I wasn't there (it was a long time ago!), but I am told they used to weigh everything and this was changed to just weighing the bare platform. From what I've read this was just done to make it easier to do the weighing rather than reduce the overall weight, and they based the platform weight on the ones that were around at the time.

What would a modern Mosquito such as yours weigh all inclusive?

Also because I am a hoarder of boat plans, brochures and the like, I can confirm through an early brochure from the Victorian Mosquito Catamaran Association, which states the weight as being 60kg or (130lbs).

It's been a while (10 years or so) since we tried weighing them complete, but from memory I think they come in around 88kg to 95kg depending on whether they are cat or sloop rigged.

Someone else may have more definite numbers in mind.