Is It Necessary to Haul Out Each Year To Let the Boat "Dry Out"

[boatpoker]

Originally Posted by buzzstar

In my in non-expert opinion it was the builder and the technique that caused problems, not so much the resin products.

Absolutely !
Cured polyester has a water saturation maximum of about 1.5% by weight which it will reach in just a few years in water whether hauled or not. Remember the water gets in there under pressure but the there is no reverse pressure when hauled. It would take years to dry out unless peeled. The glass fibers do not absorb water to any measurable degree.

The problem occurs with sloppy layup leaving voids and an excess chopped mat as a veil (sometimes called a "skinout") layer which acts as tens of millions of wicks just under a gelcoat which is hygroscopic. combine these issues with improperly mixed or cured resin, non-continuous layup and layups done in high humidity and blisters become possible if not likely.

If water permeates into a void in the laminate that contains uncured or improperly cured polyester the water and chemical residues (styrene, chemical salts etc. ) mix together and form a new molecule that is bigger than the sum of the original molecule. This is known as hydrolysis and can lead to large blisters and delamination.

Most blisters however are limited to the chopped glass veil (skinout) in or just under the gelcoat and can be considered a cosmetic issue, ugly but still non-structural.

Professional Boat Builder Magazine has run tests for years and found the epoxy and vinylester resins are not permeable and no record of blisters in vinylester or epoxy hulls could be found.

Tens of thousands of polyester boats kept in water year round have never produced a blister while many boats that are hauled for six months every year do. There is no way to predict which will and which wont.

PS. Pro Boatbuilder studies show that moving, warm and fresh water is a worst case scenario for blisters.

[Polux]

Originally Posted by boatpoker

Absolutely !
Cured polyester has a water saturation maximum of about 1.5% by weight which it will reach in just a few years in water whether hauled or not. Remember the water gets in there under pressure but the there is no reverse pressure when hauled. It would take years to dry out unless peeled. The glass fibers do not absorb water to any measurable degree.

....

Don't doubt your expertise on the matter but what I do know, for having tested a number of boats (with a very experienced surveyor, when I was testing for buying my actual boat) is that if you run an hygrometric test on a hull some 1 or two days out of being hauled up the difference would be substantial if you run the same test a week days later (if the weather is dry).

This on a "dry" boat because others will be so saturated of water that even 15 days later they would show a high hygrometric reading.

[boatpoker]

Originally Posted by Polux

Don't doubt your expertise on the matter but what I do know, for having tested a number of boats (with a very experienced surveyor, when I was testing for buying my actual boat) is that if you run an hygrometric test on a hull some 1 or two days out of being hauled up the difference would be substantial if you run the same test a week days later (if the weather is dry).

This on a "dry" boat because others will be so saturated of water that even 15 days later they would show a high hygrometric reading.

What do you mean "Hygrometric Test" ?

[Stakaman]

I think Pollux referring for Hygrometric boat test wich calculates the moisture of the hull but I am not sure that is reliable enough .. there are so many parameters that and must be consider. I have it on my servey report for a boat that I am looking but I am not take it very serious .. to many question hadn't answered enough to convince me ..

[boatpoker]

Originally Posted by Stakaman

I think Pollux referring for Hygrometric boat test wich calculates the moisture of the hull but I am not sure that is reliable enough .. there are so many parameters that and must be consider. I have it on my servey report for a boat that I am looking but I am not take it very serious .. to many question hadn't answered enough to convince me ..

That does not answer the question .... What is a "Hygrometric Test" ?

[boatpoker]

OK, it looks like Polux is not going to respond so I am going to assume he is talking about moisture metering. Actual hygroscopic testing requires some highly specialized equipment and a labarotory .... don't know of any surveyor who carries those in his bag.

I have some strong opinions on these meters which contrary to general belief do NOT measure moisture. The measure capacitance !

I don't agree at all with a couple of posts on this thread and would refer you to Moisture Meter Mythology where I lay out my evidence and reasoning.

[Polux]

Originally Posted by boatpoker

That does not answer the question .... What is a "Hygrometric Test" ?

Stakman answered for me: A calculation of the moisture content on the hull through a reliable device and a skilled operator (a very experienced surveyor).

Remember that the better quality modern boats have almost all a sandwich hull and a high moisture content on the hull will turn with the years (if the boat is always on the water and never dry out) to water in the hull. On a sandwich hull that can mean more than some blisters and depending on the core it can lead to serious problems.

I think it is from this reason that somebody said on this thread that his surveyor strongly recommended his boat to be out of the water for some time each year to dry out.

[Polux]

Originally Posted by boatpoker

OK, it looks like Polux is not going to respond so I am going to assume he is talking about moisture metering. Actual hygroscopic testing requires some highly specialized equipment and a labarotory .... don't know of any surveyor who carries those in his bag.

I have some strong opinions on these meters which contrary to general belief do NOT measure moisture. The measure capacitance !

I don't agree at all with a couple of posts on this thread and would refer you to Moisture Meter Mythology where I lay out my evidence and reasoning.

There are highly professional very expensive devices that measure effectively the water moisture on the hull and some cheap Chinese devices that are not reliable.

In any case you need also someone very experienced with reading the device results. One of the things I learned is that you have to wait for about a week (sometimes less if the weather is hot and dry) to make a reliable measure: all boats will have a somewhat high moisture measure one day out of the water even if the hull looks dry.

Regarding the effectiveness of the readings I know it works because I was able to avoid a boat (from the same brand as the one I bought) that had a high moisture content. The owner did not know but after he decided to check it out. It turned out that the boat had a small quantity of water on the sandwich due to a small water ingress maximized by the boat being usually on the water all year long, being only taken out for antifouling.

[Sailmonkey]

Originally Posted by Polux

Stakman answered for me: A calculation of the moisture content on the hull through a reliable device and a skilled operator (a very experienced surveyor).

Remember that the better quality modern boats have almost all a sandwich hull and a high moisture content on the hull will turn with the years (if the boat is always on the water and never dry out) to water in the hull. On a sandwich hull that can mean more than some blisters and depending on the core it can lead to serious problems.

I think it is from this reason that somebody said on this thread that his surveyor strongly recommended his boat to be out of the water for some time each year to dry out.

I'm not sure I would want a "high quality" modern boat that could not survive year round immersion in its natural habitat.

[boatpoker]

Originally Posted by Polux

There are highly professional very expensive devices that measure effectively the water moisture on the hull and some cheap Chinese devices that are not reliable.
.

Please provide a link that shows one of these "highly professional very expensive devices" that your surveyor used.

[Factor]

Originally Posted by noelex 77

I would not be concerned in a boat built from epoxy resin or even perhaps a full Vinylester resin layup, but these are not common.

They are common in my part of the world. Personally I have owned many multis, all have been Epoxy or Vinyl. None had osmosis, The monos I had were all Poly and all had osmosis, but I haven't owned half a boat for about 20 years

If a boat you are considering can't float all year, don't buy it.

[boatpoker]

Quote:
Originally Posted by Polux View Post
There are highly professional very expensive devices that measure effectively the water moisture on the hull and some cheap Chinese devices that are not reliable.
.
Please provide a link that shows one of these "highly professional very expensive devices" that your surveyor used.

Still no response ??

[Kenomac]

Originally Posted by boatpoker

Quote:
Originally Posted by Polux View Post
There are highly professional very expensive devices that measure effectively the water moisture on the hull and some cheap Chinese devices that are not reliable.
.
Please provide a link that shows one of these "highly professional very expensive devices" that your surveyor used.

Still no response ??

I happen to know that Polux is out cruising and probably in an anchorage, his internet isn't 100% like those of you sitting in your house.

Allow some time.

[Dockhead]

I've never understood what good "drying out" the boat can do, if you just put it right back in the water? Does it make any difference absorbing water (if that's what it does) 9 or 10 months out of the year versus 12?

I do not claim any special expertise, however. I've always kept all my boats in the water 24/7/365 as I have always used them year round. A boat out of water seems an unnatural thing to me -- not supported right and subject to being knocked over by a storm, and also subject to be frozen hard inside in a cold snap.

I haul out for a week or two every other year for antifoul and stern gear maintenance. Once I was out for a couple of months with the mast out. Otherwise my boat has been in the water year around for all of her 16 years of life as far as I know. Bottom is immaculate and moisture readings are fine.

[Kenomac]

Thanks. Going to scuba dive under the boat to service the anodes and dust it off next week. It's the first time it was wintered in fresh water. I can hear that the prop anode is a little loose.