The early ski nautique 2001s came with a short trailer, I read somewhere they were left over trailers from the earlier models that were shorter then the 18'6 SN 2001s. Whatever the reason it bothered me being short as well as not having a prop guard.
As a temporary remedy I moved the boat forward on the trailer a few inches, resulting in a few inches of trailer and minimal effect on younger weight.
Then I pulled the boat off to do stringers so I made some of the mods while it was off. I added 24" to the rear of the trailer, extended the bunks, paint and new carpet.
One concern of somebody else, was extra weight on the rear of the trailer, but keep in mind the boat (the load) is sitting in the same spot, I really only added a few pounds of metal to the rear. Tows fine.
When extending the trailer i butt welded the 24" piece on either side, for strength I welded a plate over the joint. Unfortunately the new steel is a bit thicker so the plate had to be on the outside of the frame. It's nearly invisible though once painted.
While the boat boat is off the trailer, I'd recommend checking the wiring as well as running it through some pvc pipe to keep it neat. I hate seeing wires dangling riding down the road.
Once complete with the above, I knocked out the stringers and other junk, and the boat went back on the trailer.
After a short time, the prop guard was due up to be built. And asking in the nautique boats Facebook group, I learned the prop/rudder sat about 2-3/4" above the guard and the width of the bottom flat edge is about 17" wide on the later SN2001 factory trailers.
I stuck pretty close to the 2-3/4" clearance between the prop and guard but I made my flat bottom edge wider, in my opinion 17 or wider is the way to go, I'd avoid narrower demensions to give some Lee-way while loading.
I built the guard first first out of 2x4 lumber and copied the angles on to steel then welded it up.
Then keeping it it a little like the later factory guard, I bolted it on. I used grade 8 bolts.
The factory guard also had a center bar that ran forward and bolted to the nearest cross member on the trailer, so that was added as well.
Last item on the list was to move the 3-light bar for wider trailers. I had previously built a replacement out of angle aluminum and LED lights, it was riveted on to the center of the prop guard and wired in.
Project complete, I haven't scraped it yet beyond the gravel I park on, but I have piece of mind the running gear is now safe, and it looks like the correct trailer is under the boat.