Hull Blisters

weephee · #1 08-24-2009

I am in the process of having my hull soda blasted as I write this. I'm sorta panicking because the hull is full of blisters the biggest being about the size of a dime. This is from the water line down to the keel. Do I soda blast off the white gel coat while the guy is here or what. Thanks

zeehag · #2 08-24-2009

blisters are waaay overrated--i f there are no holes in centers to make them wet blisters then leave them alone. if there are holes in centers, then grind them out and let them dry and fill them and epoxy the hull..if the faqct yoiu have blisters freeks you out, then call for a 245000 dollar hulltek job, where they peel the hull and relay glass and epoxy coat it--this takes a very long time and flattens the wallet considerably. there is no problem with tiny dry blisters. all boats made after 1974 get them. is a fault of epa and layup techniques and material toxicity----you might add a coat of epoxy and monitor the size of the blisters and the quantity and nextr haulout again measure and check to see if there is tunnelling or wet blisters then see if ypou need a hull blister job----dry blisters donot hurt anything--when they get wet--they will tunnel and grow..they will then need to be repaired. been there done that--goood luck--

weephee · #3 08-24-2009

Thanks, That makes me feel a lot better. The boat has not been in the water for approx 2 years so I don't expect to see any water. I don't know if that makes a difference in what you are telling me. Thanks

zeehag · #4 08-24-2009

ok--now epoxy it --as it has been out of water--perfect time to epoxy the hull---make sure the epoxy coating goes to into the boot--reboot the boat---new stripe---and should be good---blisters donot in any way affect the performnance of the boat...goood luck and smooth sailing!!!!

sailingfool · #5 08-24-2009

Sailing with a blistered bottom would be like permanently dragging an anchor behind the boat.

Leave any gelcoat that it is well-attached. Don't mess with the boot top unless that area has blisters, which would be a red flag you got real problems.

If your boat has a cored hull, hire a surveyor to test the hull for wetness and delamination, although I guess after two years even a compromised cored hull may read dry, but a good surveyor should be able to figure out what's what..

Remove any loose material from the blisters then fill the blisters with Interlux Watertite. Sand as needed. You may need to do two or three fills for the blisters to be faired. Spend as much time or yard money as you can stomach getting the bottom fair - you hopefully will live with this finish for a long time. Apply 5-6 coats of interprotect 2000E.

Properly barrier-coating a bottom is a simple but time-consuming and tiring job. For a 30' boat with s blistered bottom, assume 5-10 full work days and $5-800 in materials.

Having a good bottom on a boat you are going to keep is well worth the cost and effort.

weephee · #6 08-24-2009

Thanks for the information. When the hull was soda blasted today, a lot of the blisters were broken but hundreds weren't. I've tried to attach a picture. Should I sand the hull with 80 grit sand paper trying not to go thru the gel coat but breaking all the blisters. I'll also have a few cracks in the gel coat in the area of the shaft and I'll try and send some pictures of that. What do I do with cracked gel coat.

amarinesurveyor · #7 08-24-2009

Go here and read this, it will tell you everything you ever wanted to know about blisters and treating them. I don't not agree with what Zeehag has said (no offense intended).
Blister & Laminate Hydrolysis in Fiberglass Boat Hulls
Brian

zeehag · #8 08-24-2009

seeing these pix says to me that you should do more than just epoxy the hull--this isnt merely blister damage--there is something else going on if boat has been out of water for 2 yrs...the cracking shows damage from a different source than blisters--what does the inside of the hull at this point look like??..looks more like eggshelling to me--that is not good....

zeehag · #9 08-24-2009

Quote:

Originally Posted by sailingfool

Sailing with a blistered bottom would be like permanently dragging an anchor behind the boat.

Leave any gelcoat that it is well-attached. Don't mess with the boot top unless that area has blisters, which would be a red flag you got real problems.

If your boat has a cored hull, hire a surveyor to test the hull for wetness and delamination, although I guess after two years even a compromised cored hull may read dry, but a good surveyor should be able to figure out what's what..

Remove any loose material from the blisters then fill the blisters with Interlux Watertite. Sand as needed. You may need to do two or three fills for the blisters to be faired. Spend as much time or yard money as you can stomach getting the bottom fair - you hopefully will live with this finish for a long time. Apply 5-6 coats of interprotect 2000E.

Properly barrier-coating a bottom is a simple but time-consuming and tiring job. For a 30' boat with s blistered bottom, assume 5-10 full work days and $5-800 in materials.

Having a good bottom on a boat you are going to keep is well worth the cost and effort.

i have had 2 boats with blistered bottoms--neither one was any slower with the blisters than without. one i had repaired the other i didnt bother with as my surveyor said they are overrated and didnot need repairs unless were wet.....i trust that person, as i went apprenticing to survey with him. is a top rated SAMS surveyor. my ericson has dry blisters and still blows away any other boat on my bay. and the barrier coating took less than 2 work days....done professionally, on th eboat i had repaired

weephee · #10 08-25-2009

This 1977 Columbia sailboat sat on the hard in a marina for approx 2 years. Some one disconnected the drain lines from the cockpit so rain water drained into the boat and filled it to the water line before it was noticed. I have no idea how long it held water but likely for 3 months. The marina pumped it out and I got the boat for basically nothing. Is it possible the water leaked from the inside out rather than the reverse. I have looked at the inside of the hull and there appears to be no visible damage. The boat has been drained for 9 months now. The hull is not cored. Since I'm retired and have little to do, I wanted a project boat and I guess I got one. From what I've read and been told, I will sand off much of the gel coat and go with the 2000E repair process unless someone points me in another direction. I am a real novice at this and uncertain as to what I should do so I can only rely on people from this forum and what I read so I thank you very much for your comments and help