I am not John, but I will do my best to answer your questions about tramp effectiveness.
I have two 18s and I have raced both. My first 18 has a black mesh tramp that came with it when I purchased it. I can only imagine, but I believe that it may be the original tramp from 1981.
It is in great shape and my wife was kind enough to re-stitch it about a year ago.
When I reinstalled the tramp, I got it real snug on tightness. All of the crossbar-to-hull attaching points were super tight. With the tramp snug, if I lifted a hull at the tip of the bow, the other hull would start to come up with about six inches difference between them. This was even worse while on the water with wave action (about 10” difference).
When I purchased my second 18, a 1982 model, the tramp on it was a vinyl type, but it was completely shot. I removed the black mesh tramp from the first 18 and installed it on this boat. I got the tramp installed at about the same tightness as when it was on the 81. The hulls still had a difference, but not as dramatic as the 81 (about 3” difference on land, 6-8” on water).
About halfway through this racing season, I purchased a new white vinyl Hobie tramp and installed it onto the 82 model. This time I installed the tramp super tight. So tight in fact that when one of my daughters lays on it, it only sinks down about ½” and they weigh about 60 pounds.
With this tightness, the hulls on land have no difference when lifting (lift one or the other and the opposite side comes up instantly). On the water there might be a difference of ½” to an inch.
Now on to performance. With the old black mesh tramp, we were not able to keep up with other newer 18s. My crew and I always resorted to the fact that we were just going to come in 3rd (if there were only 3 boats competing) or later. We actually did a little better when the black tramp was on the 82 model boat, but we still could not perform to the level as some other 18s. However, all of this changed with the new tramp. All we did was change the tramp. Weather conditions have been varying, but as far as I can tell we have sailed in many similar conditions as we did with the black mesh tramp. With the new super tight white vinyl tramp this boat kicks butt!
Out of the eight races we have had this season, we used the black tramp for the first four races and placed first in one race.
The second four races we had the new tramp and have placed first in three of the four.
The one race where we didn’t place first my crew broke his hand and we had to DNC after the first race.
As for things to watch out for with a tramp super tight, we are constantly keeping an eye on the rivets holding the tramp track to the hulls. If these let go, hang on! We also inspect the tramp for nicks and cuts. If you have one, it will not take long for it to grow. Lastly, we keep a close eye on all of the grommets. We don’t need one pulling out while we are 10 miles offshore in a distance race.
Hopefully this will help.