Is Osmosis Prevention a Good Idea?

[onestepcsy37]

idle -

1. I am confused with " bottom paint " is it the original paint or antifouling?

'bottom paint' is antifouling. fiberglass boats come out of the factory with gelcoat as the outer layer. owners then apply 'bottom paint' to keep the hull from getting fouled. there are two kinds - ablative and hard. ablative works by gradually wearing away and eventually would probably wear back to the gelcoat i suppose. at some point you have to put on more ablative paint. hard paint never goes away, although it eventually becomes ineffective and has to be repainted every so many years. i have found pettit trinidad, a hard paint, to be the most effective in the area that i sail (florida/bahamas).


2. I am at the point of sanding all the accumulated antifouling by the years to the level of original paint/gelcoat. Several patches of antifouling has started to drop off.

good idea, and that's what i had to do. you have hard bottom paint and as you paint layer upon layer over the years it gradually loses it's 'grip'. but its a dirty job. i had to do it myself because i couldn't find a 'professional' to do it. do a lot of research here before setting out. you will need a heavy sander, tyvek suits, professional sized respirator, and probably, depending on your boatyard rules, tenting. if you can find someone else to do it well, pay them whatever they want.

robin3 -

1. That is my opinion and no doubt I will (again) be told I don't know what I'm talking about

i'm one who will tell you that you DO know what you're talking about.

barnakiel -

1. I always somehow imagined Kevlar was added for impact resistance. I thought stiffness came from adding carbon fibres.

when i bought my boat ten years ago i found that the bottom of the keel (full keel) had possibly been run over an oyster bed and was rough and slightly gouged. so i sanded it down and covered it with kevlar. not sheets of kevlar, but ground up kevlar fibers in an epoxy mix. i troweled it on and smoothed it out before it hardened. ten years later it's still on there and, i suppose, still protecting the bottom.


__________________

[Robin3]

Originally Posted by barnakiel

It is interesting what you say about Kevlar.

I always somehow imagined Kevlar was added for impact resistance. I thought stiffness came from adding carbon fibres.

But sure, things are connected and why not Kevlar may have this use too.

THX for sharing.

b.

You may well be right about the primary reason for using Kevlar ( as also used in bullet proof vests), so maybe it enabled them to use a lighter layup overall and keep overall hullweight down I know that our Jeanneau Sun Legende was the sweetest sailing boat we ever owned, it would sail in the lightest of winds and keep good passage speeds yet was a dream to sail in heavy weather also. 7kts close hauled and hard on the wind at 28degs to the apparent wind (22 degs was possible but speed only 6kts with the same VMG, yet always fingertip light on the wheel, not many overtook us on any point of sail and if any did there was usually a telltale waterflow exiting from their exhaust

[Idle]

I take all comments seriously. Being a foreign speaker I sometimes want to be
sure that I get the right message.
I am grateful that you all had gave so much of your time. Probably I at last did the thing which I had to do first. I sent an email to Jeaneau asking the resin they used in my boat specifically giving the hull number. To be honest, before this thread I did not know this much about resin and bottom details. I hope I will have a solid answer. If I do, I will let you know.

[Idle]

Last note for the thread. I got the mail from Jeanneau. The boat has polyester resin. No comment for osmosis prevention. Honestly I did not expect any.
Although I benefited the most from the discussion I want to decide after I see the bottom.
Thank you all.

[Robin3]

Originally Posted by Idle

Last note for the thread. I got the mail from Jeanneau. The boat has polyester resin. No comment for osmosis prevention. Honestly I did not expect any.
Although I benefited the most from the discussion I want to decide after I see the bottom.
Thank you all.

That is good news from jeanneau. If You have paint flaking off then at the least all the loose stuff should bE removed and sanded/ faired in to give a smooth transition. Then you will probably need to apply a primer of some kind to get good adhesion Of the new paint to any bare glass areas. I believe Interprotect is used foR his as is Primocon. Maybe if you have time and funds allow, removing the remaining paint would be best then decide if you want to apply a barrier coat or two or more. This is similar to the decision process we recently faced with our new to us Beneteau Oceanis 36CC from 1998. We were paying to have the bottom done for us this time after my stroke last year ( the admiral declined after helping doi it every year in the UK for 25 years on our earlier boats) and decided to pay them to sand off all the remaining old stuff, then put on 5 barrier coats of Interprotect 2000 followed by two good coats of Micron 66 antifoul They made an excellent job of all this and I was there each day to keep an eye on things. This pic is before the cradle upports were moved a bit and those spots coated as well. she is now back afloat where she belongs...

[Idle]

Robin3,That is probably what I will do at the end. What I am worried is not the fund but the procedure. They say day will scrape the old layers with a tool like a razor blade, not by sanding. Although I am a boat owner for 15 years I did not deal with this bit of care. Is this routine and does not harm the existing, if there is any, barrier coat; should I insist that they will do it with sanding?

[Robin3]

Originally Posted by Idle

Robin3,That is probably what I will do at the end. What I am worried is not the fund but the procedure. They say day will scrape the old layers with a tool like a razor blade, not by sanding. Although I am a boat owner for 15 years I did not deal with this bit of care. Is this routine and does not harm the existing, if there is any, barrier coat; should I insist that they will do it with sanding?

I have personally used that method using a tool called a Skarsten scraper several times and itis OK but there is a risk of the tool digging into the gelcoat in tight areas, not a real problem if the worker is careful. doubt you have any kind of existing barrier coat just bare gelcoat under the paint. where is the work being done??

[Idle]

In Turkey somewhere in Marmaris area. Either Yacht Marina or Martı Marina.
They are not boatyards, several contracters give the service.

[Robin3]

Originally Posted by Idle

In Turkey somewhere in Marmaris area. Either Yacht Marina or Martı Marina.
They are not boatyards, several contracters give the service.

I bet it is cheaper than here!

[Idle]

The offer for labour was 1000$ gel-shielding and antifoul. Material whatever used on top of it. Drying period is definetly shorter so less for staying on land. Though I did not check the market yet. The chap has done few services for me in the past, I presume he gave a fair price.

[Robin3]

Originally Posted by Idle

The offer for labour was 1000$ gel-shielding and antifoul. Material whatever used on top of it. Drying period is definetly shorter so less for staying on land. Though I did not check the market yet. The chap has done few services for me in the past, I presume he gave a fair price.

Sounds ok to me we paid about 50% more for the labor part but the paints were really expensive.

[psneeld]

be careful of the drying period..it is determined by material removed and means of drying...probably more than 90% of boats are not dry when barrier coating is improperly applied.

[neilpride]

Found a couple of good guys with the Sander, couple of days and the antifouling is gone maybe, with the gelcoat exposed you have a good chance to check for weird things, spider cracks , moisture in the laminate, tiny blisters etc... if all is ok, barrier coat, Interprotec or other brands are user friendly , even you dont need to sand between coats if you follow the drying times , next antifouling and done, splash!!! Good luck.