Fairing Gelcoated Rudder

I want to fair (remove material from) the LE of a gelcoated rudder; about 4-6 inches near the lower pintle.

 

staple some coarse sandpapar to a board about 18 inches long, covered with thin foam rubber , this way you will true the leading edge then wait for Par or someone to advise on the gelcoat, I dont know anything about that sticky stuff, but thats how we fair boat, boards up to 6 foot long

 

I am not sure how much you want to remove, but a grinder will remove the bulk of the material very quickly. This can be a trap, as it will take lots off before your very eyes, - so be careful. A rasp will not work, - you will only blunt the rasp in no time flat - rendering it completely useless.

Sandpaper will smooth the surface, but sanding is a slow process.

Some precautionary notes;

1. Always wear protective clothing, including eye goggles (fibreglass dust in the eyes is NO fun) overalls (taped at the arms and legs to prevent dust entering) and gloves are often a good idea.
2. Always have a cold shower (as cold as you can stand it) after the job is complete, while under the running water brush yourself down (never upwards) along all limbs and the body, (in ther same direction as the hair grows) to remove all of the fibreglass particles. This will minimise the iching that inevitabable follows this sort of job.

Once you are satisfied with the final fairing job I would do the following;

1. Remove all of the antifouling paint from the rudder.
2. Sand the entire rudder to severly break the gelcoat surface (first using 40 grit then 60 grit).
3. Coat the surface with expoy resin, or better still, use dynal and epoxy resin.
4. Sand smooth then coat with an epoxy etching primer.
5. Paint as per the instruction for the antifouling.

I have done this job many times (when I was an aprentice boatbuilder) and many time since. I can't say that it is an enjoyable job, but if carefully done the results are very satisfying.

If you follow this process the final results should be very satisfying and last for a very long time. By all means as me further questions if you need to.

Designz
Naval Architect

 

hehe,,,tip from my wife= to get fiberglass out of ya,,,,,take a pair of pantyhose < dont put them on> and run them up ya arms,,,they'll catch most of the glass,, i dont know bout the COLD shower,,cold water closes ya pores and traps the glass, i use luke warm and wipe in 1 direction. anyways,,heh, to get rid of ya material, if its less then an inch thick, use an airfile, or 6 inch DA and 60 grit, i'd even try 80 grit first,, and as you say,, theres no room for mistakes so taking a little longer to sand instead of grinding is the safe bet. sand the whole rudder,then fill and fair the whole rudder at once. and ya gel-coat should sand just like plain ole paint. are you taking off the gel? or just want to scuff it? to get ready to bottom paint,, sand with 220 then put ya bottom paint on. for fairing theres a million different things to use,, i try staying with what it was made with originally, but epoxy is the safest if you dont know what kind of resin was used, and its harder ( even tho i dont use the stuff haha)

 

Sorry

 

i wouldnt worry a bit about sanding through the gel,,,so what if ya do,,after your done all the sanding,,mix a couple cups of gel, brush it on,,thick ,,then sand with a DA with 220, then 320, then wet sand if you want a gloss,and buff. as long as its not a big area it will be easier on ya in the end,,then worrying about burning through. and i hope the gel coat isnt structual,,i cant imagine putting my life into the hands of the strength of paint. that gel is just paint,,just a LITTLE harder, but only bout 3 times the strength of regular house paint