I have used "pool noodles" with some success in modest seas (i.e. better anchorages). Ideally, I would like a similar tube with around twice the diameter, so that the tube is less prone to sliding under the boat. In short, they help - but are not a full solution for exposed situations.
That "SlapSilencer" looks like it could shred soft ablative antifoulings. Has anyone used one? How well did it work?
I have used ear plugs on nights when slap was a particular problem, but prefer to hear what's going on. Nonetheless, they take up minimal space, and also permit
sleep if well oiled crews snore & snort like hippopotamii.