Boat: 1993 Nordic 32' os twin BBC w/ b1s

Problem: When boat is moored, there is a slow leak that requires the bilge pump to be on overnight (automatic) When Im at speed with the pump off, a considerable amount of water is accumilated in the bilge. The problem was just with the port side as that was the only side that the pump would expel water. Now its with both sides.

Question: What is the most common culprit for this issue? Thanks for any input.

Check the bellows in the transom assy. All the bellows are 5-7 year service items. As water leaks in areas it shouldn't be it ruins a lot of parts if not repaired immediately.
Jim

I guess when at speed very little water, if any at all, can get in through the bellows, at least when on plane. Off plane water can get in for sure.
Try to empty as much water as possible and see if you can see where the water is coming from. I have found that using a wet vaccum cleaner is great for emptying the bilge. Then hopefully you can follow a small stream or drips of water and track them backwards.
Are you sure that your engines are not leaking cooling water into the bilge ?
Could also be a leak from the hose to the speedo.

thanks guys, I'm thinking this could be two different issues as you mentioned. When the boat is at rest and the engines off, cooling water is not going to leak, however when on plane, the transom is dry and the only thing that can leak is the cooling system. I think both of you are correct.

third option would the block off plates where the y pipe would go through the transom assy. (if you have through hull pipes only)

Had one of those plates corrode on a 1990 Donzi 33, had to pull the motor to find the leak.