GRP hull cleaning options

[Dunk130TC]

My 16ft cruiser river boat is looking a bit grotty beneath the waterline and in need of a few years growth removing. Google suggests a few home brew concoctions of acids, peroxides and whatever else is in the bathroom/kitchen cupboards. I must admit I'm nervy of mixing up a cauldron of nasties, it may well create a shiny hull but I'd like to be around to benefit from it.
Any ideas of decent product to use that is effective and not expensive?

[Simpo Two]

Does it have antifoul? If so the usual answer is to pressure-wash it off and re-coat.

[Dunk130TC]

Nope, it hasn’t been antifouled. So it looks like a limescale band on the water line and is black underneath. I’ve pressure washed which made little difference, hence a decent chem cleaner is probably the answer, but I’ve no idea what does or doesn’t work.

[Simpo Two]

Oxalic acid gets mentioned a lot, though I've never tried it. Maybe ask a good chandlery?

[Dunk130TC]

Thanks I’d heard of it, ideally after a product someone has successfully used, rather than being reliant on being sold an expensive magic nonremoving potion!

[paintman]

Stuff used on my own boat (17' open dory):

Oxalic acid.
Often sold in very small containers at very big prices to boaters.
Google 'Y10 boat cleaner'. Y10 comes as a gel so sticks to vertical surfaces.

Jif/Cif also does the job. Squirt on & work with either a sponge or a brush. Shown that one by a yachtie neighbour on his own boat.

Starbrite rust stain remover is good for ...........removing rust stains. Will do gelcoat & paintwork & - so far - hasn't damaged my boat.

If you check the MSDS sheets for boat cleaners you'll find quite a few contain oxalic acid.

Edited by paintman on Monday 29th January 14:01

[rossb]

Chine Shine - which was reviewed by PBO as best buy and has been used successfully by others at yard where my boat is kept

no commercial affiliation - google "chine shine boat cleaner" - you'll see some vids and reviews by users - i am going to be using it next month to get rid of slight yellowing on waterline on a boat which is dry-sailed

edit to say i think it was £20 for 2 litres

[Mr Pointy]

Cheap Oxalic acid with free delivery:

https://mistralni.co.uk/products/oxalic-acid-dihyd...

For a gloopy mix try adding a bit of wallpaper paste

[robinh73]

I run a chandlery and Y10 is superb stuff. One of the products you have to put no effort in to selling. PM if you want some and I will do a good price for you on it and send it out.

[Dunk130TC]

Thanks for the recommendations, I really don't want to mix the stuff myself.
Y10 it is!
(Robin - please could you contact me as your email link doesn't work.)

Edited by Dunk130TC on Monday 29th January 16:54

[robinh73]

Dunk130TC said:

Thanks for the recommendations, I really don't want to mix the stuff myself.
Y10 it is!
(Robin - please could you contact me as your email link doesn't work.)

Edited by Dunk130TC on Monday 29th January 16:54

I can't seem to change my primary email for some bizarre reason. if you want to email me at work on [e-mail], i shall sort this out for you.

[Dunk130TC]

Have emailed you

[MOTORVATOR]

Y10 or Oxalic acid are great products but it sounds to me like you have a build up on there that needs removing first. Y10 will only remove staining not layers of limescale.

Get a bottle of Starbrite boat bottom cleaner first (mix of Hydrochloric and Phospohoric acid) then go with Y10 after if you still have staining of the gelcoat.

Then after all that make sure you at least polish, but ideally rubbing compound and then polish. If you don't the surface left behind will be back to square one in no time.

[Hard-Drive]

What kind of pressure washer did you use OP? A normal domestic one isn't really up to it, you need something pretty industrial. Y10 is good stuff, however mixing Oxalic really is no big deal, and it will be truck loads cheaper. It will also bring the deck and superstructure up really nicely too, as well as any wooden strakes/handrails etc.

I'd then finish off with a slow start polisher and some Farecla compound before a polish down to the waterline, apply new A/F, and go boating.

[Dunk130TC]

Thanks for all the responses and particularly Robin for a great deal on Y10 and startbrite to give a go. Fingers' crossed!

[robinh73]

Dunk130TC said:

Thanks for all the responses and particularly Robin for a great deal on Y10 and startbrite to give a go. Fingers' crossed!

Pleasure, just hope it does the job for you. It should all be with you today if Royal Mail do their thing. Let me know how you get on.

[TiminYorkshire]

With my Rib I haul it out over the winter, then scrub it with Persil and a brush early spring! Given any growth has died off I find this remarkably effective, but you may not have the luxury of time out of the water...