J/30 Class Association Forums J/30 Forum The Boat, Sails and Equipment Bulkhead Disection

Should anyone be interested, I can describe in exact detail the contents of the main bulkhead now. One thing I'm now certain of, if the laminate on the forward side is loose, question the condition of the bulkhead. I'm not sure why my port chainplate stayed put. Now to put it back together!

Mark....Inquiring minds want to know!! Please fill us in on the details

OK.

I knew I had some sort of trouble. The white laminate on the forward side was no longer glued down over large areas. I took the cabinets and sink out of the head and everthing off the bulhead and started peeling (carefull, the laminate is sharp along broken edges!). It helps a lot that Foghorn is sitting on her new trailer next to my garage and workshop!

The blukhead is almost entierly blasa cored. There is a thin layer of fiberglass matt over the foreward side, I suppose to hold the balsa together. The chainplates bolt into a triangle of 3/4" marine plywood. The plywood is about 15" wide at the top and 24" long and does not extend over to the hull (there is blasa from the edge of it to the hull. On the aft side of this there is about 1/4" of glass in the painted areas and seems like 1/8" and less under the veneer. There is about 1/2" of 3M 5200 like stuff between the bulkhead and the hull. The tabbing is about 1/4".

After peeling the laminate the extent of water damage was obvious. I could see it right through the glass surfacing and large areas of the matt had cracked. It peels of easily with a cutting tool and a chisel. I had soaking wet, water damaged, or missing balsa over a region from the hull to about 3 feet in from top to bottom. I have almost stripped it all. The plywood that the chainplate bolts to was about the consistency of cooked lasagne noodles and peeled out in big soft flakes.

There was really nothing other than the glass on the aft side holding the chainplate in. I'm not sure what the heavy tabbing on the foreward side was for since it is connected to nothing more than a thin layer of matt that glues together blocks of end-grain balsa.

A warning. The laminate on the foreward side started peeling last spring. Before that all looked well. However, this must have been going on for a long time. There are two places you can inspect the bulkhead core material: the access for wires and waterlines under the cabinets, and under the floor just foreward of the keel. Also, in the cabinet over the head you can tap holes into the plywood that the port chainplate bolts to and the starboard chainplate in accessable in the closet. My starboard chainplate looks fine from tap holes and visually with the laminate removed.

Mark, after seeing your note about bulkhead symptoms I inspected Volcano's similar situation. However, all sample holes drilled were bone dry, and it appears on mine only the formica type laminate on the forward side is loose. I am going to attempt to re-glue the laminate via some of the whole holes just tested. I also pulled a couple of bolts on the chainplate and tested the inside of the holes with a probe ... everything is solid and dry. Whew!

Tom,

My boltholes were dry and solid to. Anywhere there was an escape for things to dry, like near the holes, things were dry. The plywood was a disaster not an inch from each hole. However, sounds to me like you're good if all your test holes are dry. Good luck.

How do you plan to refinish after the holes are filled?

Mark,

Did you put marine plywood back in, and if so, what kind? Seems there are many different types of marine plywood. Some people I know that repair boats say they use MDO plywood instead of the marine grade. Does this make sense? Also, did you extend the plywood at all, or make it the same size that was there? Just curious, as I'm doing the same repair right now...I'm not sure how the mast stayed up...the plywood was the consistency of oatmeal.

Thanks.

Scott,

I used 1/2 inch marine plywood. I don't know what kind, whatever could be had in St. louis. I added an eigth inch of glass on both sides and redid the tabbing on the forward side (Although, I have no idea what the foreward tabbing was for sice the structure was all on the aft side.) Put it through some tests last year. One six mile beat in 15 - 25 with 1600 pounds on the high rail and the other in the water several times. Didn't move a bit. I think the glass on the aft side is all that holds 'em up when they get like your's is and mine was. Send and e-mail address and I'll sen pictures.