skipper info

Osmosis

Nightmare of each boat owner: Osmosis

Fortunately not all blisters at the bottom of a ship are "genuine osmosis", which requires extensive and expensive repair. There are 2 types of blisters:

1.	Blisters between 2 layers of gelcoat	The "mild" form of osmosis. Only the damaged gelcoat layer is to be removed and to be renewed.
2.	Blisters between GRP and gelcoat	The feared "genuine osmosis", which requires extensive and expensive repairs: Complete removing gelcoat up to GRP, repair of GRP and reconstruction gelcoat.

Today is certain: GRP is not a maintenance-free material and ages differently:

-	The more warmly the environment liquid, the more largely the danger of osmosis. The same trunk, which shows at east and North Sea after 20 years osmosis, has in the Mediterranean after 10 years osmosis and in the Karibik after 5 years.
-	Usually osmosis arises first at the waterline.
-	Darker hulls are affected more strongly by osmosis than brighter ones.

If osmosis

arose	In each case let accomplish an osmosis treatment as fast as possible, in order to avoid further damage, clearly.
did not yet arise	also then let accomplish an osmosis - prevent - treatment as fast as possible, in order to let osmosis damage not arise.

We want to examine, which marina or wharf in the Caribbean will repair osmosis well and which one badly.

Therefore we asked the following boatyards / marinas the following questions (August 2004):

Are you doing osmosis treatment ?

If not:	Do you recommend someone else as to be expert on this job ? Then please forward this email.
If so:	How many osmosis repairs did you manage during the last 5 years / during 2004 ?
If so:	What kind of way of repair do you generally advice - against blisters between 2 layers of gelcoat and - against blisters between GRP and gelcoat ?

The follwing answers we got:

	country	name marina / boatyard	answer	email address
-	ABC Islands	Seru Boca Marina		stbarba@attglobal.net
-	Antigua	Antigua Slipway Ltd.	answer	antslipway@candw.ag
-	Grenada	Tyrell Bay Yacht Haulout		tbyh@usa.net
-	Grenada	Grenada Marine		info@grenadamarine.com
-	Martinique	Multicap Caraibes		info@multicapcaraibes.com
-	Martinique	Carenage Center Marina		carenfdf@sasi.fr
-	St. Lucia	Rodney Bay Marina Ltd.		rbmarina@candw.lc
-	St. Maarten	Simpson Bay Yacht Club Marina		marina@sintmaarten.net
-	St. Maarten	Simpson Bay Yacht Club Marina		marina@marina-pap.com
-	Trinidad	Coral Cove Marina		coralcove@trinidad.net
-	Trinidad	CaribbeanYachtWorks	answer	bb@caribbeanyachtworks.com
-	Trinidad	CrewsInn Marina		inquiries@crewsinn.com
-	Trinidad	IMS Yacht Services		imsyacht@tstt.net.tt
-	Trinidad	Peake Yacht Services Ltd.		pys@cablenett.net
-	Trinidad	Powerboats		pbmfl@powerboats.co.tt
-	Venezuela	Navimca		gneri@telcel.net.ve
-	Virgin Islands	Nanny Cay		nannycay@surfbvi.com
-	Virgin Islands	Village Cay		villcay@surfbvi.com

It seems to be: Most Caribbean boatyards / marinas are not able to repair osmosis correctly. But as long as they do not answer to this point, instead of promising a work they cannot fulfill, they seem to be honest at least.

Antigua: Antigua Slipway Ltd.

"We have done about 10 osmosis jobs in the past five years. All have been
successful and up to now have no signs of reblistering. We use smith and
company penetrating epoxyx3 coats then 7 coats of west system with graphite
addative. Over the past 10 years we have never had a comeback yet!
Mike Goldsworthy gm asl" 08/06/2004

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Trinidad: CaribbeanYachtWorks

In the last 5 years we have done around 8 vessels ranging between 35 feet to 88 feet.
We have currently in our yard 2 vessels that we are treating against this problem . One is a Hatteras 88 with a very serious problem and the other one is a Cheoy Lee 90 feet with a light osmosis problem.
In case of grave osmosis we remove all through hull fittings and below water line accessories and we clean and dry all bilges. Once this is done, we proceed to a full peeling of the hull below water line.
Once this peeling is completed we put the vessel for a drying period under our covered shed (3 acres of covered roof) during a period which could vary according to the number of washing with fresh water we give to the hull in order to remove all salts crystals and osmosis acids.
Then we run regularly moisture tests until the right level is reached.
Then we start rebuilding the hull with bi-axial or matt sealed with either West system or Epiglass epoxy resin.
if the vessel was built with vinilester we use vinilester.
If fairing is required we use either West system fairing compound or Epiglass fairing compound.
Once this process is done, we seal with Epiglass or west System resin.
While this resin is still tacky we apply Interprotect 2001 E as barrier coat. We apply around 5 coats of this Interprotect.
When the last coat is still tacky we apply the first coat of the antifouling.
We recommend to our clients a full inspection with removal of the antifouling every 5 years to inspect the hull.

In case of light osmosis we recommend treating each blisters individually after full removal of the antifouling and clean sanding and washing.
Drying time is then scheduled for a period of around 2 to 3 weeks.
Each blisters is dug with Drummell type tool, then the clean hole is filled with epoxy 407 or 410 west system, then we proceed to sanding and then primed with epoxy West System or
Epiglass and then we prime with barrier coat Interprotect from Interlux,
then antifouling first coat when the barrier coat is still tacky. Then full antifouling.
we recommend our clients to make a full inspection with removal of the antifouling every 3 years after the treatment to ensure that the osmosis has been stopped.

In a case by case basis we bring our yard warranty on the above jobs.

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