F-330SS Bulkhead Replacement
 

I have been monitoring a 'wet' bulkhead on my 1996 Formula 330SS over the past year. This bulkhead is the 'firewall' bulkhead, which separates the engine bay and the fuel bay. The high moisture level was discovered during the pre-purchase survey (in 2012) and the surveyor advised to keep an eye on it. Overall the boat was a good deal, so I went forward with the purchase and have been keeping an eye on the moisture levels.

I drilled some test holes in various areas of the structure to get an idea of the moisture levels in various parts of the structure. The problem area is in the center of the bulkhead, around the area where the center engine mount stringer attaches. The source of the moisture was from the fuel tank bay. I drilled a hole in the bulkhead and installed a thru-hull in that area to allow drainage. I pulled about 1 quart of water out of the fuel bay using a shop vac. I believe that the moisture is also propagating from the bulkhead into the center engine stringer. I have exposed some of the wet areas to see if I can get them to dry out. . . . That has only been marginally successful, as the center of the bulkhead remains wet. The wood is still fairly solid, and to head off rot, I have injected Ethylene Glycol into the wettest areas.

Here is a picture of the firewall bulkhead and the center engine mount stringer with some of the glass coating removed for inspection and to help the drying process.
http://home.comcast.net/~tpenfield/F...s/IMG_2048.jpg

I was able to get some moisture reduction, but since the boat lives outdoors, it really does not have a chance to dry out very well. So, now for 'Plan B' . . . I am thinking about replacing the middle section of this bulkhead so that the moisture does not continue to propagate throughout the structure. I know that there are a few folks on this forum who have done some bulkhead and stringer repair on their Formula's over the years. So, I wanted to get some inputs on my plan of work.

Using my 1990's "CAD" software, I have created a drawing of the structure of my 330SS. The main bulkhead is shown in blue. The wet area is the orange hashed area low and centered in the bulkhead.
http://home.comcast.net/~tpenfield/F...330WF4600X.jpg

I plan on cutting out the center section of this bulkhead and removing it. The section to be removed goes right up to the main stringers that are along side the fuel tank.
http://home.comcast.net/~tpenfield/F...330WF4601B.jpg

Then I will have access to the fuel tank bay, where I can remove some of the foam from behind the tank, inspect the butt end of the tank, etc. There is about 6" of foam between the tank and the bulkhead. So, with this area cleared out, I will have room for tabbing in the new bulkhead.
http://home.comcast.net/~tpenfield/F...F330WF4602.jpg

There is a spacer/stiffener for the bulkhead (shown in Yellow) that I will probably leave in place, unless it seems to be in rough shape once I expose it. After a bit of grinding the tabbing contact areas, I will make and install a replacement of this bulkhead section.
http://home.comcast.net/~tpenfield/F...F330WF4603.jpg

In order to get the tabbing installed on the 'blind' side of the bulkhead section, I will probably need to drill a couple of 4" holes in the new bulkhead on both sides of the center line. Then I can install a deck plate in those holes. I will probably keep some sort of drain for the fuel bay, but give that drain its own 'mini bilge' so that the engine bilge water does not find its way up into the fuel bay. (See below)
http://home.comcast.net/~tpenfield/F...inage-Dam1.jpg

I am hoping that replacing the bulkhead section at this time will avoid more significant work in the future. I had to do some similar work a while ago on my 242SS, but that was a single engine and a much smaller boat. Just looking to get any input from folks who have done a bulkhead or stringer repair on a twin engine Formula.

I will probably do the cutting work a week or so after the Thanksgiving Holiday (USA), and let it sit until until Spring 2014 to do the fiberglass work (3-4 months).

I'll post updates as I go, but for now looking for any input, comments, ideas, gotchas.

T.I.A.

wow kudos to you for taking this on, and your cad drawing very cool, will follow you along, hope it goes well

Only advice I'd give is to make sure it's REAL dry before you begin. Locking any moisture in could just make the problem continue to get worse.

Looks like a challenging project. Good luck!

Dave

It is a PAIN IN THE AZZ!!! After doing it on my boat I don't know how it can be done properly with out removing the last foot or so of the floor. You need to be able to tab the the ouside of the stringers as well as the inside. I don't think a 4" hole is going to do the job. You have to round over the inside edge before you glass and doing that blind will be super hard if not impossible. It sucks because you start to get into all the "may as wells". You know while I have this ripped apart I may as well go a little farther… I glassed mine up on both sides before I put it in the boat. That way I knew I had a real good bond of the glass to the wood. Then I removed the entire floor of the boat and re tabbed in the thing. Then I poured in new foam, put the floors back in (oh ya had to re-core them as well because they had delaminated) and then got it all back together. It can be a never ending excavation project…

Thanks for the cautions and advise, Audiofn. IIRC, you have a thread (or 2) on your rebuild work, so I'll search those out. I figure that if I map out a game plan, I can (hopefully) avoid many of the "may as well" items. I did a bit of that when I had to do the bulkhead on my 242. Ended up replacing the fuel tank, adding a secondary bilge pump, etc.

I plan on making my cuts of the bulkhead just inside of the main stringers, so that the outside tabbing of bulkhead-to-stringer will remain intact. I might have to overlap the bulkhead in that area where the new section of bulkhead joins the existing section. We'll see how that goes . . .

I have been trying to 'avoid' doing this 'project' by seeing if I could get the structure to dry out. But, without a heated indoor place to store the boat over the winter, it does not seem to be happening. As much of a PITA that this will be, I am hoping that it will prevent more extensive work in the future.

My game plan is to start cutting on the weekend of Dec 7-8th, so I still have some time to anticipate the 'fun'.

The water will go a lot farther then you expect! Even if you have a dry area it would take for ever for it to dry out if it ever would. Best thing to do is to do what you are and cut it out. Just realize that the wet area is going to go a LOT farther then you think unless you are lucky. Keep us updated when you get started!

Understood, wood is like a sponge, so I know that the moisture has traveled a bit already. It is something that I will continually have to monitor, even after I replace the bulkhead section. I probably should get a professional grade moisture meter to make an annual inspection easier.

just so you know this is a common problem on the 28 ss 33 ss and the 336 sr1 boats
their is 3 in my area and all have the same issue

Yes, probably a lot of boats have the moisture issue in the bulkhead, yet remain unknown. It seems that the problems are related to the fuel bay accumulating moisture . . . the lower part of the foam retains the moisture up against the bulkhead . . . The moisture then makes its way into the wood core and migrates outward towards other structural components. This process takes many years to play out.

I contacted Scott Smith at Formula about the issue, when my 242 bulkhead had the same problem, just to get some guidance on the corrective actions to take. I'll apply that same advice here as well.

It would seem that it is not an issue exclusive to Formulas though, any boat of similar design could have the same issues.

If I ever get to working on my 302 again I plan to put a way for water to move around a little more freely. You can't possibly keep it out 100% so I am going to let it go in under the tank and then back out. I have not figured out how to do it 100% yet but I have some ideas I have been running through my head. This will allow water that may get up in the cabin or anyplace along the deck to just run down and out the bilge…. Like I said not sure how I am going to do this yet. Or I may change out all the inspection plates to water proof ones and glass the floor in place so that it is in fact water tight...