: Anyone try this product? Any comments whether there would be any real benefit
: if this product was applied to kayak hulls, either composite or
: tupperware?

The stuff probably does what it claims. But there are several steps that will have more of an effect and you should do first.

#1 is get strong. If you want to go faster and get less tired, tune up the motor. Good, strong technique will beat goop on the hull every time. This will take the most effort, but has the best payoff. If you think you have done all you can do in this regard, go to #2.

#2 Paddle a more efficient design. An efficient design will among other things have low wetted surface area. The less surface for water to rub against, the less area you would need to cover with goop.

#3 Make your hull as smooth as fair as possible. A poor sanding job will introduce a lot of friction that no goop will be able to overcome.

#4 Keep your boat unscratched. There is no point in a smooth hull if you just go and scratch it up. No goop will be able to fill in the results of running over a rock.

#5 Keep the hull clean. Goop won't help if there is other crud on the boat already.

If you have all these things taken care of some magic goop may have a chance of making a small fractional difference. I can see a racer who keeps losing by 1/2 a boat length looking for any advantage trying some of the goop, for anyone else it probably won't make a noticable difference.