OSMOSIS - Do all boats get it? Or just a few?

[skipperpete]

My boat has Osmosis, not the full Monty but enough for people to point it out when she’s parked up on the hard stand ...... which is most of the year because I only use her for 3 months in 12......but on the basis of my usage I have no plans to rectify the problem. My question is, does osmosis become most active in fresh or salt water? My usual routine is to splash at the marina on the Mediterranean coast and enter the canal system which is all fresh after leaving Sète then a short period in the Atlantic and back into the canals again and home to the hard stand.
I’ve seen some truly horrific osmosis on boats over many years with the worst being a Swanson 42 at Barlow’s old slip in Ballina, she sagged in the cradle and was left for a few years untouched next to the rails but I’ve never heard of a boat sinking because of it. I did some engine work on a modern 75’ motor cruiser that had really bad below w/l delamination.... like one giant blister and the entire bottom was stripped to base layers and re glassed. One of those buyer beware types of cover up jobs... sold for a really low price to an absentee owner after a tame surveyor gave it a good hull report.

[Searles]

Be verry carefull in identifying blisters ,have seen a number if hulls with blisters not underwater these were catalyst blisters,as result of poor layup,by chopper guns poorly set or maintained or poor hand lay up,have never seen osmosis blisters that weren’t on immersed surface,not to say that you cannot have catalyst blisters underwater ,carefull annaysis is a must to make forewarn .⛵️⚓️

[ItDepends]

You'll quickly find that people who own boats with serious hull blisters will say "every boat gets them"

Boats that are 25 years old with NO blisters have no interest in the conversation.

Source: Owner of a 27 year old boat with NO blisters, and the former owner of a 35 year old boat with NO blisters. So NO every boat does not get them.

[AKA-None]

No blisters that I’ve ever seen on my boat but being freshwater and wet only part of the year may have something to do with it

[Jim Cate]

I reckon that I've been pretty lucky, for I've owned three glass boats and nont of them have had blisters:

Catalna 22 (hull #61, so very early production 1969) owned from new for 7 years
Yankee 30 (hull #123, 1974) bought when 3 years old, owned for 7 years
Palmer Johnson 36, (hull #9,1974) bought when 10 years old, owned for 17 years

None had epoxy overcoating, all were kept in the water in the SF Bay area (PJ only until 1986 when we set out cruising).

Jim

[fstbttms]

Originally Posted by mrk123

No, but if a boat is listed as with osmosis, it's a cause for concern yes?

In most cases I would say that is more of a good bargaining chip than a cause for serious concern.

[smj]

Originally Posted by fstbttms

Speaking as a professional hull cleaner with almost 28 years (and many, many thousands of boats) experience, I can say that the majority of boats do NOT get blisters.

I’ve heard that blisters are more prone to show their ugly heads while out of the water. Not sure if this is factual.
I worked for a boat builder and he thought one of the main causes of blisters was the workmen sweating in the hull during the layup process.

[boatman61]

Boats I've had with blisters, 1987 Bene 321.
My Westerly just had a high moisture reading, have not seen blisters on 10 other of my glass boats.
Steel and wooden obviously not included..

[FPNC]

In an earlier time, I worked in fiberglass boat manufacturing. All types, from dinghies to high speed off shore racing boats, to custom designed high speed attack craft for the US Navy. All of these while using various types of materials. Polyester, vinylester, s-glass, e-glass, carbon fiber, kevlar, and a duke's mixture of core materials.

Having literally and personally, applied many tons of gelcoat and many, many tons of fiberglass by hand. Without a doubt, I can attest that blistering comes from poor manufacturing process during the gelcoat application and the first 1-2 layers of fiberglass application.

This is not a secret in the industry. ~Excluding filled resins~, it does not matter what material is used. If the application is not performed correctly during the first few steps in the process, you will have blisters develop later in the life of the vessel.

Quality control at these first few steps is crucial. Unfortunately, in boat manufacturing, the lamination process can be the lowest end of the pole and entry level employees with high turnover is the norm. This can lead to sloppy work practices and less attention to detail.

The idea that 'Chopper guns' directly lead to blisters in fiberglass is a myth and completely unsubstantiated. In my opinion, a superior first layer of fiberglass, called a 'skin coat' can actually be created using a chopper gun versus using rolled fiberglass product. Particularly in larger vessels.

The main cause of blisters is:

Improper gelcoat application

Improper application of the 1st and/or 2nd layer of fiberglass

Contamination of the materials

Contamination of the bonding surfaces

Improper calibration or faulty spray equipment.

I do not dispel the idea that better materials make better boats. This is a fact. However, excluding the use of filled resin, blisters are mainly the result of defects caused by substandard material application.

[Rumrace]

Nice to hear from a pro. Great info and a taste of reality. I agree the first coat is key. I disagree on chopper gun. Water doesn’t migrate through chopper gun it parts it and crushes the structure loosing everything but bulk. I’ve listened to several brand crushing right where is say put slings here.

You understand the mechanical bonding we get from different roving which the rest of us kinda understand. Hanse basically printed a wooden boat. Recycled wood at that. 60 wood fibre 40% polymers.
You can also use carbon fibre or polycarb. My pick is fibre in PEEK. Zero chance of a void and a continuous connected carbon fibre. Each layer is fused to the next although there is still an 8 hour cure.
What are your thoughts on the next generation of printed hulls?

[FPNC]

[QUOTE Water doesn’t migrate through chopper gun it parts it and crushes the structure loosing everything but bulk. What are your thoughts on the next generation of printed hulls?[/QUOTE]

There is absolutely no structural difference between fiberglass roll mat and the same amount of glass fiber applied with a 'chopper gun'. Anyone who says different does not understand the process.

Printed boats are just another way to make a solid plastic boat. This has been tried before with roto-molding and was not successful in the market. The printed boat does have an advantage for one off design testing. I doubt it would be marketable.

[captpati]

I have a 1990 Bristol 38.8 I’m thinking of selling if you’re interested. It’s a beautiful boat and has never, ever had blisters.

[Redreuben]

There are two main types of polyester resin orthothalic and isothalic and many types of glass reinforcements.
When I was glassing boats the quality builders used iso and split strand csm for the first layup. Ordinary csm and rovings followed. Cheaper builders, usually power boats used ortho and chopper guns, if these hulls stayed in the water osmosis was just a matter of time.
Later as osmosis became a talking point vinylester was used as the layer behind the gelcoat not only as insurance but as a sales point. There is little doubt vinylester is vastly superior.
But, boats built with iso resin and a split strand skin have gone many decades with no osmosis.
Luck of the draw.

[Nomad57]

Redreuben,


A broker explained the ortho/iso difference to me several decades ago, but I couldn't remember the specifics. Thanks for the refresher.


Nomad

[Gerrit Coetzee]

Originally Posted by fstbttms

In most cases I would say that is more of a good bargaining chip than a cause for serious concern.

Agreed.

I have a 2012 Fountaine-Pajot Orana 44.

Decided to repaint the boat blue. The darker paint showed up every blob, which I was told is blisters/osmosis.

I thought it nothing, but the contractor convinced me he will fix them cheap at a friend's price, as he did not approve of it and will spoil his paint job. There were almost as many blobs or blisters (?) above water line, then under the water line.

$36,000 later and three layers paint I almost fainted. Final bill $52,251 . Friendship gone as well.

Is Fountaine-Pajot or any builder responsible for such damages ? Damages that occurs only years after you left the factory.