Engineer wanted for preliminary scantlings

[fallguy]

I built in a female jig with tortured panels. It was fun.

walk in and out, hulls were a bit wider, but bottom was 20" only

I might have built a nosecone instead next time; the bow work was a bit tight.

 

[rxcomposite]

Your right about the Fn. I’m counting on the slim catamaran hulls to push past hull speed.

Of course you can always achieve 10 knots with lots of power. Just don't punish your propulsion equipment by burdening it with too much resistance.

You can lengthen the hull as others have suggested. 8 to 8.5 meter seems to be a sweet spot. Length is always beneficial. Try to design at cruising speed of 6 to 7 knots, 9 to 10 max. Your Length to Displacement ratio should be around 9 to 10.5 in order to be a high speed/ light displacement craft. Cannot be a displacement craft form.

At that Froude number, you need a high speed semi-displacement hull form. The midship coefficient you have suggest an elliptical hull or a deep V. Try a parabolic and higher midship coefficient. You Cb is also low at 0.408. Ideal would be in 0.48 to 0.52, typical of frigates and corvettes. If you look at modern AC hulls, you will see the same section except that the hulls are much slimmer because it is a cat. Low entrance angle also.

LCB of these hulls tend to be aft, around -2 to -2.25% so check your configuration. Bowrider might not work.

I am still at the early design analysis, I try to fit the ratios and coefficient around the design lane. In the final stage, I work around the same principle of Michlet. I create a "family" of hulls that fits the design goal, then choose. That way, I don't feed the program with random numbers that I just think of.

 

[rxcomposite]

planning on using duflex strip planks for the hull bottoms. The foam panels are joined end to end to the full length of the hull and laminated both sides. Then the panels are ripped into strips of varying width depending on the degree of curvature in the hull. When the planking is completed the surface is faired and a second laminate is applied both sides to complete the structural requirements. At least that is my plan so far.....

Agree with Alik. You can always build a birdcage mold, screw from inside the foam planks to follow shape, sand the joints, glass one side, remove screws, invert to a cradle and glass inner side. You can use heat gun if the foam is a little hesitant. Wear a mask. The fumes/outgassing is toxic.

 

[Brentmctigue]

Looking into foam in lieu of Duflex. Watched a few videos and it looks easy enough.
Ive had another go at the boat design. Appreciate all your input. Ill post it in the boat design section.
cheers
b