centre board
Posted: Sun Jun 24, 2012 10:16 am
Joe,
My boat a Telstar 8m has a centerboard without the large curved quadrant that I think you are referring to. Unfortunately I will not be getting to my boat for at least a couple of weeks so I will try to describe it. It is simply a rectangle with a half circle top and the pivot bearing at the center of the half circle. It has the advantage of not requiring the curved trunk protrusion below the table as in the earlier model Telstars. But I think this curved section of the centerboard has the advantage of closing the back of the centerboard slot? My centerboard requires a mechanism to raise and lower it. The original had a small diameter drum several inches above the centerboard inside the trunk which is rotated by a crank from inside the boat. The small diameter drum has several turns of line wrapped around it to prevent slippage. The line ends then extend to either side of the centerboard and are fastened. The whole system effectively becoming a small pulley driving a larger half pulley which is the top semicircular section of the centerboard.
My boat's centerboard system has been modified with a stainless steel chain as a substitute for the line and a small sprocket which is substituted for the small drum. I use a looped bungie chord on the end of the crank to hold the centerboard down. Curiously it is not needed in the up position as the centerboard floats! The system works very well with the bungie chord allowing the centerboard to also act as depth finder in the shallow waters of the Chesapeake Bay.
The only problem is one has to go into the cabin to raise and lower the centerboard. To avoid this I had considered a modification of attaching an uphaul and a downhaul to the centerboard, running them through some pulleys then inside a tube attached to the mast post and exit through the cabin top and back to the cockpit.
I hope this helps
Geoffrey
My boat a Telstar 8m has a centerboard without the large curved quadrant that I think you are referring to. Unfortunately I will not be getting to my boat for at least a couple of weeks so I will try to describe it. It is simply a rectangle with a half circle top and the pivot bearing at the center of the half circle. It has the advantage of not requiring the curved trunk protrusion below the table as in the earlier model Telstars. But I think this curved section of the centerboard has the advantage of closing the back of the centerboard slot? My centerboard requires a mechanism to raise and lower it. The original had a small diameter drum several inches above the centerboard inside the trunk which is rotated by a crank from inside the boat. The small diameter drum has several turns of line wrapped around it to prevent slippage. The line ends then extend to either side of the centerboard and are fastened. The whole system effectively becoming a small pulley driving a larger half pulley which is the top semicircular section of the centerboard.
My boat's centerboard system has been modified with a stainless steel chain as a substitute for the line and a small sprocket which is substituted for the small drum. I use a looped bungie chord on the end of the crank to hold the centerboard down. Curiously it is not needed in the up position as the centerboard floats! The system works very well with the bungie chord allowing the centerboard to also act as depth finder in the shallow waters of the Chesapeake Bay.
The only problem is one has to go into the cabin to raise and lower the centerboard. To avoid this I had considered a modification of attaching an uphaul and a downhaul to the centerboard, running them through some pulleys then inside a tube attached to the mast post and exit through the cabin top and back to the cockpit.
I hope this helps
Geoffrey