Painting around mushroom vents

[Gareth E]

I'm in the process of re painting my roof. I've removed all rust, I'm at the priming stage. There was a fair amount of rust around the mushroom vents. I'm wondering now whether to build up layers of primer around them, to the level of the surrounding sound paint. This will look neater but will close the gap between paint and vent. I'm not sure this is a good idea, might it be better to allow this gap, in order that I can get some sealant in there?

[rusty69]

Take em off, paint beneath, put em back. 

[Nightwatch]

Do like what I have done. Take your mushroom vents off. Grind off all the rust. Vactan the area, paint, replace mushroom vents. I haven't completed the whole task yet but I've promised that'll I'll paint the top coat very soon.

 

You don't know what's going on under your mushrooms until you have a shufty.

Rusty!! Beat me to it.

[OldGoat]

3 minutes ago, Nightwatch said:

Do like what I have done. Take your mushroom vents off. Grind off all the rust. Vactan the area, paint, replace mushroom vents. I haven't completed the whole task yet but I've promised that'll I'll paint the top coat very soon.

 

You don't know what's going on under your mushrooms until you have a shufty.

Rusty!! Beat me to it.

Wot he says...

I'm assuming from your description that they are not really 'mushroom' shaped but more like 'cow pat' - flatish and chrome plated - in which case you should be careful when removing them, 'cos they're quite delicate.

[BWM]

Take them off as others have said, i'm in the process of doing mine and have been making neoprene gaskets for them. I've found this much more reliable than sealant and has the added bonus of not reacting with paint.  

[captain birdseye]

I agree with BWM above, when I removed all my fitting to repaint I made neoprene gaskets for everything and fitted them. A much better job

[BWM]

54 minutes ago, captain birdseye said:

I agree with BWM above, when I removed all my fitting to repaint I made neoprene gaskets for everything and fitted them. A much better job

It seems to allow for the movement of different metals and avoids the fine cracks that develop where they join. An added bonus is being able to remove them afterwards without destroying the paintwork. 

[mrsmelly]

As others have said you must remove them and prep properly. One very valid point is make sure you cover over the wholes inside the boat or you will end up with rust and dust everywhere. paper taped round with masking tape does the job.

[ditchcrawler]

3 hours ago, BWM said:

It seems to allow for the movement of different metals and avoids the fine cracks that develop where they join. An added bonus is being able to remove them afterwards without destroying the paintwork. 

When you say neoprene do you mean the closed cell foam type or solid sheet ? Its something I will need to do soon

[BWM]

12 minutes ago, ditchcrawler said:

When you say neoprene do you mean the closed cell foam type or solid sheet ? Its something I will need to do soon

I used the solid, rubber like sheet, i've not had any experience of the foam type but would have thought it would deteriorate quicker, both by weather and compression? 

  My hand was forced a little by having a wooden back cabin, which with all the temperature related movement is impossible to seal. The neoprene has been so successful that I am using it wherever possible on both cabin top and portholes. Easily available via eBay, the price drops quite a lot depending on the size of sheet purchased. I used 3mm and that seemed to cope well with the curved surface. 

[ditchcrawler]

Any sealant on it when putting it together. We use to make lid  gaskets for cast iron junction boxes out of sheet neoprene (just wish I could spell it)

  

[WotEver]

26 minutes ago, ditchcrawler said:

Any sealant on it when putting it together. We use to make lid  gaskets for cast iron junction boxes out of sheet neoprene (just wish I could spell it)

  

I. T. 

[WotEver]

 

[mrsmelly]

1 hour ago, BWM said:

I used the solid, rubber like sheet, i've not had any experience of the foam type but would have thought it would deteriorate quicker, both by weather and compression? 

  My hand was forced a little by having a wooden back cabin, which with all the temperature related movement is impossible to seal. The neoprene has been so successful that I am using it wherever possible on both cabin top and portholes. Easily available via eBay, the price drops quite a lot depending on the size of sheet purchased. I used 3mm and that seemed to cope well with the curved surface. 

Love the mushrooms ? ours are painted matt black with gloss red tops. You wont believe this but they are usualy made of a dull alloy metal and some people spend ages rubbing them with some compound until they go shiney for a day then they go dull and the action is repeated ?

[BWM]

2 hours ago, mrsmelly said:

Love the mushrooms ? ours are painted matt black with gloss red tops. You wont believe this but they are usualy made of a dull alloy metal and some people spend ages rubbing them with some compound until they go shiney for a day then they go dull and the action is repeated ?

Thanks, this is a cast iron one but I know what you mean. Most modern brass ones are made of low grade alloy and tarnish as soon as you look away!

[blackrose]

On 21/06/2018 at 10:11, BWM said:

Take them off as others have said, i'm in the process of doing mine and have been making neoprene gaskets for them. I've found this much more reliable than sealant and has the added bonus of not reacting with paint.  

A decent sealant won't react with the paint. I've never had any paint reaction from sikaflex, marine flex or stixall. 

Edited June 22, 2018 by blackrose

[blackrose]

On 21/06/2018 at 11:59, BWM said:

It seems to allow for the movement of different metals and avoids the fine cracks that develop where they join. 

A good flexible sealant will do the same thing. 

[BWM]

28 minutes ago, blackrose said:

A good flexible sealant will do the same thing. 

That hasn't been my experience, and having the ability to remove a component without needing to repaint the area around it works for me.

[ditchcrawler]

I am just concerned about moisture creeping between the gasket and the roof

[Janey72]

Hi there

 

I painted my boat and am now helping a friend - his is grp top steel hull. With mine i sealed then painted - but now appreciate that means re painting if the seal deteriorates - around windows and wooden rails (that are not being removed) would you recommend prep, paint then seal or visa versa? Thanks

 

any advice on best sealant on grp much appreciated - marine sikaflex gets good reviews but is pricy - is it worth the price?

 

PS glasticord is a miracle product for a gasket that we used to make a porthole seal and then sealed again with a sealant around the edges (did the latter after painting)