260DA Engine Hatch Issues

FishOn

FishOn

Member
May 2, 2018
128
Washington State
Boat Info
2000 260 Sundancer 260DA
Engines
5.7 Mercruiser w/ Bravo3
Surprisingly I wasn't able to locate any posts on this matter. I have a 2000 260DA and would like to alert members to an issue they may have as well. If you notice any springy-ness or cracking sounds when you walk over your engine hatch then this may be of interest. Also, if you don't I'd highly recommend that you read so yo know how to prevent the issue. The engine hatch is constructed of fiberglass and a balsa core. There are fixtures mounted through this and the manufacturer did not properly seal these. The fixtures are 2 receivers for the legs of the rear bench, the access port for extinguishing engine fires, the receiver for the cockpit table, and the hatch latch. The first 2 listed are the ones you want to worry about. On my boat these were unfortunately not sealed. I have no idea why not. When I removed them to inspect I found rot in the starboard side receiver for the rear bench seat. I removed the hatch and began exploring. This is what I found:
20210417_174446.jpg
 
All of the blackish colored core is rot which originated from the smaller hole on the left in the photo. It travelled quite a way. I'll post the repair process. I'd recommend that everyone check to see if these fixtures are sealed on their vessel and at a minimum use some 4200 sealant if not. Itd only take you about 30 minutes max.
 
If anyone has a suggestion on replacement core material I'd be interested in hearing. I'm thinking of using 1/2" marine grade plywood but am a little worried about the weight. I may need to change the lifting struts to accommodate it. Also I'll need to find some new insulation I guess from an automotive store.?
 
FishOn said:
If anyone has a suggestion on replacement core material I'd be interested in hearing. I'm thinking of using 1/2" marine grade plywood but am a little worried about the weight. I may need to change the lifting struts to accommodate it. Also I'll need to find some new insulation I guess from an automotive store.?
Click to expand...

There are several transom repair compounds that you could look into, I'm not sure how well they would work in your situation. They are basically a pourable epoxy that eventually match the strength of marine plywood but usually lighter weight. Just google "transom repair compound" and check out some of the videos.
Another option might be Coosa board. Again, similar strength but much lighter weight than marine plywood...and it cannot rot.
 
You can look into foam (Coosa, Divinycell), but given that it's a relatively small repair, I don't think the weight difference is going to be enough to make a difference. The foam still needs to absorb quite a bit of epoxy and there's a weight gain there. But there are charts out there that show weights and you could look into that. Certainly can't go wrong with the foam, though.

One of the reasons (amongst others) for the balsa is that it easy to lay down and conform to the surface without trapping air pockets like a large sheet of plywood would. You could cut the plywood into something like 8" squares (see pic) and do the same thing. It's also less likely to transfer moisture laterally than plywood.

"For fun" I repaired a 2-1/2'x4' hatch and re-cored it with that pinkish foamboard insulation that you can buy at Home Depot. I knew it would only take a few hours to re-do the repair "properly" if I needed to, so it was no big deal if it didn't work. That was 6 years ago. The core, itself, is not what give strength to a hatch - it's the separation of the top and bottom of layer that gives the rigidity... as long as the core and the glass don't delaminate... ;)

But, yeah, been there done that!

IMG-3923.jpg
 
Thanks guys! Going to look into that coosa board, if I can find it. LD you have me seriously thinking about the foam insulation.
 
Just to be clear, I used marine ply for that floor. But I also redesigned the layout and structure to be different than it was originally. That would take longer than a couple hours to redo! Here's some hatch/foamboard insulation - nothing fancy - pretty basic, actually:

IMG-4070.jpg


IMG_4097.jpg


IMG_4228.jpg


FYI, don't use poly for this - use epoxy - poly will melt the foam. I used one layer of 1708 for the underskin, but I'd probably use at least 2 for your hatch.

Oh... make sure your worktable (or floor) is perfectly, 100% level and true. Otherwise your hatch won't be!
 
Thanks LD! I'm really thinking that I'll try the foam. Maybe the R-Tech stuff. Most stores are pretty low on supplies due to covid. I have the west system 105 epoxy and a bunch of 6oz. cloth. The previous glass was about 1/8" thick so I think I need to put down about 12 layers to match that. The cored area on this hatch is inward of the part that mates with the deck when closed. That being the case it doesnt really matter if it's perfectly level, fortunately. I will need to source out some more sponge/foam insulation. The foam core may also help keep down noise better than the plywood. The old insulation is shown in this earlier photo.
20210417_153124.jpg
 
Fish, "level" is not about how pretty the underside looks - you have to make sure the hatch is being rebuilt level so that it's not warped, otherwise it may not sit right on the boat.

Check into mass loaded vinyl (mlv) for the sound deadoning foam - much better than egg crate. Soundown is one manufacturer.

Buy some 1708 glass.

Buy an oscillating tool - much faster than your hand scraper.
 
LD thanks for this information and sharing your experience. Agreed the 1708 is undoubtedly the better choice, but the 6oz. should still work, wouldn't it? Also it sounds as though you are saying that the new glass layer (to encase the core) may actually warp the existing structure? I hadn't considered that at all. It's the first I've heard of it.
 
FishOn said:
LD thanks for this information and sharing your experience. Agreed the 1708 is undoubtedly the better choice, but the 6oz. should still work, wouldn't it? Also it sounds as though you are saying that the new glass layer (to encase the core) may actually warp the existing structure? I hadn't considered that at all. It's the first I've heard of it.
Click to expand...
Sure, you're welcome, Fish!

1708 is a stronger cloth. You'll also need less of it since it's thicker to start with. But it's stronger because of the "style" of cloth it is. Yes, you most likely would be fine with many layers of the 6oz, but best practice would be to use the 1708.

No, the warping can happen because of an uneven table. The table will likely take on the uneveness of the table/work platform.
 
Ah, I think I see what you are saying. The issue would be resulting from flex in the remaining part of the panel (which seems very stiff). If the panel is flexed then the new work would essentially lock that shape into the repair. Oy, looks like I'll be working on the garage floor. My back aches just thinking about it.
 
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