Bad chalking off on gelcoats is generally due to rather a casual attitude to the proportions of resin and hardeners at the factory.... no different to modern 2 pot isocyanate car paints...
to much hardeners an u get Free harder in the product, not enough and get free unreacted resin...

A cut and polish.. works well, but this depends very much on the thickness of the gelcoat , be it how thick when laid up the moulds or how many times its already been cut... ideally u should have between a 18/1000" to 25/1000" thickness.

So assuming i have enough meat to work with, and real bad chalking....start with a coarse cutting compuond to cut MOST of the chalking off.. u may even consider something like a 600 grit wet sandpaper, then coarse cutting compound...
With the coarse paper compound dont take right down to now chalking.. just use these to fer most off , then cut polish as if it is only lightly chalked as per instructions on the gelcoat cutter polish u have purchased.
leave all edges  outside cnrs till last, it is very easy to cut into (thin) these area a lot harder than flat areas.

Painting... well in my books a re paint, like cars, is when serious damage , repairs have taken place... or the gelcoat has already been cut back and u can see very easy right thru it over huge area. (which is basically  damage)

 if u get a co polymer floor polish, and wipe 2 to 4 layers over faded  chalk areas that have been thoroughly cleaned down a nd dries (water blaster ) that will bring a semi shiny nom slippery surface back... this stuff require ammonia to strip off ... like floors, but on a boat that make a crappy job to do... this surface will wear. and discolour in a salt environment.....but if the surfaces are not walked on, a routine maintenance of a aerosol tyre shine and rag wipe brings up a nice finish

To remove other dis colouration , like browning of the bottom of the hull, phosphoric acid (rust kill) without epoxy etc additives... a 60/70% soln that diluted down to 5/6 %....then wiped on , left over night then water blasted off... then do the tyre shine... like brand new
About 70 to 100ml of the made up soln on a rag will do the full hull, bottom sides of a 5.5 to 6m hull.

Caution thu... any epoxy hull chip and minor repairs need to be replaced with gelcoat.. and any minor/ chips damage needs to be sealed before and tyre shine or polish is used.
A small dremel to clean out the chip and roughed surface, makeup the gelcoat... wipe into the damage, and before it sags, lay some masking tape tight over...u can then sand. the cut the area to blend in later....
Personally I dont bother with the finishing....I repair/ seal any damage as it may happen when home...then one day when bored will finish all of them off at the same time with the boat hanging high off a hoist

PS common sence.. "tyre shine" above is the clear stuff , not the black stuff.

"Work hard at being lazy"  means quick regular maintance and u wil have an orginal 1970s/ 80s glass boat looking like it has just rolled off the factory floor.

Have had good results in past with mould release wax used for polishing fibreglass moulds.

cheers Rodger

Gelcoat is the coloured outer layer of your fibreglass hull. It isn't painted. They lay gelcoat into the molds and then lay the fibreglass over it to build the boat. The gelcoat bonds to the fibreglass and looks like a paint finish. On most boats this is the white colour unless you have a multicoloured hull.

http://www.trademe.co.nz/motors/boats-marine/motorboats/auction-537096818.htm  It is the black stripe on the side of the boat as seen on this boat. where the Haines Signature is displayed. ( Not actual boat but similiar

So all i would need is to cut and polish? do you have any products you could recommened?

Best way to avoid it, maintenance. Thats the truely down side to owning a glass boat, its not park and forget after a trip.

Interesting port of view.. thu never had a ally .. it notable there are far fewer older ones of those than 'glass
regardless thu, and this applies to everything .. maintenance is the essence to stuff being reliable and long lasting... what I describe above keeps a glass boat in good nick.. and it only takes a few minutes

Hell my lawn mower is 1950s reel mower, my daily driver for the last 30 odd yrs is near on 45 yrs old
The secret is maintenance.....and a little basic maintenance means "working hard at being lazy" I  means dont need to fix things.. nor have the expense or waste time doing so.

Car stuff will do it if you have some. Some of the good quality marine ones are definitely better than the average car ones, but they will all work with a bit of effort.