I know your question was a "how to", but really, why bother?
A few points to consider:
Mine are blue, and while they do receive a bit of dirt and bird droppings,
the amount does stablize.
The sun and rain cleans them good enough for me, after all the purpose is to
protect what is underneath.
The bird doo doo cleans up completely by itself and all that is left is a
bit of black on the sail cover from air pollution.
The seams in my sail cover are starting to give. The thread used to sew it
together is not as UV resistant as the cloth.
If your covers are old like mine, you may also run the risk of having them
come apart if you put them in a washing machine.
In any event, machine washing will speed the demise of most fabrics.
The choice is a trade off.of appearance verses function in this case.
(I do advocate washing one's clothing

Steve Thomas
C&C 27

"Bobsprit" wrote in message
...

I have new sunbrella sailcover and pedestal covers for the C&C 32. Can
they be
machine washed or should I just rinse them off and dry?
This may be common knowledge, like grey water, but please answer anyway so
I
can be a better sailor!

Thanks,

Capt RB