Hull been soda-blasted (pics and a short video clip).

[carlton]

After taking out my boat recently and managing 24 knots at WOT, I thought it was time for a lift out/inspection. (WOT should be 40 knots).

This is what the underwater sections look like after 5/6 coats of antifoul have been applied over previous years.

So we tried paint stripper together with a very manly scraper thing (£25). Using the scraper alone was possible but an absolute b*ll-breaking job. Paint stripper was useless. This shows how ineffective paint stripper was after being left on for 24 hours. (Scraped areas visible).

The same section after being soda-blasted.

The finished job - back to the original grey Gelshield coat. I asked the operator to leave the last inch to indicate the waterline.

Company called T.C.S. - website here

Took the bloke (Les) about eight hours. I'm delighted with the result, and would recommend them to anyone.

Poor quality (21 Mb - 1 minute 3 seconds) Video here showing how it was done.

[image][/image]

 

[DAKA]

Compared with my experience you have been very lucky, i know many claim amazing success but anyone with an older hull (over 5 years old ) needs to consider other alternatives.

Perhaps your hard gel shield coat has protected your gel coat but my last boat suffered serious damage to the actual gel coat.

A few years ago at lift out a friend had his 1987 Fairline corniche at the side of my 1988 corniche.
He wanted me to join him for a slurry blast of 'gentle soda'.
I wasn't keen even when offered a two for one deal and declined.
My mate went ahead and I saw the damage the following weekend

Whole hull was riddled with small holes in the gel coat.
The whole boat had to be filled and epoxy coated.
At some stage a section of 1 ft by 2 ft on my bow had also been blasted.
It is unclear if
they started on the wrong boat.
they hit it by accident
they wanted to see if my hull would also be wrecked
they thought it was such a good job I would want mine done


My 'test' section was also covered with pin prick holes that I needed to fill.
I was pleased a small section had been tested as it confirmed to me that GRP shouldn't be grit blasted unless it needs an osmosis treatment.
A friend was then kind enough to clean my hull with an electric chisel, the old antifoul came off and left beautiful white shinny gelcoat with no visible signs of weakness.
It is clear that older boats have naturally occurring bubble holes deep within the gel coat that are created during the mixing. These bubbles are fine and will not cause a problem unless the Gel coat is overpolished with compound, over sanded or slurry/grit blasted.

The slurry blast had not made the holes but it had exposed voids that had been water tight for 15 years (moisture reading were very good).

The grass under the treated boat has still not grown back and turned into a bog for a while.

From my experience I would only have a slurry blast on a modern boat that had used a vacuum technique to mix the gel coat and so reduce the amount of bubbles.

If you read the professional sites they warn about this in a round about way " leaves a nice key finish ready for filling and epoxy coating " shouldnt the surface be ready for AF Primer ?

 

[carlton]

Yikes ! Seems it's lucky for me that my boat has a coat of gelshield. In the light of your comments I'd be reluctant to have it done to standard gelcoat.

(BTW, my boat - and its original gelshield- is 15 years old).

 

[DAKA]

stab in the dark but could end up looking silly.............

Bayliner ????? have being using this vacuum mixing technology for years so you could well have got a very well mixed gel coat where many perceived better built British boats were slow to catch on, I would expect some builders still do not use this vacuum mixing technology.

If you dont have any pin prick holes your hull gel must be very well made up.

If she is a Bayliner (1990 -91 isn) I think the lower hull was grey gel coat, are you sure the gel shield has been left behind /forums/images/graemlins/confused.gif
your man must have been hell of a lot more careful than the butcher that did the corniche at the side of mine !

edit

you added the age thanks /forums/images/graemlins/smile.gif

I may have confused the issue /forums/images/graemlins/blush.gif

Gel coat is the original lay up moulded in.
when i refered to gel shield I was thinking of an additional twin part coat of water proof paint added after the boat was moulded.

either way yours has been done well and looks good which is all that matters /forums/images/graemlins/cool.gif

 

[carlton]

She's a Bayliner 3055. According to the previous owner, Bayliner gelshielded many of their boats at that time to erase their poor reputation for their boats suffering from the "O" word. Seems to have come through the process fine, except for revealing a couple of previous owners' (repaired) groundings...............

 

[BrendanS]

It could be that the guy who did Carlton's actually knew what he was doing? The video suggests that, as the spray is never held in one postition, and is constantly moving. A novice would maybe concentrate on an area?

I do know what you mean about hulls with pits, but on a similar scenario, people who clean paving slabs can take the surface off, or simply clean it, and experience with high powered cleaners seems to be the difference.

 

[Nick_H]

... and the fact that it took 8 hours suggests it was done using a very mild abrasive grit, if the operator just wanted to finish the job and go home I guess they may use a bigger/harder grit which is more likely to cause damage

 

[sarabande]

Sorry guys. NO eye protection, NO ear protection, NO apparent shielding of adjacent boats, and what about disposal of the ablated antifoul (hazardous waste) ? /forums/images/graemlins/shocked.gif

 

[carlton]

Wot's this - a visit from the HSE police ?!?!?!? It's bicarbonate of soda, fer chrissakes.....

 

[[2068]]

...i think he was on about all the bits of old antifoul.

dv.