Fairing

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Jeff Griglack

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Mar 31, 2025, 10:10:24 PM3/31/25
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While preparing the bottom for new paint, last month, a chunk of filler fell out around the top of the strut.  On the 365, where the strut is mounted is recessed about 1/2" into the hull (it was pretty much flush on the P30).  Somebody, PO factory, I don't know, had built it up to actually be a little proud of the bottom.

The build up looks like some sort of putty.  I am wondering if I can use 2 part, epoxy fairing compound to replace this.  I am thinking of Total Boat TotalFair.  Do you think I can build this up that far?  Only 1/2 of the old stuff came out, and the rest appears to be holding in there pretty well.  Should I remove all of the old stuff (even if I have to force it out)?

Thanks,
Jeff
------------------------------------------------------------------
| Jeff Griglack             "Jabberwocky" P-365 #269
------------------------------------------------------------------
| "Don't take life so serious, son, it ain't nohow permanent"
|                   - Walt Kelly
| 'Years ago my mother used to say to me, she'd say, "In this
| world, Elwood, you must be" – she always called me Elwood –
| "In this world, Elwood, you must be oh so smart or oh so pleasant."
| Well, for years I was smart. I recommend pleasant. You may quote me.'
|               —James Stewart as Elwood P. Dowd
------------------------------------------------------------------

Dan Pfeiffer

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Mar 31, 2025, 10:33:41 PM3/31/25
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I would remove all the old stuff.  You can't trust the bonds.  It will probably come out pretty easy.  Then, if the filled portion is thicker than say 1/4" I would fashion some blocks from G10 or McMaster extruded fiberglass to fill most of the void then fill around and maybe a couple layers of fabric over and fair smooth to the hull.  I wouldn't make it too strong because someday you may need to remove it to service the strut mounting.  Although it'll all be secondary bonds and easy enough to remove regardless of how well you do it.  But strong enough for this duty. 

Dan Pfeiffer

Robert Laforge

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Apr 1, 2025, 9:29:14 AM4/1/25
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Hi Jeff,  Not all fairing compound is watertight.  I would probably coat the damaged area with a couple coats of expoxy before fairing.  Bob. (P365 Ketch)

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Dave Cole

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Apr 1, 2025, 10:12:50 AM4/1/25
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What about using epoxy thickened with glass micro balloons?   Dont want to have it setup too fast but most days its still pretty cool at least here in the midwest.  A few thin layers applied "hot" to get some thickness build should work?
I would clean it out and do an initial coat of epoxy to get started. 


Peter McGowan

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Apr 1, 2025, 10:59:21 AM4/1/25
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Is it just me that's nervous about burying those screw heads for the strut under fiberglass? My skeg is 50 years old and appears to be going strong, so perhaps my anxiety is misplaced.  I'd be considering using a small brush (like one for nail polish) to paint a layer of release compound on the screw heads and in the slots.  I'd just use compound, as if you do need to replace that strut later it'll be a little easier to dig to the screw heads, release the bolts, and give the strut a good whack with a mallet.   



Jeff Griglack

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Apr 1, 2025, 11:18:57 AM4/1/25
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Bob,

No, I agree with you.  The same way that I would not rebed the strut in 5200, I would not bury it in epoxy or fiberglass.  This should be a semi-permanent solution like a thru hull, not a permanent solution like a deck-hull joint.

As far as things being watertight, I am not depending on the fairing compound to seal the water out of the boat where the strut is located.  There is sealant in place already that is keeping water from coming in through the bolts, so I do not want to add a layer of epoxy to seal things.

I just got off the phone with TotalBoat.  They said that I can't apply a single coat of TotalFair thicker than about 3/8", but I can build it to the full thickness that I think I need.  I might be wrong, though, and 3/8" might be thick enough.  I didn't actually measure the chunk that came out.  I just eyeballed it.  He also said that it was okay to leave the old fairing in place as long as it was solid, but I will try to get it out just to make sure.

The fairing compound should arrive Friday, and I should be able to apply it Sunday, weather permitting.  This is the last thing I need to do before painting the bottom and be ready for launch.

Thanks,
Jeff

------------------------------------------------------------------
| Jeff Griglack             "Jabberwocky" P-365 #269
------------------------------------------------------------------
| "Don't take life so serious, son, it ain't nohow permanent"
|                   - Walt Kelly
| 'Years ago my mother used to say to me, she'd say, "In this
| world, Elwood, you must be" – she always called me Elwood –
| "In this world, Elwood, you must be oh so smart or oh so pleasant."
| Well, for years I was smart. I recommend pleasant. You may quote me.'
|               —James Stewart as Elwood P. Dowd
------------------------------------------------------------------

Jeff Griglack

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Apr 1, 2025, 11:19:28 AM4/1/25
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Oops, that should have been "Peter, I agree with you."
------------------------------------------------------------------
| Jeff Griglack             "Jabberwocky" P-365 #269
------------------------------------------------------------------
| "Don't take life so serious, son, it ain't nohow permanent"
|                   - Walt Kelly
| 'Years ago my mother used to say to me, she'd say, "In this
| world, Elwood, you must be" – she always called me Elwood –
| "In this world, Elwood, you must be oh so smart or oh so pleasant."
| Well, for years I was smart. I recommend pleasant. You may quote me.'
|               —James Stewart as Elwood P. Dowd
------------------------------------------------------------------

Dave Cole

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Apr 1, 2025, 12:33:32 PM4/1/25
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I see your point, but what's the chances of you removing that strut, ever?
I dont see why a filler like bondo could not be used, but I keep reading its not water proof?  How could that be?  Its polyester mixed with a filler.  

Im repainting a car I first painted in 1977.  So 48 years ago.  Its a 1970 Camaro.   You can bet I wont be repainting it again in another 48 years.  😄

Dave
10M #26 

Guy Johnson

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Apr 1, 2025, 1:15:15 PM4/1/25
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Is Bondo waterproof? 
Is polyester resin waterproof?
We know that hull blisters occur when polyester resin is applied underwater. 
If the filler in Bondo is even slightly hydroscopic water absorption could cause the bondo to swell and crack. 
I won't use Bondo underwater and on cars only in very thin layers. 
I would cover the strut with total fair filler and hope it lasts another 50 years. 

Guy
Puffin 10M #6 

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From: pearso...@googlegroups.com <pearso...@googlegroups.com> on behalf of Dave Cole <dave...@gmail.com>
Sent: Tuesday, April 1, 2025 12:33 PM
To: pearso...@googlegroups.com <pearso...@googlegroups.com>
Subject: Re: [pearson ] Fairing
 

George Dubose

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Apr 1, 2025, 1:37:26 PM4/1/25
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I would be thinking of using West System epoxy and collodial silica. West System is a good water barrier and I don't think collodial silica (ground glass) will absorb any water.

When Skylark was built, I don't believe they used any epoxy, but Skylark's hull only had a few tiny blisters when I bought her and after removing everything down to the gelcoat and using GelShield over the years, I have had no signs of blistering.


Uma has had her rudder dropped, the rudder's stuffing box replaced and the foam filler in the skeg replaced as it was wet. Skylark also has high humidity readings in her rudder and skeg, but I have no plans to rebuild the rudder and skeg anytime soon. Maybe my boys will get around to that project someday.


George/Skylark

Dan Pfeiffer

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Apr 1, 2025, 1:38:25 PM4/1/25
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Agreed.  I fared the bottom a few years ago with a two part epoxy fairing filler intended for below water line use (Interlux Watertite Epoxy Filler).  The others will say be sure to seal with a barrier coat to prevent water intrusion and that will work until it doesn't.

Dan Pfeiffer

Peter McGowan

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Apr 1, 2025, 1:42:08 PM4/1/25
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Didn’t their rudder turn out to be solid?  I was surprised by that…

Dan Pfeiffer

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Apr 1, 2025, 1:46:02 PM4/1/25
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I'm not.  I think the way they made those was to glue two halves together and fill the void by chopper gun.  Simple and sloppy. 


On 2025-04-01 12:41 pm, Peter McGowan wrote:

Didn't their rudder turn out to be solid?  I was surprised by that...

Dan Pfeiffer

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Apr 1, 2025, 1:49:38 PM4/1/25
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Here's a photo of the Pearson 30 rudder mold...

http://dan.pfeiffer.net/pearsoninfo/info/factory/factory12.jpg

Peter McGowan

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Apr 1, 2025, 2:39:46 PM4/1/25
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Well hopefully George can relax about the high moisture readings :)
 

George Dubose

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Apr 1, 2025, 2:46:46 PM4/1/25
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George is relaxed about moisture readings in general. Skylark spends winters in the water from time to time.

I believe Skylark's rudder post is bronze and that leads me to believe that the rudder's fingers that are welded to the rudder post are bronze as well, so I am not worrying about rust or anaerobic corrosion as aluminum or stainless might be susceptible to.

BTW: I will be on the north coast of Sicily in June and from May 27th to June 14th, I have no crew. Airfares are down at the moment?

Anyone want to go roast marshmallows on Stromboli?

George/Skylark

Dave Cole

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Apr 1, 2025, 3:12:06 PM4/1/25
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The blister problems with Polyester, I thought were related to some bad polyester formulations.  
Certainly not all polyester fiberglass had blister issues.
Btw, I thought my topsides paint/fiberglass was suffering from some small blisters.  Nope, something new is starting to form on some of the boats at the marina.  I found it on other boats as well.  It looks like an acidic cleaner, like vinegar will take it off.   Wierd.  A light buff and wax job will hopefully keep it from coming back.



Guy Johnson

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Apr 1, 2025, 3:25:16 PM4/1/25
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Blisters in polyester laminates is a complex subject. Anything I say here will only scratch the surface of the problem. 
My understanding of the issue is that polyester resins used in fiberglass layups are not entirely water resistant and under the certain conditions can form blisters. A dry layup is one factor that increases the damages associated with blisters because the water intrusion can follow the dry layup into the laminate. I think blisters need to be anaerobically trapped between layers of laminate to form. Gel coat helps to prevent water intrusion. Newer vinylester resins do a good job of preventing water intrusion. Epoxy resin is waterproof. 
All resins need to be mixed and cured properly to work as desired. 

Some have suggested a relationship between the jump in oil prices in 1973 and 1975 and a change in resin formulation that led to blisters, I don't know if that is true. 

Guy


Sent: Tuesday, April 1, 2025 3:11 PM

Jeff Griglack

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Apr 1, 2025, 3:32:32 PM4/1/25
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My P365 is a 1979 model and there were no blisters when I had it soda blasted.  Then I barrier coated it, so I shouldn't have to worry about it.

Guy Johnson

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Apr 2, 2025, 10:00:05 AM4/2/25
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Jeff, I think Pearson owners have been fortunate when it comes to blisters. The factory seems to have done a good job with the layups. 
Puffin has also been soda blasted and barrier coated without any blisters. Probably the fact that she is hauled out every winter helps. 
I did have blisters develop in one of the sail locker lids, the balsa core was saturated, and the inner layer of class had red oozing sores. The lids are now cored with divinycell and epoxy. 
Guy

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Dave Cole

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Apr 4, 2025, 12:13:40 AM4/4/25
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I thought Id follow up on some digging I did on body fillers and why some are not waterproof.  Its the filler material that is mixed with the polyester resin.  Talc, calcium carbonate, etc sucks in water.   This is the standard Bondo filler.   Some time ago 3M acquired Bondo, Dynatron and some other autobody suppliers.
The 3M fiberglass reinforced polyester is waterproof.  (This used to be Dynatron).
On top of this, 3M also sells a Marine filler using a vinyl ester which has lower water absorbency. 

Here is a link:
https://www.3m.com/3M/en_US/bondo-us/

I have an interest in all of this since I have 4 project cars at the moment.    Plus my 10M.  I looked at the Dynaglass repairs (short chopped fiberglass in polyester resin) I did back in the 70s on a Camaro and they are still solid.  I also peeled some conventional Bondo off a 56 GMC pickup I have and it shows signs of water migration into the filler.  I bought the GMC from a good friend a month after getting married in 1982.  I thought $800 was a good price, my new bride disagreed!  Oops.
Ill try the Dynaglass/3M short chopped strand filler on my boat as I already have a gallon of it.  I have a few spots to fill.  But its pretty minor. 

Fwiw, the new 3M Cubitron sanding disks are very good.  I bought one of the Festo/3M/Mirka  6" DA clones off Amazon with the built in vacuum collection and the 3M papers works really well.   Virtually no dust to deal with.   I use a small shop vac with it.

Dave
10M #26



Dave Cole

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Dec 29, 2025, 6:28:59 PM12/29/25
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Just wanted to follow up about using body filler for below waterline use.  

I did use this last season to fill in some spots on my 10M hull.    It worked well and set up in about 30 minutes so I could sand it smooth.   I then applied bottom paint the same day over this.

No issues with it, at all.  No cracking, nothing.   It worked fine for me.  

Yes, it is very cold and crappy in Indiana, Ohio and Michigan right now.  
Apparently I must be mentally preparing to launch my boat again.   I'm a bit early.  ;-) 

Dave
10M #26

Guy Johnson

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Dec 30, 2025, 1:49:26 PM12/30/25
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In past car repair days, I learned a time saving technique for smoothing Bondo. During the curing process the filler reaches a state where it firms up to the consistency of hard cheese. A Stanley surform file a.k.a. Cheese grater can be used to quickly cut off the high spots and shape the filler, save a lot of sanding. 

Guy

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Subject: [pearson] Re: [pearson ] Fairing
 

Dave Cole

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Dec 30, 2025, 4:34:10 PM12/30/25
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Yes, that's a great trick.  There are lots of youtube videos on that as well.  😃

Dave
10M #26

Jeff Griglack

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Dec 30, 2025, 6:47:06 PM12/30/25
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Bondo body filler isn't a fairing compound. Way back when I worked on cars, we would use a separate fairing compound on top of the Bondo. The fairing compound i bought from Total Boat goes on much another than Bondo filler.

------------------------------------------------------------------
| Jeff Griglack             "Jabberwocky" P-365 #269
------------------------------------------------------------------
| "Don't take life so serious, son, it ain't nohow permanent"
|                   - Walt Kelly
| 'Years ago my mother used to say to me, she'd say, "In this
| world, Elwood, you must be" – she always called me Elwood –
| "In this world, Elwood, you must be oh so smart or oh so pleasant."
| Well, for years I was smart. I recommend pleasant. You may quote me.'
|               —James Stewart as Elwood P. Dowd
------------------------------------------------------------------

Guy Johnson

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Dec 30, 2025, 7:37:55 PM12/30/25
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I used red nitro-stain to fill in the small air bubbles in Bondo. Now they sell some two part stuff. 

Guy

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To: pearso...@googlegroups.com <pearso...@googlegroups.com>
Subject: Re: [pearson] Re: [pearson ] Fairing
 

Dan Pfeiffer

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Dec 30, 2025, 8:57:28 PM12/30/25
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I did a big fairing job on my 10M bottom a few years ago.  I used Interlux Watertite epoxy for fairing.  Excellent stuff to work with.  Cures very fast and feathers beautifully.  I also have some very large spreaders that flex to conform to the hull shape.  They made quick work of the fairing with very little sanding required.  Pricey but worth it to me. 

I barrier coated the whole bottom with 7 coats of West epoxy.  Coats 2 through 6 had West 422 barrier additive, coats 5 through 7 had grey pigment.  It took about 2 gallons of epoxy total.  All applied in a continuous process with hot coating and about 1hr 15 min between coats of whole boat.  I used 206 slow hardener.   75 degrees.

https://www.interlux.com/us/en/products/watertite
https://flexisander.com/collections/flexible-filling-spatulas

This job was a follow-up to a blister repair I had done back in 2008.  And that was a re-do of a job that had been done by a PO in the late 80's that was failing because they coated the whole hull in vinylester before filling blister holes.  Acted like a release agent for the filler. 

I have info on the 2008 part of the work here:
http://dan.pfeiffer.net/10m/bottom.htm

I now have a very good bottom.  I'd say almost race quality.  Almost...
16 years on from the blister repair and 5 years on from the final fairing work with no issues.  I am in fresh water and on the hard for winters. 

See photos.  Last show where I drilled a hole for something and got a look at the thickness of the barrier coat. 



Dan Pfeiffer
Screenshot_20251230-203213_Gallery.jpg
Screenshot_20251230-203406_Gallery.jpg
Screenshot_20251230-205309_Gallery.jpg

Dave Cole

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Dec 30, 2025, 10:06:04 PM12/30/25
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Ive been working on cars since 1977, and still do.   "Bondo" is a generic term that covers a range of body fillers.  I believe I have 3 or 4 kinds kinds of it right now. 
The waterproof polyester with chopped fiberglass is what Im referring to.
It works fine.    Mixes nicely, and spreads out very well.  And it is easily sanded (as easily as the rest of the hull)  It worked fine as a marine fairing compound for me.  

Bondo type fillers are used for the final "fairing" under $20k plus paint jobs before the primer surfacer.

Was the Total boat filler you used a vinylester? 
I didnt see the need for that since these old hulls are polyester.  

Dave
10M #26



Peter McGowan

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Dec 31, 2025, 8:40:29 AM12/31/25
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Dave Cole

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Dec 31, 2025, 9:18:44 AM12/31/25
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Total boat also sells polyester fairing compound.  I didnt know that.  But very likely its rebranded waterproof autobody filler.  In the US it appears that 3M almost has a monopoly on polyester body fillers.  They bought Bondo and Dynatron years ago.  


Total boat polyester is a little bit cheaper than the epoxy based filler.  The big difference is can I apply it, sand and paint in one day.   It doesnt mention if it has glass fibers in it or not.   
Time is a big deal for me since the boat's not close.  
The other difference I have seen between polyester and epoxy is that the shelf life of polyester seems to be almost indefinite.  Epoxy is years, but the activator component seems to degrade first within 4 years.  With polyester, the activator is a paste that comes in a tube.  
The paste activator also goes bad, but the polyester activator is universal.  And a replacement tube, which is good for at least 1/2 a gallon is $6 or so.  So if it goes bad, just buy another.   
The polyester waterproof filler is a permanent repair on a car body.   Ive got two cars I repaired 40+ years ago and the repairs are still solid.  Rust wont creep under it.   Thats not the case for standard Bondo.  But standard Bondo is not waterproof. 

Dave
10M #26



Peter McGowan

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Dec 31, 2025, 10:12:26 AM12/31/25
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The TotalBoat Fairing Compound doesn’t have activator paste in a tube, it comes in two identically sized tubs that you mix 50/50.  One is blue, one is yellow, and you learn pretty quickly the color green it produces when you’re close to the correct mix.  You also know you have nice mix when there are no “strands” of blue or yellow as you mix.  I find it very easy to work with, it spreads out to an exceptionally smooth surface and has no or very few blemishes after sanding.   I believe it’s microspheres.

Dave Cole

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Dec 31, 2025, 11:22:53 AM12/31/25
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Thats the epoxy version.  That comes in two tubs.

The Total Boat polyester version comes in a 1 gallon paint can container and it says they include a mekp hardener.  That's the generic chemical hardener thats used by all the bondo type polyester filler auto products.  But .. their mek comes in a bottle.  Thats not ideal for mixing into a paste.
They also dont say what they use for a filler and they say its only for above the waterline.  Its also white, like regular bondo.  Not good.  

The 3M Dynatron type waterproof filler looks like polyester resin before and after it sets.  Just like fiberglass hull layup.  

The Total Boat epoxy version is priced right imo.    If I was going to use a bunch of  epoxy fairing compound, I would just buy that rather than mixing my own.

Waiting for epoxy to set is a time killer for me.  Plus the polyester waterproof body filler (Like Dynatron), just works. 

Dave
10M #26

Peter McGowan

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Dec 31, 2025, 12:31:54 PM12/31/25
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Well, I’ll be darned, I had no idea there was a polyester one.

Dave Cole

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Dec 31, 2025, 1:04:53 PM12/31/25
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Its interesting whats out there.  
I heard that 3M was making a vinylester filler as well, but I never saw the advantage.  Here it is
$100/qt !!! Yikes.  
What's interesting to me is that it sets up like a polyester filler.  It says 30 minutes to sanding time.   Still, $400/gallon!?!?   
I dont think so.  😄

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