Split moulds are relatively common. Most large boat hulls are made from a split mould as it allows much more 'styling freedom' and avoids the need for a building high enough for the hull to be lifted over the top of the mould to get it out.
However it adds labour cost to split and rejoin the mould each time it's used and you have to work out how to hide the little ridge that will be found where the join was. For many split mould products the answer is to sand off the little ridge and then polish it invisible - more labour cost.
Frederick's comment that there is a rough line on the Fiber Stream
at the point of maximum width confirms that that is where the mould was split to get the part (the body moulding) out of the mould.
I recently made a split mould for the bottom of a scooter tail box
and it can be seen at the bottom of this construction web page
. In this case, the part was laminated by reaching through the top and bottom openings. For a part as large as the Fiber Stream
, it's surprisingly easy - once the first layer of glass is laid down and cured, you just stand on an adjacent section to work.