Definitely only for the calmest of freshwater bodies. I'd really hate to see what extended saltwater immersion does to the wheel bearings and trailer coupler, and a ski boat wake would really mess up that romantic meal in the video.

Laszlo

Funny they chose windless days for their videos!   

I’d be really interested seeing just how much any kind of breeze affects how well this design tracks! Even with its entire trailer hung underneath somehow I’d think it’d be easy to get blown off course?

You know they are not similar at all. Well, they're both small maybe.

The Sealander has access from the interior to the whole unit. The Teardrop you access from outside in two places.    

 The Sealander's wheels and trailer toungue are integral to the unit. The Teardrop sits on a trailer.

If the Teardrop was turned into a Sealander type it would be something else.

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Of course what would it be. Do you suppose the Sealander makes a good boat? or a good trailer?   Encased in a boat hull how easy would servicing the axles, bearings, and tires be? How about trailer lights?  How stable or seaworthy would it be in a summer storm?