I'm looking at windguru which is predicting 18mm/hr of precipitation midday tomorrow.

Trying to find out what that actually means, I'm seeing 4-8mm/hr being defined as heavy rain, and over 8mm/hr as very heavy rain.

So the forecast is for something rather more than double very heavy rainfall.
I'm a little concerned that I could be facing something far outside my experience in 20+ trips to the BVI.

Our plan was to stay on a mooring ball here at BEYC. Advice? TIA

EDIT: Predictwind doesn't exactly corroborate this dire prediction, maybe this is just a data error?