Jackdaw's solution is simple; but there's a wrinkle (see below). Also, Allan's picture apparently shows a 1980s-or-later Hunter with a 1970s Schaefer double cheek block ('organizer'?) on it-- is this original?
Here is another example of when 'the boatbuilder is not your friend' (as I used to tell my customers at WM). I'll say this as succinctly as I can:
EVERY piece of hardware that can potentially a) leak, or, b) be replaced before the boat goes to a landfill, should have its mounting bolts accessible from both sides. No blind tapped holes in a buried aluminum backing plate is sufficient, no matter what the boatbuilder (who is not your friend) has done or your friends (who may be less than technical experts) have said.
Reasons for this opinion (which is
not a personal opinion but technical fact):
- What happens when the aluminum backing plate parts from the 'glass, inside the headliner where you can't see it? This can happen due to water intrusion. (Also, what's holding the aluminum in place? --do you know? Trust me-- it could very well be the piece of hardware itself. Take the bolts out and listen for a dropping sound. Now what?)
- How can you tell if there's water intrusion? --when water is coursing down the outside edge of the headliner into your bookshelves? And how do you know where it's coming from? This is the well-discussed problem with all molded headliners-- and the reason why only the cheapest boats still use them.
- Cheek blocks, halyard stoppers, organizers and winches are under shear loads, not tensile loads. This means the load is trying to rip the hardware laterally off the boat, not upwards. You don't need a block large in area for a backing plate; you need one that's thick. The plate of aluminum is probably 1/4". This isn't good enough. The unthreaded section of the mounting bolt needs to lean up against something thick to stop it moving along with the load. This necessitates a thick block, adequately bonded to the underside of the deck, in which a thick deck layup won't hurt either. I seriously doubt either of these is present in 1980s Hunters. How thick do you think your deck layup-- minus the core, which provides no strength-- is? With the metal plate, this is what's holding the load of your cheek blocks. As I have so often said before, this is definitely a case for bonding the backing block with 5200, which is excellent in shear and tensile loads. Butyl tape under the hardware is okay here, given a proper backing block (which the aluminum plate is not), because all it has to do is to temporarily hold out water (about all butyl tape is good for). 5200 under the hardware would be great; but the hardware needs to be replaced or upgraded someday, so it needs to be removable.
- Long fasteners under shear loads are more prone to bending than short ones. This means the longer bolt needed for a double-stacked cheek block is less than optimal (especially for the upper sheaves' lines). Handrails are under bending loads and have the same problem. The shorter the fastener, the stronger the hardware will be, in use. This is why you see teak handrails in which the mounting bolts are way down inside deep-bored plugged holes; and why you see stainless ones with mounting flanges.
Solution (you won't like this):
Cut an access panel in the headliner, dress it off as prettily as you like, and gain access to the bolts and their locknuts and have a means of inspecting against water intrusion. (
Rule number one: it's a boat; therefore water gets everywhere. Rule 2: never dismiss the primacy of rule 1.) Install an adequate backing block, properly bedded to the underside of the deck. I have discussed this sort of block before in these posts.
Sorry; but, again, the boatbuilder was not your friend here. Don't hesitate to call into question practices that are clearly inadequate. You questioned how to remove and replace this piece of hardware, because it wasn't obvious to you how that could be done. You were right: the boatbuilder left you no means of ascertaining it yourself. So, as I said, you might not like the solution; but I'm willing to bet you already thought of it. And that should tell you something!
(Forgive me for preaching; I was tutoring kids all day today!
)
