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Old 02-15-2011, 05:03 AM   #1
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GarryP's Avatar
City: Homosassa River, FL
Country: USA
Vessel Name: Mango Mama
Vessel Model: Krogen Manatee 36
Join Date: Mar 2010
Posts: 114
Manatee Blister Questions

We bought Mango Mama knowing she had some blister problems. Shes in the yard now getting inspected to determine our options. The blisters actually looked smaller and fewer than when we did the haulout. Maybe the difference is the water. She was lying in fresh water before. Now shes in brackish salt water.
A number of the blisters have been popped and it appears they are in the gel coat only. The bottom of each one is a hard, solid resin layer which appears to be infused with glass mat. When punctured, the blisters dribble water and have no styrene smell which the surveyor said was indication that the blisters did not go into the structural glass layers. There are a small number of blisters on the stern near the waterline that may go a little deeper. Have you seen blister problems like this?
One option we may be considering is peeling the gel coat, repair where necessary and barrier coat the hull before bottom painting. A more economical option would be to simply sand and patch the worst of the blisters and apply antifouling paint. The first is of course the right thing to do. The second may be the more practical thing to do considering limited finances and other priorities. The boat has been in the water at least two years and shows no sign of structural problems. Maybe the practical thing to do is the right thing. Any thoughts or recommendations?

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Old 02-15-2011, 06:15 AM   #2
City: Carefree, Arizona
Country: usa
Vessel Name: sunchaser V
Vessel Model: DeFever 48
Join Date: Apr 2008
Posts: 5,367
RE: Manatee Blister Questions


From reading* your post is it correct to say your hull is solid FRP and not core? Blisters are not dependent upon fresh vs salt water - so say most. Lower water temperatures and annual on the hard layups can forestall the growth of blisters. Most water stored FRP hulls will sooner or later start to show some blisters. Opinions vary as you have noted*regarding the question of patch or peel. There are better and worse ways to do either.

This subject has been oft debated on this and other boating sites. One participant on this site has done a well documented peel job on his vessel - Ralph Yost. You may want to PM him to get some details.

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Old 02-15-2011, 06:29 AM   #3
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City: Hailing Port: Charleston, SC
Country: USA
Vessel Name: Moonstruck
Vessel Model: Sabre 42 Hardtop Express
Join Date: Nov 2008
Posts: 7,312
RE: Manatee Blister Questions

Garry, only you and the yard know how severe the problem is.* From what you said, it doesn't sound bad enough for a peel.**I would look into repairing the blisters, prepping the bottom, applying an epoxy barrier coat, and painting.* Just an opinion, and you know what they are like.
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Old 02-15-2011, 07:53 AM   #4
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City: Boerne, Tx
Country: USA
Vessel Name: HEY JUDE
Vessel Model: Kadey Krogen 36 Manatee #46
Join Date: Jan 2011
Posts: 196
Manatee Blister Questions

In '08 BON DIA was in similar or slightly worse condition than MM. PO chose your option 2. At pre-purchase survey Dec '10 no blisters were observed. We'll haul for other hull work later this week & will know more about. Cha-ching

Interesting reading of another Manatee hull repair http://www.klutch-kargo.com/Projects1.htm

-- Edited by BON DIA on Tuesday 15th of February 2011 10:36:16 PM
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Old 02-15-2011, 09:17 AM   #5
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City: Longboat Key, FL
Country: USA
Vessel Name: Bucky
Vessel Model: Krogen Manatee 36 North Sea
Join Date: Oct 2009
Posts: 3,843
RE: Manatee Blister Questions

Gary: *Those blisters are pretty much part of the game of owning a Manatee, or lots of other boats of that era. *The Manatee, of course, is a fully cored hull, and needs to be watched for water intrusion, but it's not like balsa or something that rots. *Using a moisture meter and hammer, you'll know whether there's any real delamination problem or not, but I pulled Bucky just a couple of weeks ago and re-checked it since the survey was done about 6 months before. *Same results. *The hull had a about a half dozen blisters just like the ones you described. *I ground and filled, then bottom painted it again with Trinidad. *It really didn't need to be done now, but the boat was in Daytona Beach, and I didn't want to yank it again here in Miami 9 months from now. *Barrier coats work well, but there's probably nothing wrong with your hull. *Don't spend 12 to 20 grand on a peal and glass job unless you've got trouble, and it doesn't sound like you do.
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Old 02-15-2011, 10:59 AM   #6
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Posts: 613
RE: Manatee Blister Questions

if you do a peeling, is it then the entire hull or can you do spot peels?

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