29' Catamaran Mold Laminate Thickness

Hi All,

This 29' power cat has been in the works for a while now. I am building a plug to make a mold that would allow me to produce several units (estimated at 10-20 units before major retooling). The scantlings and layup schedule for the prototype hull have been estimated. However I am not sure on the mold's laminate thickness or materials.

Does a 15mm mold laminate thickness with 1.5" sch 40 steel tubing bracing sound adequate? 15 mm would be equivalent to the keel region laminate thickness for this hull.

The layup schedule in mind for the mold is like this:

Tooling Gelcoat @ 25 mils
.75 oz CSM
1.5 oz CSM
6 layers 1708
6 layers 1808 (alternating with the 1808)

Iso blend resin.

I also have access to core mat, heavier matt, and woven roving.

 

The 1708 will print through to the surface. You need more CSM or some sort of print blocking layer.

 

I don't see any reason to use any glass other than basic CSM as it is easier to persuade to a hull shape and the loads on the tooling are pretty minimal,laminators walking around inside the hull or loads from the framing and wheels fed into the structure.I would estimate that a 4500gsm laminate would be more than sufficient with external foam stringers and plywood framing laminated to the external stringers.don't rush the bonding of the stringers to avoid local distortion.I do have a mild preference for a band of coremat beneath the stringers for this reason.

 

Thank you, how much more CSM?

Do you think I could do away with the double bias completely? Or maybe just on layer per every 5 oz CSM layer?

 

Thank you Wetfeet, it would make the layup easier. When you say foam stingers I envision like 10o x 100mm foam stringers both longitudinally and transversly, is this what you mean?

 

Could be 100mm square,could be 60mm square,could be 100 X50.,depends on what you may have available.A couple of further points;plan for some pads to attach wheels to and don't forget to mark a waterline on the outside of the mould so that you can set it level.