Beyond the comments above: Do you have an access port on the top of the tank? If so, I'd get in there and visually inspect the tank. You can get growth on the bottom and sides which additives don't touch and which will encourage additional growth. If you don't have a problem, there's piece of minds. If you do, then that's the only way to clean it.
You' can also see whether there is water which, in addition to encouraging growth, can accelerate deterioration of the tank.
Assuming you have primary and secondary filters for particulate and water reparations, I think that you should be good to go. Watch the filters vigilantly for the next 10 hours, or so. (I'd take a photo of the filter bowl and filter, if you have a Racor that will allow you do so. You can then compare what's happening.)
Your Islander shouldn't have a turbo charged engine; and, I think that a simple, aspirated diesel engine that is operated within "reasonable" rpm and load ranges is more tolerant of fuel quality than a high performance engine that you're "pushing". Having said that, running an engine that is warmed-up, with clean oil at higher RPMs is good for it.
Also -- MAKE SURE YOU CHANGE THE OIL and filters before you go out for a variety of reasons. I'd plan on checking that a bunch during the first 20 hours of rerunning the engine.