Abrading old antifoul to accept new layer

[oGaryo]

Hi, sorry for the basic question, been trailer sailing up to now but will be moving to a marina this year.. I need to apply a fresh coat of antifoul over the top of the existing Hemple Hard Racing coat current applied that's now a couple of seasons old... question is what do I need to do to the existing coat to ensure the new layer takes hold.. it's a mobo so will be doing 25kts + at times.

I'm also thinking of applying Hemple Tiger Xtra this time instead of Hard Racing driven by cost comparison between the two products.

The boat is used in and around the Solent with home berth up the Itchen.

thanks in advance

Gary

 

[RivalRedwing]

many just slap on the next coat but that just leads to a buildup that eventually needs scraping off.. I use a sanding mesh abrasive on a pole sander after wetting down the surface (rinse again at the end to complete the job). The mesh has the advantage of not blocking up and it is very water tolerant. I would caution against dry sanding for all the usual reasons.

 

[oGaryo]

many just slap on the next coat but that just leads to a buildup that eventually needs scraping off.. I use a sanding mesh abrasive on a pole sander after wetting down the surface (rinse again at the end to complete the job). The mesh has the advantage of not blocking up and it is very water tolerant. I would caution against dry sanding for all the usual reasons.

thanks.. started my own reading and found an RYA document on the subject with this advice for hard antifoul:

- Hard antifouling paints leave an exhausted layer of resin at the end of the season. This layer cannot be overcoated without some prior preparation. Therefore the old antifouling should be wet abraded before applying a new coat onto it.

they've also mentioned it's important to check antifoul compatibility but presume Hemple Hard Racing will be ok overpainted with Hemple Tiger Xtra

 

[davidej]

I use a sanding mesh abrasive on a pole sander after wetting down the surface (rinse again at the end to complete the job). The mesh has the advantage of not blocking up and it is very water tolerant. I would caution against dry sanding for all the usual reasons.

Can you tell us more about the mesh.

I am about to start rubbing down soon and am happy to consider ary alternative to wet and dry

 

[oGaryo]

very impressed with Hempel customer service.. sent them an email a couple of hours ago just to be sure it's ok to apply Tiger xtra over the top of hard racing and have received this in reply within 2 hours of sending:

Thank you for your e-mail.
You are correct with your assumption. It is best to wet abrade to 240 then make sure the hull is both clean and dry after a fresh water rinse prior to application of the Tiger Xtra.

Kind Regards

Keith Davies
Hempel UK Ltd

 

[Pye_End]

Can you tell us more about the mesh.

I am about to start rubbing down soon and am happy to consider ary alternative to wet and dry

This sort of thing:

http://www.toolbox.co.uk/silverline...gleBase&utm_medium=GB&utm_campaign=GoogleBase

Well worth using.

 

[RivalRedwing]

Can you tell us more about the mesh.

I am about to start rubbing down soon and am happy to consider ary alternative to wet and dry

Pye end has identified the mesh, I believe it is far better than wet and dry. There are a couple of grades available, I think I use the coarse but you could push the boat out and get a roll of each to see which you prefer, a single 12" length does my 34' boat. I use a pole sander because it enables you to work much more efficiently and quickly (and from the standing position), I also have a little hand held block for detailed work. Some form of holder is almost essential for the mesh (and they only cost a few £). As already flagged, use it wet, try a small area first and rinse off to see how effective it is.

 

[z1ppy]

We use Hemple hard racing on Aviator. whats the difference with the Tiger Xtra?

Mark (Elleasar) of this parish is the one to ask although i know he is busy at the moment, yes, he was one of the people i phoned!!!

 

[SolentPhill]

I use hard racing and have done for 5 years, at boat show I had a chat with Hempel guys on the stand they said to wet the whole area then go and Get a cuppa whilst it's soaking in, (I did this and it dried) then keep wet sponge handy and use wet and dry, I used polisher with hook and loop 240 grit plenty of water on the sponge and it worked great, not as dusty but messy on the floor around me. I took it right back as it went White in places, my boat is black, used their primer to touch up a few places and applied first coat. After 24 hours I rubbed it down on the sides only with smooth wet and dry ready for top coat tomorrow.

There a place on eBay saved £20 a tin on chandlery prices

http://www.ebay.co.uk/itm/Hempel-Ti...cessories_SM&hash=item3369b56600#ht_532wt_689

 

[William_H]

Rubbing down old antifoul paint

This is a horrible job. Basically you rub down as much as your determination will take you then give up and slap the new paint on. If you don't rub it down much and slap on lots of new paint the old paint will build up in thickness until it can be flaked off in lumps making horrible steps in the hull. good luck olewill

 

[oGaryo]

We use Hemple hard racing on Aviator. whats the difference with the Tiger Xtra?

Mark (Elleasar) of this parish is the one to ask although i know he is busy at the moment, yes, he was one of the people i phoned!!!

a little more research and Tiger Xtra is erodable albeit still suitable for powerboats up to about 25kts... will go for Hard Racing again or Hempel Glide, both of which aren't erodable.

I must get out my system this attitude of doing things the most cost effective way i.e. do it myself. Will have a go at it this time but pretty sure I'll come round to your way of thinking Howard.. pay someone to do the nasty stuff

 

[lw395]

I use the wet and dry sponges.
It is a horrible job though. But it does not take that long, particularly if you do it soon after lift out. Even hard AF seems to be softer then.

 

[ratbag]

many just slap on the next coat but that just leads to a buildup that eventually needs scraping off.. I use a sanding mesh abrasive on a pole sander after wetting down the surface (rinse again at the end to complete the job). The mesh has the advantage of not blocking up and it is very water tolerant. I would caution against dry sanding for all the usual reasons.

just tried this today, best tip ever thankyou, after many years coming home looking like papa smurf, so much easier than wet & dry on a block

 

[oGaryo]

just tried this today, bets tip ever thankyou, after many years coming home looking like papa smurf, so much easier than wet & dry on a block

I ended up using this method too with great results

 

[tt65]

Does it work on mud.

My boat seems to allow mud to impregnate the antifoul on my deep mud drying mooring. Can any one tell me if the sanding mesh and pole will clean off that stuff too. It sounds so good that I have ordered a pole and mesh anyway.

 

[alahol2]

Yes it will take the top layer of A/F off. You may have to scrub a bit harder than the rest of us though

 

[prv]

+1 for the drywall sanding mesh. B&Q sell it too if that's more convenient. Theirs comes in squares sized for their sanding pole ends; one square does a thorough job of my 24-foot boat and would probably keep going for a longer one.

I bring a wide bucket (actually an old tile-adhesive tub) and dunk the end of the pole in that frequently while scrubbing. Helps to keep the buildup of sludge (abraded-off paint and water) down which makes the sanding work better. You'll need to empty and refill the bucket periodically, and a hose to rinse down sections of hull is very handy (but not essential; I did it with buckets one year when the hose wasn't available).

The only thing I can think of that would improve on this method would be a lightweight powered (presumably air-powered) end to the pole. I'd rather use the pole manually than a powered sander that had to be held against the hull directly.

Pete