I made a set of guide post for my trailer using pvc and pool noodles .. I have a long foredeck and the guides help me in locating the trailer in dirty water. they show me how deep to back down the ramp. they center the boat on the trailer since i set them snug against the rub rail.. The guides were a little bent up to start with when i got the trailer, and one of the guides got bent further -- so at this point they're basically not usable. i'm keeping the boat in a slip at a marina, and the only time it will go onto the trailer is once a year to go for outboard maintenance..
Re: diy trailer guide ons i have found that the pvc only guides don't last long. one good hit and they don't recover. if the boat is half on/off, and it pivots around the guide, lots of force will be applied.. The rear guides metal inner structure should rise above the boat. these are typically aluminum and are flexible. the cost to repair you paint/fiberglass is going to far out weigh the cost of the savings of these guys.. That's a lot of guide work for a 20' trophy . unless your boat is light, i would recommend staying away from the metal conduit guides you purchase at marine stores. tried the shipshape guides (purchased at west marine) and my 2002wa trophy bent those out while putting the boat on the trailer in a strong wind (eventually broke)..
