Blasting the hull - what to do next ?

[baart]

Hi all,

the time has probably come to remove the years of accumulated antifouling. Looking to get it done this winter. But what do I do once the paint is removed? The hull was epoxied when new, no signs of osmosis so far. If I understand correctly the blasting will not remove the epoxy layer. So can I just use the primer and then antifoul or shall I apply a few extra layers of epoxy anyway ? What are your thoughts ?

 

[Tranona]

Hi all,

the time has probably come to remove the years of accumulated antifouling. Looking to get it done this winter. But what do I do once the paint is removed? The hull was epoxied when new, no signs of osmosis so far. If I understand correctly the blasting will not remove the epoxy layer. So can I just use the primer and then antifoul or shall I apply a few extra layers of epoxy anyway ? What are your thoughts ?

Coppercoat on the hull and probably the keel, although that, if iron will need epoxy coating.

 

[guyc]

I tend to use the International guide. It is quite good for identifying what needs to be done.

Paint Guides

 

[KeelsonGraham]

We were in your position this time last year. The blasting process took off much of the epoxy primer base (can’t remember the proper name for it) so the hull had then to be sanded down and prepped for a new one. At the same time we discovered a few minor voids in the skeg and rudder which had to be filled and finished. Ours is a 2006 boat with an immaculate looking hull, so we were surprised to find any voids. I guess that’s normal for a boat of this age.

Anyway, having unintentionally got down to gelcoat, we decided to go the whole hog and have the hull done with Coppercoat. This doesn’t require an epoxy primer layer. Happy with the decision so far.

 

[Jon magowan]

So glad you asked this question Baart.

I‘m a newbie having bought my first boat a year ago. It’s a 2013 Bavaria 33. The hull has 10 years of anti foul on it and the surveyor recommended I clean off the hull and start again.

So I’ve booked the lift out and ‘sand’ blasting for the beginning of May. Beyond that, I don’t know what to do !

I’ve already bought epoxy primer and anti foul from SeaJet, but the thing I’m interested in is what I need to do to the bare gel coat.

All wisdom gratefully received.

 

[KeelsonGraham]

So glad you asked this question Baart.

I‘m a newbie having bought my first boat a year ago. It’s a 2013 Bavaria 33. The hull has 10 years of anti foul on it and the surveyor recommended I clean off the hull and start again.

So I’ve booked the lift out and ‘sand’ blasting for the beginning of May. Beyond that, I don’t know what to do !

I’ve already bought epoxy primer and anti foul from SeaJet, but the thing I’m interested in is what I need to do to the bare gel coat.

All wisdom gratefully received.

1. Repair any voids
2. Key the gelcoat with 70 grit
3. Apply epoxy primer when the hull is warm and dry
4. Apply anti-foul

 

[Tranona]

So glad you asked this question Baart.

I‘m a newbie having bought my first boat a year ago. It’s a 2013 Bavaria 33. The hull has 10 years of anti foul on it and the surveyor recommended I clean off the hull and start again.

So I’ve booked the lift out and ‘sand’ blasting for the beginning of May. Beyond that, I don’t know what to do !

I’ve already bought epoxy primer and anti foul from SeaJet, but the thing I’m interested in is what I need to do to the bare gel coat.

All wisdom gratefully received.

It really is worth considering Coppercoat if you are going to the expense of blasting. The hull is straightforward. Same prep as for conventional but no need to epoxy as Coppercoat is itself an epoxy. The extra cost is more than offset by the longer life - typically 10 years. My Bav 33 was in the water for the 6 years I had it with just an annual lift and pressure wash. Keel is more problematic as epoxy does not always stick well, but still worth doing. My keel lasted 4 years before I had it blasted again. I Coppercoated again with better prep than the original, but have since sold the boat.

 

[Ian_Edwards]

I'd get hold of a moisture meter, and check the hull and especially the rudder(s).
Unless you use a commercial grade moisture meter, I wouldn't believe the results, but I'd be looking for areas with significantly higher readings, in essence looking at the difference in value rather than the absolute numbers.
If you find any anomalies, it would be worth investigating them whilst the boat is out of the water and there's no antifouling on the hull, keel and rudders. It might save a lot of money and hassle in the long run.

 

[rogerthebodger]

It really is worth considering Coppercoat if you are going to the expense of blasting. The hull is straightforward. Same prep as for conventional but no need to epoxy as Coppercoat is itself an epoxy. The extra cost is more than offset by the longer life - typically 10 years. My Bav 33 was in the water for the 6 years I had it with just an annual lift and pressure wash. Keel is more problematic as epoxy does not always stick well, but still worth doing. My keel lasted 4 years before I had it blasted again. I Coppercoated again with better prep than the original, but have since sold the boat.

Can you apply copper coat over epoxy tar as a, undercoat as epoxy tarle iss less hydroscopic than other epoxies

 

[baart]

It really is worth considering Coppercoat if you are going to the expense of blasting

I thought about that but then we are planning to sell next year and I am not sure if the expense in that case is justified. I have to do something though as at the moment the bottom looks like the moon surface

 

[rogerthebodger]

I thought about that but then we are planning to sell next year and I am not sure if the expense in that case is justified. I have to do something though as at the moment the bottom looks like the moon surface

If that is the reason I would just sand it smooth as described elsewhere the slap on another coat of anti fouling

 

[baart]

I would just sand it smooth

you might have just saved me quite a bit of money. I shall investigate

 

[harvey38]

We'll be getting soda blasted in May ready to accept another 12 years of Coppercoat.

 

[Chiara’s slave]

We'll be getting soda blasted in May ready to accept another 12 years of Coppercoat.

A good soda blaster works wonders. However, that gold standard treatment is for keepers, not flog her next yearers. If I were flogging my boat, a decent sand, and new conventional antifoul and a late launch to make her look clean is the way I’d go. Nobody is going to pay you 3 grand extra for brand new coppercoat, sadly, even though it’s the best thing to do at this pount.

 

[Tranona]

I thought about that but then we are planning to sell next year and I am not sure if the expense in that case is justified. I have to do something though as at the moment the bottom looks like the moon surface

Then don't waste money on blasting. Just clean it up as best you can and re antifoul. It will have no effect on value. Fresh antifouling always makes a boat look good even if it is not smooth! Proper jobs are only worth doing if you plan to keep the boat. Save the pennies and do it on the new boat

 

[Tranona]

Can you apply copper coat over epoxy tar as a, undercoat as epoxy tarle iss less hydroscopic than other epoxies

No. No need for anything on a clean GRP hull. Coppercoat is an epoxy coating although some people do apply epoxy first usually because of the need for remedial work on the gel coat.

 

[Stemar]

Apologies for the thread drift, but I started cleaning the old antifoul from Jazzcat yesterday and it's depressingly slow and much harder work than I like. Can someone give an idea of the cost of soda/dry ice blasting and 8m Cat?

BTW, Coppercoat, while not maintenance free, is good, unless you're on a mud berth, where the makers don't recommend it, from my experience, with good reason.

 

[baart]

give an idea of the cost of soda/dry ice blasting and 8m Cat?

For a 30ft mono fin keel I got quoted £650.

 

[Chiara’s slave]

I’ve asked a mate who used to do it. Back soon I hope. Removal with chemicals and scrapers is bloody awful. We did it 2 years ago.

 

[Chiara’s slave]

He asks if it’s soft or hard. Hard isn’t much different to gel coat, only a skilled operator should be let loose on it. Soft, about 6-800 depending on where you are, yard charges etc.