Propeller update

The 12x10 propeller turned out to just not have the bite we needed.  We exchanged it with a 14x10 3-bladed prop that is excellent!

Yahoo group for Mercator Sailboats.

There is a new yahoo group newly formed for Mercator 30 Sailboats.  Please see the following link for details:

http://groups.yahoo.com/group/mercator30/

Adam


 

Barrier Coat bottom paint and all new through hulls

It's been a while since my last post.  Mainly because of the long hours prior to launch, and since launch we have been sailing..

The Barrier Coat we chose was Interlux 2000E.  We chose this in part due to the recommendations of our boatyard, and in part due to the temperatures at which we were going to be applying it.  Hull temperatures during the drying out period were in the 50s farenheit in the tent, even with a heater going full time.  We planned to apply four coats of barrier coat over the two coats of epoxy already on the hull, then two coats of bottom paint.

We purchased 2 gallons of grey Interlux 2000E, and two 2 gallons of white. This way, we could alternate between grey and white to better determine coverage. I strongly recommend alternating colors. It made the coverage so much more uniform.

The barrier coat was mixed with a drill and paint mixing handle and the coating was left to stand about half an hour prior to application. Just enough time to go for a stroll in the marina and come back.  At first we mixed only a partial gallon, not knowing how long the working time would be before it kicked. After the first gallon, we only mixed gallons up. There was no problem using them up!  The boatyard routinely puts unused but mixed barrier coating in a freezer overnight to keep it from kicking when they have extra.  We did not try this.

Another requirement is adequate ventilation, and a high quality organic vapor cartridge mask.  We had the whole thing in a plastic tent,  with gallons of solvents. In order not to die, we set up giant fans blowing air into the tent at one end, and out of the tent at the other while coating and allowing the coat to dry. We also used a 3M 6000 full face respirator, the same one we used to sand the hull, but now with an appropriate organic vapor cartridge.
We rolled on the Interlux 2000E with a 1/4 inch nap roller that was of good quality.  We have found that the cheap rollers disintegrate from the solvents, and recommend a better quality roller.

The first grey coat when on quickly over the sanded, washed and dried epoxy already on the hull. A tooth of about 60 grit seems appropriate for covering and bonding without getting excessive scars coming through.

I started under the keel, and worked my way up one side, then the other. 

 

The stands were straightforward. I simply coated around them, then moved them one at a time and coated underneath.After a few days drying time, I repeated this procedure again and again.

After 3 coats (grey/white/grey) I didn't want to move the jackstands any more. So I painted the fourth coat (white), allowed it to dry, and put on two coats of my bottom coat of choice prior to moving the jackstands one final time.

Once the final barrier coat was on, I mixed up some of my bottom paint  (Pettit Unepoxy) and rolled it on.

2 Coats and tear out of the tent-done!(sort-of)

At this point you can still see the tape line on the hull and the residue of the duct tape- A healthy dose of WD-40 and some elbow grease and they come right off from the hull. The tubes hanging from the two aft through hulls were to drain the cockpit outside of the tent.  

The next step was to attach the throughhulls and prop. The waterline on our boat was about an inch above several of the existing connections.  Thus, if any of the connections gave out, the ocean would be coming in.  Not my plan.  The through hull on the left was existing. The through hull on the right is it's replacement.  I went with Groco IBFV adapter plates, and full witdth 316 stainless and bronze ball valves. Pretty ambitious and beefy change.  Certainly overkill, but what is the alternative? Sinking? 

In this case, one of two cockpit drain throughhulls is shown in the middle, and the replacements for it on either side.

Here is my assortment of through hulls and ball valves.  I used some Marelon one piece fittings due to space and use concerns.  I love these things and would replace everything on the boat with them if I could.

  

Finally I fitted a new prop. 

We went with a smaller 12x10 3 blade prop to replace the old 15x12 2 blade prop.  The blade areas are about the same, but it turns out this prop is just a tad too small. I am now going to replace it with a 14x10 3 blade that I have.

Thats enough for now.  Here is the hull, finished, with through hulls installed and prop on. Everything that touches the water is new except the cutlass bearing and the shaft. Those were fine.

Next, I will describe the new engine intake system, and new alternator. 

Drying out the hull, laying on the tie coat epoxy

Once the hull was sanded- old bottom paint, epoxy, filler, gelcoat, and down to the glass, with all the small surficial blisters exposed- it was time to tent and dry the hull.

I used 6 mil plastic sheeting with 2 x 4's, attaching the plastic using carpet strips and staples. Because it needed to survive the upcoming winter storms, we used lots of duct tape to attach to the hull. - Duct tape comes off after a month leaving a nasty residue, but the residue comes off easily with WD-40 and a rag, and some elbow grease.

We then rented a low temperature dehumidifier, one that has a heating element cycle to melt the ice that forms on the coils, and turned it on full blast for a month between December and January. I washed the hull every few days, to draw out the glycols in the fiberglass.

In conjunction, we used a space heater plus a carpet blower in the tent to keep the air temperature up, and the air flowing.  We measured the moisture content of the hull with a borrowed moisture meter at regular intervals, marking the water content on the hull where each measurement was made, with the date taken.  The moisture dropped substantially, then leveled out, and finally raised slightly again when the last water was drawn out of the hull. This took only a couple weeks, as the hull was pretty dry to start with. I could have probably not bothered with the drying out at all, but as we had taken the trouble to grind the whole hull, we thought it prudent to try.





After a month of drying, it was time to start rebuilding the layers of protection. Bare fiberglass needs a tie coat to Interlux 2000E barrier coat, so we used West System 105 with 205 fast hardener, some foam rollers, and a foam brush to get into the corners, and applied a coat of epoxy to the hull.  We did half the boat the first day, and then washed the dried epoxy with soap and water the next weekend to remove the amine blush that had formed. Then we scuffed the epoxied half with 80 grit sandpaper, and repeated the process to the other half, with a small overlap down the middle.. When the whole thing was dry, we washed the amine blush off again, and scuffed the hull with 80 grit.

The next step was to fill the holes I had ground into the hull to remove all the small blisters. There were hundreds of small blisters that were easily filled with West System 105, using 205 hardener and West System 407 light structural filler, mixed to the consistency of peanut butter. I spent a couple days filling and fairing this. The results of the 16 hours or so spent filling and fairing was well worth the hassle in the long run.

It was important to seal in the filler, so after filling and fairing, I applied another coat of West System 105 with 205 hardener to the entire hull, and then washed the amine blush off and sanded with 80 grit once again. This effectively sealed in the filler in between two layers of West System Epoxy, and prepared the smooth hull for laying on the barrier coat.

Mercator 30 Mark II Offshore Articles

Here are some articles regarding the Mercator 30.

Mercator 30 Hull Peel and Barrier Coat

I research the internet extensively before setting off on my boat projects. Unfortunately, little information was available to document peeling an existing epoxy barrier coat from a fiberglass hull. I thought to document this process on my boat, in order to provide information on what worked, and didn't, to the internet.

Our boat is a Mercator 30 Mark II, a wonderful fiberglass sailboat hand laid up in Kent, Washington in 1977. The hull is bulletproof. However, many years ago the gelcoat was partially sanded away by someone, and an epoxy barrier coat was applied over a lightweight filler-probably piranha paste or something similar. It is this barrier coat that has now given up, creating thousands of surficial pox. Allowed to go unchecked, this situation will cause water to enter the outer laminate layers, and damage the hull. My solution was to remove the old barrier coat, clean out the surficial blisters, and reapply epoxy in a new barrier layer.

My plan is to bring the hull down to bare fiberglass, remove the blisters, apply two coats of West System epoxy, then fill and fair with epoxy thickened with lightweight West System 407 filler, and then two additional coats of epoxy over that. Finally, I will apply two separate coats of bottom paint using two colors, to identify when the outer coat of bottom paint is giving out. Applying filler sandwiched between unthickened epoxy coats, using the same epoxy as base, will probably eliminate the future risk of epoxy failure over filler, as apparently happened in this case.

We hauled in November, and began the process.


Many fiberglass boats received barrier coats in the bad old days of epoxy. I imagine that as time goes by, many of these good old fiberglass boats will start to show failures in the barrier coats applied during the 1980's and later, and will require similar treatment. I hope this record helps all to approach the problem, and learn from my experience.

 The first task was to remove bottom paint and epoxy. There is a tool called a Gelplane that is said to do this fast and efficiently- I looked into purchasing one, but the unit was over 2500 dollars, and not possible to rent.

My yard requires dust extraction into a Shopvac or similar vacuum. Therefore, my arsenal of grinders was not useful. I did look into a plastic dust hood that is made to fit over my Bosch 4 1/2 inch angle grinder and then attach to a vacuum- but it looked clumsy and not a realistic solution.

Instead, I read reviews of 6 inch random orbital sanders in FineWoodworking magazine.  While many boatyards rely on the Fein 6 inch sander, the Fine Woodworking review found it overpriced and not efficient. They recommended a two mode sander, where there was a turbo removal and the second mode a random oscillation. For the money, the highest removal rate was achieved by the Makita BO6040. I bought one from Toolsforless.com, for a little under 300 bucks- Plus a few bucks for the attachment handle, which later proved invaluable due to the bulkiness and action of this beast. After using it exclusively on turbo mode for the last couple months, I agree with the review- It rips through material, but is very hard to control. I might consider another dual-mode sander like the Bosch 1250DEVS 6 inch or the Festool RO 150 next time I have a similar project.  I find the Makita tools generally good quality, but often vibrate.  I wound up throwing out a Makita 5 inch random orbital sander after too short a time, due to excessive vibration.

I looked into sandpaper options and wound up going with Festool Brilliant 2 in 40 grit. 36 grit might have been better if I could get it- Brilliant 2 is a closed coat paper- Important to not grind deep into the glass.  I bought 2 boxes of 50 sheets each from Jamestown Distributors for this 30 foot hull and wound up using about 75 total sheets- Changing them often made the sander do the work, not me!

after I had purchased all of this, it occured to me that I might be able to make use of my old 3 x 21 Craftsman belt sander- That epoxy was thick, after all- So I pulled out the belt sander and went at it, much to the amusement of the yard workers-..

I found that going through 2 coats of bottom paint, 4 old layers of epoxy, filler, and primer allowed me to see how deep I was sanding with the belt sander- and gave me sufficient control to remove much of the epoxy without grinding too deep into the fiberglass.  There were a few slip ups, but for the time saved by using the belt sander, I recommend at least thinking about the possibility- Remember I was grinding off a barrier coat, not just the gelcoat..

Here are a couple of pictures of the hull after the belt sander-The gray layer is the epoxy- Leaving a little gray meant not going too deep on this first pass. Also, Notice how high I had them block the boat- This provided much better access to the underside during sanding.

Another important piece was that this time, I broke down and bought a 3M full face respirator and dust cartridges- I can not emphasize how this mask made the whole job bearable- I would come home covered in fiberglass, dust and bottom paint- but my face and lungs were fine- I will never do this kind of work again without this important purchase!

Next, I started systematically removing the bottom paint and epoxy using the 6 inch sander.

Notice the tape set up to protect the waterline. I could sand to within a half inch of the waterline with the orbital sander. The last half inch I removed using a Bosch 1294 VS corner sander with 60 grit sheets. This corner sander is like the Fein multimaster at one third the price. Great for sanding edges and corners. I used it extensively around the rudder, skeg and propeller with the different attachments. However, I don't buy the expensive attachment sheets, but just use old sheets of 6 inch 40 grit cut to size with a shear. Works fine.

So that is where this project is at today. I will post information about drying the hull and new throughulls next.