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sneuman 06-04-2003 11:46 PM

replacing bulkhead
 
any thoughts on how to do this? The bulkhead is tabbed to the hull - can a new one plywood one be just slipped in and secured?

Jeff_H 06-05-2003 03:23 AM

replacing bulkhead
 
This question came up the other day but in a lot of cases you can''t just slip the bulkhead in because the original bulkhead was installed before the deck went on. The way to handle that is to build the bulkhead out of two layers of plywood that are half the thickness of the original bulkhead with each layer being split in half horizontally. The split should be offset horizontally by perhaps a foot or so. The one that I did I sealed all of the edges and faces of the new bulkhead with epoxy and then epoxied the pieces together during installation. You should have a rubber strip around the edge of the bulkhead so that the bulkhead does not actually touch the hull. Tabbing can be very difficult on some of these newer boats were there is a hull liner against the bulkhead at the hull and deck. There is no easy answer except that you will need to cut away the liner. If you make a careful cut you should be able to put the liner back when you are done. One word of caution, on a lot of newer designs there is a main transverse frame molded into the liner and that frame should not be cut. I suggest that you go with wide tabbing and that the tabbing be tapered at its edges.

Jeff

Jeff_H 06-05-2003 03:28 AM

replacing bulkhead
 
You may not have seen this but here is the answer that I gave you last time you asked this question:

Even a badly damaged bulkhead will often be holding a boat in shape. It is important that before you remove the existing bulkhead you take all loads off of the hull and deck in this area. That means unstepping the mast and carefully placing the jackstands so that the hull won''t get distorted.

Before you remove the bulkhead, you should take careful measurements and make a cardboard or plywood template that you can later use to check that there hasn''t been distortion of the hull and deck.

Many times bulkheads are installed before the decks are put on and so in some boats you cannot install a replacement bulkhead in the finished boat. In those applications you may need to build the bulkhead in pieces. The technique that I have used in that situation is to build the bulkhead in several pieces. Bacically I made two bulkheads each half of the thickness of the finished bulkhead(in my case two layers 1/4" thick). Each lamination of the bulkhead was cut horizontally so that the bottom could be put in place and the top sprung back in above it. The horizontal joints were staggered roughly a foot. The process consisted of sliding the taller of the two lower half bulkheads into place, buttering up the shorter bottom bulkhead half with slow cure epoxy and sliding it in place. Buttering up the longer half of the upper bulkhead and putting it in place and then installing the shorter upper bulkhead. They were clamped with small sheet metal screws that were later removed and the holes patched.

All sides of the bulkhead were sealed with multiple coats of epoxy before assembly and strips of rubber were used as a spacer between the new bulkhead and the hull. When cured the new bulkhead was tabbed in.

Marine surveyor firends tell me that this issue of rotted bulkheads is becoming ''the next blister problem of the 21st century'', meaning that it is becoming extremely common to find older boats with plastic laminate (formica) on their bulkheads masking serious rot. Once rot begins behind plastic laminate it is free to spread un-noticed until the bulkhead is shot. The plastic laminate actually contributes to the rot by not allowing the bulkhead to dry out as quickly when it does get wet.

Good luck
Jeff

sneuman 06-05-2003 04:10 AM

replacing bulkhead
 
Hi Jeff,

Indeed, I did see your response last time, just fishing for more information. Actually, your response this time was even more helpful - many thanks. One last question - the mast is deck stepped not directly over by a few feet to one side of the bulkhead. The present bulkhead is in two horizontal pieces just as you suggest for the replacement. Can I swap one half and then the other without taking the mast down or is that a no no?

Jeff_H 06-05-2003 04:57 AM

replacing bulkhead
 
It is hard to say without seeing the boat, but unless there is a king post right under the mast, I would suspect that you would need to remove the mast and also at the very least release the shroud tension. If you make a template before you removing anything then perhaps you can try removing the bulkhead and see if it distorts. I would only do this if the yard can remove your mast without moving the boat.

The big thing is that you do not want to have anything distort the hull in a way that might get locked into the shape of the boat by the new bulkhead.

Jeff

Jeff

sneuman 06-05-2003 05:52 PM

replacing bulkhead
 
that makes sense. many thanks.

sailingbauble 07-27-2003 08:32 AM

replacing bulkhead
 
Briefly, and simply stated, in home improvement projects on older homes, where there is sagging in a load bearing wall, a second bearing wall is often built right up against the original wall to assume the load. The original wall can either be removed or left in place. Given the relatively thin cross section of the typical bulkhead, this might be a type of "fix" worth exploring.

sneuman 11-12-2003 09:44 PM

replacing bulkhead
 
Hi Jeff,

Could you explain what the "strips of rubber" are for?

Cheers,
Scott

Jeff_H 11-13-2003 03:29 AM

replacing bulkhead
 
The rubber strips prevent hardspots where the bulkheads touch the hull.

Jeff


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