Keeping a boat slipped

rsmitty814

Petty Officer 3rd Class
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Jul 28, 2013
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Is there an age when the gel coat deteriorates and you should not keep a boat in the water all season? I've heard things about different boat manufacturers and blistering gelcoat.
 

airdvr1227

Lieutenant Commander
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Jul 15, 2009
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If you are planning on leaving your rig in the water 24/7 you need a good bottom paint. Its my understanding that hull blistering is caused by leftover release agent used in the molds or something of that nature.
 

rsmitty814

Petty Officer 3rd Class
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Jul 28, 2013
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Yeah, the bubbling is a chemical reaction between the fiberglass process and water that produces acid. Thanks for the response. I thought it a pretty good question and I haven't seen it on this forum so I thought more than one response. I'm considering a boat that I'm not going to want to trailer. I want to slip it for the season with maybe a half season pull out and cleaning. I thought bottom paint more of an anti fouling? Does it protect the gel-coat?
 

Thalasso

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If you are planning on leaving your rig in the water 24/7 you need a good Barrier coat and bottom paint. Its my understanding that hull blistering is caused by leftover release agent used in the molds or something of that nature.

Fixed it for you
 

rsmitty814

Petty Officer 3rd Class
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Jul 28, 2013
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THANKYOU THALASSO. So you say there is no age, but rather a good BRRIER COAT and that makes all the difference?
 

RobTX

Cadet
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Nov 4, 2013
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There's other considerations besides gel/paint when keeping a boat in the water permanently like you suggest. Big one is the additional wear and tear/maintenance required on outdrive unit. At my marina, I see several like this, many with the automatic bilge pumps running constantly. Is a lift out of the question?
 

southshore30

Recruit
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Sep 4, 2014
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Barrier coats are a great thing to do. Gel coat is pourus and water can infiltrate it over time. If in cold climate the moisture freezes and expands when boat is out of the water. Also there are bottom paints for fresh and salt water
 

rsmitty814

Petty Officer 3rd Class
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Are you saying that I should stay away from an older boat, say 12-14 yrs old that is not barrier coated? Regardless of owner care?
 

gddavid

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Jan 4, 2010
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Are you saying that I should stay away from an older boat, say 12-14 yrs old that is not barrier coated? Regardless of owner care?

It depends. If the boat was trailer/lift kept it doen't matter, if the boat hull was laid up with epoxy or vinylester resin (rare) it doesn't matter, if the hull is shown to have no blisters it doesn't matter. Basically if the boat has been exposed to 12-14 years of being wet slipped without barrier coat and doesn't show any signs of blistering then it will probably be fine, however it may have been saved only because the boating season was short and the hull was able to completely dry out between each season (practically dumb luck) and you use the boat differently you could run into problems. As long as the boat is blister free now, I would take any bottom paint completely off of it and barrier coat it and avoid any future headaches.
There are a variety of factors that can lead to a boat being succeptable to the problem and it isn't exclusive to lower quality boats. The key thing to realize is that gelcoat is permeable to moisture and if the fiberglass/resin composite is exposed to it for long enough and has any small voids in the mix (due to off gasing, poor layup, climate conditions where the boat was built) the hull is at great risk to developing blisters. Bottom paint does nothing to prevent this, it only prevents marine growth. A well applied barrier coat is relatively cheap insurance yet surprisingly too many boats go without it.
 

alldodge

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+1^ All kinds of boats around here which look good but still wind up with blisters because they didn't have barrier coat applied first, only had antifouling. Any boat that will spend a lot of time in the water needs barrier coat (3 coats min) applied. The regular bottom paint is for antifouling and looks. Still every 5 years the bottom needs to be inspected and determine if paint needs to be redone
 

Scott Danforth

Grumpy Vintage Moderator still playing with boats
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some of the boats around here have 2" of barnacles, not sure if you would notice the gel blistering :facepalm:
 

rsmitty814

Petty Officer 3rd Class
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Haha thanks Scott. If blistered, is there anything that will stop it? Seems like not as its a chemical reaction. But how long in the water will it take to permeate the wax and gelcoat?
 
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gddavid

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It really isn't a chemical reaction, it is osmosis which is a physical process. In regards to stopping it, the problem doesn't reveal itself till the damage has occured and blisters have formed. Hence if a 12 year old boat hasn't developed blisteres yet, it probably isn't ever going to, but without protection it is a crapshoot. The damage can be fixed at great trouble or expense by mechanically grinding out each blister and repairing them with fiberglass, resin and fillers just like you would with any other physical damage/delamination in fiberglass.

As far as how long it takes for water to permeate the gelcoat that is a hard question to answer. Think of it this way: Imagine a sponge sitting on a wooden table and you are pouring small amounts of water into it, how long till the table is damaged? Well it depends on a bunch of things like how thick is the sponge, how much salt is in the water and are you ever stopping and allowing the sponge to dry out again. Just because the surface of the table gets wet, the table doesn't get permanently damaged immediately it will depend type of wood and the particular grain structure of that board. (Hint: the sponge is your gelcoat and the wood is your fiberglass laminate)
 
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rsmitty814

Petty Officer 3rd Class
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Jul 28, 2013
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Thanks gddavid. We (at least I do) take boats out of the water before it is not water. Which means I winterize and store my boat for the winter. Ususlly around Nov. 1st my boat is out of the water. That means 6 to 7 months of dry storage. So plenty of time to dry out. Thanks everyone for responding.
 

gddavid

Petty Officer 2nd Class
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I would not take that chance, the fiberglass may absorb water in that 5 month season. Imagine water filled voids in your hull laminate structure freezing and expanding. It may be a low probability but the potential risk is massive.
 

jc55

Senior Chief Petty Officer
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Nov 3, 2006
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I've personally experienced 6 weeks to develop blisters on a 24 year old boat that never had them before.
 

louiefl

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Apr 11, 2012
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At my marina, I see several like this, many with the automatic bilge pumps running constantly.
this is probably cooling water for marine AC units. In theory, your bilge pump would never come on if it isn't leaking.
 
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