Scarab I Deck Hatch
 

I am looking for any and all advice on installing a deck hatch on my 1985 21 Scarab I. The boat is in excellent original condition. However, I believe the cabin would benefit greatly from the increased sunlight and ventilation afforded by a hatch. More specifically, would a centerline hatch diminish the structural integrity of the boat? Moreover the deck at the centerline is not flat. Please advise.

why not a small one on each side

I had a friend with a 1986 scarab I with a center mounted deck hatch. His came like that from the factory. It was wide enough to drop straight down through with an adult sized body. If I remeber it was still very tight in there and had a built in cooler in the center so you had no step down for cabin ingress and egress from cockpit.

Insted of one on center, how about two smaller hatches? One on each side.
My Formula offered two small hatches as an option on my F-206. The wood backing frames were glassed in under the deck during construction but I don't have hatches installed.

THe bigger scarabs reinforce the coring with plywood around the hatch cutouts. You may end up with a lot of cracks in your deck if it's not strong enough.
Gary

Thanks for the advice. I like Homan and Iggy's suggestion of two small hatches. At this point, i will probably install two 10 X 10 Bomar Hatchs. That should give plenty of ventilation and sunlight. However I am still concerned about stress cracks. Even though the boat is almost twenty years old there are no cracks on the deck now.