Hull Peelers Vs. Sanding

[goboatingnow]

Originally Posted by minaret

Curious why you didn't have it peeled? Have you considered a hard pad grinder for this job? I'd 16 grit that sucker if I had to do it that way, break out the big guns. That is a big bottom to 36 grit all the way to bare glass!

Or grit blasted.

Dave

[shamrock]

Originally Posted by Chasing Summer

I re-read the entire Interprotect 2000 pdf. You're right, I stand corrected. I need a coat or two of Epiglass to seal the raw laminate. Yuck ... one more step and one more thing to buy.
I've started sanding the bottom. I started with a 6" random orbit with 40 grit ... ya, right ... so I bought a 7" grinder at Harbor Freight (7800 rpm). The discs just flew off. After a phone call with Oceanside Marine Center I got a low speed sander/polisher. I bought my neighbors variable speed that he got for surf boards. He should have gotten a 4" random orbit.
Now, with 36 grit and the right machine I'm slowly working my way along the keel. What a dirty job, but some one has to do it. I use the worn out discs to remove the old paint, then put on a new disc to take off the gelcoat.
Minaret ... very much enjoyed reading all your posts in this thread. I'm using the sander flat at much as possible. So far I'm in areas where the gelcoat is a consistant thickness.
Remember, this boat has been out of the water for over 25 years. Most of my gelcoat damage is not blisters, although there are a lot of very tiny ones, I think sitting in the sun for that many years the gelcoat just shrank and cracked. None of the damage entered the laminate layers.

With the big 36 grit pads on the 7/9 inch trigger grinder it started moving along pretty quickly. I don't think my gelcoat was all that thick. I also removed most of the bottom paint with smart strip onto a tarp. Whatever bottom paint was left, I used the vacuum sander into a shop vac with bags. You really should not be open air sanding the bottom paint. I'm sure the yard and def EPA has stiff rules there.
I found doing it really early in the morning and at night was way easier then mid day in the hot sun. just set up a flood where you are working.

Also, what kind of mask are you using? Get a full face 3m with the pink cartridges for sanding dust.

[jeanathon]

Originally Posted by Chasing Summer

They are 1" stainless steel bolts. I've contacted, in the past, other Spencer owners and none know if they are J bolts or all-thread with washers or a plate.
Would I be safe to put a lot of torque on the nuts? Just throwing out numbers here ... if, say I put 300 ftlb torque on a nut it's probably a good bolt? I'm I good with 8 out 9 bolts?
Several months ago I talked with a company in the east coast and they told me how they take a keel and simply melt the lead away from the bad bolt, replace it and re-pour that section. It doesn't cost that much but shipping a 9K lb keel across country ... well, can't do that.
When I took the boat off the cradle and put it on stands so Willmington Boat Movers could pick it up the keel was just hanging for a short time before I put timber under it. So, I know it won't just "fall" off.
Oh, well, tomorrow I sand some more until it either gets hot or my arms fall off.

300. Lbs is a lot of torque.
I would check the specs to make sure even a new bolt could handle it, and glass.
What is your plan if you shear off more? Is your boat positioned so that the keel can be supported?

[Chasing Summer]

I thought about peeling. I watched a couple Youtube videos of boats being peeled. Wow, zip zip zip ... clean hull ! ! ! Couple reasons: 1. I'd like to do all the work myself 2. the gelcoat is very thin on the bottom and the blistering is only gelcoat deep. Also, remember that this boat has been out of the water for at least 28 years. I'm finding that most of the gelcoat damage is cracking where the sun hit it every day. Above that line, onto the under curve the gelcoat is mostly good. There are only even very few places that I will have to fair when I'm finished. Using the pad flat it's coming out really fair and smooth. I'm quite pleased with it. I use 25 grit on my 4-1/2" grinder. That's what I took of the gelcoat non-skid on the deck with. I'm pretty good with it after 3 years. Then went back over it with 6" random orbit 40 grit. It was slow and tedious. I wish I had had the 8" then. oh well ... I think 16 grit would be to aggressive for both my skill level with a 7" machine and for what needs to come off. One day at a time ... no, 15 minutes at a time :-)
I am going to find a way to hook up my air hose to the back of my paper coveralls, though.

[Chasing Summer]

Originally Posted by jeanathon

300. Lbs is a lot of torque.
I would check the specs to make sure even a new bolt could handle it, and glass.
What is your plan if you shear off more? Is your boat positioned so that the keel can be supported?

300 ftlb was just a number I pulled out of the air. I'd have to check the normal spec for a 1" keel boat. If another nut snaps off then my plan of attack is fixed in stone. I remove the keel and have it either repaired or recast. YUCK ... not looking forward to either, but better here than have it fall off later. Couple years ago I found a company if Canada that would recast with my lead but I've lost the contact. $2000 but I had to get the keel up there and make my own mold and stud plate. ... So, if anyone reading this knows of that foundry in Canada please comment. Thank you
Keel is very well supported and 1 ft thick with a flat bottom.

[shamrock]

I'm just about finished sanding the West 105 epoxy, it took about 40 hours of sanding. These are pictures from a few days ago.

[Chasing Summer]

Lookin' good ... you're ahead of me. I finished sanding off the paint on the port side this morning, I'll finish the stbd side today. Then I still have to sand out all the pimples and crack in the gelcoat. ... but at least I know where they all are now. With the boat being out of the water for 25 years there's no de-lam damage, just gelcoat. I think a lot of the cracks are from just plain sitting in the sun for so long. The gelcoat is thin and doesn't take a lot of sanding.

[AbaftAndBaffled]

Looks like this is the summer of bottom work, lol. We still haven't got our tent up. Going to do errrythiiiiing once we do.

[shamrock]

6 gallons of interprotect


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[Chasing Summer]

Shamrock ... do you have paint or gelcoat above your waterline? If paint did you use consecutive rows of tape to move your waterline up so you get barrier coat higher than just the bottom? Just wondering what different people do.
I moved mine up about 4 inches, then I'll move it back down when I paint to bottom and sides.
Boat's looking great. Lot's of work, huh.

[Chasing Summer]

Oh, since were on the subject ... I found this thread on Boat Design forum. It was posted my a man with a degree in chemistry and has worked on the testing side for many year. It's really long but I think it should answer the question of epoxy first or just 2000e on bare frp.
... ok, here goes ... I only posted Colin's reply since that was really only what was relevent.

Sorry if I confused topic by being less than precise talking about Interprotect 2000e. The OP mentioned this, I was talking of this.

I must 1st state that in my youth I worked in the labs for International Paint. I have seen the numbers regarding barrier properties. I have seen numbers regarding barrier properties/corrosion/anti-osmosis properties for many epoxies from hot twin feed to solvent free to solvent based etc. And also competitors and weird high tech stuff.

I originally stated that the Interprotect 2000 was better for use, for the average Joe.

My point of, much "anger" is the phrase used regarding barrier properties.

Actually everything is a barrier...some barriers are better than others. Chemically almost nothing is 100% barrier. In normal use this is not a problem. You only need "sufficient" barrier.

Interprotect 2000e is EXCELLENT barrier. At 250microns it will protect steel from corrosion almost as good as you can get. Measured rates of water transmission (it is standard ISO test but is also tested with other methods) are as low as you need. On GRP it will/does work as barrier.

The use of solvent in a coating CAN make a coating bad but that is not a fact. It is no more true than saying 100% solvent free is better barrier coat.

Sorry for using the example of corrosion but this is a) more understandable for most people b) is a hideously strongly measured and controlled area of technology. Most, almost all, primers on steel has solvent in them. It doesn't stop make oil rigs rust to bits.

100% solvent free cannot cure 100%. Solvent helps resin systems cure to higher degree. The solvents are chosen to not be negative in final film.

The clever addition of pigments increase barrier properties over pure resins in most normal cases. A prime example is primers for steel eg oil rigs. The paints are pigmented. Pigmented for a variety of reasons but a major reason is increase in barrier properties.

The reason the use of pure resin is recommended on exposed glass is to minimise the risk of wicking on the glass ie solvent gets trapped on the size used on the glass which MAY then cause osmosis under the system. The evidence of this risk is mixed...it depends on the glass size and how it was originally well wetted. There are people who do osmosis repairs with paint on exposed glass and they have had no problems. The added benefit of resin on the exposed glass is also that you can wet it out good as you see any dry patches. The worry with paint over glass is that someone will just roll on gently and not wet out any dry areas. The story is risk minimisation as opposed to large risk.

I stand by my previous comment. Interprotect 2000E is a barrier. (and in lab better than equivalent thickness than West etc.

ps volume solids mean nothing in this subject. If you applied 10 coats of thinned Interprotect 2000E or 5 unthinned the results would not be noticeable (overcoat times, temp dependent). The higher solid products often give you more risk of failure as you get into this whole problem of degree of cure and there are a load of other paint chemistry factors involved, and I am talking about average molecular size and volume of the curing agent etc. It is interesting but complicated to explain. eg polyethylene has almost ifinite molecular size so it is almost impossible to dissolve/move. 100% solid curing agents are small (this is why they are fluid). The smaller the "bits" you have in your system the more problems you can get
__________________
Regards

Colin
　
Actually interprotect is almost 100% solid WHEN it is cured...ie once the solvent evaporate. Unlike most 100%solid epoxies which are loaded with benzyl alcohol in many cases. This benzyl alcohol is not classed as a solvent for the simple reason that its evaporation rate is so slow as to be not much of problem in most cases. However if you put a film in oven at 200c for a while you would see weight loss due to evaporation. And also weight loss due to sublimantion of low molecular weight amine in uncured film....but of course heating film promotes cure thus masking this loss. However it does mean that the resin matrix is not as barrier proof as some people like to imagine.
__________________
Regards

Colin
　
We will leave it here. You are right, the permeability of Interprotect 2000e is not very good. It is a good barrier. I wasn´t proposing use as sealer.

How a product is called is on MSDS is not always relevant. Especially in labelling ie legal terms. eg a resin when used as a sealer on wood is a sealer. When used as a resin with glass it is what? Still a sealer? And as a glue.

A primer on steel is a barrier surely.

ps I am a graduate chemist is polymer chemistry. I worked 15 years in paint industry labs. Add in the fact they were the biggest epoxy resin buyers in the world, it is perhaps wise to accept my declaration of fact that Interprotect 2000e is a proven barrier. Sometimes the marketing bs is true.

Don´t get always so angry or distrustful of the big guy supplier. They often deliver the goods. Whether you think you can do better or cheaper is your choice. It does not detract from fact that sometimes the `marketing hype` is true
__________________
Regards

Colin

[shamrock]

Originally Posted by Chasing Summer

Shamrock ... do you have paint or gelcoat above your waterline? If paint did you use consecutive rows of tape to move your waterline up so you get barrier coat higher than just the bottom? Just wondering what different people do.
I moved mine up about 4 inches, then I'll move it back down when I paint to bottom and sides.
Boat's looking great. Lot's of work, huh.

I have gelcoat now but am getting ready to paint.

My waterline is about 6 inches above the actual waterline of the boat so there is no need to go above that.

I don't think you should worry about going up 4 inches.


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[shamrock]

Now sanding with 80 grit per coppoercoat instructions.


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[midnightlace]

I have read this forum and would appreciate any comments on my particular situation. I have a 52 ft midnight lace. These boats were built by cheoy lee and has way too much gelcoat on the topsides which is cracked and crazed. I want to have it painted this year with me doing the grunt labor. There is no peeler in midcoast Maine although I have heard about someone in Rhode Island that travels but I haven't found him yet. Would the techniques discussed here vary for a topside job. I have fesstool 5 and 6 inch orbitals with vacuum equipment and admit to be leaning that way but I also have a grinder but would like to avoid the mess. comments?
thanks

[shamrock]

Don't bring a grinder or peeler anywhere near the topsides.

If you want a perfect finish, get automotive longboards with 120 grit and start sanding (-after you degrease with acetone). Once you use a machine sander you will never get it fair again.

My Gelcoat was crazed and as long as it is still adhering to the fiberglass it will accept primer once it is sanded. Primer will also show you more imperfections. Once you see them, get out fairing compound to fill little pin holes, etc. Then apply primer over those areas and sand the whole thing with 400 grit wet sanding.

Here are my results, could not be happier, this was done outside BTW
Let me know if you have questions, could not have done it without people like Minaret



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