J/30 Class Association Forums J/30 Forum The Boat, Sails and Equipment FYI, delaminating wood, rear of Engine Box (Older Cabin layout)

For others with the older cabin/cockpit layout, I thought I'd pass on the results of our past week's nautical archeological exploration of Hull 3 (Youthful Indiscretion)

Last season, we noticed some hints of delamination of the marine plyboard behind the back of the engine box. It looked nasty to do in the water. Well, it's spring, and we're on the hard, so we decided we actually had to do something about it.

Here's the context:
http://www.panix.com/~dwl/boat/context.jpg

The back of the engine box (At least our hull, we've found many minor oddities on Youthful, compared to boats built 50 or 100 hulls later) consists of a sandwich. The front end of the molded cockpit pan forms the back top portion of the sandwich, then a arch of marine plyboard, and then a layer of the interior faux teak laminate/veneer that forms the interior. Once we took it apart, we found the plyboard arch (3/4 inch marine plywood) totally disintergrating, and the laminate starting to go soft in spots. (Especially where the opening port goes through the cockpit pan and then the laminate.

Here's the veneer, once we pulled it.
http://www.panix.com/~dwl/boat/backVeneer.jpg

And here's what was lurking behind it...
http://www.panix.com/~dwl/boat/Arch1.jpg

Basically, this hasn't contributed much stiffness to front of the cockpit for some time. Ick.

Needless to say, we're replacing the lot. It isn't too terrible. I had to unseat the opening port (not too bad) And then it was mostly a matter of keeping all the bits intact, as I pulled them out. The arch actually screws into the front of the cockpit, somewhat lamely, with wood screws, so undo them, and it can be worked out.

We'll cut new wood to match, and probably beef up the attach to the front of the cockpit floor slightly. I am not a big fan of wood screws for anything even slighlty stiffening in a boat. (And no, I don't think this actually is all *that* structural, but still....)

- David

Interesting. On my '84 vintage new layout, the support frame sits directly over the front of the engine (roughly 6" back from the companionway).

But I noticed one day as we pounded up lovely Delaware Bay in a short steep chop, that the connection between the "mini" bulkhead and the underside of the cockpit had no fasteners (and appears to have always been that way). As we pounded through the waves, I could watch the bulkhead work about 1/2 to 3/4 inch vertically. It struck me that if the connection had been rigid, the screws probably would have shredded the bulkhead and allowed any incoming water to get into the plywood under those conditions.

As it is, the bulkhead appears sound, even if the boat around it is a bit bendy.

Urk. That's one of the more tricky questions in structural engineering, isn't it? Do you tie it together, and stiffen, and risk breaking it, or do you let it float a bit more, and let it all bend. The DOA arch was wood screwed into a chunk of wood glassed rather solidly into the front of the cockpit pan. (I'll try and remember to take a picture of that area next time) I've been leaning towards making sure the wood is sound, re-glassing a bit, and then properly tieing the two structures together. Now, I need to think a bit more, about whether that would lead to just chewing apart the new arch. Of course, the old one did make it 28 years, and the water intrusion was mostly bottom up.

Hrmph. Well, I can think about that while I scrape, clean and paint engine bits.

- David

which leads me to an interestring question .... I have two see through hatch boards.... the upper one cannot be pulled up when you stand on the bridgedeck right in the middle......

when you spread your feet apart its easy to pull out.... :-)

this is a little bit exagerated ( maybe a lot) , but it does make a difference where you stand.

Any other with the same ?

Thor

thor,

Ours does the same. I just attribute it to old age and the nature of the beast. But, maybe it is something I should look into....

Thor,

I have the same problem. It was very vexing at first. I could not figure out why the boards came out sometimes and not others. I was thinking of fixing this this year by glassing in 2 stringers that run parallel to the companion way. Thoughts?

David

The stringers would be under the companion way just for clarity (-:

My hatch boards also bind sometimes-but only when the boat is out of the water on stands-I think the position of the stands may have an impact here. But anyway, I've found that an occasional spritz of McLube down each side of the slide takes care of the problem.

i did climb over them and opened them from the inside.....

dont laugh ....

but even we J boaters have to make fun of ourselves once in a while ... dont we ...


thor

Climbing over was just as confusing because I told my wife that when I open it from the inside it works fine. But I tried to show her and it did not work because she was standing right in front of the companion way - ha ha on me. However when she backed up and stood on the traveller track - vola we could lift them out with two fingers. That is how we figured it out.

This flexing however has led to another problem. I had leaks under the sill because over the years the adhesive they used had lost its bond and they were leaking onto the quarter berths. I have now ripped the sill and hand grabs off and I am in the middle of re-milling them and re-installing them. Fun Fun.

David