Ive got some parts im working on that will be be used on a boat. Im not sure which filament to use for the parts that will be submerged under water. It will be fresh water only, but id be interested to know wht the requirement would be for salt water as well.
Ive read conflicting info about nylon for exterior applications. Does anyone have experience & recommendation for this? Id appreciate any insight.
Nylon is hydroscopic, it absorbs water and it softens up when it does.
I’d use ABS or PETG.
PETG
Polypropylene if need it 100% water proof
Acrylic
TPU
To give you a better recommendation, it would be interesting to know details regarding the use and type of print, or even better, the solicitations to which the part will be subjected.
I live near the sea and surf, so my shares relate to salty water:
PETG - the clearest choice; cheap, easy to print and works. I had some broken stuff, mostly in thinner regions of the print. I cannot confirm, but I think they broke because they were weak, not by degradation.
ASA - is my favourite filament, which I use for surf-related stuff as it works flawlessly. I couldn’t find any sign of degradation over time. Despite being underwater or just in the sun for hours, the surface continuously looks new. The only drawback is that it is costly in comparison to PETG.
PP - it is mainly used for water applications, yet I do not have experience.
Nylon - for water use, it is necessary to add some coating; epoxy is the most well-known. I use it often but never tried it in the water, as my parts are not subject to high loads. Yet, in a boat, things may be different. So it may be a great choice if the printed piece will be subject to high loads.
PLA - I’ve been using PLA under water conditions (not salty) and never had any issues. So if the use is underwater and thus not subjected to UV, I bet it works.
Some good info in this article. Are 3D Printed Objects Aquarium Safe? – PLA, ABS, NYLON, PET – The Beginners Reef
Thanks for all the great info everyone. It will be for a hydrofoil and some transducer shields & brackets. Im sure some other ideas will spring to mind over time. Ill use cfpetg.
For the hydrofoil, PET-CF is perhaps a better option.
You may run some simplified finite element analysis to verify.
The remaining parts with PETG-CF seem more than excellent.
Or, in case you feel comfortable, PA-CF with glass fibre and epoxy resin… Some time ago, I saw one hydrofoil homemade (not 3d printed), and if I recall, the coating was Kevlar.
If you don’t mind, please share your project’s results when finished and tested. I am looking forward to seeing it. And, of course, good luck to them.
I’m told PETG works well.