Bottom paint during survey

[Steve1944]

Originally Posted by tikirawker

Hello, we are in the process of purchasing our first boat. The broker was upfront that the boat needing a bottom paint job. It costs roughly ten bucks a foot to pull the boat. So $400. My question is why pull the boat twice? If the survey looks promising why not keep the boat out and paint the bottom. Is this done frequently? What would be the downside? (Besides losing money if it fails the sea test)

Sent from my Nexus 10 using Cruisers Sailing Forum mobile app

I was painting my hull when the surveyor did his job.

[FSMike]

One interesting wrinkle I've seen a couple of times -
Some boats will show blisters when they are first hauled, but a day later the blisters have disappeared. On other boats I've seen no blisters at first, but a day or three later voila! Blisters.
A good surveyor can detect problem areas with a hammer fortunately.
IIRC every time I've seen this it was only a few blisters. If you have a bottom covered with the things they seem to be omnipresent.
YMMV.

[ramblinrod]

Originally Posted by FSMike

One interesting wrinkle I've seen a couple of times -
Some boats will show blisters when they are first hauled, but a day later the blisters have disappeared. On other boats I've seen no blisters at first, but a day or three later voila! Blisters.
A good surveyor can detect problem areas with a hammer fortunately.
IIRC every time I've seen this it was only a few blisters. If you have a bottom covered with the things they seem to be omnipresent.
YMMV.

It is very common for a plethora of pencil eraser head sized blisters to disappear only days after haul-out, to reappear only days after immersion again.

Have studied a lot of bottoms and have never seen blisters appear as the hull dries out.

Trying to figure out what would cause this.

Possibly delamination, where when water drains from between layers, unevenness between layers becomes visible?

Ramblin Rod
Marine Service Provider
About Sheen Marine

[FSMike]

Originally Posted by ramblinrod

-----
Have studied a lot of bottoms and have never seen blisters appear as the hull dries out.

Trying to figure out what would cause this.

Possibly delamination, where when water drains from between layers, unevenness between layers becomes visible?
-----]

Don't know the answer to that Rod, the times I've seen it were few (twice?), and it wasn't anything I was directly involved in so didn't pursue it. I couldn't think of a reason.

[fstbttms]

Originally Posted by ramblinrod

It is very common for a plethora of pencil eraser head sized blisters to disappear only days after haul-out, to reappear only days after immersion again.

Have studied a lot of bottoms and have never seen blisters appear as the hull dries out.

Trying to figure out what would cause this.

My understanding is that water pressure can keep the blisters from protruding while the boat is in the water. Once the boat is on the hard, lack of that water pressure allows the blisters to become evident.

[tikirawker]

Thank you for all of the responses.
We are currently in the negotiation phase and with any luck getting closer to the survey phase.
After i learn the answer to my initial question I learned a few extra pieces of knowledge!
I am certainly happy to be a part of this forum and I look forward to helping others as my experience grows.

[ramblinrod]

Originally Posted by fstbttms

My understanding is that water pressure can keep the blisters from protruding while the boat is in the water. Once the boat is on the hard, lack of that water pressure allows the blisters to become evident.

Hey fastbottoms,

Interesting theory, but it doesn't add up for me.

If the blisters are near the waterline, the water pressure is near zero.

Even if a 1/4" diameter blister was 3 feet below the waterline, the water pressure against the hull is only 7psi, or a grand total of 1.4 lbs force against the blister.

I can't imagine how this low amount of pressure could be greater than the pressure of the acid/gas in the blister causing the frp / gelcoat deformation.

Then again, I've been fooled before.

Ramblin Rod

[FSMike]

I wonder if temperature change (water vs. air) has something to do with it?