Hi Al, S&G kayaks can be more delicate or as strong or stronger than glass boats depending upon how it's built and what it's built of. Seems to me that everything being equal a 35lb kayak is more delicate than a 45lb kayak than a 55lb kayak of the same overall displacement and dimension. "stronger" is also a general term. Some glass boats have weak spots that other glass boats don't have, same thing for one off wood/epoxy/glass boats. If you are considering the kind of repeated impact that whitewater and surf boats endure then plastic can't be beat for the money. A s&g kayak can be built strong enough for the same use that a glass boat would be used for, it just will take care and judicious application of materials. At some point the "strength" differences will occur at levels that make material failure a secondary issue to bodily injury. For example a vinylester glass kayak (Mariner for example) made with an extra layer of glass or glass/kevlar will certainly be stronger than the average s&g kayak (4mmply,6ozglass). Stronger as in kayak and you tumble into the rocks or dumping surf. On the otherhand you could make a s&g or stripper that would be equal to the task with multiple layers of carefully applied s-glass and or kevlar. One will only require some waiting time and <$3000, the other your time building and $900-$1500,,,,,but more to the point , which will be more impressive on your car?