Intro & my project: adding more weight to foam core swing centerboard (hunter 22)

Hi everyone. Just found this site and registered. I'm in Massachusetts, and I have a 1983 Hunter 22 with a swing keel. Just got this boat last fall and sailed her a bit before putting her on stands for the winter. I pulled the swing centerboard and have been refurbishing it. It had been slightly damaged by a few run ins with the bottom before I got her. On this boat the centerboard never completely retracts into the hull. In its fully retracted position it still extends 12" below the hull. When fully extended it draws five feet. So most of the damage was at the leading edge when retracted. Likely cause: trying to beach like you can with a macgregor or a canoe. There were also two dings lower along the leading edge towards the bottom tip, which would've resulted from running into submerged branches while under way with the board fully down.

This boat model is pretty tender. It heels quicky in fresh wind and has significant weather helm. this can of course be reduced by sail trim and retracting the centerboard, but nevertheless, it has weather helm.

The pin (on which the centerboard pivots) is 1/2" stainless steel, and the board has a nylon bushing inside that revolves around the pin. this bushing was badly worn and resulted in the centerboard being quite loose. e.g. there was about 10-15 degrees of deviation from true in either direction. Another way to say it is that the keel has a lot of play to starboard & port when it should not wiggle or have any play at all in either direction.

So, I want to do two things: replace the bushing and stiffen up the boat. My plan is to upgrade the pin and bushing and perhaps even the mounting brackets that hold the board to the hull. I am considering replacing the nylon bushing with a bronze one that will not deform under moderate pressure.

I am also considering adding about 50 pounds of lead to the bottom tip of the board. Because of this I am thinking about getting a larger diameter pin made and also boring out the holes in the mounting brackets that receive the ends of the larger pin. Perhaps a 5/8" pin would be good to handle the additional centerboard weight.

A man named John Ross made nice machinists drawings of the stock centerboard and pin mechanisms. His drawings are online here:

http://sbo.sailboatowners.com/index.php?option=com_mtree&task=viewlink&link_id=6178&Itemid=257

My concerns about the added weight to the tip include:

1) Whether or not the four 1/4 inch stainless bolts that hold the brackets (and therefore the board) to the hull will be strong enough to withstand the added weight four feet beneath them when the board is down. Perhaps I should up-size them to 3/8 inch bolts and therefore also increase the bolt holes that go through the hull to receive them. I am not at this time considering reinforcing the area of the hull through which the four mounting bolts attach.

2)Whether or not I should replace the nylon bushing with a bronze one. Here I am concerned that the bushing was made of nylon as a safety measure; in case undue strain were to be placed on the board, the nylon bushing could deform rather than transfer 100% of the stress to the mounting brackets and the four bolts that hold them to the hull. I do not know that the nylon bushing was made as an intentional weak link. it is just my suspicion.

My ideal scenario would be to have a nice new bronze bushing around a 5/8" stainless steel pin that mounts to the hull with 3/8" bolts. My nightmare would be if the additional 50 pounds at the tip would create too much strain for the four bolts and would tear one or all of them and therefore create a nice big hole in the bottom of the hull while underway.

I've been documenting my progress with the board overhaul on my website, in case any of you want to see photographs. It is http://hunter22.net

I know of one other hunter 22 owner that added 50 pounds to the tip of the board and upgraded the bushing to brass. He did not upgrade the diameter of the pin nor the diameter of the four mounting bolts. He reported significant decrease in weather helm and no problems. Still I am wary with a modification like this that could cause the boat to sink in rough seas.

Any thoughts or constructive ideas would be appreciated. This is a trailer sailboat that is good for inland waters and protected coastal waters. She should see good weather weekend outings and not be used in open seas or for any crossings. With good weather planning, I would expect never to put undue stress on the keel. Still...you never know what you might encounter out there.

Thanks in advance,
Kristopher Sprockett