Cal 39 bulkhead to hull?

[ipc]

My 1980 factory-built Cal 39 passed a rigorous survey with flying colours. Except for the bulkheads to hull connection which he warned was OK for coastal, not for offshore. Above waterline, well tabbed. Below, the bulkheads stop at the fibreglass liner. Is this normal? The boat's sailed in its 40 years with several owners from Florida to Seattle. No signs of flexing but I've yet to experience a real storm. Should I be worried?

[boatpoker]

The cal's had a number of structural changes over the years so I'm not sure of that specific year however, most boats with pan liners were built that way with bulkheads FRP taped to the hull and bonded (glued) to the liner section). A common and sound method of construction.

If there is no indication of bulkhead movement I wouldn't worry about it unless there are other signs of compromise.

[DougR]

Here is how my 1979 Cal 39 is built, and probably the same for your 1980 version...( Mk 2 & MK3 models)...My boat is the standard two cabin version with the main bulkheads even with the mast.
- the hulls were built in two separate halves, port and stub., and then bonded together. Then transverse “floors” were glassed into the hull from the middle of the forecabin to aft of the engine beds, tying the two halves of the hull together.
- next there were four 3/4” plywood “knees” totally glassed to the hull extending from the outer curve of the hull to the inner edge of the liner. Each Knee has about four feet of contact area with the hull, and that is glassed on both sides of the knee. There is a knee at each main bulkhead and at the partial bulkheads by the galley and the nav station.
- next the liner is set into the hull and sits on the knees at the two main bulkheads, the partial bulkheads, and also at the transverse floors. The liner is tabbed to the hull all around and also in all openings and at both tank areas.
- Now main and partial bulkheads are set in place and very heavily glassed to the hull above the liner. This glass extends inward on the main bulkheads well past the chain plate location so the the glass picks up the tensil load of the chain plate and not just the plywood bulkhead. The lower part of the main bulkhead, on one side on the liner, extends well down below the top of the knee on the other side of the liner
- Next ( to address your concern) the main bulkhead is thru bolted thru the lower part of the bulkhead, thru the liner, and thru the 3/4” knee with 1/2” bolts. Thus the rigging load is carried by bonding the bulkhead to the hull above the liner, and thru bolting the bulkhead to the knee located below the liner.

If you run the calculations of shear and tensil strength of the glass holding the bulkhead into the hull vs. the tensil strength of the rigging components trying to pull the bulkhead out of the hull, you will see that you have little to worry about.

[ipc]

Thank you for the wise counsel.

[Sailorlady323]

Originally Posted by ipc

My 1980 factory-built Cal 39 passed a rigorous survey with flying colours. Except for the bulkheads to hull connection which he warned was OK for coastal, not for offshore. Above waterline, well tabbed. Below, the bulkheads stop at the fibreglass liner. Is this normal? The boat's sailed in its 40 years with several owners from Florida to Seattle. No signs of flexing but I've yet to experience a real storm. Should I be worried?

Sailed a Cal 39 1979 from US to europe via Azores , Portugal into the med, back out thru the Canaries, across to Carribean and back to US. All kinds of weather etc . No issues with the hull . Great boat for the ocean.
Enjoy her.

[Sailorlady323]

Sailed a Cal 39 1979 from US to europe via Azores , Portugal into the med, back out thru the Canaries, across to Carribean and back to US. All kinds of weather etc . No issues with the hull . Great boat for the ocean.
Enjoy her.

[nortonscove]

A few years ago I had an insurance survey completed as required. The surveyor was flown in from out of province. The first thing he tells me without yet boarding the boat is that he doesn't like the way boats like mine were built. No reason given. During our conversation it comes out that he was partial to certain other vessels. Not necessarily an issue but then further on he explains how his father had been involved in the development and was a dealer for a different boat company.

In reading between the lines it became apparent that this guy only respected one type of boat built in a largely outdated way. In the end everything went fine with the survey but it was kind of weird to experience. To have been in the odd place has made me realize that being human means carrying biases no matter what we do and that it is scary to think what this bias can mean in ones daily duties.

I'd ignore the surveyor and go with the evidence given nothing's changed in the available variables. I try to see that way in more than boats.