Designing and Making Trailer Fender

[Steve_Greenway]

I’ve wanted to make fenders for my boat trailer for some time now but I’ve had a difficult time getting the project started. I decided to attend both the Dixieland and the Route 56 gatherings this fall as motivation to get this project going. I figure that once I signed up to attend I was committed to the project.

I’ve been kicking an idea for the fenders around in my head for a while, but this is the first time I put it on paper. The first few attempts didn’t look too good, but about sketch #5 it started to take shape. Here is what I came up with.



I know that some of the people on this site build things without bucks, but I have very little experience and so I think building a buck will be a good idea for me. This will also force me to resolve many of the details before I start shaping metal.

I haven’t built a buck before, but I have built several boats and the process looks sort of similar. I also bought and viewed Ron Covell’s DVD on making a fender from Scratch four times to see how he did it. I think I understand the construction ok, but he had a fender to copy while I don’t. – BIG DIFFERENCE!

First I drew out a full size profile on some cardboard and set it on the trailer to see how it looked.



I spent quite a bit of time studying the photos that I took of the cardboard and changed the design a bit and cut a strongback out of ½” MDF. Here it is back on the trailer.



Here is a ¾ view to make sure it looks ok at an angle.



Now comes the tricky part: Turning the 2D into 3D. I took a guess at the front shape and cut a piece out of ¼” plywood. (Thicker might be better, but I had a bunch of ¼” scrap and using that up seemed better than buying something else.)



I bought tail lights for this and so I have a fixed dimension that I need at the back in order for the lights to fit. I started bending a thin wood batten around the buck to see how the front-to-back curves might work. I can already see that my front shape is probably wrong, but it’s good enough for now.



I hadn’t fully figured out how the bottom front of the fender would be shaped so I cut out some ¾” pieces in the same shape as the initial form and attached them to the strongback. I also added a few more station molds to help me visualize the shape.



I drew a line that followed the curve of the wheel opening and the shape sort of became obvious. Not sure why I couldn’t’ figure this out in my head, once it is in front of you it’s pretty clear.



I glued the pieces up and then sanded them to the line.



Here it is re-attached to the strongback.



In a 3D shape like this, when one thing changes, everything else seems to be affected so I thought I’d better work on the back of the fender to keep things balanced. I wanted to put in the rear bulkhead (where the tail lights would be mounted) next.

I had to cut out part of the strongback in order to mount this.



And here it is with the bulkhead in place.



I made an intermediate station mold to go right behind the wheel opening. I made the shape very similar to the rear bulkhead, except it is wider at the bottom and a little less pointy at the top.



I have a rough shape defined at the ends of the fender, now it is time to start springing some battens and see how the shape is going to work in the middle of the fender.



The battens were a little tricky at first. The first one I made was too stiff to bend around the front of the buck. I tried a thinner batten but by the time I got thin enough to conform to the front, it was too flimsy to hold a good shape across the middle of the fender. My solution was to use thicker battens and taper the ends.



Here is the buck with five battens sprung around it. This not only helps me to visualize the shape but will help me to make the center station molds the correct shape.



Next I spent some time looking at the battens to ensure that the character of the curves all worked together. It is easy to get one that is too high or too low, or whose curve doesn't flow with the others. Viewing from a low angle seemed to help this comparison.



I decided to stand the buck up and get a look from a distance to make sure I wasn't overlooking some obvious errors. So far I think it is looking ok. Lot's of work to do before I leave for Alabama.

[Steve_Greenway]

Now it is time to start filling in those intermediate station molds.

First, I made a temporary station mold that is intentionally too small. I didn't bother trying to match the final shape - this one is just a rectangle.



Next I cut some "tick sticks" from extra batten material. One end needs to be pointy on each.



Next I used the tick sticks to mark where the station mold would meet each of the battens. I also marked the top and the bottom corners. I held the stick in place and carefully traced around it with a sharp pencil. I numbered each outline and each stick to make sure I could replicate it later.



Here I found a scrap of steel that worked better than the sticks. I traced around it as well.



Once I "ticked" the top, bottom, and each batten I removed the temporary mold. The result doesn't look like much, but it contains the critical dimensions and the shape that I need.



Now I set the temporary mold on a larger piece of ply and put the tick sticks back in place.

I put a dot on the ply where each stick point is.



Now it is just a matter of connecting the dots with a smooth curve and cutting it out.



Now the piece pops right into place.



I decided to take the buck out to the trailer to see how the width would work with the trailer. The tires are pretty skinny and I don't want to fenders to look too fat.



I think it looks ok - I'm glad the fender isn't any wider though. The inside half of the fender will have to be a couple of inches narrower to make everything fit.

[Kerry Pinkerton]

VERY nice buck Steve. Steel or aluminum?

[hillman]

Hi Steve
This is coming along really nice,thanks for posting, can't wait to see the end result.
Phil

[Doug M]

NICE. Good design, and good demonstration of buck making.

[RockHillWill]

Outstanding form. It looks very nice and it's clear you are a good wood worker. One thing that I learned from Steve Hamilton here on this site is to consider making the buck bolt or screw together so that most buck components will work on the other side as well. It might save some time. Your 'stuff' looks great!

[Overkill]

Great work.

I do have a question for you though - as you back the trailer into the water, won't air get trapped up under the fender and float the trailer?

And as with lowered cars, figuring out a way to get the tires off is important. Jacking the car up, disconnecting the shocks, putting a jack in there to push the rear axle down, just to change a tire, is a pain. But, some people do it. Your buck appears to have the tire covered, but your design does not.

Are you planning on using '59 Caddy tail lights? I did on my teardrop trailer, but even frenched in they were too long. Simply remove the lense, cut off about 1.5", re-insert the lense, then bend the tabs on the housing down to meet the new angle of the lense. No one has ever noticed, but they don't hang out so far that people would bump into them.

[Doug M]

I have a friend that put a flatbed on his pickup but got a ticket for not registering it as a "commercial" vehicle. He fit the sides of the pickup into the stake rack sockets and had the ticket removed.

About this subject, mount the fenders in sockets lift them out on need to change the tire, lock them on with the receiver hitch lock or they'll grow wings.

Doug

[Steve_Greenway]

Originally Posted by Kerry Pinkerton

VERY nice buck Steve. Steel or aluminum?

Kerry,

Thank you, the plan is for steel right now. Dan is bringing a sheet for me.

[Steve_Greenway]

Doug and Phil,

Thank you. This will be a challenging project for me. I'm in no big hurry to finish so I plan to take my time and TRY to do it right.

Originally Posted by RockHillWill

Outstanding form. It looks very nice and it's clear you are a good wood worker. One thing that I learned from Steve Hamilton here on this site is to consider making the buck bolt or screw together so that most buck components will work on the other side as well. It might save some time. Your 'stuff' looks great!

Will,

I guess great minds think alike that is already in the plan. I drilled many of the parts with the drill press so the holes would be perpendicular to the surface, and I drilled all the way through so I would already have properly located screw holes when I assemble it "backwards"

Thanks for viewing and commenting.