OK, so I'm Sanding My Bottom...

[Squidd]

Just finished up sanding... Feels like I've been sanding for a week...


Wait a second...I have been sanding for a week...


Anyway, after laying under this thing, staring at it day after day...It really doesn't look all that bad...Overall shape is still discernible just has a hundred or more "divots" to fill, so it shouldn't be too hard to "fair out" and get smooth...

After the 1/8" of ablative coating was sanded off, the resultant divots were only a 1/16" deep on average so not much filler will be required...

Worse one was the big one in the front (first page) but even that one is less than an 1/8" deep...

I think the late afternoon "shadows" were making it look worse than it is in the first couple photos...


Plan is to fill and fair with Fiberglass Marine Filler and then a coat of Polyester Resin overall, scuff sand and then hard biocide finish...

 

[Ross]

It is lookin' better an' better.

 

[Merlin Clark]

I'd definitely use a barrier coat after the filling and fairing Squidd. That will seal it up against future osmosis that causes blisters.
As I understand it, it's important to recoat at the minimum recoat time to allow for a better chemical bond.
I did my GS 41 with Sherwin Williams Marine Industrial Coatings epoxy that made for oil rigs. Way cheaper than anything with a picture of a power or sailboat on the label.

 

[Squidd]

Appreciate all the input I'm getting on this bottom factor...Kinda like "discussing" the best anchor to use...

Here's what I'm seeing...There is no gelcoat on the bottom of this boat... I know what gelcoat looks like, there is gelcoat on the cabin and deck...the topsides are painted, but there is gelcoat below the Britesides ( I saw it when I touched up fender rubs)...

Just below the waterline, (green tape) is a blue line of gelcoat <w/some dark blue paint> and then it goes to the gray "Filler"....

There is no hard gelcoat "solid surface" to sand down to without going all the way down to the fiberglass matt.I don't know where the hard coating went, but it ain't there no mo..

I do not have the time, ambition or money to do a "Full Bottom Job" before I launch this season..I may do it in the future, but I have yet to see a full repair schedual I can believe in.

So I will be forging ahead on a Fill and Fair repair job, resin coating the entire bottom to tie it all together and then a couple coats of hard biocide paint for color and to keep the slime down...

I already have and will use a polester fiberglass filler...The can I have has a picture of a boat on it, says Marine on the label, waterproof and for above and below the waterline use...I'm fairly certain the gray matter on the boat is a poly filler (as do most opinions offered) and see no reason not to continue with it to fill divot holes...

At this point "spot coating" the exposed matt is a non starter if the filler right next to it is permeable, so after filling fairing and smoothing out (with wide spreaders, flat sanders and long boards) I will coat the entire bottom below water line with "Epoxy" resin witch should bond and tie in with whatever chemical soup is underneath... 2 coats and scuff sand for adhesion of 2 additional coats of hard Marine Biocide paint...

That is good enough for me for now...I want to go sailing...

 

[Ross]

Sounds like a wise choice.

 

[WayneH]

OK, Squidd,

Now that you've got a game plan, I'll pipe up with this thought.

I saw your post title and pervert that I am immediately thought "Wouldn't a Brazilian wax be easier and less painful?"

 

[Squidd]

Yeah, but who wants to "pull tape" on a lumpy bottom...

 

[CarlN]

I'd consider using several coats of epoxy barrier coat (like Interlux Interprotect 2000E) instead of the epoxy resin. Your goal here is not really to "tie things together" - the filler will be plenty "tied". You want to stop mositure getting into the polyester parts of the bottom. Barrier coats does a better job than straight resin. It also is designed for really good adhesion of the antifouling paint.

More than one coat is important.


Carl

 

[Squidd]

I do not understand how a two part epoxy barrier coat (which is basically thinned epoxy) can be a more effective water barrier than straight epoxy...just end up putting more coats of a much more expensive product on...

Only advantage is it may be better "formulated" for additional paint to stick...epoxy primer might be a much more cost effective alternative, but again just a more expensive epoxy with a paint binder added...

I think I'll be OK with the waterproofing of neat epoxy and have plenty of paint adhesion with scuff sanding and an acetone wash...at least that's what the can of hard Marine Biocide reccomends...

 

[Bill Roosa]

Hey Squidd
I believe that if you check your "straight" epoxy can you will find that it needs a hardner (aka 2 part system) that is all "2-part" is.
There are two types of resin BTW, polyester and "real" epoxy. the poly is NOT waterproof and is the cause of most of the blister issues boats have. It is cheaper though and so the manufactures use it. "Real" epoxy is water proof and if you have the good forutne to have a boat made with same it will never need a barrior coat.

 

[Squidd]

Correct, I have "real" epoxy not polyester fiberglass resin..

1:1 mix no "fillers" that's what I mean by straight/neat... just like my burbon

 

[CarlN]

Yes, barrier coat paint is a two part as are all epoxies. I bet there are more epoxy formalizations than brands of single malt scotch (although this might be an interesting bit of research)

Make sure the epoxy you pick:

Won't run or sag too much on the upside down boat. This would be easier if you were epoxying a table top.

Has a long pot life in your temperatures so you can get a useful amount done before it kicks

Is thin enough to roll or brush but thick enough to quickly build up 10mil thickness in not too many coats

Has excellent adhesion to polyester

Is fairly flexible so it doesn't pop off when the hull flexes a bit

Has a pigment to make it easier to see your holidays

The guys who make barrier coat have researched this for you. You've seen that it's no fun to remove a failed system. Every top-end boat builder I know who builds in vinylester or polyester uses barrier coat. If a different epoxy was better and cheaper, I'd expect they'd have figured that out.

Carl

 

[Squidd]

That's why they are "top end"... they use all the expensive name brand stuff...

But this isn't a "top end boat" now is it...?

More than one way to skin a cat (or reskin a boat)..

Gotta give some credit to the mid range and bottom feeder guys too..

Just be glad they talked me out of the polyester resin and into the epoxy coatings...

 

[Robert M.]

"Every top-end boat builder I know who builds in vinylester or polyester uses barrier coat."

Would you name a few of them?

 

[Robert M.]

Hey Squidd
I believe that if you check your "straight" epoxy can you will find that it needs a hardner (aka 2 part system) that is all "2-part" is.
There are two types of resin BTW, polyester and "real" epoxy. the poly is NOT waterproof and is the cause of most of the blister issues boats have. It is cheaper though and so the manufactures use it. "Real" epoxy is water proof and if you have the good forutne to have a boat made with same it will never need a barrior coat.

There are only four factors which effect water permeation into a fiberglass hull. They are:

Time,
Temperature,
Chemistry of the resin, and
Thickness of the veil layer.

No marine resin, including the epoxies, are waterproof. However, all of the marine resins can be an effective barrier to water permeation if the veil layer is thick enough.

 

[CarlN]

Last time I was in the market, barrier coat was a standard question I asked. All said "yes" including:

Oyster
Discovery
Morris
Shannon
Hylas
CW Hood
Jarvis Newman

 

[Robert M.]

Appreciate all the input I'm getting on this bottom factor...Kinda like "discussing" the best anchor to use...

Here's what I'm seeing...There is no gelcoat on the bottom of this boat... I know what gelcoat looks like, there is gelcoat on the cabin and deck...the topsides are painted, but there is gelcoat below the Britesides ( I saw it when I touched up fender rubs)...

Just below the waterline, (green tape) is a blue line of gelcoat <w/some dark blue paint> and then it goes to the gray "Filler"....

There is no hard gelcoat "solid surface" to sand down to without going all the way down to the fiberglass matt.I don't know where the hard coating went, but it ain't there no mo..

I do not have the time, ambition or money to do a "Full Bottom Job" before I launch this season..I may do it in the future, but I have yet to see a full repair schedual I can believe in.

So I will be forging ahead on a Fill and Fair repair job, resin coating the entire bottom to tie it all together and then a couple coats of hard biocide paint for color and to keep the slime down...

I already have and will use a polester fiberglass filler...The can I have has a picture of a boat on it, says Marine on the label, waterproof and for above and below the waterline use...I'm fairly certain the gray matter on the boat is a poly filler (as do most opinions offered) and see no reason not to continue with it to fill divot holes...

At this point "spot coating" the exposed matt is a non starter if the filler right next to it is permeable, so after filling fairing and smoothing out (with wide spreaders, flat sanders and long boards) I will coat the entire bottom below water line with "Epoxy" resin witch should bond and tie in with whatever chemical soup is underneath... 2 coats and scuff sand for adhesion of 2 additional coats of hard Marine Biocide paint...

That is good enough for me for now...I want to go sailing...

The white material looks like gelcoat. Nevertheless, everything should be removed by sanding to the mat layer. Then all of the large blisters should be filled with laminate using chopped-strand mat (CSM) and CoREZYN VE 8117. The smaller blisters should be filled with a resin putty formed with VE 8117 and Cab-O-Sil TS-720. Then a layer of 1.5-ounce CSM should be applied using VE 8117 and surfaced with Cook's sanding polyester gelcoat. This will provide an effective barrier to water permeation that is 0.040-inch thick. This procedure has been an effective method of blister repair and subsequent prevention of water permeation for 30 years, including the Valiant 40s constructed with Hetron.

 

[Squidd]

Sounds expensive and time consuming... and what are the guarantees...?

What do you think of the prognosis provided by Pasco and this article Hull Blisters on Boats and Yachts - by David Pascoe, Marine Surveyor
and: Sea Lake Yacht Sales (Kemah, TX)

 

[Jackdaw]

Sounds expensive and time consuming...

Welcome, my friend, to the world of sailboats!

 

[CarlN]

I'd be surprised if a job with high quality barrier coat cost more than high quality epoxy resin since - as you point out - they are mostly the same thing just different formulations.

I assume you are going to use "name brand" resin. There's a lot of mystery epoxy out there. Old resin - even name brand - is a real crap shoot. I buy a lot of boat stuff off Ebay but would never risk buying resin there. I've always stuck with MAS, West, System 3, or Interlux. West has a barrier coat additive that you mix with resin - I've never tried it.

One reason that blisters are rare in the first fiberglass boats is that they were built with very high quality polyester resin. Unfortunately, the price of resin went up a lot during the 1974 Arab oil embargo and many builders switched to cheaper brands.

Carl