Re: Changing rollers to bunks?
I like both. I like keel rollers and load carrying bunks. I never had just rollers for the reasons mentioned and some hulls dent easily (making ripples) where the rollers support the weight of the boat.
The keel rollers (2 or 3 located on the rear of the trailer and any cross member that the boat keel could touch) are really set right at the level of the keel when on the bunks. The rearmost may or may not contact the hull, but that's ok because that is not what it's for. The rear roller is to get your boat onto the trailer without scratching the hull on the rear trailer support as are others located on structural cross members that the hull could contact before it is far enough forward to get up on the bunks.
I use 2x6 treated pine and leave it bare. I leave it bare because wet wood is almost slick as ice. If you ever slipped down on wet, bare wood steps (like at the marina.....the ones without aluminum extruded metal types) you know exactly what I mean. Carpet is fiberous and provides a lot of drag that wet wood doesn't; just like at the marina, you don't slip on carpet covered wood steps. As far as scratches on the hull, you tell me if a slick surface would scratch more readily than a porous one! Moot point.
Additionally, using treated wood that has no porous covering allows the bunks to dry faster which helps to control rotting. If you don't like the natural pine color, get a can of black spray paint and paint them.
Problem with bunks is that you need to float on and off/drive on and push off, so you need a deep ramp, especially with a heavy boat that you can't move by hand. Most ramps here in Texas are adequate even though sometimes your rear tires on your tow vehicle get wet; longer trailer tongues not only improve road stability, but help in launching.
On locating the bunks, I select a spot just outboard of a lifting strake, or bottom offset, preferably half way between the keel and chine (for lateral stability) or wider, so that the bunk will ride on the part of the boat that is usually dry at the higher speeds. I mount them to at least two cross members; transom and one other; 2 other if I have them and the boat is heavy.
I also like guides, either in "bunk fashion", rollers, or just round pipe. I prefer the bunk fashion as they are longer and give you more length for different loading situations. I locate them so that there is about an inch of space to the rub rail on the boat when loading. Don't gauge off the side of the boat as the rub rail usually sticks out farther and in certain situations, it could be the first to contact the guides.
If you don't have sealed trailer lights, guides are a good spot to locate your trailer lights and keep them out of the water (works best on long roller or pipe guides as you can make them taller and still function where as bunks would be too high to be useful for their intended purpose).
My 2c
Mark
