PaulRainbow
Well-Known Member
Post #40 ?
Centaur with osmosis
- Thread starter Lenster
- Start date
Graham376
Well-Known Member
I would start by scraping the antifoul off with a Bahco 2 handed scraper and see just how bad it is.
mogmog2
Well-Known Member
Just my two pennorth as a Centaur owner. Ours (see left) also had "rather high" osmosis readings when we bought her in 2017. I did a lot of research into it as I wanted to do the full works, buying the gelplane & selling it on, but a combination of finance constraints at the time, plus the two surveyors I had (one initial survey & the second for keel stub repairs) both said not to worry about it. So I didnt 
Sounds like you've looked into it a bit and may be aware of the need to dry the hull - there is absolutely no point in any of this if the hull isn't dried out adequately. I see so many posts about the boat being epoxied and all they've done is seal the moisture in.
Leaving it peeled in the open will still take an unfeasibly long time to dry out, it needs to be helped: This was previosuly done wit infra red lamps - a slow and expensive process but Roger Ball developed a DIY hot vac system to do his Centaur (but that website has since departed). IIRC he did, however, have Mads from Sail Life contact him to help build his system and this is shown in one of his videos (about 4 years ago maybe, IDK if he's still going). I can't remember if he documented it for the WOA wiki - worth a look on there. The cost of making a hot vac system, whilst cost-effective, is non-trivial as well, but should have at least some value for resale.
Sounds like you've looked into it a bit and may be aware of the need to dry the hull - there is absolutely no point in any of this if the hull isn't dried out adequately. I see so many posts about the boat being epoxied and all they've done is seal the moisture in.
Leaving it peeled in the open will still take an unfeasibly long time to dry out, it needs to be helped: This was previosuly done wit infra red lamps - a slow and expensive process but Roger Ball developed a DIY hot vac system to do his Centaur (but that website has since departed). IIRC he did, however, have Mads from Sail Life contact him to help build his system and this is shown in one of his videos (about 4 years ago maybe, IDK if he's still going). I can't remember if he documented it for the WOA wiki - worth a look on there. The cost of making a hot vac system, whilst cost-effective, is non-trivial as well, but should have at least some value for resale.
Lenster
N/A
My overzealous response - agreed. However, when someone starts a post with Boats are for sailing and ending with suggesting I have little interest in Sailing is equally uncalled for and I stand by the sentiment of my post.
doug748
Well-Known Member
Probably, but it made me laugh.
Anyone suggesting doing anything vaguely practical on boats tends to be patronised to death on these pages so I found the salty response highly refreshing myself.
.
Concerto
Well-Known Member
Lenster, I can understand wanting to do the best for your Centaur. With some TLC she should remain a good boat to sail. Having read a lot about osmosis and some replies on this forum, my advice would be to just grind back any blisters and then fill and fair. The moisture content of a 50 year old boat will always be high, but I have little faith in the moisture meters that surveyors depend on. They we designed for testing the moisture content in wood not glassfibre.
When I bought my Fulmar Concerto in Dec 2013, the surveyor said the small blistering with 2 to 3 mm bubbles in the hull was due to trapped micro air bubbles in the gel coat caused by poor brushing out as the gel coat was applied. I should also mention that Westerly always applied a double coat of gel coat making it 1.5 to 3 mm thick, which is far thicker compared to other builders of that period. If you blisters are 5 mm or larger and when popped they smell of a vinegar smell, then you have osmosis.
There are plenty of boats 10 to 15 years that got the a full strip of the gel coat and new gel coat applied, but are now suffering osmosis again. The full strip has not been proved to be a fix once only solution. As others have said, the cost is not warranted on a Centaur. Please follow the sensible route and just grind back any blisters and accept that in a few years time some more will likely appear. Eventually you will replace all the gel coat in simple easy stages at little expense.
If you use the link in my signature to my About Me page you will find a list of links you may find interesting, especially the PowerPoint presentations on renovating Concerto.
When I bought my Fulmar Concerto in Dec 2013, the surveyor said the small blistering with 2 to 3 mm bubbles in the hull was due to trapped micro air bubbles in the gel coat caused by poor brushing out as the gel coat was applied. I should also mention that Westerly always applied a double coat of gel coat making it 1.5 to 3 mm thick, which is far thicker compared to other builders of that period. If you blisters are 5 mm or larger and when popped they smell of a vinegar smell, then you have osmosis.
There are plenty of boats 10 to 15 years that got the a full strip of the gel coat and new gel coat applied, but are now suffering osmosis again. The full strip has not been proved to be a fix once only solution. As others have said, the cost is not warranted on a Centaur. Please follow the sensible route and just grind back any blisters and accept that in a few years time some more will likely appear. Eventually you will replace all the gel coat in simple easy stages at little expense.
If you use the link in my signature to my About Me page you will find a list of links you may find interesting, especially the PowerPoint presentations on renovating Concerto.
PaulRainbow
Well-Known Member
Not wishing to drag it out........ but he didn't suggest you have little interest in sailing, he said"if the OPs interest isn’t sailing but boat working, that is their call."
There are and have been plenty of people on here that spend years building a boat or refitting one and probable never sail it, but they enjoy the task.
Anyway, welcome to the forum, or should i say welcome to your second thread in 10 years
Don't be put off by an odd comment, there's lot's of knowledgeable folks on here who are happy to share what they know (as well as some that know nothing and like to share it more 
)So, stick around
justanothersailboat
Well-Known Member
Try a brushless die grinder with a carbide burr. Friend of mine with a somewhat bubbly 1980ish 26' motorboat borrowed my 12v Milwaukee and I was amazed by how quickly he got through them all, all cutting done in under an hour. It's a bit neater than grinding too.
RunAgroundHard
Well-Known Member
That’s not true. Lots of advice, in fact the majority of posts by a country mile, offered on practical work on boats by members of this forum, is supportive of DIY by members. The majority of posts in this very thread are supportive of your desire to repair osmosis yourself.
Alternative opinions, suggestions and solutions are given as well but are usually less in numbers, compared to the other advice.
chriss999
Well-Known Member
I thought that was a sensible comment from Dunedin, and certainly not needing a heavy response. Some people do major work on boats because they enjoy it, even if objectively that work is OTT for the value of the boat and for the benefits it will bring. I’ve done that myself on a boat that I had time to work on but no chance to sail at the time.
This is an internet forum where a range of skilled and experienced people read posts and are invited to respond. There will be a range of views. That’s what posters come here for.
