3d Printed hydrofoil section / glassfiber reinforced

So i decided to test bonding and strength of fiber reinforced 3d prints.
This is mainly to illustrate capabilities of 3d printing use as core material. And an easy and cheap way to achieve complex shapes. With high strength to weight ratio.

Such as Rudder, cup holders.
Maybe a custom tiller for your sail boat?


The parts you see here are two section of 75mm height.
Originally they were printed with interlocks. but the interlock had very little surface area and strengh,
So they broke off.
Anyways, the parts are printed with PETG at rather rough setting of 245deg/C nozzle temp and 80 deg/C bed.

Total part weight is 98 grams with 20% infill (simulated honeycomb structure.)
this means that a foil of 1 meter length woulg whey aproximatly 980 grams before reinforcement.




Since the interlocks broke off i used some excess material and welded the parts together with a soldering iron. This makes the bonding stronger than the print itself because of perfect layer adhesion. (For future projects i will exclude interlocks and thermally bond only because it gives the best results)

This also leaves the connection very even and verry little work has to be done afterwords



Since this was just a test of concept, i grab the first available composite material next to me, which was a polyester repair kit that i had laying around on the shelf from other projects. As you later will see this might not have been the best material choice.


The hand layup really does not work well with a leading edge being so sharp . AND/OR the cloth being 300gm/m^2 might be to big to layup. You can see that in next picture, where the leading edge delaminated prior to curing

Vacuum bagging is highly encouraged, to achieve better results





After 30 seconds of sanding with grit 80. I must admit that even to the results were not optimal, i was very impressed with the possibilities of this method.

1) Layer adhesion to the surface was very strong.

2) The part did not show any bending from body load. (Raw 3d printed version would break under 10kg load (very low infill) )

3) The contour of this eppler 817 foil section is very precise, even though some delamination has occurred i believe the tolerances overall are far smaller than those you see in homemade wooden foil sections.

4) The 3d part can be made lighter but not without sacrificing strengh.

The idea is that you could make complex shapes. As in foils with variable angle of attack or other boat equipment.



Here are some extra pictures. Let me know what you think.