9 or 4 inch rollers?

[SteveGorst]

9" on a pole.

plus 1 for that

 

[ghostlymoron]

It all depends on size of boat. On my 28 footer, the larger size saves a lot of time but you still need a smaller one for tight spaces or a brush. On my current 20 footer, I use a couple of cheap foam 4" ones with a short extension pole.

 

[PowerSlapper]

I was thinking of a cheapie spray gun from screwfix, sufficiently thinned it should do antifoul

Not good to thin the AF unless you are thinning it with TBT 10~15% .
For spraying teh thick AF i would suggest a Schutz gun aka a splutter gun like:
https://www.amazon.co.uk/Underbody-Coating-Underseal-Schutz-Stonechip/dp/B00TQUUJZ6
or
https://www.amazon.co.uk/Profession...coding=UTF8&psc=1&refRID=7PPFGD5XTMF3GFDYNECA

 

[thinwater]

I was thinking of a cheapie spray gun from screwfix, sufficiently thinned it should do antifoul

You will also need to tent the boat and wear full PPE. And then there is the problem of overspray on your deck and topsides.

 

[MikeBz]

These days where do people buy foam rollers which are genuinely good for solvent-based paint? These claim to be but fall apart quickly when used with anti-fouling paint: http://www.decoratingdirect.co.uk/viewprod/1/11CM_MINI_PAINT_ROLLER_CONCAVE_FOAM_BLACK/

 

[Lucky Duck]

I bought a pack of ten 'Harris' 4" foam rollers for just under £7 on Amazon, these worked with both Micron Extra and Hemple Tiger Extra this year without any problems.

 

[ghostlymoron]

I use Toolstation cheapies and discard at the first sign of disintegrating.

 

[MikeBz]

Those ones I linked to last a bit better than other cheapies I have tried, but I still used 7 of them doing 1 coat on a 32 footer. They are so cheap that the cost isn't issue, but after a few strokes they go limp and floppy (ooer) which makes them less effective. They hang on for quite a while longer before they start disintegrating and leaving flecks in the paint.