Newbie post... Feel free to move it.

Go 80 . 37kg line obviously stronger and you never know when u mite get something realy big on . Not eady trying to work a dead blue off the bottom with 24 ! I went 24 when i setup for standup thinking they wiuld be easier to handle but affter using 80s on standup they are just the same as theres not realy much weight to lift if your harness is setup right .

Man buy talicas. But 50s are heaps. Some colapsable outriggers will work well on ur surtees.5.5

Cheers guys. Appreciate all this. 

Blues on 50s are easily do-able. You have a small manoeuvrable boat....drive the boat to the fish. 

when i first started i went all out and bought 4 80's. 

fished 80w for 2 seasons very heavy setups bit of overkill for stripeys changed to 50w with 37 kilo braid and mono topshot great to use on stripeys and still have the same amount of line as a 80 incase the big girl jumps on 

I have 5 x 80w Tiagras on a 6.5m ally and use on both coasts and have had times we have hooked up and been very thankful we ran 80w's but have just recently bought 4 x 30w LRS and running 80lbs Daiwa Boat Braid and 75m of 50lbs topshot ... haven't been run yet but will be very soon ... hope I dont regret it

Get the 50w Tiagra LRS/Talica 50  or similar reels and go braid or hollow braid then mono topshot. Or you can look for some second hand standard shimano or Penn 50 wides and get Swordfishsteve to pimp the drags. You'll get as much stopping power as an 80 and will as much 80lb line on there as an 80w which sorts your capacity issue ( effectively an 80w reel ). plus I imagine from a small trailer boat 50s would a lot more practical taking up less room, not so bulky to handle, would be a heap less weight which in turn also helps your boat and crews efficiency.