Hi Nick, when I got that hatch lid there was no seal on it. I bought a length of seal, 12mm x 25 from memory, from Clarke's and put it on making some 45deg cutouts to help it bend 90deg at the corners. I don't like the idea of two layers of foam, messy. The bungy makes the single layer seal work fine and no water makes it in. I can check size and take a pic if you wish.
And the front hatch is 150mm opening. I don't think you'd fit a hobie hatch (200mm) in that position. Make sure you shine a strong torch up into the chute at night to mark the wall positions on the deck as they are not always central in the hull. Not sure it's the best position for a battery as it will get a bit wet at times. Good idea though as the space is available. Note that some guys have changed the day hatch lid for a Hobie lid so maybe it's an option there? Not as easy to get the cables to the sounder head though.
Yak PB's. LT 110cm, Spanish 105cm, Spotty 93cm, Snapper 65cm, Grassy 53cm, Flathead 70cm, Tailor 41cm, Jew 70cm,