Moving from E27 to E35-2 - Question about blisters

Hi all,

I've sold my beloved E27, Symbiosis, and moving up (hopefully soon) to an E35-2. We hauled the E35-2 today and found that the port side had blisters below the water line. Blisters don't scare me terribly much, but it's these that have me scratching my head a little: They're underneath the bottom paint only, not the gel coat.

As we examined this a little more closely, we found that the blisters were easily popped, and many were popped simply by pressure washing the hull. It was definitely just skin deep. As we dug into one of them more, we found that the blisters were behind (in this order) two layers of bottom paint, a layer of what looked like primer, and another layer of bottom paint after that. Is this typical of paint jobs?

Even more bizarre is that the blisters were only on the port side, which doesn't get much sun where she's been berthed for the last 4 years.

Any thoughts on this (the prior paint jobs and the fact that the blisters are only on one side)?

Another strange thing: there were no zincs. So the prop was pretty shot. The stainless steel shaft still looked good, though it was still the 3/4 inch shaft.

Thoughts welcome!

Cool Boat!

Congrats on your (presumed) move! Thanks for the photos.

The 35-2 is one of the finer-looking classics on the water. They sail well, too!

Unless you have a friend with a paint chemistry major willing to diagnose this blister stuff in return for a case of Pyramid ale....
causes of localized paint blisters may never really be known.

Personally, I would just remove all the ancient layers of paint and start over with your coating of choice.

No zincs? Ouch!
Check the strut as well. And any other underwater metals like thruhulls, too.
(including the tiny ss shaft in the KM impeller)

A 3/4" shaft seems small for this size vessel. A4 gas engine originally?
I would expect a diesel to have a 1" shaft, but I'm no mechanic.

FWIW -- When we bought our boat, moored all its life in Balena Bay, the prop was noticeably dezincified, and had to be replaced by the seller as part of the sale transaction.

Keep us posted!


LB

Its all in how long you stir your pot

The latest research on blistering problems on GRP boats shows that the leading cause of blistering is a failure to properly stir the MEKP into the resin when doing the lay up. This results in tiny MEKP pockets, which are incredibly Hydrophilic.

There is a great paper on this from one of the people who was instrumental in developing the Polyester Resin compound. I can't find the paper at the moment or would have included a link here.

Your situation is not uncommon. There were two teams mixing and laying up the GRP one on each side of the boat, the ones on one side mixed a whole lot better than the ones on the other side.

Compositional and failure analysis of polymers: a practical approach By John Scheirs. Goes into it in some detail, but there is another reference that I felt was better, but I can't lay my hands on it.

Guy

That is good information, but Ignacio is saying that the blisters are only in the several layers of bottom paint, not in the gelcoat or fibreglass. Although there may be a possibility that he is wrong in his initial diagnosis and the blisters actually penetrate the hull itself, but if not, then the fix would be quite easy by stripping all the bottom paint. I have seen blisters in bottom paint that were unrelated to any blisters in the actual hull, so this could be a possibility.

But Ignacio may want to get a second opinion, just to be sure, as blisters in the hull my help him get a better deal on the boat.

Frank

Oh I missed that

If they are only in the bottom paint that it is generally poor preparation or we have some solvent blistering issues, generally from overcoating while the previous layer was still outgassing.. This happens when people try to push the time required between recoating listed on the can.

Guy

Blisters only behind bottom paint

The blisters are really just under the bottom paint. The surveyor, yard manager, current owner and I all looked at this pretty closely. The blisters are behind what appears to be 2 layers of bottom paint, some kind of primer, and then more bottom paint. The water blister is trapped between all of that and the gel coat, but not under the gel coat.

Even so, removing all the paint seems like a messy, long, and toxic job. I imagine it would be a combination of peeling and lots of sanding before getting it to a point where it can be painted.

The blisters are already a sign that the paint is failing; anything you put on over it seems like it would be doomed to failure as well. At some point (now?) you are going to have to paint the bottom; I don't think it would add that much more to go ahead and sand down to the gel coat and apply an epoxy barrier coat. That is what I did when I had my bottom painted. The layers of previous paint were cracking and peeling off; you couldn't tell until the boat had been out of the water for a few hours and the bottom had a chance to dry.

Mark,

I have heard that one should be cautious about applying an epoxy barrier to a used boat unless it has been out of the water for a long time. The risk as I understand it is that the epoxy coating could seal in moisture and cause future problem where there might not be one now.

Others may correct or add to this...

Frank

Repair job

Here's what the yard is quoting for the port side only (with the bottom paint blisters). The yard mgr. says this would be an alternative to doing a full strip and barrier coat, and would be a temporary solution. He was specific that this is not a gel coat blister job...just a temporary solution to get the port side to a point where the bottom can be painted again. No work would happen on the starboard side (no blisters there):

• Heavy sand bottom port side only
• Die grind open blisters
• Flush with fresh water
• Apply epoxy resin in bottom of holes
• Fill holes with VC water tight filler
• Sand and glaze filler
• Spot prime with one coat epoxy primer

Engine

Loren, BTW: this boat originally had an Atomic 4, but it was replaced about 10 years ago with a Yanmar ~28HP...it's got a little less than 1000 hrs on it. The shaft (stainless steel and looking good)) is still 3/4", though the strut and the cutlass bearing were in good shape.

But lots good on this boat: no deck delam/rot, newly painted decks, nonskid, spars, and topsides. New canvas (incl. SS dodger), jibs (3) with furler and spinnaker and gennaker all in good to very good shape. Electronics are fair (10 years old), but workable. No stove.

The rudder post bearings/bushings need replacement too (posted another thread on that).

Here's another shot of the ol' gal

Here's a side shot.

I fail to see how any blisters need to be "ground and filled" if they are just in the bottom paint??? I would soda blast the entire hull, then barrier coat it and hot coat ablative antifouling as the final step. There should be no need whatsoever to fill anything if the blisters are just in the paint. Just do it right the first time and be done with it. RT

I've seen that boat.

Really pretty. It's the Katherine B down by the pumpout in Sausalito Marina. Looks like a nice one. How long has it been listed?

I'd remove all the paint, dry out the hull, barrier coat and repaint. What yard are you using? IMHO, that's a DIY job, and the Sausalito yard doesn't allow DIY. I'd even consider stripping, and if I found no real blisters, just painting. To do the barrier coat right, the hull needs to be really dry--like haul the boat in Sacramento for the summer dry. I wouldn't pay a yard for a temporary job--I've never had a really good yard experience--but I know the itch to get sailing.

I'm over in clipper basin 4. If you buy the boat give me a holler.

I have heard that one should be cautious about applying an epoxy barrier to a used boat unless it has been out of the water for a long time.

Click to expand...

I hope that is not the case. When it was painted it was out of the water for about a month having other work done as well. There were no gel coat blisters at the time.

Soda blasting

The soda blasting sounds like a great way to strip the hull. I'm thinking I'll take it to DIY yard and have the yard do the stripping (soda blasting seems like a good route...thanks for the suggestion!). There were no gel coast blisters that we could see, so I really think that simply removing the old layers should be enough. Once done, I'll sand the remaining parts and apply 2 coats of bottom paint. Anyone see any major issues with that approach? Thanks a bunch for your thoughts fellas. Big decision for me (which I just made).

Anyone see any major issues with that approach?

I don't. Frankly, I think it's the smartest choice in the short run. In the long haul, it could be another matter.

We've had our '77 E35II for almost 11 years. There was a series of small blisters below the waterline, port starboard. In all these years and under several bottom paintings, the blisters haven't worsened or spread. Years ago, and despite the graphic warnings of a yard seeking to seperate me and $13k for a barrier coat job, I truly believe the boat is no worse today without it.

Don't get me wrong; I'm not against a WELL done barrier coat. But I AM against a half-assed job that might open a can of worms that otherwise would've been better left as is. Simply put, if it turns out down the road blisters are intruding on the laminate (unlikely in my opinion), pull the boat, let her dry thoroughly and do the job right. Otherwise, let sleeping dogs lie while keeping an eye on the situation.

All that said, the E35II is a wonderful boat. I love sailing ours as much today as the first day we delivered her in 2000.

Best wishes and happy sailing.

Capt Dan G>E35II "Kunu"