Re-using anti-fouling?

[Sybaris]

We had a liftout in May 2011 at which time we applied Jotun SeaForce 90 anti-fouling.

Due to a change of plan for the winter we then lifted out again in October 2011 and will not launch again until April 2012.

The anti-foul was totally spotless when we lifted out, and still looks as if it was put on just yesterday.

I am now wondering if it will loose it's properties while out of the water.

Most makes give a maximum number of days that the boat can stay on land after a fresh paint (The SeaForce 90 Technical Data sheet does not), but my guess is that this might be different once the boat has been immersed.

Question: Regardless of what one might think the answer might be I would like to know if anyone here has done this with Jotun or any other brand, and if so how did it work out?

Cheers,
Per

 

[Quester]

Don't know about Jotun but I always apply Seajet Shogun 033 immediately after winter lift out in Oct before the nasty winter weather sets in incase its still nasty before lift in Mar/Apr. Seajet claim 6 months is OK before immersion and the performance of my antifoul for several seasons now seems to bear this out.

 

[VicS]

Product description
SeaForce 90 is a TBT-free high solids self-polishing antifouling based on Polymeric Plasticizer Technology (patented)
designed to last up to 60 months (consult your Jotun sales representative). The performance of SeaForce 90 is
achieved by a combination of unique synthetic polymers designed to impart features not found in the traditional
hydrating/CDP/Hybrid range of antifouling. IMO Anti-fouling System Convention compliant (AFS/CONF/26).
Recommended use
To be used on vessels operating in global service with drydocking intervals up to 60 months. SeaForce 90 is well suited
to offer 60 months antifouling performance on all underwater areas on vessels trading at high frequency.

Id say you are well inside the 60 months and it will be fine but you could do as suggested and consult a Jotun rep.

 

[Pasarell]

You are unlikely to get good performance from Seaforce 90 on a yacht for any extended period of time. The key phrase is in the last line of the quote posted by VicS. "High frequency".
Seaforce 90 is designed for commercial vessels that are active for a high percentage of the time and, for a 5 year antifouling, operating at relatively high speeds.
During the first few months you have already experienced the biocide release rate will be quite high so even on a yacht you will see good performance. After that initial period the release rate will slow right down and be very dependent on abrasion of water moving past the surface to allow a controlled release. If you operate at too low a speed with periods at rest the biocide will not be sufficient to control fouling.
Also, it is probably not meant to be left out of the water for an extended period as you have done. Commercial vessels antifoul in dry dock and get out again as quickly as possible to start trading. There is no requirement for being left out of the water for more than a couple of weeks so not built into the formulation.
If you are in a warm climate you may get away with it by regularly swimming under the boat and abrading lightly with a Scotchbrite pad but that won't create a very healthy climate to be in!

 

[Sybaris]

Pasasell and VicS,

I actually bought it last year when in the Red Sea because it was the only product I could get. I wrote to Jotun at the time and they said it will work similarly to their "NonStop" range. They also said that the "SeaQuantum" range would be more robust against low activity.

I decided to give it a go anyway because, well it was the only thing I could get, but also when we are in the water we are always on the move, i.e. we generally don't stay put for any length of time.

The product sheet does state that it is designed to last up to 60 months in the water, but does not say how long it will be ok on land before launch.

The whole thing is a bit of an experiment which so far has shown an incredible result. Apart from having had absolutely zero growth the first 5 moths it is also the easiest product to apply that I have ever used.

My plan now is to coat with one new coat before launch and then see how it goes. As I said it is a bit of an experiment.

Thanks for all comments

 

[Pasarell]

Before recoating I suggest you rub down lightly with wet and dry (used wet) as you may remove the hardened top layer and activate the rest of the coat. Putting an extra coat on is a good idea anyway as it will last for a while. If you can't rub down then a thorough pressure wash will be better than nothing.
Moving regularly in a small boat will be better than most yachts but nothing like the activity of a commercial vessel the antifouling is designed for. Think of a long distance container ship that will typically be at sea doing 20+ knots for 5 or 6 days with only 12 hour stops in port between each trip. It's all about abrasion of the water flowing over the surface and as soon as you get a layer of slime it will pretty much stop the antifouling from working. Good luck anyway - you've got the paint so use it while it lasts!

 

[Plevier]

I think Pasarell is being a little pessimistic. I've used Jotun SeaGuardian which is supposed to be only slightly different and been very impressed. Of course you can't expect 5 years, but it was better after 2 years than my new boat on the same mooring, done with Cruiser Uno, is after less than a year. I'm intending to use Jotun again.
P'l also says the initial biocide release will be fast. This seems illogical to me. Surely on a coating designed to be on continuously fast moving vessel and supposed to last 5 years, it must be designed to release at a slow rate, and on a stationary or slow moving vessel, it will release even slower?
Incidentally SeaGuardian must contain a lot of copper, the weight of a 5L can is astonishing.
Go very gently rubbing it down - if it's like SeaGuardian it is very soft. I don't know if it will have developed a hard layer. The data sheet gives a minimum time to recoat when applying but doesn't give a maximum time, suggesting it doesn't skin. I can't see any reason why having been in water for a while then dried should make any difference - but I'm not a chemist.