osmosis blisters

abbott013

abbott013

Well-Known Member
Joined
30 Oct 2005
Messages
168
Location
East Sussex
Visit site
I have a boat that has been out of the water for some time, it has very small osmosis blister all over the hull. what i would like to know is, would it be better to do a preventative treatment now or put the boat in the water and allow it to absorb water, so the hull can be peeled to allow the salts to drain out, as recommended by the surveyer.
 
If the blisters are small, is it actually worth doing anything about it. All too often the cost of an osmosis treatment cannot be justified by the value of the boat, after all osmosis will not sink it.
 
Martin, was the survey done for insurance? if so and the surveyer suggests putting it back in the water will the insurers except this? it would be a good idea to clarify this with them.
BTW have you got any pics of your E30 that you can send me, as I want to see the hull/keel and transom area, just to see the difference, as the Humminbird 30/s were built in the same (modified) mould as the E30's
Cheers, Eamonn.
 
it was a prepurchase survey, the sureyer recomended the boat goes back in the water for a couple of years before treating the osmosis.
the insurance companys have told me to treat the boat before the end of the year, as a condition of the policy.
this help you

Kiam019576x432.jpg
 
If the blisters are small, is it actually worth doing anything about it. All too often the cost of an osmosis treatment cannot be justified by the value of the boat, after all osmosis will not sink it.



Tough one this, blisters are no bigger than 10mm, they are not sitting proud of the hull but are convex in shape, i was told that because the hull is very dry the blisters have sunk.
To get the hull peeled and epoxyed seems so drastic and expensive.
Or strip the hull of paint, abrade and barrier coat with epoxy, not so expensive, and the job can be done now.
 
Get a new insurer. You are being ripped off in the name of indemnity in the same way that house buyers had to treat rising damp, settlement, re-wiring, chloridation of the foundation slab, radon gas, etc, etc. In fact whatever was the latest fad.
Your boat won't break up and sink. The worst that will happen is it will lose a little value.

read This Remember your boat is not a youngster
 
My sentiments exactly, you would think i had a mortgage on the boat. as if there was a big financial investment on the boat, but i own it outright. Thanks for the link.
 
I am no expert on osmosis, however if the hull is reasonably 'dry' now (can check this with a moisture meter) I am sure that I would be tempted to give it a light sand (to 'key' it) if the antifouling has already been removed, and then slap on a coat or two of epoxy. That will help to keep any more water out of the hull, and I think it should slow down (?) the progress of all the current fine bubbles.

And bear in mind that (as mentioned above already) boats dont sink too readily from osmosis.....

Ie dont lose sleep over it!
 
[ QUOTE ]

Tough one this, blisters are no bigger than 10mm, they are not sitting proud of the hull but are convex in shape, i was told that because the hull is very dry the blisters have sunk.
To get the hull peeled and epoxyed seems so drastic and expensive.
Or strip the hull of paint, abrade and barrier coat with epoxy, not so expensive, and the job can be done now.

[/ QUOTE ]

Blisters can be caused by a number of things. One of the key symptoms of osmosis is not blisters but a hull that wont dry out significantly when left out of the water, so either you have misunderstood the surveyor with the "very dry" bit or he is wrong and you dont have osmosis.

Surveyors often say to leave a boat for a couple of years and then treat, but I never understand why. Would a doctor l eave a case of leprosy to develop for a couple of years before treating? Whats going to happen in those 2 years apart from more damage to the laminate? Ask him - he might have an answer.

You must be talking to a "call centre" type of insurer. Given that the "leave it for a couple of years" suggestion is common, there are lots of insurance companies who accept that approach. If there is a problem, get the surveyor to talk to the insurance company. Bang heads together. Either waiting a couple of years doesnt matter (insurance company wrong) or it does (surveyor wrong)

Having previously bought a boat with the pox, I wouldnt do so again. Not so much a structural issue but the aggro/cost/time wasted of the treatment followed up by the realisation that it isnt a permanent cure and you may well have to repeat 5 to 10 years down the line. Avoid.

P.S. Unless the hull really is dry, dont clean up and epoxy. You're just making the problem worse.

P.P.S. 10mm is a fair sized blister. Mine were more like 1mm
 
Re: osmosis blisters ...... couple of points ...

Based on your later posts as well ....

a) Tell the insurers to think again. It is unusual for an Ins. Co. to require treatment against that recc'd by Surveyor etc. In fact most Ins. Co's are only interested in liability of boat overall as fit for purpose. Osmosis does not in itself constitute "Unfit for Purpose". I would look to alternative Insurers ...
b) Surveyor would not advise to put back into water to absord more moisture ... but as later post clarifies .. he says actually you can leave the boat for some period before applying treatment.

OK ...... so I've said - contact other Ins. Co's for quotes.

As to Osmisis ... 10mm blisters are not small and if visible to eye without need to "sight along" hull etc. - are past the "ignore" stage. I would certainly advise strongly against covering up with epoxy coats ... without doing some work on the problem. The blisters will contain various that cannot "dry-out" .. cannot leech out. So all you will do is seal in the problem. If you do not carry out full treatment - then best is to actually leave them and NOT seal up. Then at least any moisture that has not increased density can leech out to reduce pressure inside blister ... unlikely to leech - but you have given it chance.

The survey is Pre-Purchase ......... so that means you have chance to come to agrement with seller ... price reduction in consideration of survey and Ins. Co requirements ... Use BOTH in your argument ...

Oh and don't be put off by others comments about 5 - 10 yr guarantees .. etc. New Hulls have 5 yr g'tees often - and still suffer. So why should old hull be special - just because a few thou of epoxy is applied ? I would far more trust an old treated hull for 5 yr than a new one.

Once treated - you will have a boat that has good resale potential, you will have a boat you can be proud of. You will know exactly what is what with it ....

Go on - negotiate with seller, seek alternative insurance ... get quotes from a number of Osmosis Centres. (IMHO stay away from Mobile, non permanent facility treatments ... and I prefer slurry blasting to peeling ... as it opens up all wicking, voids, blisters etc. ..... but its your choice ...)
 
G'day Martin (bananaman),

Problems Problems Problems Not.

As others have stated look for another insurer, use the surveyors findings to reduce the purchase cost etc.

Now onto the problem:
If the blisters are now craters I would be double checking to ensure this is the dreaded boat pox. It may well be a fault other than Osmosis.

Given that it is Osmosis and the hull is returning low moisture levels you could grind them out and fill with epoxy and cloth, top off with some closed cell balloons and lay on 4 coats of epoxy, a primer and top coat, then antifoul and off you go, any further eruptions can be dealt with when she is hauled out, grind and leave open but protected and reseal at the start of the next season.

We did this on an old and very heavy yacht for about 5 years and each year the number of blisters was less, more important, none of the treated areas ever failed.

It's not a big job at the end of each season, less than than that required on a timber or steel hull and less than repairs after a season of racing.

Avagoodweekend......
 
I'm with oldsaltoz.

We do seem to have some osmosis-specific hypochondria in the uk! Interesting to note oldsaltoz is based in oz... apparently this is what they do in the states to. I guess the only problem is loss of value if you try to re-sell in the uk, but if this is several years down the line and you have persued this option and proven it, maybe buyers will be swayed.

As far as the insurance goes, who was that quote from? sounds rubbish to me!
 
G'day Tobble,

I seen boats treated this way for many years and get to the stage that no blisters are evident when hauled out, probably a good time to put her on the market with no sign of blisters.

Avagoodweekend.......
 
Micro-balloons / spheres ....

An extremely light powder like filler that is actually tiny "balls" ... so small it resembles salt. A kg tub is BIG .... about the size of a large bucket.

It mixes with resins to form a filler and also aids sanding to a smooth finish. Being closed cell it doesn't lead to water / moisture absorbption.
Colour normally white.

If you have a divot in your GRP ... that doesn't require structural work ... mix this stuff up and spatula it ... adding layers till its proud ... then sand back. You can get spec's suited to either Polyester or Epoxy ... some in fact will work with both.
 
Find out if the hull is dry using a moisture meter. If not dry then at some point you will need to peel or blast and allow to dry. I blasted my Pioneer and it took a year to dry correctly. Peeling removes all and not just some of the gel coat and may speed the drying process. The work to make good afterwards is not that bad with a couple of blokes and some good sanding machines. Mine cost about £1200 to do plus the storage cost for a year ashore (put mine in a friends car park to save a few quid!) PM me if you want any more info.

Yoda
 
Re: Micro-balloons / spheres ....

G'day Nigel (sbc)

Thanks for the fuller explanation my reply was a shot one last night, must be getting old can only work 24 hrs a day, I'm sure I used to do 30.

I also forgot to mention that 'Closed Cell' also comes in sheet form and can be used to build a whole boat or just a little project. It comes in many forms ranging from sheet foam with a good range of thicknesses to exotic lightweight composites designed to withstand moisture and flex without breaking.

The 3 inch thick foam sheeting makes a great cool box or refrigerator and is very easy to work with using poly or epoxy resins.

Back to work now, avagoodweekend......
 
You must log in or register to reply here.

Other threads that may be of interest

P
Essential pre purchase or even pre survey checks
2
Replies
28
Views
913
Refueler
Refueler
I
Sadler 32
3 4 5
Replies
93
Views
3K
Mark-1
Mark-1

Share this page

Top