Antifouling advice please

[Nigbb]

I have decided to apply the antifouling myself this winter but there seems to be a huge difference in price for eroding paint. Is it a simple as the more you pay the better it is and if so whats better about one thats £100+ as apposed to £40 for 2.5lt . The brands that I have looked at are Hemple, Jotun and International . We are a 35 ft sports boat crusing about at 20-25 kt
Any advice please.

 

[rafiki_]

Best advice is to check what others use where you keep your boat. Not all a/fs work well everywhere. I used to use Jotun, but I believe they only sell to commercial applicators these days due to hazard concerns. I used coppercoat on my Azimut and would do the same in the future.

 

[Nigbb]

OK thanks for that, there are lots of boat out now at our marina so I will ask around, cheers Nigel

 

[Bandit]

Speed wise you are on the cusp between an eroding antifoul and a hard antifoul.

If you have a mid season lift and pressure wash you will remove a lot of the self polishing af, with hard no problem.

If you have hard antifouling and you then change to eroding for two or three seasons you cant successfully go back to using hard as the hard does not stick well to eroding afterwards.

Probably International Ultra 300 would be a good one to go for, consider getting a hoist out and pressure wash July or early august for best performance/ better diesel mpg.

 

[oldgit]

Go for budget hard A/F. ?
Many mid sized boats capable of 20 knots plus but who mostly spend time at around displacement speeds but with the odd 5 min WOT thrash at the end of trip out could get away with a soft £60.00 A/F, especially if 99% of the year is spent tied up.
On the other hand on smaller boat which spends a lot of its time nearly flat out, then a hard A/F makes some sense.
Do know several of highly experienced skippers with Turbo 36 who are perfectly happy with soft A/F.

 

[Sianna]

Hi Nigbb I'm in a similar situation we have a 28ft Leader 805 which cruises between 20-25knts , last year I used International Ultra 300 and the boat was in the water at Bucklers all year, in fact it still is, a couple of times in the summer whilst swimming I had a good look underneath and it was surprisingly clean with very little growth and a gentle brush cleared that up. So this year I'm going to use the Ultra 300 again. The outdrive was a different matter and had loads of growth so I need to rethink that one

 

[Farmer Piles]

I have the same dilemma. Used Hempel hard racing as that is what was on the boat when I bought her. I applied two coats and was underwhelmed with its efficacy. By contrast, my mate put International 500 on his Shetland 2250 last year, never got round to antifouling her this year and I reckon that his boat was cleaner than mine. I also did two bottom scrubs on mine with a nylon scouring pad and still his was as clean. Horrible job even with a dive bottle.

 

[DavidJ]

I used to use eroding antifoul on my Sealine S37 with similar speed use as yourself. It was very successful and kept the hull nice and smooth.
I changed yard about 10 years ago and although I specified eroding they have been putting on hard antifoul (Seajet in my case). My hull is now quite rough and crusty.
I would stick with eroding.

 

[Scubadoo]

In the last two years I have changed to Teamac D Plus eroding Antifouling paint and really pleased with it (Solent based). Design for speeds up to 25 to 30 knots and with my two coats applied last me the season easily. The best price is between pacermarine and tools-paint.com usually. But as others have said, a paint with good results in one part of the country may not be the same elsewhere.

 

[Momac]

If you have a mid season lift and pressure wash you will remove a lot of the self polishing af

I have not found that to be so on my own boat nor from observation of others but guess it depends on the fouling and the amount of force needed to remove the fouling.

 

[Portofino]

Been using hard and yes it’s got scabby ish .Used soft once and basically it was a disaster esp the bow strike area .
We cruise slightly higher in the 27-30 knot range so maybe the international micron just washed off , well it did never mind the “ maybe “
How ever in Italy with covid and travel restrictions I started to use the local yard a massive concern .Loano branch is the smaller of the group .They do SY s with there 800 T lift .Insurance wise you can’t DIY in there .
The hard stuff they have used previous two seasons this eco sprint 2 has been the best ever .
Veneziani Yachting: Antifouling

Having said all this they or I have now got the holy grail of prop and sterngear AF which incredibly works they charged an additional €200 .Previously we just gave up as do the majority of yards on SoF , they just polish the gear .Inevitably it fouls up .
What I have fond is a quicker boat , less fuel burn and lower load / EGTs for a given speed.
I think they use the prop stuff in the link ^^ .
For those grappling with stern gear be it outdrives ( I used to run one too btw ) or shafts the importance of there hygiene often is overlooked during the season , which makes a mockery of the actual hull surface growth .You ideally need to address both simultaneously .
Itama 42 ship yard

The above was June this year and in August one day to illustrate a point re achieving rated rpm at WOT on another thread about sea trails we saw this below .Rated WOT is 2200 rpm .


^ Just went out , no prior prepping achieving 38 knots .1080 hrs on 2002 engines .No alarms .

Normally we cruise under 1800 rpm say 1760 which hits 30 knots and a more modest 80-90 L / hr each .Equates to under 80 % load .
Previously In the SoF the sterngear always needed a clean by snorkelling and tbh you never get it back to yard standard .


Here is a pic of the scabby hull .


I came into mobo ing from a yacht racing background.So wearing a polished hull mindset .Buts let’s reflect for a moment.
6.1 knots to 6.3 wins the yacht race .

Its a different dynamics at planning speeds I reckon .I know this because my 20 y old tub reaches the same speed as it’s debutant magazine test with its scabby hull .More over still within rated WOT .

So what’s going on ? I have a golf ball theory ? But who cares it’s working” as is “

So where is my motivation apart from aesthetics and the deeply embedded racing yacht ( sail boat ) mindset to go for a Uber smooth hull ? Bear in mind the stern gear hygiene trumps hull hygiene point .

 

[Nigbb]

Thanks to everyone for your comments, I think on balance I will go with the more expensive International 300.
Cheers Nigel

 

[Nigbb]

OK a quick update, I have now been in contact with the company that antifoued it earlier this year when I purchased the boat and because that is a Thames base company they automatically used Seajet Hard not realising that I was taking the boat to the Solent and would use at significant higher speed than on a river.
This seems to be a bit of a minefield but I think I want to change to eroding, I have found a Practical Boat article that says you can put eroding on top of hard (obviously with the appropriate prep) but not the other way around. I guess they know what they're talking about but just wanted a second opinion .
Cheers Nigel

 

[Momac]

Antifouling Compatibility Table

 

[Portofino]

It will erode / wash off with planning speeds .Stick to a marine hard .
But it seems you have made your mind up before posting ?

25 knot cruise against a 5 knot current on the bow , not unheard of around coastal U.K. = wash it all off esp the bow / hit areas

 

[Sianna]

OK a quick update, I have now been in contact with the company that antifoued it earlier this year when I purchased the boat and because that is a Thames base company they automatically used Seajet Hard not realising that I was taking the boat to the Solent and would use at significant higher speed than on a river.
This seems to be a bit of a minefield but I think I want to change to eroding, I have found a Practical Boat article that says you can put eroding on top of hard (obviously with the appropriate prep) but not the other way around. I guess they know what they're talking about but just wanted a second opinion .
Cheers Nigel

Mine was the same Nigbb I bought it from Penton Hook and now use her on the solent, so went from hard to eroding, it's not a problem, I gave her a quick sand down then used the Ultra 300

 

[Nigbb]

It will erode / wash off with planning speeds .Stick to a marine hard .
But it seems you have made your mind up before posting ?

25 knot cruise against a 5 knot current on the bow , not unheard of around coastal U.K. = wash it all off esp the bow / hit areas

Thanks for coming back, wow such devided opinions, I had pretty much decided to stick with hard until reading the Practical Boat article and then was swayed towards eroding.

 

[Scubadoo]

It will erode / wash off with planning speeds .Stick to a marine hard .
But it seems you have made your mind up before posting ?

25 knot cruise against a 5 knot current on the bow , not unheard of around coastal U.K. = wash it all off esp the bow / hit areas

That's not my experience, used eroding for years on the Solent without any problems, so much easier to work with than hard antifouling. I have used both hard and eroding and definitely for me eroding is better. In my experience with hard antifouling you end up with layers that after so many years that needs removing to start again.

I don't see a problem applying eroding over hard providing it is in good condition and not flaking off, if a problem good preparation with wet and dry sandpaper then apply a primer.

 

[DAW]

My boat was supplied new with Ultra 300, which is a “hard” anti foul. After the first year of use, I switched to Micron 350, a self-polishing copolymer “soft” anti foul. No special preparation was required before application … the surface just needs to be clean and reasonably smooth.

I don’t like the build up of layers that you get with traditional hard anti fouls, so I’ve used Micron 350 for many years and have been very pleased with its performance.

I’ve not heard of any problems with Micron 350 on planing boats. The International website recommends it for use at speeds of up to 25-30 knots and it’s supposed to last two years. I have my boat repainted every year even though the anti foul is always in good condition and there’s usually almost no fouling.

Going from soft back to hard anti foul requires more intensive surface preparation as you need to completely remove the soft anti foul before you can apply the hard.

 

[gordmac]

Seajet do an eroding one for higher speeds.