triple roller assemblies are just under 5 inches wide, so they fit nicely between the hull ribs and thus guide the hull straight onto the trailer. 
8.  I bolted the roller sets to the plywood, flush with the back end of the plywood, and aligned between the hull ribs.  Lock nuts, of course.
9.  The roller manufacturer would not guarantee the roller sets against bending if they were extended beyond support from the rear trailer cross member.  So I used “U-bolts” again to bolt a 2X4 parallel to each 8-foot roller assembly.  Then I bolted a 2X4 underneath the rear of those 2X4s, and thus under the end of the plywood and the ends of the roller sets.
10.  So, the “extended” roller sets have three forms of support:
 a.  The steel channels themselves
 b.  The plywood
 c.  The 2X4 crossing underneath the plywood.
If the steel channels do eventually bend a bit, the rest of each 8-foot roller assembly still provides much more hull support than the original 5-foot carpeted bunks would have. 

11.  When loaded, the transom of the boat extends about 12 inches past the rearmost rollers, and the trailer balance is still rather tongue-heavy. 

12.  Knowing that when launching the boat it would quickly roll off the trailer, I attached a cleat to the winch stand to temporarily secure the bow rope when I unhook the winch strap.

13.  To load the boat, I attach the winch strap and then move the boat out to the end of the trailer by walking on the plywood or wading out.  Then align the rib spacing with the rear rollers and winch the boat on.

14.  The trailer capacity far exceeds the weight of the boat, and the torsion bar axle makes for plenty of bounce on uneven surfaces.  So I transport the electric motor, battery, and gear in my truck rather than in the boat.

15.  The wood doesn’t get wet;  when loaded, the boat shields more than all of it from rain.  And I don’t submerge any of the wood at the launch ramp.  (Note that carpeted wooden bunks DO get wet when a typical bunk trailer is submerged.)


Here e-trailer roller bunk units in 4' sections



You will notice the cleat installed on the winch support to help control the boat from sliding off the trailer too quickly when unloading, after the winch line is disconnected.  



Here is his later trailer configuration with the rollers


The trailer rollers work perfectly!   They reduce the effort needed to crank the winch by about 70%, compared with winching the boat onto those “bunk slicks.”   And the steel channels show no evidence of bending".


The new trailer bunks being used to reload the boat


The photo above got my interest in his removable modifications of outfitting this boat to make it "Fishable", so I requested a few more photos when he took the boat out later.   This platform unit is made from plywood and bolted together, readily removable, since his boat storage is in a open RV storage area on the retirement center, he feels like he has to make all his attachments readily removable and placed in his apartment when not in use. 


And the old brass rod holder brings back memories to me, which he also has, it belonging to his father.  The two wooden rear cleats are used for a second anchor when perch fishing if the wind is blowing to keep the boat from swinging off the bow anchor.


Here is a closer look at John's OFFICE


In the photo below, you will have to look hard to see just the rear end of 3/8" All-Thread that he uses to clamp this platform onto the boat seat lips.  The "pole" is a removable balance support for him to use if standing to stretch his legs.  You can see the seat back is removable and from viewing it in the above photo, made so it is angled outward at the top for more comfortable seating.   And his tackle boxes are out of the way under the seat.


His "Christmas Tree" that he "C" clamps on the Port side is the basis to attach the depth finder, a battery voltage meter and a anchor rope cleat readily available from the OFFICE seat.


Another view of THE OFFICE





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Originated 12-08-2014, Last updated 11-06-2016

Photos & text provided by John Wicklund
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