Strengthening cabin roof

[Ryan]

I am looking for ideas on how to make the cabin roof of my Hughes 25 more sturdy. The cabin roof was flimsy underfoot even before I removed the interior fiberglass liner, and now that the liner is gone, I have the opportunity to do some structural work to fix this. As it is now, the entire cabin top is 1/8" fiberglass. Do you guys think that coring the cabin roof is the best option, or should I build it up with fiberglass mat/cloth? The outside of the cabin is in horrible shape and there is a ton of grinding to do there, so I can apply core/mat to either the inside or outside at this point.

[Tim]

If you really want to stiffen the overhead, you have a couple viable options. While I don't recommend this route, note that adding pure fiberglass will strengthen the overhead, and will stiffen it to a degree, but to truly create something stiff that doesn't flex underfoot, you probably need to do one of the following two things:

1. Apply a core material to either the inside or outside, and cover the new core with new fiberglass, making a sandwich construction.

If you can stand the idea of adding 3/4" or 1" to the exterior dimensions of your cabin trunk, then adding core directly above the existing exterior, then laminting new glass, may be the easiest option. Consider the ramifications carefully. If you feel this could compromise the looks or function of the boat, then coring from inside might be the only way here.

2. Apply structural beams from inside, made (most likely) from laminated wood.

You can laminate the beams off the boat and then install, or can also laminate them right in place. As with everything, it depends on the exact situation, your skill, and your expectations. You can install the beams with epoxy or 5200 inside and possibly mechanical fasteners from above, if you need to do deck work anyway.

[Ryan]

Tim

I have considered both possibilities before now, and originally leaned towards the beam option. However, because my cabin roof has a huge pop top, the beams would have to run parallel to the centerline of the boat which leaves me no clean way to tie them into the hull. Since the deck is being recored, and the original deck skins can't be reused and I have to laminate new ones, the added work to core the cabin top isn't as big a deal as it could be. Do you think that an additional 3/4" is necessary (as much as you can say without actually seeing the boat anyway)? The original top was about 1/8" glass with a 1/16" liner on the inside. I was strongly considering 1/4" balsa core and another 1/8" glass skin on top. Of course this doesn't include fairing either...

Thanks for the opinions!

Ryan

[Tim]

No, the 3/4" number was just picked at random, and assumed a somewhat thicker core, plus the fiberglass overlay. I'm sure you could use much thinner, as you suggest, with results that match the need.

Given everything you've said, I'd say that the core-on-top option is the best way to go.