Painting a hull

[Bushwacker]

Those vents are there for a reason (bilge ventilation), so I wouldn't remove them. I believe it's a USCG requirement to ventilate the bilge unless the gas tank is foamed in, because SeaCraft has always had bilge vents and non-foamed tanks, at least in the Moesly and early Potter days. Don't know about the later models - they may have gone to the foamed-in guaranteed-to-corrode tanks with no vents style of many modern boats!

BTW - I wouldn't crawl under that boat with the way those cinder blocks are oriented! At least turn them vertical so all the load is in compression. The way you have them sitting, you're trying to BEND the top surface, and concrete has virtually NO strength in bending! Cinder blocks are much weaker than most folks think. If you have any more of the solid concrete blocks or wood blocks, it would be much safer to use them! At least wood deforms before it fails; concrete is brittle and fails without warning!