I've been cruising 5+ years on relatively high dose Coumadin because of an artificel heart valve. I don't get routine monthly INR done as there are few places in the islands where it can be done convieniently. I have had a couple of bad bruises after falls but when wrapped and compressed the were self-limited. I looked into buying my own machine to do the testing but it was way expensive. Head injuries are a worry a subdural hematomas are are risk but so far I'm not wearing a helmet. For two years and with monthly testing my dose was fairly stable but remember to balance booze and green vegatables as they work against each ither in determining clotting times.