DIY anti fouling tips please

[Fjord John]

Hi, trying to reduce my boating bills a bit but don’t want to mess it up as first timer.
I understand steps are: scrape, sand, apply 2 coats.
Any tips gratefully received, but in particular: what masking tape to use for a crisp line, and how soon to remove the masking tape after application of anti foul? Do you remove between coats? How long to leave first coat before applying second?

Boat is 10m fibreglass motor boat on Thames. Annual salty trip. Want navy antifoul.
On Force4, Shogun Self Polishing seems best at £99 a tin, think I’ll need 4 tins for 2 coats. Is this a good antifoul? She will probably be in the water for 2 seasons.

Thanks in advance - John

 

[Aardee]

It depends how many old coats are already on the underside and how smooth it is as a base. Ours is still pretty smooth so I just tidied up and bad or flaky areas before painting. We used the green decorators masking tape and left it on for both coats (one coat per day) and peeled it immediately after finishing the second coat...All good.

As for which antifoul, your best bet is to ask neighbouring boats what works best for them as it varies enormously by location. We used one 2.5 litre tin of Hempel Tiger Xtra per coat for a 10.4 m deep v planing hull.

I hope this helps.

 

[oldgit]

If in a Thames marina and 8kph for most of the time .
Get them to use their powerful jetwasher to remove any fouling and loose anti foul.
No scraping and def NO sanding
Oxlic acid to remove any staining from hull around waterline. Y10 or bulk powder from Ebay at a fraction of the price (mix with washing up liquid for added adhesion)
Decent quality masking tape, thick backing paper and as sticky as possible . Cheap rubbish will keep snapping as you run it along the side of the hull and not give a sharp edge to the A/F after removal.
If cost is important there are other ablative ie. soft anti foul products on sale in Navy that are perhaps better value.
Not totally convinced on the Thames that you need two coats either ?
Would go across to the Thames Forum and ask what the locals do and use, most on this forum are salt water boaters and suffer more regards fouling that anything floating in freshwater.
Do recall a friends boat that was in Bray marina being lifted after spending 2 + years afloat it came out nearly as clean as whistle.


Hempel NEW Classic Antifouling 5L Yacht Paint (True Blue) NAVY BLUE | eBay

 

[Chris_d]

Expensive anti-fouling is a waste of money on the non-tidal Thames its does nothing. Pressure wash off once a year and one coat of the cheapest stuff you can buy that is the right colour, its purely cosmetic. As OG says do not sand it as its really bad for your lungs. If going tidal once a year and you want good speed you'll probably need to pay more attention to fouling on the props and stern gear, but one coat every year or two is plenty. I usually slap this stuff on Antifoul

 

[simonfraser]

Fresh Water to kill Hull Fouling?

 

[DavidJ]

You probably know but there is hard and soft antifoul. Being on the Thames you will be using soft antifoul.
Just sharing my experience of soft and hard.
Because I tend to run at sub 25 knots I have always specified to my yard soft antifoul. It works well and jet washes off nicely every year, leaving a smooth surface.
A new yard about 10 years ago ignored my request and applied hard antifoul every year without me knowing. There is a lattice, I understand, that holds the antifoul which doesn’t jet wash off. Over years this builds up to really unsightly and inefficient crusty surface.

 

[Momac]

I use 36mm Frog tape. Remove it as soon as you finish painting
I used a sanding plate (Tool station) on a pole and sanding mesh (Toolstation) for wet sanding. Used a piece of the mesh by hand for the fiddly bits.

I did not use a a primer/barrier coat this time as I used the same antifoul as last time which was Seajet 031 - cost was £73 for 2.5L , possibly less online.
But if in doubt over compatibility or on bare GRPuse the Seajet primer /barrier coat
2.5litres covered it for me in one coat for a 33ft boat. One coat of antifoul did the job last time .It lasted 4 years had been less effective in the 4th year so probably 2 years would be a better lifespan.

Next time I may try Seajet 021 after a primer coat.
Fresh water based with salty water trips


.

 

[oldgit]

Just finished jet washing and single coat of Seajet 37.
Last done exactly 12 months ago.
Remarkably clean,very thin layer of slime and 30 or so barnycules on hull.
Props clean as a whistle.
All anodes totally gone.
Now waiting for tide to come back in.

 

[RAI]

Choose a different colour than the existing antifouling for the first coat. This makes seeing where you're painting too thinly visible. The your chosen different colour for the second coat for the same reason. As the soft antifouling wears thin it shows up better.
Use long handles on your paint rollers to reduce back strain and paint in your hair.

 

[Fjord John]

Thanks all, for your generous advice. Really appreciated. I’m looking forward to putting your tips into action. Kind regards John

 

[bowler]

If you need to scrape flakey bits use this type of scraper. Expensive but way superior to the cheap ones. Also useful in many other scraping applications.

Bahco 665 665 Carbide Edged Heavy-Duty Paint Scraper BAH665 | DIY at B&Q

 

[oldgit]

Choose a different colour than the existing antifouling for the first coat. This makes seeing where you're painting too thinly visible. The your chosen different colour for the second coat for the same reason. As the soft antifouling wears thin it shows up better.
Use long handles on your paint rollers to reduce back strain and paint in your hair

Did the job yesterday............. some of the anti-fouling may have got onto the bottom of the boat.

 

[Parabordi]

Did the job yesterday............. some of the anti-fouling may have got onto the bottom of the boat.

Mine got done too, I got a man in!!

 

[oldgit]

Mine got done too, I got a man in!!

Its the rich that get the pleasure, it the poor that do their own bottoms ?

 

[Parabordi]

Its the rich that get the pleasure, it the poor that do their own bottoms ?

You did it all on your own then? You sure?

 

[jon and michie]

First and foremost - have the correct PPE ie dusk masks, eye protection and coveralls best for me are the disposal type of coveralls

 

[oldgit]

You did it all on your own then? You sure?

Can assure you that everything that ended up on the structure of the drying blocks, my overalls, me and the mud below, was entirely from my own efforts.

 

[AndieMac]

First and foremost - have the correct PPE ie dusk masks, eye protection and coveralls best for me are the disposal type of coveralls

Indeed, most don’t, even sanding old paint with an electric sander without a proper mask or dust extraction, and too bad for your neighbour working on his/her boat.
The fumes from AF paint while being applied is nasty as well, if you aren’t used to high potency paint fumes, mask up with a respirator suitable for organic fumes.

 

[Scubadoo]

Sanding should only be done with wet&dry (wet) paper and a sponge, no dust to worry about.

 

[Pleinmont]

Yes only sand AF using wet paper - never dry.
No dust problems.