3 ms·

If you're an engineer, I'm just going to x3 to x10 that time estimate to come to something realistic, just like I do with the engineers at work. That way it in

If you're an engineer, I'm just going to x3 to x10 that time estimate to come to something realistic, just like I do with the engineers at work. That way it includes going to buy the paint and sandpaper, putting the boat in a drydock or otherwise on land, finding and dragging out the tools and getting power to them, drying the boat, cleaning it, eating, toilet breaks, taping off the edges etc, letting the paint dry, cleaning up everything afterwards, putting the boat back into the water and probably tons more that I missed. x5 sounds about right for this one.

yobbo 2y ago
It depends. For example, if the previous paint contains environmentally harmful compounds, you can not sand it without the infrastructure to collect the dust. The details depend on the location (regulation), but typically you need to hire this out. Sanding takes multiple person-days and can be the wrong method (depending on details). Media blasting (like soda) is much preferred but requires machines and infrastructure to collect the run-off. In ideal situations, sanding is not necessary at all. It can be several boat bucks, or just about a hundred dollars. It depends.
- jcgrillo 2y ago
  It does contain harmful compounds. It wouldn't work to prevent growth otherwise. You use a random orbit sander hooked up to a shop vac just like when you sand anything else (unless you prefer dust going everywhere). For a 40' sailboat it doesn't take multiple person days, it takes about a quarter of a person day. More if you really have to take off a lot of layered up material. And you're right, blasting would work better in that case.
  - jabl 2y ago
    > It does contain harmful compounds. It wouldn't work to prevent growth otherwise. Nowadays there exists bottom paints such as polysiloxane based ones that work by creating a very hard and smooth surface that critters find it very hard to attach to, rather than poisoning them.
    - jcgrillo 2y ago
      Interesting! I'll look into that. My boat is overdue for a full paint job so that could be an option.
  - yobbo 2y ago
    There are levels of toxicity. For some old paints, allowing the dust or run-off from pressure washing to touch the ground would be violating some regulation. Removing those old paints is more complicated. They need to be removed completely and cleanly, so sanding is a bad choice. This isn't the case for any paint now purchasable, but most still contain biocides that you want to avoid for your own health when cleaning or sanding.
jcgrillo 2y ago
No, it's not an "estimate". It takes half a day. If it took 5x that I would have said so.

yobbo 2y ago

It depends. For example, if the previous paint contains environmentally harmful compounds, you can not sand it without the infrastructure to collect the dust. The details depend on the location (regulation), but typically you need to hire this out. Sanding takes multiple person-days and can be the wrong method (depending on details). Media blasting (like soda) is much preferred but requires machines and infrastructure to collect the run-off. In ideal situations, sanding is not necessary at all. It can be several boat bucks, or just about a hundred dollars. It depends.

jcgrillo 2y ago
It does contain harmful compounds. It wouldn't work to prevent growth otherwise. You use a random orbit sander hooked up to a shop vac just like when you sand anything else (unless you prefer dust going everywhere). For a 40' sailboat it doesn't take multiple person days, it takes about a quarter of a person day. More if you really have to take off a lot of layered up material. And you're right, blasting would work better in that case.
- jabl 2y ago
  > It does contain harmful compounds. It wouldn't work to prevent growth otherwise. Nowadays there exists bottom paints such as polysiloxane based ones that work by creating a very hard and smooth surface that critters find it very hard to attach to, rather than poisoning them.
  - jcgrillo 2y ago
    Interesting! I'll look into that. My boat is overdue for a full paint job so that could be an option.
- yobbo 2y ago
  There are levels of toxicity. For some old paints, allowing the dust or run-off from pressure washing to touch the ground would be violating some regulation. Removing those old paints is more complicated. They need to be removed completely and cleanly, so sanding is a bad choice. This isn't the case for any paint now purchasable, but most still contain biocides that you want to avoid for your own health when cleaning or sanding.

jcgrillo 2y ago

No, it's not an "estimate". It takes half a day. If it took 5x that I would have said so.