What is this junk on my hull

[Skippy]

So I was getting my boat ready for summer and i noticed these tiny raised bumps on my hull. they're each roughly the size of pinhead. There is a field of them about six inches high, it covers about 1/6 of one side of my hull. I tried to pop them, but they were fairly solid and nothing came out of them, so Im really hoping its not boat pox. I sanded that area just a little and they went away pretty much. There wasnt a bigger hole underneath them or anything. I really just want to know what these things are and how i can get rid of them. Ill upload some pictures but you can barely see them unless you look really hard. For comparison purposes, thats inch wide painters tape in the pictures.

Thanks
Zach

P.S. that area of the hull is both above and below the waterline

 

[Ross]

Scrape them off and see what is inside/underneath them.

 

[RichH]

The first pic, in the upper right corner .... those pimples are suggestive of 'failing' gelcoat, a gelcoat that had too much catalyst added when sprayed into the mold. Quite common when gelcoat is sprayed and allowed to fully 'kick' (for a day or two) before the next matting layer is applied. The result is an improper bond between the gelcoat and the matting layer.

Also sometimes caused when idiots spray on polyvinyl alcohol to help 'kick' the gelcoat and dont thoroughly wash/scrub it away before spritzing on the next layer ... will have 'purple' underneath when you pop a pimple ... if its PVA. A lot of boat manufacturers seem to have used PVA over top of gelcoat in the late 1970s and early 1980s ... and such pimples dont show up for 25-30 years when the gel weakens. Q? - These pimples are showing up on the side of the boat that normally get full sun exposure?

 

[Skippy]

no. well there are actually pimples on both sides, but the majority are on the side that did not get full exposure to sun while in the water (i keep it in a slip 7 months out of the year)

 

[Steve Dion]

Be smart and leave them alone.

 

[RichH]

Be smart and leave them alone.

Probably Steve gives the best advice for these.

If you sand them down you'll have thinned out gel at the 'crown' of the pimples, making the 'lift' worse, and ultimately ending up with zillions of teeny holes in the gel.
If you elect to paint over the pimples, even with a thick epoxy prime coat, the pimples will keep on growing and youll get 'print through' of the pimples as they continue to 'grow'.
The usual only way to correct such is to totally remove the gel !!!!! ..... and start over with new gel, or epoxy primer and paint .... which will cause you to have shoulder bursitis for the rest of your life after you endlessly ad-nauseum fair and longboard sand the hull flat again.
Dont ask me how I know all of this; but, I have the tee shirts for sale. :-(

 

[Skippy]

Probably Steve gives the best advice for these.

Duly noted. However, I have already slightly sanded a small patch of them : / How should I go about fixing those? Since Ive already thinned the gelcoat in that area.

 

[RichH]

Just wait to see what happens to them. If they stay stable, simply buff and wax the hull as usual, etc.