MacGregorSailors.com

fiberglass chemistry 101

Think of it this way, you know that new fiberglass smell on a new boat?
Those VOC/radicals have to come from somewhere.

new boats are far more susceptible to blister damage than fully cured older boats that have gone through a summer or two on a trailer in a hot climate.

Gas and water and voc's move very slowly through fiberglass, but the uncatalyzed materials in the gelcoat and hull resin outgas for a while until fully cured. freshwater has a lower density and and results in ever so slightly lower pressure against the hull., In most cases the gasses permeate slowly through a dry hull easily, however a hull in the water has static pressure for the gas to work against, plus the pressure of the gasses in the water trying to go back through the hull to the inside.

All in all, if you are in a northern climate, you are better off letting that boat sit on a trailer and outgas that first summer than throwing it in the drink with an unprotected bottom. hard bottom paints and antifouling provide that extra protection from gas transport.

That was almost 3 months in the water unprotected, it is not an unreasonable time to have such a result. I personally dont feel it is a quality control issue, larger boats need sealing and sacrificial bottom coatings, smaller boats are not in the water as much unprotected either. many manufacturers keep the boat heated to promote curing during construction. If your boat was made during a cool week in california, perhaps curing was delayed or incomplete.

It generally does not affect performance, IF you are going to keep a boat in the water 3 months a year, it should have bottom coatings, and they will easily go over blistered bottom. Most hulls have to be scuffed up anyway to get the best adhesion of paints to the hull.

RussMT wrote:RE Blisters:

From what I've read, it seems they are more prevalent in fresh water than salt. I guess it's less dense and gets through the gelcoat easier. Also, from the numerous posts, the Mac seems to have a crappy hull gelcoat. After 1 season in fresh water, my '08 Mac had blisters. How serious a problem depends on how many and how deep they are. I let my Mac dry out over the winter and many of them subsided but there are still quite a few left. The next season I applied a coat of Aura bottom wax and no new blisters. In retrospect, I wish I had done this before any blisters, it might have given enough of a barrier to protect it.
My old powerboat had zero blisters and I haven't seen other boats in my marina with blisters so I'm convinced it's a quality control issue that Mac will never admit to. Some say it could be a bad batch of gelcoat, who knows. It doesn't matter since the warranty excludes it.

--Russ

I have to second the quality control issue as being the main culprit, happens on automobile assembly lines too. Sometimes the workers just are not into it that day. I have hull #72 which would have been fabricated within the first few months of M production when quality control was more stringent for the launch of a new model.

The Auroa 721 bottom wax is what I used from day one and the company even lays claim to helping against ossmosis with this wax, it sure worked for me, for six seasons staright. But...a big but, it is a lot of work keeping your hull clean and re-waxing every six weeks and in hindsight I would not recommend it. Just because I was a stubborn old mule does not mean everyone else should be so. I do recommend the painting though because now I no longer have to perform that big ugly dirty job of working on my back on a creeper cleaning and waxing that hull.
Opie:
I used the Interlux Epoxy barrier coat brand for the first four coats then I used an ablative anti-fouling paint over that, I forget the name but maybe it was CSC, a dark blue color to match the hull, looks nice, I even left a white space below the bootstripe line to create an additional white stripe.

Terry wrote:

RussMT wrote:RE Blisters:

I even left a white space below the bootstripe line to create an additional white stripe.

Cool! I did the same, and my no. 47 hull is...knock on wood..... still blister free.


Q1

M production when quality control was more stringent ...


WADR , have you ever visited the mac factory??

I found a heartbreaking anomaly on the aft in the blue gelcoat. I bought the boat in mid November and sailed her then. I went over the entire blue area of the hull when picking her up. This blemish wasn't there. I've been out to the boat and checked it over many times throughout winter and washed her on a warmer day in November and never saw this. It did get down to -8 degrees F with a lot of temp fluxuations.

Today, it was warm enough to finally apply her Registration and name decals. In the sun, a glaring area which looks like the boat was hit very hard with a baseball or something was very noticeable behind the starboard rudder. I couldn't see any cracking on the inside. There are no scuffs in the wax/gelcoat indicating something hit my boat in the barn. It's just that suddenly, there are very noticeable spider vein blemish in th blue gelcoat. Weird. Heartbreaking.

Sorry the picture doesn't show it well do to the reflection and glare of the sun. Has anyone seen this before?


Doug

http://starsloop.blogspot.com/

This is moving away from 'blister', but I raised a similar issue as yours at
http://macgregorsailors.com/phpBB/viewt ... 44#p176944
Your photo does not seem accurate to what I have had....that white reflection is misleading.
I know blue looks absolutely brilliant.....but at times I wonder about its longlivity...especially when I am polishing one!!
A great look tho.
Cheers
Phillip

Kelly Hanson East wrote:M production when quality control was more stringent ...


WADR , have you ever visited the mac factory??

WADR - I see this acronym from time to time but I have no idea what it stands for, so I lose the meaning of your post Stephen.

WADR means With All Due Respects

i had just bought my used 06 in december and have been fitting it out since, i have owned many different boats the last 20 years and have never seen blisters before, until i looked at the bottom of the mac, there are hundreds of little bumps all along the bottom of the hull. buying the boat used though i cannot really pin down the cause, but i have ran into many quality issues with this boat that concern me including 3 spots on the deck in the gelcoat about the size of a number2 pencil eraser that it looks as though the gelcoat was very thin and just popped off?, again never seen anything like it before

Thanks for all the comments and help on this string.
The Mac Community is a great bunch of folks.
Looks like I will be spending some of the spring sanding, epoxing and painting the bottom of my NEW boat.

I talked to MacGregor customer service at the factory who talked to Roger Himself.
Bottom line is too bad, your problem. MacGregor doesn't stand behind their product (Read the fine print)
McGregor said it would cost 2000 more per boat if they epoxy sealed their boats.
As this problem is not common it is not worth the cost--their words.
Thank you Macgregor for passing that cost on to me- I would have gladly paid the 2K for some quality from the factory
I thought it was made in America---PUT A MADE IN CHINA STICKER ON IT--SAME QUALITY.
Cheep boat with a company that will not stand by their product, I am very disappointed.

For comparrison, I have my boat in a marina with about 100 other boats that stay in the water from May to October.
I walked around the marina and could not find another boat with blisters.

DON'T BUY A MAC, I WON'T AGIAN.

Hi PES, I'm sorry to hear about your blistering problem. I would be very disappointed too.
I haven't had that problem (yet?) Maybe because I use mine in saltwater, store it on the trailer & wash it down after every use?
You are not far off with the "made in China" statement, so far I have found the steering wheel, wheel rims, tires & wheel bearings all made there. There's probably more.......It is hard to find anything that isn't made there these days & I always try to buy from elsewhere if I can. Getting harder though unfortunately.

I got blisters after the first year in the water. The reports of them seem to be more common in fresh water. Maybe because salt is more dense and harder to penetrate. There have been many reports of blisters from unsealed Mac bottoms. I agree that other boats in my marina have "raw" bottoms and don't have blisters. Something isn't right here.

The factory wont admit they are using cheap materials or craftsmanship. In fact they claim the opposite.

Mac Web site wrote:Many builders continue to mix resin and catalyst (the catalyst causes the resin to become hard) in gallon buckets and apply the resin with a brush. Using that method, it is virtually impossible to determine if the catalyst ratio is right and the resin stirred properly. It is also hard to control the amount of resin applied to the fiberglass. (The fabrics seem to soak up any amount of resin and the result can be a seriously overweight boat.) We use automated spray equipment that injects the catalyst in exact amounts at the head of the gun, mixes it completely, and applies it uniformly to the fiberglass. These systems are expensive, but reliable. Improper catalyzation is, in our opinion, the leading cause of blistering that can occur later in the life of the boat. We have been remarkably free of this problem, and
believe that our automated mixing guns are the reason. Practical Sailor did an extensive study of blisters, and found that MacGregor was one of two builders experiencing the lowest incidence of blistering.

link Maybe he's talking about the 65 not the 26.

I couldn't find the Practical Sailor issue.

--Russ

I was told by BWY in seattle that if you plan to leave the boat in the water to seal & paint. I then ask what about 3 - 4 week trip they said no problem due to the fact that you be on the go.
So paint or trailer storage is word of the day. Best of luck.

The spider cracks in the photo looks like someone hit the dock hard. I have a similar scrape a just bit more forward on my port stern but it is not spider cracking. Happened when I was backing my into a slip and got caught in a eddy and I overpowered to correct. Should of just let the current take me where it wanted and aborted the docking. As a wise old Captain once told me, " Always approach the dock at the speed at which you wish to hit it"

PES wrote:Thanks for all the comments and help on this string.
The Mac Community is a great bunch of folks.
Looks like I will be spending some of the spring sanding, epoxing and painting the bottom of my NEW boat.

I talked to MacGregor customer service at the factory who talked to Roger Himself.
Bottom line is too bad, your problem. MacGregor doesn't stand behind their product (Read the fine print)
McGregor said it would cost 2000 more per boat if they epoxy sealed their boats.
As this problem is not common it is not worth the cost--their words.
Thank you Macgregor for passing that cost on to me- I would have gladly paid the 2K for some quality from the factory
I thought it was made in America---PUT A MADE IN CHINA STICKER ON IT--SAME QUALITY.
Cheep boat with a company that will not stand by their product, I am very disappointed.

For comparrison, I have my boat in a marina with about 100 other boats that stay in the water from May to October.
I walked around the marina and could not find another boat with blisters.

DON'T BUY A MAC, I WON'T AGIAN.

This has been discussed here in great detail. Macgregor boats are designed to be trailered and to cut the cost down. If you trailor you don't need the epoxy or bottom paint and don't have to pay for it. That's why people buy Mac's.

If you want to leave it in the water, the manual states " You must apply a high quality epoxy primer and bottom paint" or you may experience blisters. The manual is very up front with this.


Wally