This site gives an estimate of energy produced and comparative cost of solar with local AC costs at any location worldwide.
PVWATTS v. 1
Please note that changing the size of the array to anything below 0.5kW doesn't seem to work. Still, it's quite instructive for guesstimating the return on investment for your yacht's array.
One thing that stands out is that by mounting panels flat - as is necessary on a yacht due to rotation - the difference in efficiency seems to be less than 10% from the ideal array tilt angle.
The derating factor field assumes conversion to AC so real results on a yacht will be better if using DC directly, but battery charging inefficiencies are not taken into account for storage and later use.