I found a website very early on in my journey called EyelineHer by Carly.
http://eyelineher.blogspot.com.au/search/label/eyebrows. She has alopecia and has some great tips.
I followed Carly's links and I bought a sealer from 'Bald Girls Do Lunch' online which is supposed to be excellent.
http://www.baldgirlsdolunch.org/?page_id=689. I must admit I never got around to using the sealer because by the time ordered and received it, my eyebrows were growing back. I think it took two or three weeks for it to arrive from the US and might be too late for your trip up North. But I only had it shipped standard post and you could see if there's an express postage. Not sure if it will stand up to the water test though.
Have a read of Carly's website and see what you think. Good luck and I hope you enjoy your trip.
Love Janey xxx