I understand the theory about mast floatation, but few of the finer points are confusing. If a 170 takes a knockdown and the center board is locked down, will the boat go upside down immediately or only when the mast fills with water. If it's the latter, I would think stepping on the centerboard would right the boat very quickly.
I haven't examined the mast as I've only had the boat about 10 days now and it's been in the water the entire time. Except for leaking around screws, etc, the only major hole is in the bottom. Is that right?
I'm a little sensitive to "knock downs" as I experienced one about a month ago on a smaller 12' boat due to operator error (mine). The wind was fairly gusty that day and in retrospect, I should have passed on sailing. However, I was hot to trot and almost immediately when I left the shore, I was "in to it". With my hand full, I did get the dagger board down, but didn't have time to bungee it. First mistake. Second mistake was my "kick-up" rudder which I thought I got down, but it either kicked back up or I failed to get it fully extended. Second mistake. Third mistake was flying both the main and jig as I was over powered. Fourth and final mistake was jam cleating the main while on a tight tack.
I suspect because of lack of fully rudder, I couldn't hold my tack line. The boat quickly turned 90 degrees to the wind and before I could pull the main sail sheet out of the jam cleat, the boat went over on it's side and continued to an upside down position. As it was going over the dagger board departed along with the rudder. If I had had the dagger board bungeed down, I think I could have pulled and then stepped on it and the boat would have righted itself.
I was only a 150' or so off shore and the wind and my towing quickly brought it toward the beach where a passer by helped me right it.
$500 later I had a new dagger board and a new rudder. I still have that boat and when I go out in it, I now double bungee the dagger board down and have line tied to the rudder.
As I related in another post here, a few days after I launched my 170, I saw 2 clowns dump a 170 in similar or perhaps worse wind conditions. I was on the dock when the boat was righted and I observed that the center board was locked up. I watched the boat go over and didn't see any center board extending downward. I realize the center board is NOT the same as a lead keel, but there is weight there and also a great lever for righting a boat.
I don't know if the mast had floatation or not, but I don't think the boat ever went very far past 90 degrees.