Bull City

A pox on me, or Blisters on my Bottom - Ouch!

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As I mentioned in the topic "Is this right about barrier coat?" I just discovered blisters on my H-Boat. I decided to start a new topic.

 

By way of background, the boat was built in 1980, and was sailed in New England. I bought it 2 1/2 years ago. It had no blisters. The yard and I did a pretty extensive renovation, and put it in the water in May 2015. The water is an inland fresh water lake. This haul out was the first one since then.
This blisters are pretty small, mostly less than 1/4" and don't protrude very much, maybe a 64th or 32nd of an inch. Some pics below. I poked a few open with an awl, and it looks like they're just under the gel coat, not into the laminate.
Today the marina operator (MO), who did the haul out and who does repair work, did some moisture meter measuring. Above the waterline, readings were around 5%, below 20 - 25%. He feels we need to get to 15% or better before we do any painting.
After discussion with the MO, we have this plan:
(1) Media blast the bottom aggressively, which will open up many of the blisters. Grind the ones that don't open.
(2) Let them drain and dry. Take more meter readings.
(3) Fill and fair with epoxy fairing compound
(4) Prime with 3 or 4 coats of epoxy primer/barrier coat
(5) Bottom paint
(6) Cross fingers, sacrifice to god of osmosis, etc.
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post-54228-0-07532900-1487614956_thumb.jpg

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Bull, It might be worth sanding an area of the hull down through the paint to see how deep they actually go. I had blisters that looked a lot like that and after sanding a window through the paint, then through the gelcoat, it became clear I had a bigger problem. In my case we had the bottom peeled and the boat dried out for a summer to get the moisture levels down before putting it all back together. YMMV.

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Bull, It might be worth sanding an area of the hull down through the paint to see how deep they actually go. I had blisters that looked a lot like that and after sanding a window through the paint, then through the gelcoat, it became clear I had a bigger problem. In my case we had the bottom peeled and the boat dried out for a summer to get the moisture levels down before putting it all back together. YMMV.

When you have the bottom peeled, is it true that you then apply an epoxy compound sort of like a skim coat of plaster?

 

Bull, she may be out this season. Drying out the hull is painfully slow.

I'm hoping that this case isn't too bad.

 

The tough part is lining up the media blasting. We had a guy lined up to do it this past Saturday. On Thursday night he checked himself into the ER with chest pains and had a triple by-pass on Saturday. I think he's doing OK, however, we're having a hard time getting someone else.

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Depends on how deep of a peel. In our case, we put a layer of glass back on to replace the lost thickness. Then several rounds of thickened vinylester as a fairing compound. Not unlike skim coating and sanding drywall. Smells a lot worse though, and the surface isn't nice and flat like a wall...

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His heart attack saved you a lot of grief. Under no circumstances media blast.

 

That is totaly uncontrolled and will mostly remove good material and leave the soft bits behind.

 

Shave is best but need special planing gear so maybe no other options but other hand methods. Unless you get moisture down to low single figures your just covering it up for it to resurface another day.

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Agreed. Media blast will leave you with a bottom that resembles the moon. 60 grit discs and random orbital sanders would be my first step. The blisters may simply be in your bottom paint -- I've seen this a lot when people use incompatible products over each other. Also the blisters may be at the size where you can simply sand them out -- i.e. partially in the gel coat. These usually will sand out and not even secrete.

 

No matter what, I would sand/scrape all your AF off and then take moisture readings. The anti fouling and/or moisture trapped in the antifouling could be confusing the moisture meter. Finally, many armchair shipwrights on this forum who like to tell you how to do a job having never done it, willl swear by a moisture meters readings -- I recommend that you take them with a grain of salt and read into what could cause a moisture meter to display elevated humidity.

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PS A media blast by someone who knows what they are doing to remove coatings ONLY but not touch the gel coat is fine if not the best, fastest and cheapest way to get rid of all coatings to properly reveal the problem. Logged and relative moisture readings using above waterline as a baseline help quantify the amount of drying that has occured more so than the actual readout which will vary day to day according to conditions if not in a shed.

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On the media blast:

I'm going with it as a first step in order to open up as many blisters as possible/prudent. A peel/shave would be much better, but at present there is no one in our area who is set up to do the whole job. I would have to have the boat transported about 200 miles and back, which would add quite a bit to the cost.

 

If the "blast - fair - barrier coat" plan doesn't work, i.e. the blisters come back, then I'll look at the peel. My previous boat, a J22, had been peeled and resurfaced before I bought it, and it did fine for the 7 years I had it.

 

The Moisture Meter:

We hauled the boat on 2/13, and pressure washed most of the ablative AF paint off. What's visible is mostly the remains of old hard bottom paint. We took the first readings on 2/20. I agree on the readings: they are just a baseline. We'll take more as we go, and rely on observation.

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On the media blast:

I'm going with it as a first step in order to open up as many blisters as possible/prudent. .

Well Bull I take it you are blasting beyond the gell coat??????

 

If not ignore what I say as follows. If so then my quick excuse is I'm on a mission from God to rid the earth of stupid people.

 

You post here looking for advice on something you have absolutely zip experience on and no doubt wanting something to question the advice your getting on the ground. You get that here including advice in other similiar threads and in some cases coming I suggest from some who have a fuck more experience than your on the ground people gauging from what they tell you ie 25% moisture reading wtf ???..

 

But hey the Bull plows on regardless oblivious to what he has heard??.....the Bull ..now I get it.

 

Good luck....

 

PS Would have been polite of you to just slink away and do your own thing as your obviously quite entitled to do. As you broadcast your decision, then I just wish I had put my humble advice to you both time and bandwidth wise towards some more porn...would have been far more productive.

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Thanks, Jack. There are some limitations on what I can do about the problem.

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Bull,

 

Take Slick's advice. In 2-3 places per side, grind a window through the gelcoat and take moisture readings of the laminate. You may have simple gel coat blisters or you may have a deeper problem, up to hydrolysed laminate the goes pretty deep. I take it that you have no pros in your area to have a deeper look.

 

If the entire hull below the waterline looks like the first picture, I would plan to remove the gelcoat with a planer or grinder (amazing what a good auto paint an auto body tech who has worked on fiberglass cars (vette) can do with a grinder and still maintain a pretty fair surface.

 

Jack is correct. If you misdiagnose the problem and do a cosmetic job on a deeper problem, it will come back. On the other hand, doing a full depth peel and relamination if the problem is just in the gelcoat is expensive and a waste.

 

Good luck.

 

Edit. Not many boats "die" from blisters unless its a full on delamination (not osmosis). If you are limited to only the blisters you can see and a limited drying period, you'll get another chance when they come baclk.

 

Gouv has seen plenty of "Salt to fresh" boats and may have a good approach to share if you PM him and invite him to the thread.

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I spent four days under a 33 footer grinding gel coat with 80 grit pads on a random orbital sander with soft pad. I was young (34) in great shape and it kicked my ass. Holding a heavy grinder upside down for hours at a time isn't fun. I would never do it again. I think there are various media that can be selectively used to remove layers of gel without damaging the laminate and I would rather pay the freight for that. I do agree you don't want to go any further than you have to.

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I'd second IB's advice and PM or call Gouv. He is the resident warm fresh water induced blister guy...plus he's pretty pragmatic as well.

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For reference, Gouv has previously posted a link to this article he wrote about how he does blister repair.

 

http://schrothfiberglass.com/BlisterRepairsArticle.htm

 

It is a system that seems to work for him and his clients in a warm water lake where blisters seem to be a fact of life. Other experts will call this article heresy, but from the research that I have done prior to tackling our boat's bottom, few of the experts actually agree with each other.

 

After having gone through an extensive bottom job once, I would probably use Gouv's approach for a boat with a few to a few hundred blisters, anything more than that, I would go for a full blown bottom job.

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Yeah. I've done 2 boats. A 31 footer with thousands of "pimple" blisters limited to the gel coat that showed up on my purchase survey in 1991. Got a price reduction that recognized the repair cost and on advice of the surveyor that folks were still experimenting on how to address blisters,I sailed it for 3 seasons before fixing it by having the gel coat ground off (16 grit and move fast) by a guy with lots of experience and then did multiple coats of West with the barrier coat additive. 6 years later, I took all of the paint off, scuffed it with 80 grit and reapplied 3 layers of West (per the surveyor's recommendation) but had no evidence of blisters coming back.

 

Second was a 42 with a solid hull (not cored) that had a few obvious blisters (1-3") at 23 years, 10 on Lake Michigan and 13 on the Chesapeake. Took all of the paint off and found some real ugliness and ground 2-3 windows on each side to dry laminate almost 1/2" down. Engaged a surveyor to oversee repairs and did 2 passes with a planer and relaminated with epoxy, triax and a veil cloth followed by fairing with an air file. Yard guarantees they will fix any blisters that show up as long as I own the boat. Expensive but the boat is lighter and stronger than when we started. No sign of any problems after 4 years.

 

As Slick says, there are lots of differing opinions in what it takes and it sounds like you don't have anyone local with any real expertise. Tough situation.

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Crash, Slick & IB, and all,

 

Thanks for telling me about your "dreaded" experiences and for pointing me to Gouv's article. I was actually encouraged by it and I sent it to my repair guy. I'm lining up a soda blast. After that, I figure the repair guy and his boys, with cameo appearances by me, will spend many hours grinding out blisters and listening to country music. I'm actually looking forward to it.

 

I think Gouv summed it up pretty well:

 

We recommend the "get what you can easily find each time" system because it would cost many more dollars to ATTEMPT to find all the blisters in one try. If we were to remove 100% of the old 2000 epoxy and 100% of the gelcoat, and wet the bare laminate, we might find 95% or even 99% of the blisters. We would triple the price of the repairs. We would take the boat out of service for a longer part of the summer. We would still need to repair a few blisters over the next ten years. In other words, we do not believe the extra money spent now would improve the condition or performance of the boat. We do not believe we can significantly decrease the cost of future bottom jobs. We can think of many better things to do with our labor, and the boat owner's money.

This guy has done a lot of this over the years.

 

I'm going to do a few windows too.

 

B.C.

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I was able to set up a blasting for tomorrow. The guy whose doing it suggested we start with fine glass. If it's too aggressive, switch to soda. I have not had a chance to do any windows, but I feel the blasting is the logical first step.

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I spent four days under a 33 footer grinding gel coat with 80 grit pads on a random orbital sander with soft pad. I was young (34) in great shape and it kicked my ass. Holding a heavy grinder upside down for hours at a time isn't fun. I would never do it again. I think there are various media that can be selectively used to remove layers of gel without damaging the laminate and I would rather pay the freight for that. I do agree you don't want to go any further than you have to.

 

If you ever wondered just what those sets of "front squats" in the gym are for... That's what they're for.

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I am going to rename my boat Chicken Pox.

 

Blasterman came this morning and blasted the bottom with fine glass. It took about two hours and he removed all of the old bottom paint and took the top off of most of the blisters. He said that water came out when they opened. The open ones are small, maybe 1/4" or less, and some a little bigger. There are some blisters that didn't open, and we will open them soon, but they are also small.

 

There is still some old paint just below the white boot stripe. This is because I did not want Blasterman putting duct tape on my $1,000,000 Awlgrip paint job. <_<

Looking at the blisters after he washed the hull, the underlying fiberglass looked very solid. Time and the moisture meter will tell, but I am optimistic that these are more gelcoat pimples than serious blisters. I plan to sand a few windows as has been suggested.

 

Here are some exciting pics. Comments and observations are welcomed.

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I think I would have had him take all the gelcoat off right down to the bare laminate. But that's just me. There are likely another 10,000 blisters ready to form in that old gelcoat that is still there.

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I think I would have had him take all the gelcoat off right down to the bare laminate. But that's just me. There are likely another 10,000 blisters ready to form in that old gelcoat that is still there.

That is crazy moonscape shit...do it in steps exactly as Bull has done. First identify. Bad blisters are in the laminate, gel coat blisters are inconsequential other than they are allowing moisture to permeate the substrate and they are now largely gone. Time for the next step.

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How did the fresh opened blisters smell ?

I suspect if Bull goes and does a couple of control panels/windows and bursts blisters that grit blasting the paint off didn't expose nearly all will exude liquid and have a strong styrene smell to them. If so then it is laminate plane or grind time. If not he will be a happy man and still have his gelcoat largely intact.

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I think I would have had him take all the gelcoat off right down to the bare laminate. But that's just me. There are likely another 10,000 blisters ready to form in that old gelcoat that is still there.

In retrospect, that couldn't have hurt.

 

How did the fresh opened blisters smell ?

The whole area just smelled like new fiberglass. I didn't see anything dripping from the exposed fiberglass. When I open the unbroken ones, I'll give them a sniff.

 

 

I think I would have had him take all the gelcoat off right down to the bare laminate. But that's just me. There are likely another 10,000 blisters ready to form in that old gelcoat that is still there.

That is crazy moonscape shit...do it in steps exactly as Bull has done. First identify. Bad blisters are in the laminate, gel coat blisters are inconsequential other than they are allowing moisture to permeate the substrate and they are now largely gone. Time for the next step.

 

The ones that did not open were mostly in areas where, because of the plastic tenting, Blasterman could not get many angles. I think they open very easily.

 

 

How did the fresh opened blisters smell ?

I suspect if Bull goes and does a couple of control panels/windows and bursts blisters that grit blasting the paint off didn't expose nearly all will exude liquid and have a strong styrene smell to them. If so then it is laminate plane or grind time. If not he will be a happy man and still have his gelcoat largely intact.

 

I hope that will be the case. According to Gouv, I may have to do this again in a few years, but on a much smaller scale. I was also interested to read this about old gelcoat from David Pascoe (http://yachtsurvey.com/moreonblisters.html.htm):

 

Even though a hull may be built with inferior resin, osmotic pressure is not normally sufficient to force a separation between plies that are completely chemically bonded. If it can't force a ply separation, then the blister can't form. In this case, if there are sufficient numbers of voids directly under the gelcoat (which softens with age), small blisters, or what I call pimple rash, will develop that will extend only to the general area of the void. The osmotic pressure is sufficient to raise the gelcoat, but not to cause a ply separation. It is particularly insightful here to note that pimple rash almost never occurs in conjunction with larger blisters.

 

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How did the fresh opened blisters smell ?

I suspect if Bull goes and does a couple of control panels/windows and bursts blisters that grit blasting the paint off didn't expose nearly all will exude liquid and have a strong styrene smell to them. If so then it is laminate plane or grind time. If not he will be a happy man and still have his gelcoat largely intact.

 

The gelcoat does nothing for the boat except act as fairing when the boat is originally moulded, and in this situation potentially hides/creates problems. In the end a whole lot of epoxy barrier coat will be applied - I would rather apply that to the bare laminate than to gelcoat. Better to remove it. But what do I know?

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How did the fresh opened blisters smell ?

I suspect if Bull goes and does a couple of control panels/windows and bursts blisters that grit blasting the paint off didn't expose nearly all will exude liquid and have a strong styrene smell to them. If so then it is laminate plane or grind time. If not he will be a happy man and still have his gelcoat largely intact.

 

The gelcoat does nothing for the boat except act as fairing when the boat is originally moulded, and in this situation potentially hides/creates problems. In the end a whole lot of epoxy barrier coat will be applied - I would rather apply that to the bare laminate than to gelcoat. Better to remove it. But what do I know?

 

This makes a lot of sense to me. It would have required a lot more blasting bucks.

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Youre right, gelcoat does nothing for water tightness or stiffness, its a mould thingy. It adds only weight.

But replacing it with something that is water tight and is still adding weight is to complex for this.
IMHO

 

I would repair it with gelcoat filler, based on gelcoat, look for easy to sand, long potlife and easy to apply.

 

The good part, its still not watertight, if your laminate is too moist under the gelcoat, a few winters stored out of water will bring balance again.

You had it in water for a long time.

If you want to keep it again for years in the water, a water tight barrier coat makes sense.

 

Its for you to think what will work on the long haul... Both are good solutions.

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Leo,

 

Once we we're sure we've got all the blisters opened, and any damaged fiberglass removed, we'll fill with epoxy. For any deep spots, I understand there is a hard variety, and for the top, an easy to sand filler as you suggest. Then we will apply an epoxy barrier coat. I'm not sure how many coats yet, but it will be a generous amount since I'm in fresh water that gets warm in the summer. Right now it's about 50º F.

 

On Monday I'm planning to open up some or all of the remaining blisters/pimples, sand a few windows to look at the laminate, and take some moisture meter readings.

 

More after that.

 

B.C.

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Wow. A day. Most of my blisters that had any fluid in them burst on their own - because it was February and zero degrees out. By the time I got the job done, it was 104 degrees.

At least it all dried out well. The vast majority of the rash stuff simply disappeared under the sander.

 

Fun to go into a locker and take a picture of sunlight coming in through the bottom of the boat!

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I did some sanding yesterday. I have a 5" RO sander, and used 60 grit on blisters that had not opened. After going over an area of them for a while all I did was make them blend in to the surrounding gelcoat. I got some 40 grit discs and I'll give them a try.

 

I also picked open some blisters: they had a tiny bit of moisture that had a faint vinegary smell.

 

Moisture meter readings were slightly lower since the blast job on the 24th, but still over 20%.

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That vinegar smell means they are "real" blisters - that's the smell of the uncured chemicals leaching out of the glass.

 

36 grit on a soft pad is the best thing to use - if you can get coarser discs, use them.

 

I'd spend a few bucks at HF to get a 7" sander/polisher to do that bottom - R/O's don't cut nearly as well - they are really a finishing tool.

 

http://www.harborfreight.com/power-tools/polishers/7-in-10-amp-variable-speed-polisher-60626.html

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i drill open un -popped blisters instead of sanding large areas. I use pretty big diameter, shallow countersink bit. I did about 200 gelcoat blisters this way.(they were small)

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If there are flatter parts of the hull you can get it done faster with a small belt sander with 24 grit. I bought a cheap one with a vacuum attachment, burned it out in two days removing coatings from the bottom, replaced it under warranty, then removed more with it. The second one is still alive, not sure how.

 

One of these.

 

I don't know how old you are or how fit, but I'm a bit long in the tooth. It was easier to hold the belt sander over my head than the sander/polisher, so I could work longer. With the sander/polisher you need to apply a fair amount of pressure, which is tiring, but with the belt sander only light pressure is needed.

 

Be careful. If you use the belt sander on the round parts of your hull you can add fairing to the work ahead of you.

 

As the pro in the yard said "Now all you have to do is fly at her!"

 

dash

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i drill open un -popped blisters instead of sanding large areas. I use pretty big diameter, shallow countersink bit. I did about 200 gelcoat blisters this way.(they were small)

Looking at the pictures, this hull has bazillions of tiny blisters. Sanding is the way to go with this one.

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The boat is on marina property, which they lease from the ACOE. I'm not supposed to get anything on the ground. If I use a vacuum-attached sander, I'm OK. I've been sanding off bottom paint just below the boot stripe where the blaster could not reach, and picking open some unopened blisters.

 

I've got a ball-shaped rasp that fits on a drill that would probably work well on the unopened blisters.

 

I'm a pretty fit 68 year old, but I know my limits. I've worked on boat bottoms before, and I am going to have the marina folks do most of the work. It will go a lot faster than me on my own, and at this stage of life, getting back in the water is important. Still, I want to muck around a bit myself, so I can see and understand what's going on.

 

Happily, the stock market is way up, so I can make my bottom great again. :)

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For spot repairs, you may want to try 2" mini grinding discs - something like these: http://www.canadiantire.ca/en/pdp/maximum-assorted-mini-grinding-disc-kit-2-in-9-pk-0542025p.html#srp

 

Not sure if I linked to the right product, but what you would be looking for are basically Scotch brite pads with velcro backing that can be attached to a drill - you'll know them when you see them. Surprisingly, they make pretty short work of grinding/sanding through gel coat and into the laminate (you have to be a bit careful). I would say I spent about 2 minutes per blister max. They leave a nice feathered edge. Can be a bit "skittery" at first but you quickly get the hang of it. Surprisingly durable little discs.

 

I almost ended up using these to do the blister repairs on my previous boat, but I went all OCD and removed the entire bottom mainly using a small and light (3x18) belt sander. I bought a Rigid one which has proven to be a very durable unit (as opposed to the Skil).

 

In hind sight, I wish I had just done the spot repairs using the mini grinding discs - but I really didn't have much of a clue at the time about how much effort it would take to remove the entire bottom.

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after having the bottom peeled on our boat I used a 5" palm sander with 40 grit disks hooked up to a shop vac for most of the deeper digging and cleanup around the bootstripe, rudder, keel, propshaft and anywhere else he couldn't get the planer in close. The shop vac kept the yard happy.

 

For the tough stuff I used a 4" grinder with 36 grit sanding discs and did my best to keep the dust down with the shopvac.

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I did some sanding just below the boot stripe today in order to remove old bottom paint that the blaster couldn't get. I also sanded a "window" through the gelcoat and the laminate looks fine. In addition, I don't see any liquid coming out of the open blisters.

 

The MO is going to turn one of his guys loose on the "Unopened" and then we'll wait for things to dry out.

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The MO and I took some meter readings and they are getting lower. We put a dehumidifier in the cabin and will see if it has any effect. I noticed that the readings on the rudder are high. I'm guessing the rudder shaft has some influence. Could there be more metal inside? Maybe I need a metal detector and a goofy hat?

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There is some sort of frame inside the rudder that couples the blade to the shaft.

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Rudders have a frame of "rake" inside to couple the blade to the shaft. They also tend to be saturated. Some are foam filled. Some have some concoction of resin and fillers. You may want to hand drill a 3/8" or so hole in the bottom of the rudder and see what comes out. Not unusual for them to week visibly at haul out. Just remember to fill the hole before you splash again.

 

I removed the rudder while I barrier coated the bottom on my first keelboat and then an unexpected transfer overseas lead me to sell the boat before splashing it again. Buyer's surveyor was able to tell what side of the rudder was "down" over the winter by the relative moisture readings on that foam filled rudder.

 

Goofy hats always help.

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Another thing was interesting abut the meter readings. There is a transverse structural bulkhead just aft of the cockpit winches - it separates the lazarette and cockpit lockers from the cabin. The readings aft of the bulkhead are higher than those forward of it.

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Bull where there is moisture collecting on the inside...be it either side of bulkheads, clogged lumbers, integral water tanks etc etc...Expect hull moisture readings to spike. That's normal...and also possibly an indicator of inside out osmosis.

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That vinegar smell means they are "real" blisters - that's the smell of the uncured chemicals leaching out of the glass.

 

36 grit on a soft pad is the best thing to use - if you can get coarser discs, use them.

 

I'd spend a few bucks at HF to get a 7" sander/polisher to do that bottom - R/O's don't cut nearly as well - they are really a finishing tool.

 

http://www.harborfreight.com/power-tools/polishers/7-in-10-amp-variable-speed-polisher-60626.html

 

 

what pads do you use with the 7"? where'd you get them?

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I get my consumables - pads & disks from the automotive refinishing section of a really good tool store we have here - KMS Tools. It's sort of like HF but better quality stuff is available. Stan carries several levels of most things and the good stuff is good but still good prices.

 

For doing bottoms I prefer a 7" diameter X 1" thick softish foam pad. Its density is such that you can squeeze it to about 3/4" twixt thumb and forefinger. Velcro surface for quick disk changes.

 

That density of foam keeps it flat for cutting but flexes enough to keep the edge from digging in.

 

Also, get a stick of sanding belt cleaner. They are some type of gum rubber, sort of golden in colour that you just drag across a spinning disk when it gets clogged. You get way more life out of the disks that way - like 3 or more times as long.

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Bull where there is moisture collecting on the inside...be it either side of bulkheads, clogged lumbers, integral water tanks etc etc...Expect hull moisture readings to spike. That's normal...and also possibly an indicator of inside out osmosis.

Jack, the boat has no tanks. There's a couple of spots where rainwater can accumulate: one on the centerline in the lazarette, maybe 1/2 cup (which I need to sponge up), and the bilge, which has been dry.

 

I also noticed a few high readings at the bow, where the anchor rode locker is. Could a soggy rode cause that? There could be a little water in the locker. I'll need to check.

 

The weather here has been sunny, breezy and dry and unseasonably warm (50s to 70s). The MO said he emptied a quart from the dehumidifier today - that's 24 hours worth.

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Bull, I think Jack's point was your tranverse structural bulkehead that separates the laz from the cockpit lockers is likely trapping moisture and humidity....which may be leading to higher moisture readings aft of said bulkhead. Or there is somewhere aft on the hull that is letting moisture into the core, and it just is a coincidence that the bulkhead seems to be where the difference is....

Crash

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The MO and I took some meter readings and they are getting lower. We put a dehumidifier in the cabin and will see if it has any effect. I noticed that the readings on the rudder are high. I'm guessing the rudder shaft has some influence. Could there be more metal inside? Maybe I need a metal detector and a goofy hat?

Here is a drawing of the rudder: http://h-boat.se/nya/wp-content/uploads/2013/03/baada33.pdf

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Joakim, thanks for digging up that drawing and posting it. It shows the "rake" that Innocent said was likely to be there, and it's stainless steel. The rudder is GRP filled with polyurethane foam.

 

Crash, I understand. The changes in readings were pretty abrupt forward and aft of the bulkhead, both port & starboard. Something I need to check.

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Bull,

 

We had a Shark (solid glass, early 70s) with a Performance Epoxy bottom that started blistering quite badly the last few years. Several hinder 3/16-1/4 blisters. The theory is that the boat blistered in the past (signs of repair work done) and the bottom was stripped and the classic mistake of immediately sealing the bottom was made. As we all know the blisters reappear, eventually.

 

In the late summer we stripped the hull of most of its performance bottom (brutal) via 5" DAs, and sanded most of the gel coat off below the water line. Most of the blisters sanded out at this point, save for a few dozen that needed to be opened up. The hull was grided and moisture readings were done per roughly square foot and noted on the hull.

 

We let the boat sit with its bottom bare and with heat lamps on it for close to a month. When the cool weather came we moved the boat into a very dry and 15C storage unit. Yesterday I put the meter to the hull. Our Tramex Skipper Plus which reported a relative moisture reading of 70 in the late summer, is now showing us 15.

 

TL;DR: there's hope.

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Will, thanks for passing that on. My readings are coming down, but slowly.

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Bull and I are tackling this same project right now. I used a 7" grinder with with 36 grit paper for bottom paint removal and a 4.5" 80 grit flapper for the gel coat. Hindsight I should have used the flapper on the whole thing and saved many hours. I plan to use wash the boat tomorrow with Dawn and use Awlfair on Sunday. I have a ~24" painting shield I plan to use for filling. I was hoping to see something online for filling other than a Flexicat. For sanding I will make a torture board. All of that will be followed with three coats of 2000E.

all finished

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You're going to need more than 3 coats of IP2000

 

Unless he can apply 1 gal per coat :P

 

On my 27 footer, which granted was beamier with longer LWL, I used the better part of 4 gallons (including keel). For a narrow boat like this, maybe 2 gallons, but I would count on 3. Build thickness or gallons applied are the important numbers, not the number of coats. I think on my boat I ended up with about 10 coats. I can't remember the required thickness but probably about the same as gel coat so maybe 20 mils?

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IP says 10 mils.

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IP says 10 mils.

 

Yeah, that was the number I tend to recall but wasn't certain.

 

I do know I used as many gallons as recommended in their sq ft per gallon coverage

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I think I used 3-gallons on a 29-footer. I can't remember how many coats, but it was more than the literature suggested from that much paint. The weather was very hot and dry, and I may not have had the exact kind of roller recommended. Alternated colors between coats, but obviously that didn't come out exactly even with an odd number of cans.

 

Oh yeah... had a little bit of gray left over and got it into my head to paint the cockpit non-skid with it. Deck was going to be repainted the next year anyway... Not a recommended use but it still looks OK after four or five years.

 

Maybe I better paint the deck this year.

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I think the alternating colors is a good idea. I can envision going mad without that kind of help. Gouv says to pile it on, which is also a good idea. Given all that, a high build product makes sense.

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I recommend closed foam rollers if you plan on getting a decently smooth bottom. Spraying is even better because you can get all your coverage in 1/4 of the time. Alternating colours is nice, but there is a colour change as it cures, so you should be able to see where is old and new when coating.

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Yes, the right rollers are important. I'd like to get a lot of build and reduce the number of coats. Maybe I'll add some flour to it. So much chemistry. Sheesh, you'd think we were flying to the moon.

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Bull and I are tackling this same project right now. I used a 7" grinder with with 36 grit paper for bottom paint removal and a 4.5" 80 grit flapper for the gel coat. Hindsight I should have used the flapper on the whole thing and saved many hours. I plan to use wash the boat tomorrow with Dawn and use Awlfair on Sunday. I have a ~24" painting shield I plan to use for filling. I was hoping to see something online for filling other than a Flexicat. For sanding I will make a torture board. All of that will be followed with three coats of 2000E.

His boat was a trailer for 10 feckin' years! I'd love to know what his moisture meter readings were.

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Bull, I did pop some blisters inside (prev owner let it fill with water) and they had water in them. I finished up the application of filler this past weekend. Still have the logistics of filling where the pads sit. Plus painting where the pads are. I may wait to get it to my club and hog the hoist for painting.

Filling

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I recommend closed foam rollers if you plan on getting a decently smooth bottom. Spraying is even better because you can get all your coverage in 1/4 of the time. Alternating colours is nice, but there is a colour change as it cures, so you should be able to see where is old and new when coating.

 

as more worthwile people have said before, the alternating color was to help when sanding, like a guide coat..

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I recommend closed foam rollers if you plan on getting a decently smooth bottom. Spraying is even better because you can get all your coverage in 1/4 of the time. Alternating colours is nice, but there is a colour change as it cures, so you should be able to see where is old and new when coating.

as more worthwile people have said before, the alternating color was to help when sanding, like a guide coat..

You seem a little hostile

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I recommend closed foam rollers if you plan on getting a decently smooth bottom. Spraying is even better because you can get all your coverage in 1/4 of the time. Alternating colours is nice, but there is a colour change as it cures, so you should be able to see where is old and new when coating.

 

as more worthwile people have said before, the alternating color was to help when sanding, like a guide coat..

 

Dreaded, I can definitely see the benefit while applying multiple coats, but not so much while sanding. If you were sanding a barrier coat, why would it be important to know when you reach the next coat?

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Bull, I did pop some blisters inside (prev owner let it fill with water) and they had water in them. I finished up the application of filler this past weekend. Still have the logistics of filling where the pads sit. Plus painting where the pads are. I may wait to get it to my club and hog the hoist for painting.

Did you use a moisture meter during the project?

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Bull, I did pop some blisters inside (prev owner let it fill with water) and they had water in them. I finished up the application of filler this past weekend. Still have the logistics of filling where the pads sit. Plus painting where the pads are. I may wait to get it to my club and hog the hoist for painting.

Did you use a moisture meter during the project?

 

No, I have taken the low road on refinishing this boat. I bought it with the trailer for $400. So every expense seems immense when compared to the cost of the boat. I was just pricing 2000E... :blink:

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I recommend closed foam rollers if you plan on getting a decently smooth bottom. Spraying is even better because you can get all your coverage in 1/4 of the time. Alternating colours is nice, but there is a colour change as it cures, so you should be able to see where is old and new when coating.

 

as more worthwile people have said before, the alternating color was to help when sanding, like a guide coat..

 

Dreaded, I can definitely see the benefit while applying multiple coats, but not so much while sanding. If you were sanding a barrier coat, why would it be important to know when you reach the next coat?

 

The whole point is you are throwing money away if you are sanding your barrier coat. Why would you sand away the surface you paid cubic dollars to create? I'm busy applying a thin coat of WEST epoxy filler to my bottom, which will then be board sanded, and only after I am satisfied with the bottom will the oh-so-expensive IP 2000 be applied. If anything there will only be cursory sanding of any screw ups after that. If you are interested I will describe what I am doing - I'm pretty happy with the results.

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I recommend closed foam rollers if you plan on getting a decently smooth bottom. Spraying is even better because you can get all your coverage in 1/4 of the time. Alternating colours is nice, but there is a colour change as it cures, so you should be able to see where is old and new when coating.

 

as more worthwile people have said before, the alternating color was to help when sanding, like a guide coat..

 

Dreaded, I can definitely see the benefit while applying multiple coats, but not so much while sanding. If you were sanding a barrier coat, why would it be important to know when you reach the next coat?

 

The whole point is you are throwing money away if you are sanding your barrier coat. Why would you sand away the surface you paid cubic dollars to create? I'm busy applying a thin coat of WEST epoxy filler to my bottom, which will then be board sanded, and only after I am satisfied with the bottom will the oh-so-expensive IP 2000 be applied. If anything there will only be cursory sanding of any screw ups after that. If you are interested I will describe what I am doing - I'm pretty happy with the results.

 

Dash, I agree. I was trying to understand dreaded's point. What's your project?

 

Would there be much waste if you were to apply the coating in alternating colors?

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For reference Bull, as you know, I did a barrier coat a couple years ago on my Olson 911 which is a 30 footer. I used the Pettit Protect product which supposedly has a higher build per coat than the IP 2000. I was using Pettit Trinidad bottom paint, so staying within the family made some sort of sense at the time.

 

Anyway, I alternated colors between coats. Even with the color shift when it cured, I preferred the white to grey contrast between the coats to make sure I was getting complete coverage and wasn't missing any spots. After doing the recommended # of coats, I only had a little bit of each can left. So, in my case, not much waste.

 

As far as sanding between coats, the primer does lay on pretty smooth with the right roller, but it is thick so it may not be racer approved burnished bottom smooth and if you are looking to get that level of result, then you may want to sand everything smooth a various points in the process. I was more concerned with re-coating within the hot coat windows to get the various coats to link and then the first coat of bottom paint hot coated as well.

 

I'm not planning on seriously racing my boat right now, so I'll worry about the baby smooth bottom when that time comes and for now the bottom is good enough. I assume if you are going to sand it after doing all of that, you would add a coat or two extra and then the alternating colors let you track how far down you are sanding to maintain the primer thickness while being able to sand off any stipple left by the rollers. Rolling and tipping may help too, but the product kicked pretty quickly.

 

Oh, an on the rollers, I used the West System epoxy rollers. They left a nice finish, but took a bit to get the technique down. If you weren't careful you would eat a roller in a few feet, but if you were, you could get a side of the boat out of one or more.

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Slick, thanks for the info. My boat is still drying. I last took meter on March 10th. I'm making myself wait until Friday to take more. I think I'll do a pencil grid as Will 1073 suggested, and make a note of the readings.

 

The only racing I will be doing is low key PHRF stuff, so I ain't going to be burnishing.

 

Do you recall the thickness you got, how many coats it took and how many gallons of Pettit Protect?

 

Thanks.

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For reference Bull, as you know, I did a barrier coat a couple years ago on my Olson 911 which is a 30 footer. I used the Pettit Protect product which supposedly has a higher build per coat than the IP 2000. I was using Pettit Trinidad bottom paint, so staying within the family made some sort of sense at the time.

 

Anyway, I alternated colors between coats. Even with the color shift when it cured, I preferred the white to grey contrast between the coats to make sure I was getting complete coverage and wasn't missing any spots. After doing the recommended # of coats, I only had a little bit of each can left. So, in my case, not much waste.

 

As far as sanding between coats, the primer does lay on pretty smooth with the right roller, but it is thick so it may not be racer approved burnished bottom smooth and if you are looking to get that level of result, then you may want to sand everything smooth a various points in the process. I was more concerned with re-coating within the hot coat windows to get the various coats to link and then the first coat of bottom paint hot coated as well.

 

I'm not planning on seriously racing my boat right now, so I'll worry about the baby smooth bottom when that time comes and for now the bottom is good enough. I assume if you are going to sand it after doing all of that, you would add a coat or two extra and then the alternating colors let you track how far down you are sanding to maintain the primer thickness while being able to sand off any stipple left by the rollers. Rolling and tipping may help too, but the product kicked pretty quickly.

 

Oh, an on the rollers, I used the West System epoxy rollers. They left a nice finish, but took a bit to get the technique down. If you weren't careful you would eat a roller in a few feet, but if you were, you could get a side of the boat out of one or more.

 

Unless you are dry sailing there is no point in sanding finer than 80 grit before AF paint. If you want a super slick bottom with AF, do the fine sanding of it, not the substrate.

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Bull, looking back through my notes I went through almost 4 gallons, two of white and two of grey. I still have a bit left of each color from each can and it worked out to a little under a gallon per coat, so for me, 4 coats. I followed their recommendations on how many gallons for a 30 foot boat and looking at their current guide it is 3.75 gallons, which they estimated would work out to 3 coats. Per that I probably didn't get as good of a film thickness per coat, but made up for it in the number of coats.

 

If I remember correctly, the IP needed more coats to get the same recommended thickness.

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IP specs a film thickness, I believe 10 mils. We do a minimum of 6 coats with high density foam rollers, no sanding between coats, recoating as soon as you can gently touch the previous coat without leaving a finger print. No major sanding should be done afterwards, except to promote adhesion to your AF system. You shouldn't need to alternating coats for sanding, as you shouldn't be sanding off any major amount of film thickness.

 

We alternate colours on cast iron keels, to avoid blowing-through to bare metal.

 

Bull how are your readings going? Is she completely stripped?

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IP specs a film thickness, I believe 10 mils. We do a minimum of 6 coats with high density foam rollers, no sanding between coats, recoating as soon as you can gently touch the previous coat without leaving a finger print. No major sanding should be done afterwards, except to promote adhesion to your AF system. You shouldn't need to alternating coats for sanding, as you shouldn't be sanding off any major amount of film thickness.

 

We alternate colours on cast iron keels, to avoid blowing-through to bare metal.

 

Bull how are your readings going? Is she completely stripped?

Friday will be 4 weeks since the media blast. I'm going to do a grid and take some readings so I can really know what's happening.

 

As to the bottom being stripped, the blasting opened a lot of the blisters. A couple of weeks ago, the MO showed me how most of the remaining little ones he has opened are dry. He thinks we should leave them alone for the time being, and see how the drying out goes. We did not do a gelcoat peel.

 

Some questions:

 

1) On the grid, would a 12" grid make sense? If that doesn't sound stupid, would pencil or Sharpie be better? I'm thinking I'll spray the bottom with fresh water from time to time, and pencil might wash away.

 

2) I have a cast iron keel, which was barrier coated. It has some small blisters, but these are obviously not due to osmosis, but to unavoidable oxidation of the iron. I don't plan to do anything fussy with them: fill with epoxy compound if they're open, otherwise ignore them. I'll likely put one coat of barrier coat on the keel, just so things look nice. :)

 

3) The meter readings just above the hull-to-keel joint are high. Is this the keel bolts?

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IP specs a film thickness, I believe 10 mils. We do a minimum of 6 coats with high density foam rollers, no sanding between coats, recoating as soon as you can gently touch the previous coat without leaving a finger print. No major sanding should be done afterwards, except to promote adhesion to your AF system. You shouldn't need to alternating coats for sanding, as you shouldn't be sanding off any major amount of film thickness.

 

We alternate colours on cast iron keels, to avoid blowing-through to bare metal.

 

Bull how are your readings going? Is she completely stripped?

Friday will be 4 weeks since the media blast. I'm going to do a grid and take some readings so I can really know what's happening.

 

As to the bottom being stripped, the blasting opened a lot of the blisters. A couple of weeks ago, the MO showed me how most of the remaining little ones he has opened are dry. He thinks we should leave them alone for the time being, and see how the drying out goes. We did not do a gelcoat peel.

 

Some questions:

 

1) On the grid, would a 12" grid make sense? If that doesn't sound stupid, would pencil or Sharpie be better? I'm thinking I'll spray the bottom with fresh water from time to time, and pencil might wash away.

 

2) I have a cast iron keel, which was barrier coated. It has some small blisters, but these are obviously not due to osmosis, but to unavoidable oxidation of the iron. I don't plan to do anything fussy with them: fill with epoxy compound if they're open, otherwise ignore them. I'll likely put one coat of barrier coat on the keel, just so things look nice. :)

 

3) The meter readings just above the hull-to-keel joint are high. Is this the keel bolts?

1) Roighly ever 12" is probably good. I go down either side of the waterline placing a mark ever foot, then with a helper using a bit of line connect the two marks (following the contour of the hull. I then mark the centerline and make my boxes. The critical thing with the grid is that you're placing your moisture meter in the exact same location each time. Example: bottom left corner of the box. Note reading right at the top left corner of your moisture meter on the hull, and repeat for the next box. Cross them out as you do new readings. Sharpie 100%, you'll need a few.

 

2) sounds good. I would probably do more than one coat, just add it into the mix while you're coating the rest of the hull.

 

3) Two possibilities, it could be the metal keel bolts throwing off the meter (I am no expert with a moisture meter, however, a professional surveyor might be a better source), alternatively it may just be that water in the bilge (or humidity trapped beneath the liner/floor) contributing to the relative reading. I can't really say without seeing the area and how you are positioning your moisture meter.

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Some very good info on the Interlux site here: http://www.yachtpaint.com/LiteratureCentre/interprotect-tb-usa-eng.pdf

 

One thing mentioned there that may not have been brought up yet is that in order to dry the hull, you need to wash it down with water (preferably warm) several times a week for at least a month to remove and draw out the glycols. This greatly speed up the drying out, and you want the glycols removed in any event.

 

You can also thin out IP 2000e with 2316N or 2333N - might give a smoother finish.

 

One thing to note about IP 2000e (and it likely applies to the Petitt product as well) is that behaves the opposite of epoxy as far as hardening goes. I found the thinner the coat the faster it hardens. Conversely, I had at least a cups worth left over one day and the next afternoon I could still stir it to a degree while a cup of epoxy would be smoking in a half an hour. Thin coats dried almost instantly IIRC.

 

As far as sanding goes I wouldn't. But I would try to get it on as smooth as possible. Mine had a fair amount of stipple which really became apparent when I applied the VC Offshore. I ended up sanding a lot of expensive AF rather than expensive IP 2000e. Expensive either way, but the last thing I think you want to do is remove any protection (i.e. barrier coat), otherwise why even put it on?

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Bull, looking back through my notes I went through almost 4 gallons, two of white and two of grey. I still have a bit left of each color from each can and it worked out to a little under a gallon per coat, so for me, 4 coats. I followed their recommendations on how many gallons for a 30 foot boat and looking at their current guide it is 3.75 gallons, which they estimated would work out to 3 coats. Per that I probably didn't get as good of a film thickness per coat, but made up for it in the number of coats.

 

If I remember correctly, the IP needed more coats to get the same recommended thickness.

The Pettit Protect sounds like the way to go from a labor standpoint. The price of PP ($93) over IP ($40) for 4 gallons is about $200. Seems like the higher build will pay for itself in labor by requiring fewer coats - even if it's only one coat less. Plus I may need only 3 gallons.

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For the Pettit stuff, we followed their recoat time recommendations which I think was 2.5 hours between coats at 70 degrees hull temp, with prep and everything we got two coats on the first day. The next day, we got the following 2 coats and the first coat of bottom paint. I let the bottom paint cure a week and then had them move the jackstands and then did those spots. I'm sure a pro who has more experience with these coatings can get it done quicker.

 

With the 2.5 hours or so between coats, make sure you bring something to keep your help busy. I had food, beer, radio and chairs to keep us comfortable while we literally watched the paint dry.

 

Looks like the IP stuff is 3 hours at 73 degrees hull temp... so similar wait times.

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IIRC you are supposed to put the AF on over IP2K in a pretty short window to get it to bond or you have to sand the IP2K first.

 

Bull do I read correctly that you are getting IP2K for $40 a gallon? :blink:

 

It's like $200 or so here

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IIRC you are supposed to put the AF on over IP2K in a pretty short window to get it to bond or you have to sand the IP2K first.

 

Bull do I read correctly that you are getting IP2K for $40 a gallon? :blink:

 

It's like $200 or so here

 

I'm thinking he means IP is $40 more than PP.

 

Shelter Island has lots of IP2000e in stock at CAD 120/gal

 

The store there has improved a lot and they are moving towards only stocking products relevant to their boat yard clients. So getting rid of a lot of crap you find at your typical WM style chandlery and focusing more on R&M stuff only.

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It's possible the Defender website is causing the confusion on the pricing. They have a smaller package of IP2000E for $41.99 with a somewhat deceiving picture.

http://www.defender.com/product.jsp?path=-1|2200442|2200444&id=1245053

 

but the gallon size is $98.99.

http://www.defender.com/product.jsp?path=-1|2200442|2200444&id=728760

 

The Pettit Protect is $92.99.

http://www.defender.com/product.jsp?path=-1|2200442|2200444&id=1796776

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It's possible the Defender website is causing the confusion on the pricing. They have a smaller package of IP2000E for $41.99 with a somewhat deceiving picture.

http://www.defender.com/product.jsp?path=-1|2200442|2200444&id=1245053

 

but the gallon size is $98.99.

http://www.defender.com/product.jsp?path=-1|2200442|2200444&id=728760

 

The Pettit Protect is $92.99.

http://www.defender.com/product.jsp?path=-1|2200442|2200444&id=1796776

 

That makes sense - I guess.

 

Not sure what is deceiving about the picture - that is exactly how the quart kit comes. Only the gallon size comes in a box.

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