savageseadog
Well-Known Member
Regarding modern racing yachts with fabricated ribs and stringers. How should bulkheads and internal lockers be attached to the inside?
Attaching Internal Joinery to the Inside of a Modern Yacht Questions
- Thread starter savageseadog
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Poignard
Well-Known Member
Not too rigidly, I would have thought. Using a flexible bonding method.
bigwow
Well-Known Member
CT1 ?
Poignard
Well-Known Member
Yes, CT1 is excellent stuff
lw395
Well-Known Member
How 'modern' are we talking?
People are suggesting flexible mounting.
The thinking behind that is you don't want a bulkhead or whatever to be much stiffer than the hull.
This will be much more of an issue in an 80s single-skin GRP boat than a modern-modern foam sandwich boat.
Things like Sigma 33's can distort measurably between sat in the yard, floating, and racing with breeze.
You don't want the lockers to be distorting the hull when it's floating. Or bonds from furniture to hull breaking when you crane the boat.
There are stories told about various one-designs coming together at marks, the hulls bounce apart unmarked, but the interior woodwork looks like someone's lost their temper in Ikea.
With a sandwich construction, the bigger issue can be point-loading the inner skin. Maybe best to primarily attach to existing strong bits like bulkheads and frames?
pagoda
Well-Known Member
Our late 80's Jeanneau had all the furniture glassed to the interior of the hull. Bulkheads included. Very stiff and solid arrangement. Never had any problem with the alignment or fit of doors etc. Current 2007 boat has lots of material similar to CT1 used between panels and to the hull. It appears to do the same job in a different manner. No creaks either!
I suspect it is down to the reduction in construction time - and ease of building rather than other considerations?
savageseadog
Well-Known Member
I know about avoiding point loads but did wonder if new designs used the internal "joinery" (often moulded GRP) to stiffen the boat. I suppose there must be a size factor in play because small lockers must be OK glassed in because there won't be much movement across the span of the structure. Larger fitting out must be a bigger issue.
What's the correct approach for bulkheads because they have to keep the shape of the boat stiff but flexible sealers can only stretch or compress so much before the load is more or less directly on the hull.
What's the correct approach for bulkheads because they have to keep the shape of the boat stiff but flexible sealers can only stretch or compress so much before the load is more or less directly on the hull.
lw395
Well-Known Member
There is whole spectrum from non-structural furniture through to moulded liners which form integral, essential parts of the structure.
Was I wrong to assume you were intending to discuss adding additional internals to an existing hull?
Was I wrong to assume you were intending to discuss adding additional internals to an existing hull?
savageseadog
Well-Known Member
Taking some out. There's also repairs which may have been glassed in where they previously weren't.
lw395
Well-Known Member
I don't think we can generalise too usefully.
Maybe you just have to look at each bit and ask yourself if it could be intended to be structural?
Even quite thin panels like say the settee fronts can stiffen up other bits.
What appears to be a pointless divider in a locker might be an essential deck knee or something.
Luckily, most things are grossly over-built rather than finely engineered down to the minimum.
Iain C
Well-Known Member
I've read that you can glass the structure to the hull, but rather than having the bulkhead actually sitting against the hull, the (for example) 12mm bulkhead should sit on a piece of 20mm wide piece of 5mm Airex foam. Chamfer to foam down so that it forms part of the "fillet". Don't actually glue the edge of the bulkhead to the foam...just the GRP "tabbing".
bluerm166
Well-Known Member
Sikaflex 292 is made for and used for this kind of structural purpose.
It has tremendous strength and grab and is a damn sight easier to use than two part resins.
It has tremendous strength and grab and is a damn sight easier to use than two part resins.