Hello Gentlemen and Ladies

[curious aardvark]

pet-g has fabulous layer bonding.
It can be tricky to get the settings right - but once you do layers are not a problem.

The LAST material you want to use is 3d printed abs.
It's sucks in outdoor applications is broken down readily by sunlight and fdm abs is one of the weakest materails you can use.
I have no idea why abnyone still uses it. bog standard pla - fdm printed - is superior in every way.

Pla would actually suit your purposes quite well. Certainly for prototyping purposes
Carbon fibre infused filaments are weaker than those without, slightly stiffer - but the stiffness is offset by increased brittleness.
They eat nozzles and aren't even conductive enough to be of any real use.
It's a gimmick that doesn't deliver on any aspect.

But spend some money and you can start using serious filaments.

ninjatek's Armadillo is probably exactly what you want. It's a rigid polyurethane. Tough as nylon, stiff as pla with more strength than pet-g and excellent layer bonding. Also as easy as pla to print as well as light.
https://ninjatek.com/products/filaments/armadillo/


And children - play nice :-)

[Just Harry]

@Aardvark,,, Thanks for the input. I am not adverse to any material if it can provide what I need. This rigid polyurethane sounds like a winner, but I have a question. The Data Sheet at Ninja doesnt give any flexural test data, but Im thinking that it would work and certainly worth a try. If you will look at the attachment you will see a long, thin, piece. 18 " long, 3.25" at its widest point below the trunk, and just under 2" at the bottom. Those are profile dimensions. The thickness profile starts at approximately .215" at the top and tappers down to .180" at the bottom. It has a NACA chord profile. For all FDM printers can do, this would be a tough assignment. It would need a split on the vertical, with a resulting left and right side profile. That is now highly doable and would be aligning the print grain in the best way to resist deflection. The problem then becomes how to bond the two pieces together. Is this product even friendly to bonding to itself? Let me give you an idea of the stress involved. The top portion of this keel, 4", will fit inside a trunk in the boat. The remaining 14 inches will extend down into the water. On the bottom end of this piece, will a keel bulb in the general shape of a torpedo. It will weigh approx. 4 pounds or a bit less. IT has to be resistant to deflection when the boat heals over. These are sailboat racers, not motorized. Its not necessary to bench this piece and clamp at a 90 degree angle to perpendicular and put 4 pounds on the end to test deflection. The most angle that efficiency will be needed to around 65 degrees from perp. After that, all the sailing dynamics are seriously degraded and a flexing keel wont make much difference. I can buy a laminated carbon fiber/epoxy keel fin that is actually overbuilt for the job but its cost is around $200 and its not a commercial purchase. You may or may not get one in a decent amount of time. Its for a different boat and is definitely not optimal for the development boat class I am building for and competing in. If I can find the right build for this piece with material, design, and 3D printing,, I will sell dozens of them. This one piece is just part of a collection of Hardware I have designed in 3D (for 3D printing) for the boats, but it is the most important piece to succeed with. The rest are a piece of cake. Any further assist will be greatly appreciated. Thanks Again.