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Old 06-12-2010, 04:10   #1
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'Hand Laid Hull'

I see this statement all the the time "hand laid hull". What does this mean as aren't all hull fiberglass laid down by hand into the mold? If they aren't does that mean some machine or something laid it down.

Is this case of a cool marketing phase being used that really has no definition and can be applied to anything?
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Old 06-12-2010, 04:17   #2
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no not all are hand laid sheets of woven roven, the alternative is chopper gun construction (commonly used for fiberglass dock boxes etc) where chopped strand matt is shot out of a gun allready wet out, some boat are built like this and it is far inferior
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Old 06-12-2010, 05:08   #3
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Generally there are some techniques of laying up the laminate.
Chopped strand matt shot out of the gun is the most inferior fo them.
Hand laid hull means (normally) the traditional method - lying the reinforcement layer by layer, wetting it manually by resin and rolling it up by hand tools. It is very controllable process, resulting in strongly built, but often quite heavy hull, as somewhat more than necessary resin is used.
Sometime a resin gun is used in the process of wetting to save on labour costs, but often to not the best result. Delamination is more often if compared to pure hand made process.
When using the modern reinforcements, allowing for thinner skins (often with foam sandwiched between two laminate skins) the vacuum bagging is used after preliminary rolling up the laminate by hand tools. This also can be called "hand laid" and is also very controllable process, but rather impossible for monolitic hull, as vacuum must be applied early enough i.e. before curing is finished in all the layers.
The vacuum infusion is other way to go - basically it mean that the reinforcement is laid up by hands, next the reinforcement is pressed up by vacuum bag for some time (24 - 48 hours) and then the resin is infused. The process is very difficult to control, but when well done, provides for the lightest possible hull. When using infusion for sandwiched hull it is better to make outer skin first, then glue the sanwich foam to it under the vacuum bag and then to infuse the inner skin. AFAIK Southern Wind use this three stage method as opposite to the Sunreef which is infusing all the hull (with sandwich in place) in one process. Single stage infusion of sandwich hull is more risky and less controlable process, possible rather for very light hulls, with thin laminate skins. Main reasons for using infusion are: it is more enviromentally friendly, it let to use most modern resins, difficult for hand lay-up and it gives the lowest ratio of resin in laminate weight. The risk is possibility of delamination if something goes wrong.
Oyster and Contest use the infusion for monolithic hulls with great success.
For me infusion or hand laid laminate is good for monolithic hull, and the vacuum bagged hand laid laminate or three step infusion laminate is good for sandwich hull.
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