Bulkhead repair/replacement

[millerthegorilla]

I have a 1980 sailfish 25, and the bulkhead behind the chain plates that take the side stays, have rotted and cracked.
I am in the initial stages of considering a repair, and want your advice. My first thought having read a few forum posts is to whether the bulkhead is one piece.
I presume it is. The sides of it are set into a slot in the grp, so I'm thinking the bulkhead was probably dropped into the slots in one piece, and then the top bolted/sealed on.
That the tension forces from the mast stays are distributed through the whole bulkhead makes a lot of sense, and if that is the case then cutting out the rot and replacing just that is probably a very bad idea indeed, as I doubt that any glue would be strong enough to hold the mast tension.
It's a trailer sailor by design, and I use it for open sea, and it has proved to be a good yacht, but if the bulkhead can't be replaced and a repair isn't possible its probably time to move on to another boat.
So my question is:
1. Does the bulkhead have to be one piece, or can a local repair be used?

 

[AntarcticPilot]

A bulkhead such as that is a major structural component of the boat. I think you need advice from the designer, as the specific answer will depend on the nature of the stresses at the point where new material is bonded to the existing structure. If the join is under compression, then I'd imagine it would be fine. If under tension, then you probably need to arrange straps or GRP to take the tension.

I'd imagine that the bulkhead could be replaced by two pieces joined at the centreline, perhaps with reinforcement to take compressive stress from the mast at the centreline

 

[Poignard]

I suggest you contact the support team at Wessex Resins Ltd, the UK agents for WEST Epoxy.

Support - Wessex Resins & Adhesives

Contact - Wessex Resins & Adhesives

 

[jwilson]

A bulkhead such as that is a major structural component of the boat. I think you need advice from the designer, as the specific answer will depend on the nature of the stresses at the point where new material is bonded to the existing structure. If the join is under compression, then I'd imagine it would be fine. If under tension, then you probably need to arrange straps or GRP to take the tension.

I'd imagine that the bulkhead could be replaced by two pieces joined at the centreline, perhaps with reinforcement to take compressive stress from the mast at the centreline

The designer was the late Angus Primrose - he died 45 years ago. I'm sure it is repairable, but you might take advice from a surveyor. A photo of an undamaged one attached.

 

[AntarcticPilot]

The designer was the late Angus Primrose - he died 45 years ago. I'm sure it is repairable, but you might take advice from a surveyor. A photo of an undamaged one attached.

Is the design company still going?

 

[billskip]

The designer was the late Angus Primrose - he died 45 years ago. I'm sure it is repairable, but you might take advice from a surveyor. A photo of an undamaged one attached.

Surley ,as in your photo irt would be possible to splice together at the top and bottom of the door opening

 

[LittleSister]

I have a 1980 sailfish 25, and the bulkhead behind the chain plates that take the side stays, have rotted and cracked.
I am in the initial stages of considering a repair, and want your advice. My first thought having read a few forum posts is to whether the bulkhead is one piece.
I presume it is. The sides of it are set into a slot in the grp, so I'm thinking the bulkhead was probably dropped into the slots in one piece, and then the top bolted/sealed on.
That the tension forces from the mast stays are distributed through the whole bulkhead makes a lot of sense, and if that is the case then cutting out the rot and replacing just that is probably a very bad idea indeed, as I doubt that any glue would be strong enough to hold the mast tension.
It's a trailer sailor by design, and I use it for open sea, and it has proved to be a good yacht, but if the bulkhead can't be replaced and a repair isn't possible its probably time to move on to another boat.
So my question is:
1. Does the bulkhead have to be one piece, or can a local repair be used?

I think it is unlikely, although possible, that it would have been slotted into moulded GRP ribs. More typical would be the bulkhead would be put in place then it would have been attached to hull with glass cloth and polyester resin.

It does look like there is a moulded rib/trim across the top, but I'm guessing this would have been in the deck moulding or internal headlining moulding, put on/in after the bulkhead was in place.

If it is slotted between moulded ribs, the question is was it also glued in place? That would make disassembly more challenging.

I think it is eminently repairable. It is not rocket science. You just need a panel (bulkhead) that is as strong as the original bulkhead which carries the loads of the chainplates and gives additional rigidity to the hull/deck assembly (the lateral not necessary ion some designs - see whether there were alternatives layouts without it).

This could be in the form of a new bulkhead (and as biillskip says this could be made of more than one part, provided these are adequately fixed together), or part-bulkhead (e.g. just in way of the chainplates ), or (depending the detail of the existing damage) simply by adding strengthening 'partner'(?) panels to one or both sides of the suspect area and somewhat beyond.

An alternative approach, if the damage in way of the chainplates is limited (i.e.

As you are unlikely to be able to exactly match the grain and finish of the existing bulkhead with any joins or partners, you might want to instead make these distinct rather than not-quite-matching.

An alternative approach, if the bulkhead is sound except so far as it relates to the chainplates, is to construct metal supports, in e.g. stainless bar or wire, to take the loads to a stronger part of the hull. Boats being what they are, there will likely be something in the way making that difficult/complicated/expensive. Also you might need to get a surveyor to sign off on that modification and departure from the original design to satisfy your insurers. (In my opinion this would not be necessary if you were simply replacing or strengthening the existing bulkhead, without changing the designer's intentions.)

 

[PetiteFleur]

I have done this on my 1979 Moody 33mk2. After purchase, from the survey, the bulkhead near the mast had rotted from the leaking baby stay deck fitting. With the mast removed, I repaired it by cutting out all the rotted area in a dovetail shape so so it wouldn't pull out after repair. I also added a stainless reinforcement plate over the area along the roofline. The area removed was replaced with quality exterior grade plywood 12mm thick(originally 1/2" thick)glued in place along all the joints with epoxy. (Originally the Ply was covered with formica which I just peeled back, any visible joints I covered with a strip of teak).
All written up on the Moody Owners Association.

 

[Refueler]

Often the offending bulkhead would be removed ..... replacement bulkhead made in 2 or 3 parts - so that it can be fitted in easily. The joints would be epoxied or weatherproof PU Resin glue.
Once bulkhead is fitted, glassed in place ... then a brace beam could be added if considered necessary - but if bulkhead is done well - it should be sufficient.
To finish off - a thin veneer can be applied over the whole bulkhead to cover the joints etc.

 

[millerthegorilla]

Thanks for all the answers. I read somewhere else that the bulkhead has been slotted in, and the bulkhead disappears into what look like slots In the side of the hull.
As to whether it's glued or glass fibres, I don't know, but I imagined it was one piece as the tension when the chainplate is pulled on is then cantilevered against the length of the bulkhead.
I cannot imagine any simple way to engineer a structure that would offer the same capacity for tension.
The rot is behind the chainplate, due to water entering from the hole from the chain stay above. Without having had a good look yet, I don't know far down the rot extends but I suspect it is significant.
I think the next step is to take a better look.

 

[jwilson]

Is the design company still going?

Taken over by Bill Dixon - Dixon Yacht Design - now seems to do slightly posher boats.....

 

[LittleSister]

Thanks for all the answers. I read somewhere else that the bulkhead has been slotted in, and the bulkhead disappears into what look like slots In the side of the hull.
. . .

Could be. Might be worth checking whether the moulded ribs or slots are actually part of the hull (and deckhead?) moulding(s), or separate strips added after the bukkhead is dropped in. Could also potentially be a one-piece moulded slot, including the 'ribs' both sides, shaped to fit the hull and/or deckhead, which is fitted either to the hull before the bulkhead goes on, or first fitted to the bulkhead and then the moulding glued to the hull as the bulkhead goes in.

Whatever it might be, if need be you could always cut out the 'ribs', either entirely or just places, and replace them with something in wood or GRP top cover the resulting gap and fix the bulkhead in place.