by GreenLake » Sat Jan 31, 2015 2:51 pm
I described my experience in some detail, because it seems that sliding the boat onto the bunks is not an issue during retrieval. (I have wider/longer bunks now than what I inherited from the PO, but they could be wider still to further spread the load). In other words, if there's an increase in friction, I've not noticed an effect.
For launching, one can either drive the trailer far enough into the water that the boat starts to float off, or, use a trailer that can tilt. Both would be strategies that would deal with any increase in friction. (In my experience, rollers do not always turn easily and they can only be serviced with the boat off the trailer - bunks are more constant that way).
There are some here on the forum who are concerned about spot loads from rollers even under the deep V section of the forward hull, but they include people who trailer across the country. Your mileage may vary - literally.
Rollers have no place off-centerline on a DS, and I'd regard them as questionable aft of the CB. While there's a remaining "crease" in the hull along the keel line, so it's not entirely a flat panel, that crease is rather shallow, whereas the forward V section is stronger, just by geometry, and then reinforced further by the keelson.
The idea is that you want to not observe "flex". If you need "data", why not walk around in your boat when it's on the trailer and have someone spot for flex (or reverse those roles). The flexing is what will damage the laminate over time.
One aspect of dynamic loads is that the distribution between bunks and rollers is different - a padded bunk has more "give" to it than a roller. It may only be a fraction of an inch, but that can change the distribution of the load.
Another way to get some "data" would be to follow in another car while you let someone drive your trailer at highway speeds (best on a section of freeway in need of repair). I've seen other peoples boats just dance on their trailers, just literally being bashed to pieces. It's tough to get an idea whether the suspension / tire pressure on your trailer is optimal and whether the straps hold down the hull well enough other than by observation while under way. You might find that revealing.
~ green ~ lake ~ ~