Composite High Speed Boat Structural Hull Bottom Grid

Thanks @rxcomposite for your feddback. I will read the ISO 12215-5 Part 1 Scope . Good point .
A boat bottom framing grid mold of the same surface as the hull mold in China is the same price
Yes in China they use wood formers they hand laminate over and they leave the wood there as the concept is that of slave workers that wont be payed for many months. When chinese workers require their pay from the Laoban they may even receive a beating

 

I use only the wood as mold. I laminate a thin sheet and use it as a former. I throw away the wood mold when the project is over.

 

Thank you all for your feedback. I did a very schematic 3D modeling of my stepped hull with tophat modular bottom framing grid and with a very simplistic composite 2D router cut flat panel grid just on the same locations of the stringers and transversals of the modular tophat section grid
To me it seems if someone wants to design and build a boat bottom structure made of 2D CNC cut panels that structure here very schematically constructed needs t o deliver the same rigidity as the modular tophat section grid structure. Before doing the calculations I think if the 2D CNC router cut longitudinal stringers are 40-45 mm thick and made of prepreg sandwich faced with monoaxial carbon fabric laminate autoclave cured and high enough I think they would do the job. As pointed out by @rxcomposite the ISO 15515-5 does not apply to boats of speed above 50 knots I did read here in the forum some debates on this subject I did not see any clear statement in regards what precisely is the EU standards the structural design of high speed boats of speed higher than 50 knots are to comply with is there a precise regulation standard ? Thank you for you feedback if they are

 

The problem with flat plate stiffeners is that you end up with about the same amount of workhours as rxcomposites method of male fiberglass formers. Flat plate can not be simply glued in with acrylate since there is not enough surface area, you need to tab it in with fillets and fiberglass, either by hand or by infusing it. Plus you need the cap of unidirectional fibers on top, so you have to choose, either you cut the foam beforehand and infuse the cap and sides on the table, or you add the cap after infusing big panels and cutting them up.
If you end up with a similar amount of workhours his method is actually cheaper because you don't have to pay for foam cores.

 

Hi @Rumars I do agree with you of course and I am myself well aware of all the aspects you mentioned above . I do however think that the concept of TOPHAT section profile of stringers predates the advent of more new fibers and composite technologies. My experience incudes one year with one racecar carbon prepreg composite company in UK not far from London. In the composite F1 racecars the design is not at all based on structure beam concepts like the tophat section beam . I do think if one designs a new type of structural beam that would be made on marble from new more modern composite fabrics and cut by the 2D CNC router this may well present a good potential in custom and semi custom boat building ; the advantages would come from saving the cost of one complex and intricate mold wich is a very substantial and quasi equal in price with the hull mold sav + save production manhours on complex concavities mold fiberglass fabric stratification.

 

DNV GL has HSC rules. LR has SSC rules.

 

Contact AdHoc if it is going to be Classed.

 

Thank you all for your kind feedback after thinking about all the above I do have a conclusion : the structural framing of a on off or short series production high speed sport boat can be designed and made in 2D CNC cut made on marble sandwich plate and the approach to design arrangement and dimensioning of stiffeners is the one taken by the race yacht sector where they build on offs or very short series