Take this answer as advice from someone who knows a bit about engineering, but has no actual experience keeping a pontoon boat on blocks. ... When a boat is afloat or on the bunks of a trailer, the weight of the boat is distributed along the entire length of both logs. Your photo indicates the weight is being supported at just two points on each log. Further, if the blocks under the logs are flat, then the entire weight at each block is being carried by the small patch where the round log touches the flat block. ... If I were to try this, I'd want large blocks at each corner with each pre-shaped to match the curve of the log. The goal is to have as much of the surface of the block touching the log as possible, so the aluminum log does not become deformed. ... Others with experience may know better than I.
