Wood Rot - Need Advice

[JohnV8r]

I'm down on Shambala this weekend removing the old Formica from the interior pieces I cannot remove so I can install the teak veneer I have. When removing the Formica from the bulkhead on the aft end of the settee, I ran into some wood rot. For reference sake, here is the area I am talking about:



Shambala is an FBC with the port bulkhead removed like a Sportfish model. That is why there is a half bulkhead. Both bulkheads have an epoxied section and then a non-epoxied section that appears to have been added on top of that bulkhead. I'm not sure if this is the standard factory installation or not but here is what I am talking about:



At any rate, I found two areas of wood rot. The first is a relatively minor area on the seam of the top/added section of the bulkhead where it appears a window leak trickled freshwater down. I think this area can be scraped out, a 2" barrier cut around it per Capt Patrick's wood rot replacement instructiona, and then refill the area with epoxy and colloidial silica. Here is the area:



I found two additional areas of wood rot at the bottom of the bulkheads where the bulkhead meets the floor. This area:



When I pulled up the aluminum trim between the aft interior floor panel and the floor panel between the motor boxes, a much bigger problem area was revealed. This area has two mahogany pieces that sandwich the plywood bilge bulkhead. When I removed the rotten mahogany piece on the interior side, I found the top of the plywood bilge bulkhead was rotten along with a bad patch in the bulkhead to the right of the picture that reaches down to the fiberglass tabs that attach to the hull:



No question that this section of the bilge bulkhead needs to be replaced. The rot is just going to spread if I don't get it out. The good news is the settee floor is coming out tomorrow, so I will have as good access as I can get. My question is really twofold: First, can I just replace the bad bilge bulkhead section by splicing in a replacement section as opposed to ripping everything out and putting an entirely new section in? If so, what do I use to glass this into place? Does this bulkhead add stiffness to the hull or is it primarily for floor support?

Please advise.

Thanks,

John Vietor

[Whaler1777]

That's a very small and easily replaceable piece of bulkhead... Mine was discintegrating as well... What I did was remove all screws holding in floor supports took a fein tool and cut out the bulkhead flush with the hull and stringers, once I had a nice clean open area I used firring strips to make a template, cut a new bulkhead out of 3/4" coosa board and laminated both sides with biaxle and installed making tabs on both sides using my favorite biaxle tape... Done... That area of the bilge is usually always wet so it is prone to wood rot... Also when I did this, I left the new bulkhead free of any holes there by separating the cabin and aft bilges keeping the stink out of the cabin...

[JohnV8r]

Capt John,

Thanks for that. I'm going to cut out the rotted bulkhead today. I'm going to see if I can find a place here in Northern CA that sells Coosa board. If not, I'll use epoxy coated plywood. I'm curious about the idea of not putting a hole for bilge flow through. I love the idea of limiting the amount of water that gets under the cabin. Shambala's bilge fills up so that the bow goes down, so yes, I too get a lot of bilge odors in the cabin. Did you put a bilge pump on the aft side of the non-flow through bulkhead? I guess my only concern would be the potential for water to reach the bottom of the engines more easily, but I'm not sure that is really all that disconcerting if I put a bilge pump in the area.

Thanks again!

John

[Whaler1777]

Here's an old pic of the replaced bulkhead...


Here is coosa composites website:
http://coosacomposites.com/
Call them and they will put you in touch with a local distributor...

John how much water are you talking about in the bilge here? Should Never have enough water in the hull that it brings the bow down or touches the engines... I have a 3700gph with float switch set about 4" higher than the one for my 2000gph in the stern behind the fuel tank, a 500 in the center bilge and a 2000/500 in the forward bilge... The small pumps are just to take the excess water that the big pumps can't reach out of the bilge..

[Pete Fallon]

JohnV8r,
Those two areas are common rot problems in the 31's, I had them on my 31 Express, after 50 years the water got in between the gap above the board where the engine box sits, remove the wood engine box rest piece and clean out the rotted area, as for the door bottom Whalers fix is right on. They are both fairly easy repairs, just takes a little time and planning. The area behind the settee, the Formica came off easy with a wide blade putty knife both inside and outside. I cut out the rot and fitted a peice of epoxy soaked plywood then I faired the area smooth with RJ putty then added two layers of bi-ax glass, sanded smooth, put the Formica back on with contact cement. The bottom of the door, I cleaned out all the rot all the way down to the hull, left the original tabbing in place, I used 1/2" Coosa board fittted into the old tabbing, epoxied into place and thru bolted the Coosa board between two pieces of starboard then screwed the old aluminum threshold back into place. I kept the limber hole cut out and installed a Johnson 2200 ghp pump just aft of the bulkhead, I also have 2200gph Johnson Pump at the transom and a Rule 2000 gph forward. Good luck with the repair just take it slow and think it out.
Pete Fallon

[JohnV8r]

Hey Guys,

Thanks for all the help this weekend. I'm sore, cut in several places, and have burns in a couple as well...but I'm happy and on a mission thanks to all the help here.

So the quick answer about my paranoia about water is that back around 2006 we had a torrential 3 day winter rain storm in Northern California that taught me a hard lesson. The bow pulpit on Shambala is AWESOME, but heavy. Here are a couple of pics:





Shambala did not have a cockpit cover back then and an inline fuse to the forward bilge pump had blown. I got a "you better get down here" call from my slip neighbor on the third day of the storm and showed up to find Shambala's bow sitting very heavy in the slip. When I got inside the cabin I was stunned to see the v-berth floor board floating off it's floor frame. Uncle Vic then told me that the aft bilge pump is worthless unless you're under way and let me know that all rain water would likely hit the deck and flow forward into the cabin.

Lesson learned: I now have a second bilge pump under the cabin and a cockpit cover that keeps the rain off.

I'm not sure why I thought about water hitting the bottom of the engines. She'd be sunk by then. However, I am paranoid about water getting into the bilge under the cabin and love the idea of a fourth bilge pump and a way to restrict water from flowing forward.

[JohnV8r]

Hey Pete,

I just re-read your post. Are you saying that I should remove the top L shaped piece above and to the left of the Formica and repair it out of the boat? If so, wouldn't I be just as well to replace the whole thing.



While I'm on the subject, I found several spots like these where screws had been driven into the plywood forward bulkhead when removing the settee seats and settee flooring.



There is no softness to the touch, but obviously the black is the mold that causes rot. Should I treat these areas with bleach per Capt Patrick's recommendation in his wood rot article and then plug them with epoxy to nip any future rot in the bud or can I bleach them and reuse the screw holes? I cannot for the life of me figure any way that there is any regular source of water that would be in that area other than just ambient humidity from the bilge when it's wet.

Thanks again for all the help!!!

[Pete Fallon]

JohnV8r,
That bulkhead is tabbed into the hull at the bottom and on the hull side, depending on the extent of the rot I would replace the entire bulkhead it's only a half sheet of Coosa board, but there are alot of wires and hoses that are attached and with the engine in the boat it might be easier just doing a patch job . The settee end is screwed into the bulkhead from the outside (inside the engine box) and under the Formaica, The board that holds the seat base is screwed from outside also. I wouldn't be too concerned about the black around the screw heads, if they are soft dig out the rot and patch, if not just add some thickened epoxy over the screw heads. All repairs are done inside the boat.

The rot under the door sill, dig out all the rot, all the way down to the hull between the 2 peices of tabbing, use the old tabbing as a slot to add the new Coosa board into and make sure that there is enough good material on each side of the bulkhead to tab strips of fiberglass to on each side (at least 6" on each side) If you have to tab right up or onto the engine beds for a good solid repair that's fine. Watch out where you cut under the door bulkhead there are a lot of wires and hoses in that area and the support boards for the cabin sole hatch area screwed from the outside to the inside through the old bulkhead. If your leaving the limber holes under the door I would add another 2000gph pump with float switch just forward of the repaired bulkhead. If your blocking the limber hole add another pump just forward and wire a high water alarm bell to this 2000 gph pump make sure that it has an auto switch on the pump either way you decide, you could also add a pie high 6" inspection plate 3" above the bottom of the bulkhead. Take your time, good luck with the repairs.

[CaptPatrick]

John,

Here's the way I seperated the forward bilge from the aft on Hancock's B31:

Follow the link for details: Companionway Bilge



A minimum of three bilge pumps are required for this configuration. Forward at lowest point while boat is at rest. Forward companionway between engines when boat is at rest and the bilge connection port is closed. Aft at transom when the boat is on plane.

[JohnV8r]

Pete,

Thanks for that! I LOVE the idea of sealing that bilge area and putting an inspection plate in for emergencies. I'm calling the Coosa board people this morning to see where I can get it in Northern CA.

Thanks!!!

John Vietor

[JohnV8r]

Capt Patrick,

Thanks for posting the link. That really helps me visualize the inspection plate.

Two quick questions: 1) Did you simply use a mold releasing agent and fill the removable part of the inspection plate to make the male end of the handle for the inspection plate?

2) Is that just acrylic that you glassed in for the actual handle piece?

Thanks in advance!!!

John Vietor

[CaptPatrick]

John,

Yes the inspection plate was mold released and the matching part was made by pouring catalized polyester resin into the depressions and laying up one layer of 1 1/2oz chopped strand mat. The handle is Cossa board which I supper glued to the matching part and then a layup with the mat. Once finished, the inspection plate was sanded well with 80 grit to remove the mold release, wiped with acetone, primed with catalized resin, and laminated to the handle part. I added 2 #8 flathead screws for added security.

[IRGuy]

John...

For short money I installed a couple of bilge high water alarms.. I used a Rule float switch and an electronic warbler alarm from Radio Shack (about $15.00) and wired them into seperate power supplies from the pump power. The alarms are only about the size of a 50 cent piece.. but they are so loud and obnoxious they will drive you out of the boat. The perfect thing for a high water alarm! I am also considering mounting another warbler on the flybridge so it can be heard by people on the float when I am not there.

[JohnV8r]

Spoke with the people at Coosa Composites and they recommended Bluewater 26 Coosa board. The good news is the people at Coosa were awesome. The bad news is their distributor in my area is out of Coosa BW 26 and doesn't know when they will have any in. In other words, they don't have an order in. It's the Left Coast Curse...you guys on the East Coast have all kinds of stuff at your fingertips.

So, I spoke with Svendsen's - a local boatyard in Alameda. They recommended using a 1/2" product they carry called Core Cell and reinforcing it with layers of biaxial fiberglass. Sven's stated that Core Cell lends itself well to hand lay up of fiberglass, which was a concern of mine as I do not have a vacuum bagging system. They also said it could be used to replace areas of wood rot by glassing it in

Of course the other option is marine grade plywood with an epoxy seal and/or some fiberglass.

Any thoughts?

[Whaler1777]

You should be able to mail away for coosa... If your dist doesn't have 26 then just get the 20 and throw on an extra layer of biax or 2...

[CamB25]

Corecell is much lower density than Coosa. I used it for bulkheads, with a couple layers of 1808. Coosa 26 was used for higher loaded applications with larger spans, i.e. deck panels, also glassed with 1808. Coosa takes glasses just as easily as Corecell, in my experience (limited). If you can find the lower density versions of Coosa, I would go that route. I would avoid the marine plywood, or any other wood in areas prone to moisture unless you vacuum bag a few layers of fiberglass all the way around the part and eliminate penetrations. With the quality of the synthetic materials today, there is no need to take chances. Keep working the phone book, you'll find some!!

[JohnV8r]

Good news...I found 1/2" Coosa Bluewater in the 20 lb version.

[Capt.Frank]

My question working on compainway The top of my bulked is rotted but the bottom is soild and tabbed well to hull. My question is with the boat in the water and engines 3208 in place work room limited. Should I cut the tabing and remove and replace whole bulkhead? or could I just cut the rotted area out and scab a pice of coosa in place then sister a pice of coosa to it or just cut few pices of coosa and glasses together the top 8-10" of the bulkhead ?

[Whaler1777]

You could really go either way but you're in there already and coosa will last 100 years in any environment without rotting away... Total peace of mind...

[bob lico]

Great post frank ---------- great safety factor!