What grit for fairing board sheets?

[theFunsmith]

I am going to order some of the 30" hookit sheets for the fairing boards. I remember rick and some others saying that one color (I believe purple) was the one to get, but I wanted to ask what grit(s) you guys would recommend before placing an order. The fairing process is a little out of my wheelhouse at the moment, and I am about to dive in.

[RickK]

Are you talking about fairing the inside of the boat or the outside? Not that it matters much, if you're talking about long boarding, the 3M long board sheets are bought in packs of 10 and ain't cheap but they do last - I haven't worn one out yet. I bought 3 grits - like 40, 80 and 120.
For inside the boat, an inline air sander is a good choice if you have a 80 gal compressor (or don't mind letting a smaller one charge back up - I have a 20 gal model) - using 40 grit (or lower for initial scrub, I bought inline air sander (hook and loop) paper by the box at an automotive paint place - I did have to buy a hook and loop attachment for the sander) and then 80 and then 120 - 120 is good enough to get you to final fairing - then 180 is good enough. I think using a long board inside will make an old man out of you quickly, while an inline sander is little to no effort.  A long board (check with Michael (mshuggs) on how he made his if you don't have one) is great for the outside hull where you can standup and work.
There is many ways to mix fairing compound and not too many ways to fair (they all involve a lot of arm power).
You can buy premixed fairing compound, most are poly based. Or mix your own with micro balloons, cabosil, wood fiber, etc and epoxy resin. What are you using for a finish on the boat, inside and outside? I used epoxy sealer on the bottom of my boat (and up above the water line an inch or 2) and then VC for the paint (another 2 part paint) - then I used EMC2 paint for the hull sides above the water line. for the inside I sprayed gelcoat, because everything above the floor in mine was poly based. So having a plan (which I think you do) is important.
I expect that we'll get a few responses as everyone has their one way of doing it.

[mshugg]

I used a ton of 40 grit and some 80.  I bought some 120 and 220, but never touched it.  I was using peel and stick on a homemade longboard.

[RickK]

Michael, did you use the long board for the initial scruff on the inside?

[theFunsmith]

Thanks gents. I bought the 3m fairing boards a while back, so I'm going to give them a rip. as for the plan, I am currently planning on using Alexseal on the outside of the hull, on the console and electronics box. The current plan on the inside of the hullsides and deck is to get it faired and take it to the local Linex applier to have them apply white or gray Linex to protect the insides from the crab pots and things.

[mshugg]

Michael, did you use the long board for the initial scruff on the inside?

No, I used it for the cap, hull sides and bottom.  Just used a random orbital on the inside.

[dirtwheelsfl]

Velcro ones are nice but not cheap. 3M actually stands for 3x More 

I use sticky back which lets you make any sort of block or board or pipe you want. The bulk of my fairing is done with 40 grit, with a hit of 80-120 before primer just to knock down the deep scratches. The board is usually your first and last tool( after an initial knockdown with a grinder or sander). Use it to find lows and highs, Super highs i will hit with a power tool to get it close and finish with board. Check with a batten as you go along. It might look fair and straight but the batten wont lie. Put a water hose to it and itll give you sort of a preview of the finish and ususally highlight spots that need more attention if you choose. You mention line-x so you shouldnt have to do too much fairing!

I get my paper here...    https://fiberglassflorida.com/fiberglass-supplies/fiberglass-abrasives/abrasives-long-board/longboard-file-paper.html

                                                                                                                                                                                                                                                                                                                                                                                                                     

[theFunsmith]

Damn good advice. The inside won't need as much attention as the outside for sure. While it is going to be more or less a work-boat, I still want to look good when I am pulling pots. I'll spend the necessary time on the outside to get there.