I bet having one of these attached to your hull will slow you down.
This reminds me of a race in the Star North American's two summers ago. We were having a good race and were heading higher and faster than the boats around us. My skipper S. was keeping us in the groove and I was droop hiking for all I was worth. I looked down and saw a ton of weed on the keel. I didn't want to tell S. because things were going so well and so I didn't want to give him something to worry about. I waited about a minute and we were still moving better than the other boats, so I decided not to tell him. We finished the race with the best finish of the regatta and then I told S. about the weed.