Bear in mind there are bottle jacks and bottle jacks. The cheap type like Draper etc with only one stage in the ram, and screw adjustment, are nowhere near as useful as the sort found in Land Rovers (old Discoverys etc) which have a two stage ram with much greater lifting range. Most of the ordinary bottle jacks won't have enough range to lift a 16" rim with a completely flat 4x4 tyre on it due to the height of the sidewall!
A Boat is a hole in the water, surrounded by fibreglass, into which you throw money...
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