CORRECT WAY TO INSTALL DAGGERBOARD CASE CHEEK BLOCKS
Daggerboard case cheek blocks are best secured in place by machine screws, acting as studs as shown. Pan head screws are not secure enough, and leaks here can be an ongoing problem.
The F-33 head with Cheek Block mounting block just visible at left. The best installation, as shown
Problems may have been caused in this area on some boats by the use of self tapping pan head screws around the perimeter of the Cheek block mounting plate which do not hold very well in thin fiberglass. This cheek block can see some very high loads at times, and self tapping screws are not very good at resisting such loads. Worse, when such screws are removed to check block, the threading in the fiberglass is not very stable, and can be easily damaged to where the screw will not bite when put back in place. Thus one has a guaranteed leak.
The only correct way to secure this check block plate to thin fiberglass like this is to use machine screws, tapped into the fiberglass, with the head on the INSIDE of the case, so that studs are formed inside the boat, which then take nuts. This makes the plate easily removable, and secures it to the case side in the strongest possible way - it is thru bolted, and there's no chance of stripping the threads.
If there are problems with an existing boat, then remove all screws, drill the hole out to the next size up tapping size, and tap to suit machine screws. These will hold better than self tappers, but over time have the same problems - the holding power is limited and the threads are easy to damage. Studs are the only right way.
With existing boats, it may be possible for someone with small deft fingers to insert pan head machine screws from the inside of the case via the check block hole, but this is difficult to achieve.
Another solution is to insert some threaded rod, and epoxy a nut to the rod on the inside, which should be easier than inserting a machine screw from inside the case. Then wind rod back out until nut beds itself on inside of case. Allow epoxy to set and you have studs. Bit of a fiddly job, but definitely doable.
It is also very important to protect from corrosion in this area as per my standard procedures. The cheek block should be bedded on a sealer (silicon or 5200), and all stainless screw heads, nuts, washers etc. should be insulated from the aluminum plate by a nylon washer where possible.
Then, when fitting, make sure the sealer used squeezes up inside every bolt hole to insulate bolt from aluminum.