I used one of those $10 USB rechargeable 18650 lights from Walmart to see the bolts, holding the starter in my son's boat. The bilges of the boat were wet and greasy. I laid the light down, thinking that if it rolled over, and into the mess below, it wouldn't be too upsetting.
Working on a boat is sometimes like working on a corvette. Everything is in the way, and hard to get at. My son rigged a strap around the starter, so I could hold it in place from above, while he reached in from the side and underneath to fasten the two bolts.
A half inch 3/8 drive socket got stuck on the last bolt. He was trying to tap it with a hammer, to get it loose. I told him... "Leave it, we have plenty more"