They were represented as unsinkable in the 60's and 70's because the virgin foam would create flotation and not let the hull sink. What they did not realize is that over time the open cell foam would absorb water 10-20 years later and not provide the flotation it once did. All boats used this foam because it was the state of the art in those days. Every boat built in those days had this foam including Aquasport, Boston Whaler, Mako, Robalo, Seacraft, Seabird etc. They all suffered the same dimise; wet foam and wood core rot (BW had no wood core).
Foam was applied (injected not the right word, as I don't think one injects something into an open area!) in the cavities formed by the outer stringers, under the liner, and aft between the outer stringers and the hull side. This was for any added buoyancy purposes one could get, although testing was not required (and I'm sure not performed) as to whether the foam provided any type of "level flotation", or even whether the foam could keep the boat from sinking should it be holed. Hell, even on out 35 Express at Proline, we shot foam into any cavity that we could that didn't contain wiring or plumbing or equipment, but at 15,000 lbs, I doubt that the foam was going to help her out much given a catastrophic failure...In your situation, and venturing out 60 miles in the Pacific, I would be more concerned with the thru-hull integrity of your Explorer, the ability of the pumps to function properly, the proper emergency equipment (EPIRB, PLB, excellent VHF w/DSC functioning, etc.), and the idea of establishing contact with other boats in your area to let them know of your presence. The CG may be a 1/2 hour or longer, but someone near might be 10 minutes...Remember, a bilge pump is only rated at the discharge port, no hose, no run or rise. So an 1100 in effect turns into a 600. Install the largest capacity bilge pumps that will fit. If you have room for (2) 1500s, install them. They have the same discharge (1 1/8") as an 1100. Good insurance to have 2 big ones working for you...Hope this helps!
