Aft berth liner and blister job on 26X

[Al Garrett]

I would appreciate discussion on this issue but I buried my prior appeal in a lengthy post on another subject so would like to try again.

My 2000 26X has the thin interior liner under the cockpit. Even crawling carefully, I'm afraid I'm going to break it. It already has one crack around an opening. I weigh about 185 and it's not up to supporting me. Has anyone inserted treated wood blocks with 5200 between the lower liner back there and the stringers? Another idea is to squirt some low expansion foam (used around windows and doors) to fill the gap and add strength. I wonder if it may compress too much to be effective although it seems to be closed cell in using for exterior cracks on buildings. It's biggest weakness seems to be no UV resistance. Anyone else tried to deal with this problem or were they just running low on glass the day my boat was constructed?

Finally got the interior hull bone dry. In six months, I'll be able to do the bottom job to repair a variety sized collection of blisters stretching from bow to stern. Water wicking into the interior hull is an often overlooked concern where dry fibers are likely to be found for intrusion. Considering painting all the interior compartments as an additional measure to prevent this from recurring from the interior. Any thoughts?

Thanks

[fdeoreo]

Al,

I had a similar feeling when crawling around in my rear berth recently. I noticed some styrofoam flotation type blocks in there and thought, couldn't I just add more wherever I feel the need for more support? Also, a lot easier than worrying about and working with wood and so on. My plan is to just push the pieces in where needed, slightly tight fit with no glue whatsoever.

just a thought,

francis joshua

[Hamin' X]

At one point you express concern for water ingress and at another point suggest using wood under the liner?

I would suggest using cutting boards from wally world, cut to proper dimensions and insert with 4200. That said, I think it is a non problem and I have not experienced it in my 2001 X at 195#.

~Rich

[Kittiwake]

It seems to me Al that you are describing 2 somewhat-related issues here - 1) possible weakness of the liner over the hull in the aft berth, and 2) possible water-permeation damage to the hull from the inside.

Perhaps Rich has interpreted your concern #1 as being 'damage to the removable covers in the aft berth' ... whereas my interpretation is that you are worried about the regions of the inner liner that surround and support the removable covers. Or maybe he means the cutting boards would make appropriate patches to the liner. In my 2010 26M (in which the inner liner over the aft berth hull is indeed springy) I try to spread my weight when under there; and if kneeling, I try to kneel on a well-supported segment. I just use the aft berth for storage, and I leave the stock mattress in to cushion objects placed there. But like Rich, I wouldn't worry too much if I had to repair a crack in the inner liner or hatch cover. I'd worry more about creating impediments to drying-out bilge water by jamming in a lot of foam.

With regard to your concern #2 though, I would be worried if I thought hull blistering was occurring secondary to water inside the 'bilges'. So far, I have not found significant water between the inner hull liner and the hull itself of our 2010 26M. I have seen mention of such on this web site though ... with folks wondering as to the source of the bilge water. Of course it is very well known that sailboats in general tend often to get water collecting in the bilges ... and that finding its source can be a major challenge (not to mention correcting the various sources). I owned a 1999 Mac 26X in past for a while, and did not notice bilge water in it either.
So first I would wonder where your water came from since I don't think it is a general 26X finding, and why your boat took a long time to dry out. Compared to most sailboats, the Mac has relatively few thru-hulls and of course no stuffing box. And moreover it has lots of covers you can open to dry out the 'bilges'.
Secondly I would wonder if the blistering is really due to bilge water ... or perhaps vice versa - ie. does your boat sit year after year in the water? Given the number of Macs around and their long history, there must be lots of data on this. Also I would wonder, do 'conventional' sailboats (with their more common and even permanent bilge water) develop hull blistering from the inside out?

Kittiwake

[Doupirate]

Blistering cannot come from inside.

It is impossible.

Blistering comes from infiltration through the gelcoat. H2O molecules are small enough to infiltrate micro-cracks in the gelcoat, and do so. Giant dissolved polyester molecules try to come out through the same crack but can't, hence creating blistering. All liquid molecules try to disperse. This is due to their thermal agitation. That dispersion tendency creates pressure through semi-permeable membranes such as cracked gelcoat. That pressure is called osmosis pressure

From inside, such a pressure cannot build-up since there is no semi-permeable membrane creating the necessary barrier to liquid polyester.

The first thing I did when I acquired my 2002 M, even before trying the boat in the water, was to put on Interprotec. Now that your boat is blistering, I fear it is wasted.

[Catigale]

Blistering of Gel coat causes more fear mongering in boat yards than any other Hull topic IMHO.

Thousands of boats blister, yet the FG doesn't fail and boats don't sink and fall apart.

If your boat is going to be in water for a long time, more than a month, then barrier coat and slime coat it.

If you trailer, it's your choice.

Either way, blistering is a cosmetic issue affecting resale only. If I'm buying a used boat, an uncovered hull is much easier to assess than one freshly painted of course.

[Doupirate]

On a 26 X, the blistering repair cost might come close to the boat market value.

Worse, assuming a professionnal repair, all liquid polyester having been completly dried-up prior to Interprotec coating, once repaired, your boat will still be a blisters-repaired-boat. Its market value will be under 10 000$

[raycarlson]

back to the rear berth area, i have the M model,not sure if construction was the same as yours, but my aft berth was also very squeaky and springy feeling.on the M directly below the berth liner is the upper skin of the rear ballast tank which is also only semi-rigid.I 5200'd in 4 resin coated wood blocks between the two, they now are forever bonded together thanks to 3M and are substanially more firm and solid feeling with no squeaking whatsover.

[Ixneigh]

I'm not a heavy person but the springy aft bunk bugs me on my M model.
If I was sleeping there I would choose the wood option. I personally would use epoxy glue.
My dogs live In that area so I haven't bothered. IMHO it was made for children or small adults.
There should be next to no wetness in the bilge in these types of boat and certainly no outright water. If its not coming from a deck leak you have a problem that needs solving.
Most conventional sailing vessels usually have some water in the sump due to the shaft and associated hardware. It does not cause blistering except in extremely rare times when the blisters will be on the inside of the hull.

That last poses a question for the above person who explained the blister mechanism.
It's hypothetical because eventually I intend to turn the water ballast area into storage for potable water and supplies.

In the tank it's not possibly to barrier coat. What if I made the ballast water acidic by pouring in a few gallons of vinigar? Would that preclude ever having blisters if I decided not to butcher the resale value of my boat by modifying the ballast tank?

Thanks.
Ixneigh

[Doupirate]

At the beginning of the last season, I had the boat in the water but I forgot to fill the ballast tank on my way home. The mast wasn't raised yet. Quite a windy day.
A fellow came to offer me assistance. The boat was rocking so badly he thought I had trouble. Imagine with the mast up.

For the ballast, just put in swimming pool chlorine, in the concentration recommended for swimming pools. MacGregor says to do so.

[capncarp]

Al,
All aft berths on X's are spongy but, not thin. The floor of the aft berth in my X is thick and strong. The cieling is of coarse thinner because it doesn't have to support weight. I just put styrofoam blocks under the aft berth and screwed closed the covers.
I had my X in fresh water for the first 6 months of it's life. It had a slime coat on it but still blistered (hundreds). It cost me $3000. 12 years ago to have repaired and an epoxey barrier coat applied. It is still good. Macgregor agreed to pay for the repair but wouldn't write the check (lip service). As stated above, blistering cannot start from the inside.

Glenn,
99

[Ixneigh]

I came off plane in gentle two foot swells without ballast in the boat when I first got it and didnt know any better. And that was with the mast up. I now have 250 lbs of extra lead in the bottom.
If I had to do a blister job I would use a layer of biax and vinyl ester resin. Might do that anyway to at least the part of the hull that hits the bottom.

[Kittiwake]

This is proving to be an educational thread for me - I'm glad you asked these questions Al.
I 'googled' the Interprotect mentioned by Doupirate since he has considered related issues very seriously, and I quote a piece of the result from their advertising that seems hopeful:
" InterProtect®
http://www.yachtpaint.com/LiteratureCen ... sa-eng.pdf
Applying InterProtect 3000 to boats with blistered hulls. 1. After repairing the hull as ..."
I could imagine a typical Mac owner having a good time repairing the blisters.
But the very credible consensus on this thread seems to be that a more important issue may be 'why your bilge area is wet in the first place'.

Ixneigh I often motor without ballast water, especially when I have left the mast at home. The boat handles rough water better with ballast as you say (not surprising). I would be concerned to cut hunks out of the ballast tank though if that is what you are considering - if only because the ballast tank walls must act as an effective strengthener for the hull.

Kittiwake

[Russ]

Our M has plastic covers over the aft berth compartments and they squeak and I'm waiting to hear a crack sound next.

Hmmmm... I may try gluing some blocks under them for added support as mentioned. I've found silicone caulk works well where I don't want to have to chisel it off later if I change my mind. In fact, I used silicone to "glue" my washdown pump which added the benefit of reducing vibration.


Blisters: I got 'em and honestly can't see them from the cockpit when we are sailing so I don't worry about them. As mentioned, finding the source of your water should be a priority.

[Boblee]

The hatch covers were discussed not long ago, as they break have just replaced them with multiply timber and used a laquer finish but for the ones under the rear berth have added packers to support the centre of them.
Never found any blisters but have found imperfections where I presume the mold was released these were there from new.
Here is the thread if it's works ie if I haven't mucked it up.
http://macgregorsailors.com/forum/viewt ... 02#p233302