Silicones polish warning on GRP!

Zagato

Zagato

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I have always used what ever car polish I have knocking about because it is mostly free. I have just read in my boat manual that "waxes/polishes containing silicon should never be used on GRP as silicon can cause a reaction, which is similar in appearance to some forms of osmosis".
Shame as I have just polished it with Autoglym Super Resin Polish... no ill effects so far ?
 
vyv_cox said:
I have not come across that one before but silicones can inhibit the cure of many paints and sealants. Best advice is not to use any form of them on a boat.
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That's what I always thought until I spoke to a marine painter in a boatyard. He said that with modern paint preparations it is no longer a problem. Might be different with us do it yourself owners .

I've never had a problem using off the shelf degreasers .
 
Vyv is right - you should be very wary of silicone residue from any source on the boat.

But I don't think it's because it blisters GRP as your warning says, but because even the slightest contamination on a surface you try and paint will give you blistering in the paint that then looks like osmosis. We frequently see it in the antifouling near through-hulls that have been bedded in with silcone sealant.

I know some yards that have failed to spray Awlgrip successfully on surfaces which have at some point in the past been polished with silcone based polishes.

What little silicone sealant we had at the yard for specialist glazing jobs was kept under lock and key to ensure some other 'convenient' use didn't get it on to the aluminium hulls prior to painting.
 
Chiara’s slave said:
It's also a major issue if you change your mind about Hempel Silic one.
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Or PropSpeed.

I think there are remedies, probably not very nice, but I have no idea. An acid wash comes to mind??

Prop Speed is less of an issue as you can aggressively abrade the surface with a wire brush on an angle grinder - but a hull is slightly different.

Jonathan
 
Thanks for all your replies. The boat is a little used 2003 Drascombe Lugger and was advertised on the IOW for £3950. It came with its 2003 Honnor Marine trailer and 2003 Yamaha 8HP outboard (selling). This is a £7500 boat so I was amazed it was such a nice example when I peeled back the covers. It had been sitting for 4 years unused and only used for 6 weeks of the year at Seaview! Why so cheap!
There was mention of the hull needing painting as it had a sort of white staining/weathering not the usual fading. Somebody had used something on it to leave this staining. I was so excited as all the usual possible Drascombe problem issues were not present I bought her immediately and towed her home a few days later. To my huge relief the staining has come out BUT it took 5/6 attempts by hand with 3M medium cutting compound. I have now realised my sander is also used as an agitating polisher for want of a better description so am using that. She is a lovely boat. I am hoping with a tent she will be my last boat. Easy and cheap to store at home and great for the kids to use on their own. The yard she was stored at finally realised she was a bargain. I think they thought she was ordinary day boat money but these things are 23K new plus engine and trailer!
 
Zagato said:
Thanks for all your replies. The boat is a little used 2003 Drascombe Lugger and was advertised on the IOW for £3950. It came with its 2003 Honnor Marine trailer and 2003 Yamaha 8HP outboard (selling). This is a £7500 boat so I was amazed it was such a nice example when I peeled back the covers. It had been sitting for 4 years unused and only used for 6 weeks of the year at Seaview! Why so cheap!
There was mention of the hull needing painting as it had a sort of white staining/weathering not the usual fading. Somebody had used something on it to leave this staining. I was so excited as all the usual possible Drascombe problem issues were not present I bought her immediately and towed her home a few days later. To my huge relief the staining has come out BUT it took 5/6 attempts by hand with 3M medium cutting compound. I have now realised my sander is also used as an agitating polisher for want of a better description so am using that. She is a lovely boat. I am hoping with a tent she will be my last boat. Easy and cheap to store at home and great for the kids to use on their own. The yard she was stored at finally realised she was a bargain. I think they thought she was ordinary day boat money but these things are 23K new plus engine and trailer!
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If it sat for 4 years ... Yard was probably hassling owner to move it .... probably sold at yard fees clearance ... not unusual.
 
No the owner was stuck in Hong Kong during Covid and their holiday home was in Seaview. Unfortunate circumstances thereafter meant the boat needed to be sold as they sold the home. Plenty of room for a little Drascombe to collect yard fees without doing anything!! No the yard admitted they and the owner got the price wrong, said it was a bargain and thought I was going to flip it. He also said he thought it was an old model. The yard were really not very clued up! She came with all the paperwork manual/ build certificate etc which showed its build date. The serial number on the boat is not obvious if you don,t know where to look, not that they would have even tried to. She has cleaned up so well, shiny and untouched. Came with some very nice boat and cockpit covers and all the sailing gear... VERY pleased as was the owner. Money was far less important than a quick sale ?
 
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