I agree Miriam, sail canvas is out of domestic machine range, it's just too thick, luckily there are very intersting vintage industrials :- )
Sunbrella is well within what my 201 does, and top stitch thread has been strong enough for my purposes (garden upholstery). I have inserted up to size #22 needle on my cast iron Singers (66 and 201) they take it with no problem. The later 50s models were made with a stitch plate with a slightly smaller needle hole for some reason (at least it looks like that from the 201s I've had my hands on) still I think they take up to size #21 (The green user manual for my 201 lists thread and needle recomendations up to 21, as well as the leaflet for my 1955 aluminium 201K. The pre 1950s models were made in time when polyester thread wasn't available, and they needed a thicker cotton or linen thread to get a durable seam. Models introduced post 1950 usually have the limit of #18, and this gives the old cast iron models an advantage thread wise. I have Schmetz sharp point size 19 needeles and size 20 leather tip, but the large 21 and 22 I have only found in a Chinese made brand, quality isn't as refined as Schmetz, but generally very acceptable.