Operating and understanding the Melonseed Centerboard:
The centerboard is a plate of 1/2" PVC plastic that is held in place in the centerboard trunk by a bolt, rubber washers, metal washers and a lock nut on its forward lower end. Actually, the board does not ride on the bolt as you might imagine from a visual inspection, but there is a piece of PVC plastic tube that acts as a ‘bushing” around the bolt. There is Sika-flex 291 adhesive sealant between the rubber washer and the fiberglass centerboard trunk.
It is a very strong and watertight system that should endure well as time goes on because the friction is really minimized by the water lubricated PVC on PVC system.
The board will rise by itself if you run aground or strike an underwater object.
The string that raises and lowers the board is called a centerboard “pennant”. The pennant is attached to the top aft end of the board by a very simple system of holes and a knot. Once a year or so, check the condition of the pennant where it connects with the board to be sure there is no wear on the pennant.
There are two (permanent ??) magic marker marks on the pennant to indicate the depth settings of the centerboard. With the board pulled up all the way there should be one mark on the pennant at 12” back from the cleat, and another one at 22” back.
If you lower the board and cleat the pennant off at the first mark you will have a “half depth board” with a draft of about 16" – 18". If you lower the board down even lower and cleat it at the second mark you will have a “full board” or about 28” of draft.
NEVER let the board down more than the second mark for a full board setting, as it will likely chatter or wobble in the trunk, and it is also not the best angle for the board in terms of performance. Occasionally though the board will still “chatter”. Lots of centerboards do. Usually it is a sign you are going quite fast, which is good, but if the noise or vibration is annoying, just pull the board up a tiny bit and the chatter will usually go away.
So long as you are within the limits of the recommended maximum depth setting, you can sail the Melonseed with the board set at any depth you like or feel necessary based on the depth of water you are sailing in. Note that the boat will not go to windward as quite as well with a half board or less as it will with the full board (set at the 22” mark) down. You need very little board down when running down wind, so if you want to fine tune the performance you can pull the board mostly or even all the way up. Be sure to lower it again before you tack or gybe, because it is very difficult to perform either maneuver without some board down. It you are going down wind in a very strong breeze you should absolutely have some or all of your board down for increased control.
If you set the boat down on a beach with course sand or clamshells you should ALWAYS check to see that something hasn’t become stuck up in the trunk and jammed the centerboard so that it will not fall down. Just before you set sail, give the pennant a little up and down pull to reassure yourself that the board is free to drop.
If you sail in a tidal salt marsh and there is a lot of marsh grass floating around in the water, or there is lots of floating seaweed, your pennant may collect bits of this flotsam and jamb it up inside the trunk.
This is unlikely to happen suddenly, but rather over the course of a long period of time. If this happens and the board becomes jammed or does not go all the way back up into the trunk, then you will have to lower it down and dig the grass out with a stick. You will be amazed at how much eel grass can be compacted up there.
When you remove the bolt that holds the c/b in the boat you will find
that there is really a piece of PVC pipe that is holding the board in
It is like a bushing around the bolt so that the threads of the
bolt don’t wear on the c/b and there is a tight watertight seal.
Note the orientation of the bushing when you remove it, and when you
install it back in trunk with the new board put it back the same exact
Clean off the old sealer (3m #5200 or Sikaflex #291) from the old
washers and trunk.
Lay down a big patch of masking tape over hole in
trunk. Punch hole in the tape big enough to dry fit the pin and
washers, and trace around the rubber washer to locate area that sealer
make contact with the trunk.
With a razor knife, cut out circle or tape
that is under washer and sealer, leaving area around it all masked off
so the goop doesn’t GO EVERYWHERE!
Apply modest amount of sealer on
trunk and rubber washer.
Tighten up bolt and nut just a little more than “hand tight”, not too
Melonseed Sailing Lifestyle
Wipe off excess sealer and clean up bolt and then remove the
tape and things will be really neat.