I installed my datatach prop slip gauge and aftermarket antenna and it only holds a lock for 5-10 seconds and then starts searching again. I have tried moving the antenna to different parts of the boat away from other electronics but see the same result. Any ideas?

This is the antenna I purchased....https://buy.garmin.com/shop/shop.do?cID=158&pID=27594

does the antenna have a clear view of the sky, pretty sure they can't have obstructed view

Yes it has a clear view of the sky