Cruisers Forum

Join CruisersForum Today

Thread Tools Rate Thread Display Modes
Old 16-02-2011, 10:37   #1
Registered User

Join Date: Nov 2010
Location: Erie Canal between Rochester & Buffalo
Boat: 1970 23' O'day pop-top
Posts: 471
Wet Hull

The 35 year old boat in question had the entire hull sandblasted down to bare fiberglass and allowed to dry for many months. Two coats of epoxy were applied and the hull 'appears to be dry.' The anti fouling then had to be removed because it would not adhere to the smooth epoxy. The bottom was 'roughed' and re-fouled.
I'm trying to learn more about this so I can make a proper judgment call when I go over the boat with the surveyor. The entire bottom could not be seen due to snow but the visible part was suspect to my untrained, but pretty reliable, eye.
While researching, I came across this; Boat Hull Blisters : My Wet Hull Won't Dry - by David Pascoe, Marine Surveyor which begs the question;

Can a wet hull ever really be dried and sealed to last another 30+ years?


kenny chaos is offline   Reply With Quote
Old 16-02-2011, 11:11   #2
Registered User
Ram's Avatar

Cruisers Forum Supporter

Join Date: May 2005
Location: Cruising Greece
Boat: Cat in the med & Trawler in Florida
Posts: 2,298
Images: 27
Wow never heard of that before - good luck

Ram is offline   Reply With Quote
Old 16-02-2011, 11:23   #3
Commercial Member
Mark Johnson's Avatar

Cruisers Forum Supporter

Join Date: Sep 2009
Location: New Bern NC
Boat: Searunner 34 Trimaran
Posts: 1,579
Nothing will adhere well to cured smooth epoxy, not even epoxy... UNLESS is is so recently applied that there is a chemical bond. (Hours with WEST epoxy) and a bit longer with others like Systems Three.

When you say bare glass... do you mean bare gel coat, or bare glass? If it was sandblasted down to bare glass, that does create a good "tooth" for the next step, but slapping on a couple of coats of epoxy is not going to cut it. I have hydrosanded hulls bare. If that is what you mean, you probably ended up with a surface that was in need of re fairing! If it is major, that means squeegeeing on microlite, sanding fair with a long board and/or the 8" soft pad disk, and then coat with epoxy! Always remove the blush before sanding...

If the unfairness is minor, one could coat on 4 coats in one day, sand off two the next... say, three times. MINIMUM... Then a final sand to a glaze, and you are ready for bottom paint. It should stick!

This all assumes the hull tested out very dry with a moisture meeter first! BTW, when drying a hull, it is best to hang a plastic skirt around the hull and put one or two dehumidifiers in there for months, as well as wipe it down with acetone DAILY. (just turn off the dehumidifiers and lift the skirt first, so you don't kill yourself!)

If the hull tested dry before the epoxy, the paint didn't stick because the epoxy was not sanded.

When it comes to the bond between layers of epoxy or ANY two part paints, the surface must be 100% sanded. This doesn't mean just run a sander over the hull, it means that the hull must be fair enough first, that there are NO concaves that the sander misses, and there are NO shiny spots. (Not even the size of a BB!)

I have seen so many people get this wrong, including pros. It is a lot of work, but the poor bonding between layers of anything on your boat, can be years of work, or tens of thousands of $$$. This is no exaggeration!

With any 100% solids epoxy, or LP type paints... To SAND, means to a totally glazed, no shiny spots appearance!

Once you go to the above trouble and have a dry barrier coated hull, it is WELL worth it to keep a dry bilge. You may have to go with a dripless shaft seal, or build small sumps around the shaft / engine, or even the base of the mast. Then epoxy coat these small sumps really well, and install separate small bilge pumps, or have one sump tube drain into the lower sump, and let its pump take care of the small amounts of water. Then have one or two huge pumps up 6" higher for true emergencies. Do what ever it takes to keep a dry bilge, if you want your dry hull to stay that way! Best of luck...
Attached Thumbnails
Click image for larger version

Name:	023_23_00.JPG
Views:	105
Size:	110.0 KB
ID:	23868  
Mark Johnson is offline   Reply With Quote
Old 16-02-2011, 16:02   #4
Registered User

Join Date: Nov 2010
Location: Erie Canal between Rochester & Buffalo
Boat: 1970 23' O'day pop-top
Posts: 471
Thanks for the replys.
kenny chaos is offline   Reply With Quote
Old 16-02-2011, 16:26   #5
Registered User
CDunc's Avatar

Join Date: Nov 2010
Location: Jacksonville Florida
Boat: 1972 Tartan 34C Fleur De Mer
Posts: 141
Wait a minute! when epoxy cures it leave on the surface an amine blush, this must be washed off with water before you do anything to it. If you paint over it then the paint will not stick, if you sand it you will push the amine into the epoxy making it harder to remove. After coating with epoxy wash, wash, wash, wash
CDunc is offline   Reply With Quote


Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

Similar Threads
Thread Thread Starter Forum Replies Last Post
I've Just Had My First Wet Dream mintyspilot Off Topic Forum 6 04-11-2010 13:37
Wet Core Help Beersmith Construction, Maintenance & Refit 14 26-08-2010 14:05
I Have a Very Wet Box S/V Mother Ocean Construction, Maintenance & Refit 5 19-09-2008 17:51
Has anyone used Dri Diver or Hull Super Scrub for hull cleaning??? avazquez Product or Service Reviews & Evaluations 1 02-07-2008 21:31
Getting wet again soon... bearphish Meets & Greets 7 26-06-2007 23:25

Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 17:45.

Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2018, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2018, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.