UK's cheapest osmosis epoxy barrier/treatment? 9 coats, outdoor application AND no sanding!

[dankilb]

Christina had sat 'passively' drying for 5 years on the hard in N Wales before we acquired her. Following advice (from my first ever post!) on here, the decision was made to have her professionally (wet/slurry) blasted and deal with whatever we found underneath, before applying some sort of barrier coat.

The (wet/slurry) blasting subsequently revealed gelcoat in poor condition, with multiple 'pocks', small-ish blisters, thin areas, plus the usual few dings/stress crazing. The problem was initially discussed on here back in Feb: Gelcoat pox (after blasting) - how to fill and fair before Penguard?

Having (nearly!) finished tackling the project over the past 12 months, between other jobs - and with only the areas under the props still to do (...but in this weather!) - I am now in a position to report back on our experiences. All quantities apply to a 41' AWB which we calculated has 38m2 below the waterline (which broadly reflects our real world coverage/consumption of around 7m2 per litre).

This opening post addresses specifying the paint system which, ultimately, I now think may be a contender for the cheapest 'full service' (i.e. combing non-solvent impreg, high-build, and aluminium-additive epoxy coats) epoxy barrier coat - and which our experience has shown can be applied outside/uncovered in the UK (Sept-Nov), without the need for helpers (I largely worked solo or with the First Mate) and requiring no sanding between coats (with modest hot-coating and subject to any fairing required).

Our Chosen Method (Jotun and EL2) - £571 (£15.03 per m2 - £1.67 per m/per coat)

		Unit size	Price (inc.)	Qty	Sub-total
Impreg coat	East Composites EL2	5L	65.93	2	131.86
High-build	Jotun Penguard HB	5L	58.74	4	234.96
Barrier coat	Jotun Jotamastic 87 Alu Winter-grade	5L	68.10	3	204.30
				Total	£571.12

Total coats - 9


Ease - ★★★★☆

• No sanding required (with 'hot coating')
• Maximum 3 coats in 1 day (for the impreg coat only)
• 3 month overcoating intervals

Minima - 15°C (EL2/impreg only) / 2°C (Penguard with low-temp additive) / -5°C (Jotamastic 87 Wintergrade - for the very brave!) - 85% humidity

Next, as I get a chance to compile the posts, I will share the same costings/information for the other systems we considered (inc. Int'l, Hempel, Wests and other Jotun combos) before moving on to the method itself. All assessment of the process ('ease' etc.) are of course subjective and based on our circumstances. Costs don't include sundries (considerable...) nor the addition of things like additives, thinners or fairing filler - as not all applications will require these. I haven't included tie coat/AF primer.

 

[dankilb]

International GelShield - £939.50 - (£24.72 per m2 - £4.95 per m/per coat)

		Unit size	Price (inc.)	Qty	Sub-total
Impreg coat	International Gelshield Plus	2.5L	99.95	4	399.80
Barrier coat	International Gelshield 200	2.5L	89.95	6	539.70
				Total	£939.50

Total coats - 5


Ease - ★★★★☆

• No sanding required (although max overcoating interval down to 2 days @ 23°C - I deducted a star for this, because you can't always paint a coat every 2/4/7 days)
• Short overcoating intervals (to allow 'semi'-hot coating)
• Widely available, proven product, established method, lots of info, etc.

Minima: 10°C

This method and, specifically, the number of coats were informed by the International's excellent Application Guide (specifically focused on osmosis repair). This guide - together with advice from @Elessar on here - helped focus my mind on finding a (more affordable) method with a first ('impreg') coat of non-solvent epoxy.

The commercial (20L) tins of Int'l would lower the price considerably, but I'm not aware of which (if any) of those are equivalent to the above.

 

[dankilb]

West System - £661.74 - (£17.41 per m2 - £3.48 per m/per coat)

	Unit size	Price (inc.)	Qty	Sub-total
West System 105	30L	507.76	1	507.76
West System 422 Barrier Coat Additive	3kg	76.99	2	153.98
			Total	£661.74

Total coats - 5

Ease - ★★☆☆☆

• No sanding required (strictly hot coating required - each coat wet-on-tacky)
• Must be completed within a day/shift - so sufficient helpers are required
• Excellent tech support, clever measuring pumps, plenty of info/YT videos, etc.

Minima: 15°C (everyone knows the viscosity of West's is unlikely to be any good for painting unless is 'warm', so - despite the TDS going down to 5°C - I think 15°C is generous!)

In general, the technical advantages of West's (with 422) are acknowledged (in my mind at least). However, as you can see above, I rate the method as 'hard' mainly because it requires a lot of hands on the job, during a single day/period of favourable (and warm) weather. I appreciate others may see this is an advantage, however.

One advantage is potentially having leftover laminating resin for other projects!

 

[dankilb]

Hempel High Protect - £661.74 - (£19.20 per m2 - £3.84 per m/per coat)

	Unit size	Price (inc.)	Qty	Sub-total
Hempel High Protect	2.5L	72.95	10	729.50
			Total	£729.50

Total coats - 5
Ease - ★★★★★

• Generous overcoating intervals for a non-solvent epoxy (5-12 days)
• No other product required
• Seems easy enough...!

Minima: 10°C

 

[upcountry2]

Jotun every time, used it for years on VLCC ( supertankers) and on my own boats many times, always pleased with cost, application and it’s tolerance to less than perfect conditions.

 

[dankilb]

Jotun every time, used it for years on VLCC ( supertankers) and on my own boats many times, always pleased with cost, application and it’s tolerance to less than perfect conditions.

This raises an obvious question of why not go for Jotun alone...?

Jotun Penguard HB and Jotamastic 87 - £604.10 - (£15.87 per m2 - £2.27 per m/per coat)

		Unit size	Price (inc.)	Qty	Sub-total
High-build	Jotun Penguard HB	5L	58.74	4	399.80
Barrier coat	Jotun Jotamastic 87 Alu Winter-grade	5L	68.10	3	204.30
				Total	£604.10

Total coats - 7

Ease - ★★★★★

• No sanding required (long overcoating invervals)
• Excellent supply/support from SML in the UK
• Extremely tolerant to atmospheric/application conditions

Minima: 2°C (Penguard with low-temp additive) / -5°C (Jotamastic 87 Wintergrade)


Or, arguably the most established, cheapest and simplest method would be...:

Jotun Penguard HB - £352.44 - (£9.27 per m2 - £1.55 per m/per coat)

	Unit size	Price (inc.)	Qty	Sub-total
Jotun Penguard HB	5L	58.74	6	352.44
			Total	£352.44

Total coats - 6


@James W of this parish went for Penguard HB with the same model boat, also outside (I believe) in UK and with good results/experiences: After 7 years on the hard, should I power sand antifoul (to epoxy) or leave alone?

Indeed, this is the method SML recommended to me. Specifically, they said:
"we would always recommend Penguard HB for this type of a project as it has better adhesion, meaning your paint system will last longer. Whenever starting with steel, we would recommend a Jotamastic product as it has better corrosion protection"

I can absolutely second that Penguard has phenomenal adhesion and goes on beautifully. That is why we did opt for it as the 'high build' component of our barrier system.

We went for the addition of Jotamastic - despite being contentious (inc. the respected opinion of SML) - as the aluminium additive does give it 'excellent' water resistance, according to Jotun's TDSs, compared to 'very good' for Penguard. Aluminium (with mica etc.) is an established osmosis barrier additive for epoxy (e.g. West 422).

We then added the EL2 due to specific concerns about solvent entrapment/absorbance with our substrate (very porous and badly damaged gelcoat), so wanted a non-solvent epoxy (laminating resin) impreg coat as per advice received on here and the International method linked above.

 

[Restoration man]

Hi can I ask, have you had a moisture meter on the hull before epoxy coating ? If so what meter did you use and what reading did you get

 

[dankilb]

Hi can I ask, have you had a moisture meter on the hull before epoxy coating ? If so what meter did you use and what reading did you get

Only at survey - Sovereign Quantum meter and it read between 12 - 14 in most areas and up to 17 in places. The topsides read 9 - 10, for comparison. I've seen various interpretations of the Sovereign scale that would put those readings at 'moderate' to 'high'.

Because I had no means to 'actively' dry the laminate (e.g. heat, vacuum, gel peel, etc.) anyway, I didn't bother with any further moisture readings post-survey. To me, there's only any point in worrying about moisture levels if you are in a position to do something about it (or, of course, in a position to opt not to epoxy coat!).

 

[johnsilver2]

I had often wondered what was going on with Christina as I drive past on my way to my boat in the Harbourmasters' yard. That is if Christina is the Christina Lente in the sailing club yard
I overwinter in Rhyl from my mooring in Holyhead and have done for the last 7 years.
Last year I took advantage of the lockdown and stripped the old barrier coat off and West System barrier coated and Coppercoated my Contessa 32. I have some experience of this subject now!

 

[Restoration man]

I was under the understanding that unless the hull is a certain dryness it’s not advisable to epoxy the hull ,it’s best to leave it alone as it is as it can cause more problems in the long run ?, not really sure about the science behind it ? What’s the worst that can happen the hull can fall off ??,and funnily enough this information always seems to come from osmosis treatment centres ??? ,
The so called rule of thumb is ,it’s ok to epoxy if it’s less than 15% on the scale of a tramex skipper plus meter ,
Sovereign meters read a lot lower than the tramex ,
14 on a sovereign meter is more like 25 on a tramex , when you say the top sides read 9 for comparison do you mean the hull above waterline if so the readings should be comparative to this but if your referring to the superstructure then I can’t see how you can use reading off there for comparative conversion, The reason I ask all these questions is I’ve been involved with a project with similar issues as yours with only blister repairs and not a full gel strip , and we have been debating on should we barrier coat the hull or not with slightly elevated moisture Levels, will it just blister the new epoxy barrier cote? Will it cause the hull to get even more blisters and rot it to bits ??? Ok no coatings is 100% waterproof but I can’t see the harm in slapping some on , surely if it stops the rate of water getting in it can’t be a bad thing ??? We just don’t know what to do ,
anyway I look forward in to seeing how your coating stands up please keep us informed

 

[dankilb]

Before moving on to the method - a few more additional cost factors are worth noting:

Fairing Compound

Again, Jotun comes out on top. We used 4L with one light coat over maybe 20m2 - although it's very hard to estimate. What I can say is that the Mega Fill mixes, goes on and sands beautifully.

		Unit size	Price (inc.)	Qty	Total
Jotun	Mega Fill	4L	148.20	1	148.20
Hempel	Profair	1KG	46.99	4	187.96
International	Interfill Base + Hardener	2.5L	117.91	2	235.84

AF/Tie Coat Primer

...you guessed it, Jotun wins again! I tried to be generous to International - as I know Primocon has a loyal following - and found the most competitive price to do a couple of coats. The best I could find 5L tins was around £100, so double that for enough for three coats/stripe coating/leftovers, etc. And once again, Vinyguard is lovely stuff. It couldn't go on nicer/easier/quicker and I got two coats (41' AWB / approx 38m2) inc. keel from one tin.

		Unit size	Price (inc.)	Qty	Total
Jotun	Vinyguard 88	5L	40.20	2	80.40
Hempel	Underwater Primer	5L	79.84	2	159.68
International	Primocon	2.5L	59.95	3	179.85

 

[dankilb]

I had often wondered what was going on with Christina as I drive past on my way to my boat in the Harbourmasters' yard. That is if Christina is the Leesa Christina Lente in the sailing club yard
I overwinter in Rhyl from my mooring in Holyhead and have done for the last 7 years.
Last year I took advantage of the lockdown and stripped the old barrier coat off and

It is the very same! She was in Rhyl for 7 years herself...

...until she left last Saturday (via road)! We aimed to splash her in Rhyl for a while, but bottled it in the end (she still needs another few weeks work over Xmas before we launch).

Last year I took advantage of the lockdown and stripped the old barrier coat off and West System barrier coated and Coppercoated my Contessa 32. I have some experience of this subject now!

I bet! That was top of my list of methods for a long time, but bottled it on the need for hot coating (enough/competent helpers etc.). Now - having done it (albeit a different way) - I probably couldn't used West's by doing it in sections. On the other hand, a lot to be said for being able to do it (all or a section thereof) in one day... Maybe next time?!

 

[dankilb]

I look forward in to seeing how your coating stands up please keep us informed

?... and I should say, I'm no expert. I've just done it once. It went on well and is tough as nails (had the 'pleasure of sanding it to feather the patches under the props and it tore through tough Autonet sanding discs like nothing else!). But others on here can give better advice on moisture and epoxy tolerance, pitfalls, etc.

I was under the understanding that unless the hull is a certain dryness it’s not advisable to epoxy the hull ,it’s best to leave it alone as it is as it can cause more problems in the long run ?, not really sure about the science behind it ?

I believe the risk is trapped 'moisture' (or whatever it is) ultimately tries to escape and blisters can form under the barrier coat as a result.

What’s the worst that can happen the hull can fall off ??,and funnily enough this information always seems to come from osmosis treatment centres ??? ,

Fair point. The yacht 'Esper' (FollowTheBoat on YouTube) used Jotamastic and had quite a few small blisters at next haul out. They just had them lightly sanded/ground out, filled, and repainted. I think that was 2016 and apparently been fine since.

The so called rule of thumb is ,it’s ok to epoxy if it’s less than 15% on the scale of a tramex skipper plus meter ,
Sovereign meters read a lot lower than the tramex ,
14 on a sovereign meter is more like 25 on a tramex

Our survey included a chart showing 19 on sovereign as 'osmotic'. I don't know whether that number is accepted or not. But that might indicate a level at which you definitely don't proceed until it has been dried out somehow.

when you say the top sides read 9 for comparison do you mean the hull above waterline if so the readings should be comparative to this but if your referring to the superstructure then I can’t see how you can use reading off there for comparative conversion

I believe surveyors normally take readings from the hull above the waterline (aka 'topsides'!) - logically, somewhere in the middle - as a 'dry' comparison. The coachroof/superstructure could be a different construction etc. (or might be more wet?!).

Otherwise, as I said, others on here have more knowledge of epoxy coating than me. I guess it comes down to a question of 'why epoxy?'. If it solves a problem you currently have, fair 'nuff. If it solves a perceived problem in the future, maybe think twice.

 

[Criscat]

Hi there! Has someone had tried Jotun Antipest?
Some professionals guys here at the yard have suggested to use it as a primer on whole hull, I have some big areas with bare grp and mostly thin and sanded gelcoat left that’s looks good. I have been filling old air holes so far with an epoxy mixture. Apparently no osmosis. 45 year old Kuheli (HR Rasmus35) as been on the hard since last February.
Thank you

 

[longjohnsilver]

Phantom post.

 

[Mudisox]

Similar treatment as the OP, done some 12 years ago finished with quality commercial anti fouling, every 2 seasons. wonderful and just needs a wipe off.

 

[Fr J Hackett]

I went the Gel Shield way on a Vancouver 27 must be over 30 years ago and last I heard of her she had no problems. Having said that the hull was sound before we did it as a belt and braces measure.

 

[Wing Mark]

Having spoken to a few people who've paid 4 figure bills for boatpox repairs, I think saving £100 on the gloop is a bit of a detail?