I have a 1999 X70, I've had it for about 5 years. It's been a very good boat and still is. I left it in the water uncovered over the winter and after it would rain I would wait a day or two or three and then go bilge out the water from it. The boat was under a dock but the wind would blow rain into the boat when it would come down good. It was never enough water to risk sinking it, but there was definitely water in there for days at a time. I never thought anything about it, but now the boat will only run about 47-48 MPH. Before I let it get water in it the boat would run 55 MPH before I would get off of it. Motor is an XR6 150. I'm almost positive I have waterlogged foam in the boat. The motor is not the problem. I'm replacing the carpet this summer. Is pulling the foam out and replacing it a "doable" task or will I be better off just dealing with the wet foam and going about my business. I'm mechanically inclined but I can not weld. I did some research on the subject but I can't find anything too good.

How exactly did you surmize that the motor is not the problem?

Let's just pretend like it's not the motor or prop or water temp or driver error or anything like that and it's definitely waterlogged foam. Any ideas about replacing it or drying it out?

If its waterlogged its not going to dry out without pulling the floor, and even then it will most likely loose some of its floatation properties. Many years ago I had to pull a floor out of a 16' Mon-Ark because it was saturated for about 6 months. During that time it had already started to grow mold and funky bacteria, it was totally ruined and was unsalvageable and had to go. I found replacement flotation from a guy I knew that worked with "spray on insulates". You can find the same type of stuff in many home stores and on-line. Spay it in and it will expand into all the contours and crevices of the inside of the hull, then trim to fit the floor back in. You can also spray it into the sub-floor area after the floor is in place and it will expand throughout unless there is a barrier there to stop it. Personally I would figure out a way to remove saturated floatation one way or the other, no flotation is better than saturated floatation.