I have 4 huge figerglass water tanks on my 89, 500. A surveyor mentioned to me that it is possible to have osmosis problems actually inside the tanks and due to the fact that they lack access ports, I should have the water tested for Styrene contamination, ($200/test). Anyone ever heard of there being a problem with fiberglass tanks?
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Blistering
Feb.14, 2001 Hi again Jeff, I haven't seen a case of actual blistering in a tank, but MIT in its study of the causes of osmotic blistering found that a major cause was fresh water migration from the inside of the boat where condensation collects to the outside. In other words fresh water lying in the bilges caused blisters. Here's a cheap and free test for styrene contamination: does your water taste and smell like fibreglass? If so, it's likely that you have styrene contamination and I would look at spending the money for proper confirmation or denial of my suspicions. If not I would just keep an eye out for the hint of blistering on the outside of the boat during haul outs and for the taste and smell of fibreglass the rest of the time. If it turns out that you do have styrene contamination then your going to have to cut into the tanks to get them lined. I'd look at trying to find a suitable bladder type of tank to put into the space or have polyurethane tanks built to fit the space and then glass them in. I have to ask, why do you suspect there is a problem? Fair winds, Brian Pickton of BeneteauOwners.net, aboard The Legend, Rodney Bay,St.Lucia
Feb.14, 2001 Hi again Jeff, I haven't seen a case of actual blistering in a tank, but MIT in its study of the causes of osmotic blistering found that a major cause was fresh water migration from the inside of the boat where condensation collects to the outside. In other words fresh water lying in the bilges caused blisters. Here's a cheap and free test for styrene contamination: does your water taste and smell like fibreglass? If so, it's likely that you have styrene contamination and I would look at spending the money for proper confirmation or denial of my suspicions. If not I would just keep an eye out for the hint of blistering on the outside of the boat during haul outs and for the taste and smell of fibreglass the rest of the time. If it turns out that you do have styrene contamination then your going to have to cut into the tanks to get them lined. I'd look at trying to find a suitable bladder type of tank to put into the space or have polyurethane tanks built to fit the space and then glass them in. I have to ask, why do you suspect there is a problem? Fair winds, Brian Pickton of BeneteauOwners.net, aboard The Legend, Rodney Bay,St.Lucia
Air Contamination
As a general rule, with air, if you can smell the contaminate you're most likely exceeding OSHA limits. With water, I'd think a similar situation would be true but with regard to taste (vice smell) so I'd agree with Brian. Although OSHA (Occupational Safety and Health Administration) is for workplace safety it can still be a good guide for what's good or bad for you. Since you're in BC I'm sure you have comperable regulations. The cost of the tests sound a bit steep and maybe they can be negotiated. Since the test isn't needed for regulatory purposes like wells and water systems maybe the lab could shave some of the documentation requirements and just give you a cheaper custom test?
As a general rule, with air, if you can smell the contaminate you're most likely exceeding OSHA limits. With water, I'd think a similar situation would be true but with regard to taste (vice smell) so I'd agree with Brian. Although OSHA (Occupational Safety and Health Administration) is for workplace safety it can still be a good guide for what's good or bad for you. Since you're in BC I'm sure you have comperable regulations. The cost of the tests sound a bit steep and maybe they can be negotiated. Since the test isn't needed for regulatory purposes like wells and water systems maybe the lab could shave some of the documentation requirements and just give you a cheaper custom test?
Blisters all over
Thanks for the feedback folks, The reason for my surveyor's and thereby my concern is the presence of significant eternal hull blistering. Like small pimples everywhere. We purchased the vessel a couple months ago and will have the boat in a building next winter for a full gelcoat stripping and rebuild. Is is, therefore, the presense of the external blisters that raised the concerns. However, the external blisters are apparently in the gelcoat and there would be no gelcoat in the tanks so we may be fine. Apparently styrene's taste could be masked by chlorine in the water so the test is really the only way to be sure. I guess the prudent thing to do is the test. BTW Brian - your idea of opening the tanks and installing bladders was the same raised by the survbeyor. thanks, Jeff
Thanks for the feedback folks, The reason for my surveyor's and thereby my concern is the presence of significant eternal hull blistering. Like small pimples everywhere. We purchased the vessel a couple months ago and will have the boat in a building next winter for a full gelcoat stripping and rebuild. Is is, therefore, the presense of the external blisters that raised the concerns. However, the external blisters are apparently in the gelcoat and there would be no gelcoat in the tanks so we may be fine. Apparently styrene's taste could be masked by chlorine in the water so the test is really the only way to be sure. I guess the prudent thing to do is the test. BTW Brian - your idea of opening the tanks and installing bladders was the same raised by the survbeyor. thanks, Jeff
Follow up
Feb.16,2001 Hi Jeff, Just to follow up once more, are you aware that there is extant a school of thought which now advocates against full gel coat peels and for individual blister repair only, followed by an epoxy barrier coat system being appplied? I tried to find the site that discusses this issue unsuccessfully so maybe one of the other readers can provide it. There may also be a useful discussion in a back issue of Pratical Sailor. With respect to my earlier comments, the fact that the blisters are only in the gelcoat on the outside of the hull is consistent with the cause being the fibreglass water tanks, whether they are gelcoated or not and whether they are blistered or not. According to the MIT report mentioned earlier (I'm relying on my memory here) the coating on the glass fibres which is intended to increase the bonding of the resin acts to wick water at a molecular level. Because the boat is sitting in salt water the fresh water is attracted to it ( something to do with the difference in electron valences between H2O and NaCl). The glass strands end just below the gelcoat which is a surface barrier and the water collects there just under the surface since not all of it can pass through the gelcoat. At least that is how I remember the report going. It has been several years since I read it but MIT may be able to provide you with a copy. Of course there could have been a whole lot more research since this was done and this could now be irrelevant. I am also not attempting to contradict your surveyer who is obviously the expert on the scene and best able to advise you. I do remember the report recommending an epoxy coat or similar barrier being applied to the inside of hulls to stop the process from starting. It is to be noted that this water migration from inside the hull was not the exclusive cause of blisters, but was regarded as a major contributing cause. Whether or not the water tanks are gelcoated would appear to be irrelevant to the process of microscopic water migration by fresh water to the salt water. My point is that you may wish to line the tanks and do the blister job as well if this is in fact a cause. I expect your surveyor is better informed on the issue then I am down here in Margaritaville. Are you planing on using an Interprotect barrier coat for the boat? My next major job is a blister repair for this boat and that is the route I'm taking (I've done other blister jobs and this system works well.) but I would be interested in hearing about alternative systems as well. Fair winds, Brian Pickton of BeneteauOwners.net, aboard The Legend, Rodney Bay, St. Lucia
Feb.16,2001 Hi Jeff, Just to follow up once more, are you aware that there is extant a school of thought which now advocates against full gel coat peels and for individual blister repair only, followed by an epoxy barrier coat system being appplied? I tried to find the site that discusses this issue unsuccessfully so maybe one of the other readers can provide it. There may also be a useful discussion in a back issue of Pratical Sailor. With respect to my earlier comments, the fact that the blisters are only in the gelcoat on the outside of the hull is consistent with the cause being the fibreglass water tanks, whether they are gelcoated or not and whether they are blistered or not. According to the MIT report mentioned earlier (I'm relying on my memory here) the coating on the glass fibres which is intended to increase the bonding of the resin acts to wick water at a molecular level. Because the boat is sitting in salt water the fresh water is attracted to it ( something to do with the difference in electron valences between H2O and NaCl). The glass strands end just below the gelcoat which is a surface barrier and the water collects there just under the surface since not all of it can pass through the gelcoat. At least that is how I remember the report going. It has been several years since I read it but MIT may be able to provide you with a copy. Of course there could have been a whole lot more research since this was done and this could now be irrelevant. I am also not attempting to contradict your surveyer who is obviously the expert on the scene and best able to advise you. I do remember the report recommending an epoxy coat or similar barrier being applied to the inside of hulls to stop the process from starting. It is to be noted that this water migration from inside the hull was not the exclusive cause of blisters, but was regarded as a major contributing cause. Whether or not the water tanks are gelcoated would appear to be irrelevant to the process of microscopic water migration by fresh water to the salt water. My point is that you may wish to line the tanks and do the blister job as well if this is in fact a cause. I expect your surveyor is better informed on the issue then I am down here in Margaritaville. Are you planing on using an Interprotect barrier coat for the boat? My next major job is a blister repair for this boat and that is the route I'm taking (I've done other blister jobs and this system works well.) but I would be interested in hearing about alternative systems as well. Fair winds, Brian Pickton of BeneteauOwners.net, aboard The Legend, Rodney Bay, St. Lucia
Blisters
Brian, Does this mean that if we dump a bag of rock salt in the bilge to insure any water buildup is saline, that blisters would no longer be a threat?
Brian, Does this mean that if we dump a bag of rock salt in the bilge to insure any water buildup is saline, that blisters would no longer be a threat?
Intriguing suggestion, but...
Feb.23,2001 Dear Mr.Kolbenshlag, The recommended course is to paint the interior of the bilge with an epoxy barrier coat like Interprotect 1000 to prevent water transfer. You dump rock salt into the bilges and salt boxes of wooden boats to stop fresh water rot. Inriguing suggestion, though it won't stop the problem of condensation forming below the waterline and running to the bilges along stringers, etc. which is part of the problem. Also, bare in mind that fresh water condensation is not the only contributor to the problem. Fair Winds, Brian Pickton of BeneteauOwners.net aboard The Legend, Rodney Bay, St. Lucia
Feb.23,2001 Dear Mr.Kolbenshlag, The recommended course is to paint the interior of the bilge with an epoxy barrier coat like Interprotect 1000 to prevent water transfer. You dump rock salt into the bilges and salt boxes of wooden boats to stop fresh water rot. Inriguing suggestion, though it won't stop the problem of condensation forming below the waterline and running to the bilges along stringers, etc. which is part of the problem. Also, bare in mind that fresh water condensation is not the only contributor to the problem. Fair Winds, Brian Pickton of BeneteauOwners.net aboard The Legend, Rodney Bay, St. Lucia
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